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Differences Between: [Versions 310 and 311] [Versions 311 and 400] [Versions 311 and 401] [Versions 311 and 402] [Versions 311 and 403] [Versions 39 and 311]

   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * This file contains functions for managing user access
  19   *
  20   * <b>Public API vs internals</b>
  21   *
  22   * General users probably only care about
  23   *
  24   * Context handling
  25   * - context_course::instance($courseid), context_module::instance($cm->id), context_coursecat::instance($catid)
  26   * - context::instance_by_id($contextid)
  27   * - $context->get_parent_contexts();
  28   * - $context->get_child_contexts();
  29   *
  30   * Whether the user can do something...
  31   * - has_capability()
  32   * - has_any_capability()
  33   * - has_all_capabilities()
  34   * - require_capability()
  35   * - require_login() (from moodlelib)
  36   * - is_enrolled()
  37   * - is_viewing()
  38   * - is_guest()
  39   * - is_siteadmin()
  40   * - isguestuser()
  41   * - isloggedin()
  42   *
  43   * What courses has this user access to?
  44   * - get_enrolled_users()
  45   *
  46   * What users can do X in this context?
  47   * - get_enrolled_users() - at and bellow course context
  48   * - get_users_by_capability() - above course context
  49   *
  50   * Modify roles
  51   * - role_assign()
  52   * - role_unassign()
  53   * - role_unassign_all()
  54   *
  55   * Advanced - for internal use only
  56   * - load_all_capabilities()
  57   * - reload_all_capabilities()
  58   * - has_capability_in_accessdata()
  59   * - get_user_roles_sitewide_accessdata()
  60   * - etc.
  61   *
  62   * <b>Name conventions</b>
  63   *
  64   * "ctx" means context
  65   * "ra" means role assignment
  66   * "rdef" means role definition
  67   *
  68   * <b>accessdata</b>
  69   *
  70   * Access control data is held in the "accessdata" array
  71   * which - for the logged-in user, will be in $USER->access
  72   *
  73   * For other users can be generated and passed around (but may also be cached
  74   * against userid in $ACCESSLIB_PRIVATE->accessdatabyuser).
  75   *
  76   * $accessdata is a multidimensional array, holding
  77   * role assignments (RAs), role switches and initialization time.
  78   *
  79   * Things are keyed on "contextpaths" (the path field of
  80   * the context table) for fast walking up/down the tree.
  81   * <code>
  82   * $accessdata['ra'][$contextpath] = array($roleid=>$roleid)
  83   *                  [$contextpath] = array($roleid=>$roleid)
  84   *                  [$contextpath] = array($roleid=>$roleid)
  85   * </code>
  86   *
  87   * <b>Stale accessdata</b>
  88   *
  89   * For the logged-in user, accessdata is long-lived.
  90   *
  91   * On each pageload we load $ACCESSLIB_PRIVATE->dirtycontexts which lists
  92   * context paths affected by changes. Any check at-or-below
  93   * a dirty context will trigger a transparent reload of accessdata.
  94   *
  95   * Changes at the system level will force the reload for everyone.
  96   *
  97   * <b>Default role caps</b>
  98   * The default role assignment is not in the DB, so we
  99   * add it manually to accessdata.
 100   *
 101   * This means that functions that work directly off the
 102   * DB need to ensure that the default role caps
 103   * are dealt with appropriately.
 104   *
 105   * @package    core_access
 106   * @copyright  1999 onwards Martin Dougiamas  http://dougiamas.com
 107   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 108   */
 109  
 110  defined('MOODLE_INTERNAL') || die();
 111  
 112  /** No capability change */
 113  define('CAP_INHERIT', 0);
 114  /** Allow permission, overrides CAP_PREVENT defined in parent contexts */
 115  define('CAP_ALLOW', 1);
 116  /** Prevent permission, overrides CAP_ALLOW defined in parent contexts */
 117  define('CAP_PREVENT', -1);
 118  /** Prohibit permission, overrides everything in current and child contexts */
 119  define('CAP_PROHIBIT', -1000);
 120  
 121  /** System context level - only one instance in every system */
 122  define('CONTEXT_SYSTEM', 10);
 123  /** User context level -  one instance for each user describing what others can do to user */
 124  define('CONTEXT_USER', 30);
 125  /** Course category context level - one instance for each category */
 126  define('CONTEXT_COURSECAT', 40);
 127  /** Course context level - one instances for each course */
 128  define('CONTEXT_COURSE', 50);
 129  /** Course module context level - one instance for each course module */
 130  define('CONTEXT_MODULE', 70);
 131  /**
 132   * Block context level - one instance for each block, sticky blocks are tricky
 133   * because ppl think they should be able to override them at lower contexts.
 134   * Any other context level instance can be parent of block context.
 135   */
 136  define('CONTEXT_BLOCK', 80);
 137  
 138  /** Capability allow management of trusts - NOT IMPLEMENTED YET - see {@link http://docs.moodle.org/dev/Hardening_new_Roles_system} */
 139  define('RISK_MANAGETRUST', 0x0001);
 140  /** Capability allows changes in system configuration - see {@link http://docs.moodle.org/dev/Hardening_new_Roles_system} */
 141  define('RISK_CONFIG',      0x0002);
 142  /** Capability allows user to add scripted content - see {@link http://docs.moodle.org/dev/Hardening_new_Roles_system} */
 143  define('RISK_XSS',         0x0004);
 144  /** Capability allows access to personal user information - see {@link http://docs.moodle.org/dev/Hardening_new_Roles_system} */
 145  define('RISK_PERSONAL',    0x0008);
 146  /** Capability allows users to add content others may see - see {@link http://docs.moodle.org/dev/Hardening_new_Roles_system} */
 147  define('RISK_SPAM',        0x0010);
 148  /** capability allows mass delete of data belonging to other users - see {@link http://docs.moodle.org/dev/Hardening_new_Roles_system} */
 149  define('RISK_DATALOSS',    0x0020);
 150  
 151  /** rolename displays - the name as defined in the role definition, localised if name empty */
 152  define('ROLENAME_ORIGINAL', 0);
 153  /** rolename displays - the name as defined by a role alias at the course level, falls back to ROLENAME_ORIGINAL if alias not present */
 154  define('ROLENAME_ALIAS', 1);
 155  /** rolename displays - Both, like this:  Role alias (Original) */
 156  define('ROLENAME_BOTH', 2);
 157  /** rolename displays - the name as defined in the role definition and the shortname in brackets */
 158  define('ROLENAME_ORIGINALANDSHORT', 3);
 159  /** rolename displays - the name as defined by a role alias, in raw form suitable for editing */
 160  define('ROLENAME_ALIAS_RAW', 4);
 161  /** rolename displays - the name is simply short role name */
 162  define('ROLENAME_SHORT', 5);
 163  
 164  if (!defined('CONTEXT_CACHE_MAX_SIZE')) {
 165      /** maximum size of context cache - it is possible to tweak this config.php or in any script before inclusion of context.php */
 166      define('CONTEXT_CACHE_MAX_SIZE', 2500);
 167  }
 168  
 169  /**
 170   * Although this looks like a global variable, it isn't really.
 171   *
 172   * It is just a private implementation detail to accesslib that MUST NOT be used elsewhere.
 173   * It is used to cache various bits of data between function calls for performance reasons.
 174   * Sadly, a PHP global variable is the only way to implement this, without rewriting everything
 175   * as methods of a class, instead of functions.
 176   *
 177   * @access private
 178   * @global stdClass $ACCESSLIB_PRIVATE
 179   * @name $ACCESSLIB_PRIVATE
 180   */
 181  global $ACCESSLIB_PRIVATE;
 182  $ACCESSLIB_PRIVATE = new stdClass();
 183  $ACCESSLIB_PRIVATE->cacheroledefs    = array(); // Holds site-wide role definitions.
 184  $ACCESSLIB_PRIVATE->dirtycontexts    = null;    // Dirty contexts cache, loaded from DB once per page
 185  $ACCESSLIB_PRIVATE->dirtyusers       = null;    // Dirty users cache, loaded from DB once per $USER->id
 186  $ACCESSLIB_PRIVATE->accessdatabyuser = array(); // Holds the cache of $accessdata structure for users (including $USER)
 187  
 188  /**
 189   * Clears accesslib's private caches. ONLY BE USED BY UNIT TESTS
 190   *
 191   * This method should ONLY BE USED BY UNIT TESTS. It clears all of
 192   * accesslib's private caches. You need to do this before setting up test data,
 193   * and also at the end of the tests.
 194   *
 195   * @access private
 196   * @return void
 197   */
 198  function accesslib_clear_all_caches_for_unit_testing() {
 199      global $USER;
 200      if (!PHPUNIT_TEST) {
 201          throw new coding_exception('You must not call clear_all_caches outside of unit tests.');
 202      }
 203  
 204      accesslib_clear_all_caches(true);
 205      accesslib_reset_role_cache();
 206  
 207      unset($USER->access);
 208  }
 209  
 210  /**
 211   * Clears accesslib's private caches. ONLY BE USED FROM THIS LIBRARY FILE!
 212   *
 213   * This reset does not touch global $USER.
 214   *
 215   * @access private
 216   * @param bool $resetcontexts
 217   * @return void
 218   */
 219  function accesslib_clear_all_caches($resetcontexts) {
 220      global $ACCESSLIB_PRIVATE;
 221  
 222      $ACCESSLIB_PRIVATE->dirtycontexts    = null;
 223      $ACCESSLIB_PRIVATE->dirtyusers       = null;
 224      $ACCESSLIB_PRIVATE->accessdatabyuser = array();
 225  
 226      if ($resetcontexts) {
 227          context_helper::reset_caches();
 228      }
 229  }
 230  
 231  /**
 232   * Full reset of accesslib's private role cache. ONLY TO BE USED FROM THIS LIBRARY FILE!
 233   *
 234   * This reset does not touch global $USER.
 235   *
 236   * Note: Only use this when the roles that need a refresh are unknown.
 237   *
 238   * @see accesslib_clear_role_cache()
 239   *
 240   * @access private
 241   * @return void
 242   */
 243  function accesslib_reset_role_cache() {
 244      global $ACCESSLIB_PRIVATE;
 245  
 246      $ACCESSLIB_PRIVATE->cacheroledefs = array();
 247      $cache = cache::make('core', 'roledefs');
 248      $cache->purge();
 249  }
 250  
 251  /**
 252   * Clears accesslib's private cache of a specific role or roles. ONLY BE USED FROM THIS LIBRARY FILE!
 253   *
 254   * This reset does not touch global $USER.
 255   *
 256   * @access private
 257   * @param int|array $roles
 258   * @return void
 259   */
 260  function accesslib_clear_role_cache($roles) {
 261      global $ACCESSLIB_PRIVATE;
 262  
 263      if (!is_array($roles)) {
 264          $roles = [$roles];
 265      }
 266  
 267      foreach ($roles as $role) {
 268          if (isset($ACCESSLIB_PRIVATE->cacheroledefs[$role])) {
 269              unset($ACCESSLIB_PRIVATE->cacheroledefs[$role]);
 270          }
 271      }
 272  
 273      $cache = cache::make('core', 'roledefs');
 274      $cache->delete_many($roles);
 275  }
 276  
 277  /**
 278   * Role is assigned at system context.
 279   *
 280   * @access private
 281   * @param int $roleid
 282   * @return array
 283   */
 284  function get_role_access($roleid) {
 285      $accessdata = get_empty_accessdata();
 286      $accessdata['ra']['/'.SYSCONTEXTID] = array((int)$roleid => (int)$roleid);
 287      return $accessdata;
 288  }
 289  
 290  /**
 291   * Fetch raw "site wide" role definitions.
 292   * Even MUC static acceleration cache appears a bit slow for this.
 293   * Important as can be hit hundreds of times per page.
 294   *
 295   * @param array $roleids List of role ids to fetch definitions for.
 296   * @return array Complete definition for each requested role.
 297   */
 298  function get_role_definitions(array $roleids) {
 299      global $ACCESSLIB_PRIVATE;
 300  
 301      if (empty($roleids)) {
 302          return array();
 303      }
 304  
 305      // Grab all keys we have not yet got in our static cache.
 306      if ($uncached = array_diff($roleids, array_keys($ACCESSLIB_PRIVATE->cacheroledefs))) {
 307          $cache = cache::make('core', 'roledefs');
 308          foreach ($cache->get_many($uncached) as $roleid => $cachedroledef) {
 309              if (is_array($cachedroledef)) {
 310                  $ACCESSLIB_PRIVATE->cacheroledefs[$roleid] = $cachedroledef;
 311              }
 312          }
 313  
 314          // Check we have the remaining keys from the MUC.
 315          if ($uncached = array_diff($roleids, array_keys($ACCESSLIB_PRIVATE->cacheroledefs))) {
 316              $uncached = get_role_definitions_uncached($uncached);
 317              $ACCESSLIB_PRIVATE->cacheroledefs += $uncached;
 318              $cache->set_many($uncached);
 319          }
 320      }
 321  
 322      // Return just the roles we need.
 323      return array_intersect_key($ACCESSLIB_PRIVATE->cacheroledefs, array_flip($roleids));
 324  }
 325  
 326  /**
 327   * Query raw "site wide" role definitions.
 328   *
 329   * @param array $roleids List of role ids to fetch definitions for.
 330   * @return array Complete definition for each requested role.
 331   */
 332  function get_role_definitions_uncached(array $roleids) {
 333      global $DB;
 334  
 335      if (empty($roleids)) {
 336          return array();
 337      }
 338  
 339      // Create a blank results array: even if a role has no capabilities,
 340      // we need to ensure it is included in the results to show we have
 341      // loaded all the capabilities that there are.
 342      $rdefs = array();
 343      foreach ($roleids as $roleid) {
 344          $rdefs[$roleid] = array();
 345      }
 346  
 347      // Load all the capabilities for these roles in all contexts.
 348      list($sql, $params) = $DB->get_in_or_equal($roleids);
 349      $sql = "SELECT ctx.path, rc.roleid, rc.capability, rc.permission
 350                FROM {role_capabilities} rc
 351                JOIN {context} ctx ON rc.contextid = ctx.id
 352                JOIN {capabilities} cap ON rc.capability = cap.name
 353               WHERE rc.roleid $sql";
 354      $rs = $DB->get_recordset_sql($sql, $params);
 355  
 356      // Store the capabilities into the expected data structure.
 357      foreach ($rs as $rd) {
 358          if (!isset($rdefs[$rd->roleid][$rd->path])) {
 359              $rdefs[$rd->roleid][$rd->path] = array();
 360          }
 361          $rdefs[$rd->roleid][$rd->path][$rd->capability] = (int) $rd->permission;
 362      }
 363  
 364      $rs->close();
 365  
 366      // Sometimes (e.g. get_user_capability_course_helper::get_capability_info_at_each_context)
 367      // we process role definitinons in a way that requires we see parent contexts
 368      // before child contexts. This sort ensures that works (and is faster than
 369      // sorting in the SQL query).
 370      foreach ($rdefs as $roleid => $rdef) {
 371          ksort($rdefs[$roleid]);
 372      }
 373  
 374      return $rdefs;
 375  }
 376  
 377  /**
 378   * Get the default guest role, this is used for guest account,
 379   * search engine spiders, etc.
 380   *
 381   * @return stdClass role record
 382   */
 383  function get_guest_role() {
 384      global $CFG, $DB;
 385  
 386      if (empty($CFG->guestroleid)) {
 387          if ($roles = $DB->get_records('role', array('archetype'=>'guest'))) {
 388              $guestrole = array_shift($roles);   // Pick the first one
 389              set_config('guestroleid', $guestrole->id);
 390              return $guestrole;
 391          } else {
 392              debugging('Can not find any guest role!');
 393              return false;
 394          }
 395      } else {
 396          if ($guestrole = $DB->get_record('role', array('id'=>$CFG->guestroleid))) {
 397              return $guestrole;
 398          } else {
 399              // somebody is messing with guest roles, remove incorrect setting and try to find a new one
 400              set_config('guestroleid', '');
 401              return get_guest_role();
 402          }
 403      }
 404  }
 405  
 406  /**
 407   * Check whether a user has a particular capability in a given context.
 408   *
 409   * For example:
 410   *      $context = context_module::instance($cm->id);
 411   *      has_capability('mod/forum:replypost', $context)
 412   *
 413   * By default checks the capabilities of the current user, but you can pass a
 414   * different userid. By default will return true for admin users, but you can override that with the fourth argument.
 415   *
 416   * Guest and not-logged-in users can never get any dangerous capability - that is any write capability
 417   * or capabilities with XSS, config or data loss risks.
 418   *
 419   * @category access
 420   *
 421   * @param string $capability the name of the capability to check. For example mod/forum:view
 422   * @param context $context the context to check the capability in. You normally get this with instance method of a context class.
 423   * @param integer|stdClass $user A user id or object. By default (null) checks the permissions of the current user.
 424   * @param boolean $doanything If false, ignores effect of admin role assignment
 425   * @return boolean true if the user has this capability. Otherwise false.
 426   */
 427  function has_capability($capability, context $context, $user = null, $doanything = true) {
 428      global $USER, $CFG, $SCRIPT, $ACCESSLIB_PRIVATE;
 429  
 430      if (during_initial_install()) {
 431          if ($SCRIPT === "/$CFG->admin/index.php"
 432                  or $SCRIPT === "/$CFG->admin/cli/install.php"
 433                  or $SCRIPT === "/$CFG->admin/cli/install_database.php"
 434                  or (defined('BEHAT_UTIL') and BEHAT_UTIL)
 435                  or (defined('PHPUNIT_UTIL') and PHPUNIT_UTIL)) {
 436              // we are in an installer - roles can not work yet
 437              return true;
 438          } else {
 439              return false;
 440          }
 441      }
 442  
 443      if (strpos($capability, 'moodle/legacy:') === 0) {
 444          throw new coding_exception('Legacy capabilities can not be used any more!');
 445      }
 446  
 447      if (!is_bool($doanything)) {
 448          throw new coding_exception('Capability parameter "doanything" is wierd, only true or false is allowed. This has to be fixed in code.');
 449      }
 450  
 451      // capability must exist
 452      if (!$capinfo = get_capability_info($capability)) {
 453          debugging('Capability "'.$capability.'" was not found! This has to be fixed in code.');
 454          return false;
 455      }
 456  
 457      if (!isset($USER->id)) {
 458          // should never happen
 459          $USER->id = 0;
 460          debugging('Capability check being performed on a user with no ID.', DEBUG_DEVELOPER);
 461      }
 462  
 463      // make sure there is a real user specified
 464      if ($user === null) {
 465          $userid = $USER->id;
 466      } else {
 467          $userid = is_object($user) ? $user->id : $user;
 468      }
 469  
 470      // make sure forcelogin cuts off not-logged-in users if enabled
 471      if (!empty($CFG->forcelogin) and $userid == 0) {
 472          return false;
 473      }
 474  
 475      // make sure the guest account and not-logged-in users never get any risky caps no matter what the actual settings are.
 476      if (($capinfo->captype === 'write') or ($capinfo->riskbitmask & (RISK_XSS | RISK_CONFIG | RISK_DATALOSS))) {
 477          if (isguestuser($userid) or $userid == 0) {
 478              return false;
 479          }
 480      }
 481  
 482      // Check whether context locking is enabled.
 483      if (!empty($CFG->contextlocking)) {
 484          if ($capinfo->captype === 'write' && $context->locked) {
 485              // Context locking applies to any write capability in a locked context.
 486              // It does not apply to moodle/site:managecontextlocks - this is to allow context locking to be unlocked.
 487              if ($capinfo->name !== 'moodle/site:managecontextlocks') {
 488                  // It applies to all users who are not site admins.
 489                  // It also applies to site admins when contextlockappliestoadmin is set.
 490                  if (!is_siteadmin($userid) || !empty($CFG->contextlockappliestoadmin)) {
 491                      return false;
 492                  }
 493              }
 494          }
 495      }
 496  
 497      // somehow make sure the user is not deleted and actually exists
 498      if ($userid != 0) {
 499          if ($userid == $USER->id and isset($USER->deleted)) {
 500              // this prevents one query per page, it is a bit of cheating,
 501              // but hopefully session is terminated properly once user is deleted
 502              if ($USER->deleted) {
 503                  return false;
 504              }
 505          } else {
 506              if (!context_user::instance($userid, IGNORE_MISSING)) {
 507                  // no user context == invalid userid
 508                  return false;
 509              }
 510          }
 511      }
 512  
 513      // context path/depth must be valid
 514      if (empty($context->path) or $context->depth == 0) {
 515          // this should not happen often, each upgrade tries to rebuild the context paths
 516          debugging('Context id '.$context->id.' does not have valid path, please use context_helper::build_all_paths()');
 517          if (is_siteadmin($userid)) {
 518              return true;
 519          } else {
 520              return false;
 521          }
 522      }
 523  
 524      if (!empty($USER->loginascontext)) {
 525          // The current user is logged in as another user and can assume their identity at or below the `loginascontext`
 526          // defined in the USER session.
 527          // The user may not assume their identity at any other location.
 528          if (!$USER->loginascontext->is_parent_of($context, true)) {
 529              // The context being checked is not the specified context, or one of its children.
 530              return false;
 531          }
 532      }
 533  
 534      // Find out if user is admin - it is not possible to override the doanything in any way
 535      // and it is not possible to switch to admin role either.
 536      if ($doanything) {
 537          if (is_siteadmin($userid)) {
 538              if ($userid != $USER->id) {
 539                  return true;
 540              }
 541              // make sure switchrole is not used in this context
 542              if (empty($USER->access['rsw'])) {
 543                  return true;
 544              }
 545              $parts = explode('/', trim($context->path, '/'));
 546              $path = '';
 547              $switched = false;
 548              foreach ($parts as $part) {
 549                  $path .= '/' . $part;
 550                  if (!empty($USER->access['rsw'][$path])) {
 551                      $switched = true;
 552                      break;
 553                  }
 554              }
 555              if (!$switched) {
 556                  return true;
 557              }
 558              //ok, admin switched role in this context, let's use normal access control rules
 559          }
 560      }
 561  
 562      // Careful check for staleness...
 563      $context->reload_if_dirty();
 564  
 565      if ($USER->id == $userid) {
 566          if (!isset($USER->access)) {
 567              load_all_capabilities();
 568          }
 569          $access =& $USER->access;
 570  
 571      } else {
 572          // make sure user accessdata is really loaded
 573          get_user_accessdata($userid, true);
 574          $access =& $ACCESSLIB_PRIVATE->accessdatabyuser[$userid];
 575      }
 576  
 577      return has_capability_in_accessdata($capability, $context, $access);
 578  }
 579  
 580  /**
 581   * Check if the user has any one of several capabilities from a list.
 582   *
 583   * This is just a utility method that calls has_capability in a loop. Try to put
 584   * the capabilities that most users are likely to have first in the list for best
 585   * performance.
 586   *
 587   * @category access
 588   * @see has_capability()
 589   *
 590   * @param array $capabilities an array of capability names.
 591   * @param context $context the context to check the capability in. You normally get this with instance method of a context class.
 592   * @param integer|stdClass $user A user id or object. By default (null) checks the permissions of the current user.
 593   * @param boolean $doanything If false, ignore effect of admin role assignment
 594   * @return boolean true if the user has any of these capabilities. Otherwise false.
 595   */
 596  function has_any_capability(array $capabilities, context $context, $user = null, $doanything = true) {
 597      foreach ($capabilities as $capability) {
 598          if (has_capability($capability, $context, $user, $doanything)) {
 599              return true;
 600          }
 601      }
 602      return false;
 603  }
 604  
 605  /**
 606   * Check if the user has all the capabilities in a list.
 607   *
 608   * This is just a utility method that calls has_capability in a loop. Try to put
 609   * the capabilities that fewest users are likely to have first in the list for best
 610   * performance.
 611   *
 612   * @category access
 613   * @see has_capability()
 614   *
 615   * @param array $capabilities an array of capability names.
 616   * @param context $context the context to check the capability in. You normally get this with instance method of a context class.
 617   * @param integer|stdClass $user A user id or object. By default (null) checks the permissions of the current user.
 618   * @param boolean $doanything If false, ignore effect of admin role assignment
 619   * @return boolean true if the user has all of these capabilities. Otherwise false.
 620   */
 621  function has_all_capabilities(array $capabilities, context $context, $user = null, $doanything = true) {
 622      foreach ($capabilities as $capability) {
 623          if (!has_capability($capability, $context, $user, $doanything)) {
 624              return false;
 625          }
 626      }
 627      return true;
 628  }
 629  
 630  /**
 631   * Is course creator going to have capability in a new course?
 632   *
 633   * This is intended to be used in enrolment plugins before or during course creation,
 634   * do not use after the course is fully created.
 635   *
 636   * @category access
 637   *
 638   * @param string $capability the name of the capability to check.
 639   * @param context $context course or category context where is course going to be created
 640   * @param integer|stdClass $user A user id or object. By default (null) checks the permissions of the current user.
 641   * @return boolean true if the user will have this capability.
 642   *
 643   * @throws coding_exception if different type of context submitted
 644   */
 645  function guess_if_creator_will_have_course_capability($capability, context $context, $user = null) {
 646      global $CFG;
 647  
 648      if ($context->contextlevel != CONTEXT_COURSE and $context->contextlevel != CONTEXT_COURSECAT) {
 649          throw new coding_exception('Only course or course category context expected');
 650      }
 651  
 652      if (has_capability($capability, $context, $user)) {
 653          // User already has the capability, it could be only removed if CAP_PROHIBIT
 654          // was involved here, but we ignore that.
 655          return true;
 656      }
 657  
 658      if (!has_capability('moodle/course:create', $context, $user)) {
 659          return false;
 660      }
 661  
 662      if (!enrol_is_enabled('manual')) {
 663          return false;
 664      }
 665  
 666      if (empty($CFG->creatornewroleid)) {
 667          return false;
 668      }
 669  
 670      if ($context->contextlevel == CONTEXT_COURSE) {
 671          if (is_viewing($context, $user, 'moodle/role:assign') or is_enrolled($context, $user, 'moodle/role:assign')) {
 672              return false;
 673          }
 674      } else {
 675          if (has_capability('moodle/course:view', $context, $user) and has_capability('moodle/role:assign', $context, $user)) {
 676              return false;
 677          }
 678      }
 679  
 680      // Most likely they will be enrolled after the course creation is finished,
 681      // does the new role have the required capability?
 682      list($neededroles, $forbiddenroles) = get_roles_with_cap_in_context($context, $capability);
 683      return isset($neededroles[$CFG->creatornewroleid]);
 684  }
 685  
 686  /**
 687   * Check if the user is an admin at the site level.
 688   *
 689   * Please note that use of proper capabilities is always encouraged,
 690   * this function is supposed to be used from core or for temporary hacks.
 691   *
 692   * @category access
 693   *
 694   * @param  int|stdClass  $user_or_id user id or user object
 695   * @return bool true if user is one of the administrators, false otherwise
 696   */
 697  function is_siteadmin($user_or_id = null) {
 698      global $CFG, $USER;
 699  
 700      if ($user_or_id === null) {
 701          $user_or_id = $USER;
 702      }
 703  
 704      if (empty($user_or_id)) {
 705          return false;
 706      }
 707      if (!empty($user_or_id->id)) {
 708          $userid = $user_or_id->id;
 709      } else {
 710          $userid = $user_or_id;
 711      }
 712  
 713      // Because this script is called many times (150+ for course page) with
 714      // the same parameters, it is worth doing minor optimisations. This static
 715      // cache stores the value for a single userid, saving about 2ms from course
 716      // page load time without using significant memory. As the static cache
 717      // also includes the value it depends on, this cannot break unit tests.
 718      static $knownid, $knownresult, $knownsiteadmins;
 719      if ($knownid === $userid && $knownsiteadmins === $CFG->siteadmins) {
 720          return $knownresult;
 721      }
 722      $knownid = $userid;
 723      $knownsiteadmins = $CFG->siteadmins;
 724  
 725      $siteadmins = explode(',', $CFG->siteadmins);
 726      $knownresult = in_array($userid, $siteadmins);
 727      return $knownresult;
 728  }
 729  
 730  /**
 731   * Returns true if user has at least one role assign
 732   * of 'coursecontact' role (is potentially listed in some course descriptions).
 733   *
 734   * @param int $userid
 735   * @return bool
 736   */
 737  function has_coursecontact_role($userid) {
 738      global $DB, $CFG;
 739  
 740      if (empty($CFG->coursecontact)) {
 741          return false;
 742      }
 743      $sql = "SELECT 1
 744                FROM {role_assignments}
 745               WHERE userid = :userid AND roleid IN ($CFG->coursecontact)";
 746      return $DB->record_exists_sql($sql, array('userid'=>$userid));
 747  }
 748  
 749  /**
 750   * Does the user have a capability to do something?
 751   *
 752   * Walk the accessdata array and return true/false.
 753   * Deals with prohibits, role switching, aggregating
 754   * capabilities, etc.
 755   *
 756   * The main feature of here is being FAST and with no
 757   * side effects.
 758   *
 759   * Notes:
 760   *
 761   * Switch Role merges with default role
 762   * ------------------------------------
 763   * If you are a teacher in course X, you have at least
 764   * teacher-in-X + defaultloggedinuser-sitewide. So in the
 765   * course you'll have techer+defaultloggedinuser.
 766   * We try to mimic that in switchrole.
 767   *
 768   * Permission evaluation
 769   * ---------------------
 770   * Originally there was an extremely complicated way
 771   * to determine the user access that dealt with
 772   * "locality" or role assignments and role overrides.
 773   * Now we simply evaluate access for each role separately
 774   * and then verify if user has at least one role with allow
 775   * and at the same time no role with prohibit.
 776   *
 777   * @access private
 778   * @param string $capability
 779   * @param context $context
 780   * @param array $accessdata
 781   * @return bool
 782   */
 783  function has_capability_in_accessdata($capability, context $context, array &$accessdata) {
 784      global $CFG;
 785  
 786      // Build $paths as a list of current + all parent "paths" with order bottom-to-top
 787      $path = $context->path;
 788      $paths = array($path);
 789      while ($path = rtrim($path, '0123456789')) {
 790          $path = rtrim($path, '/');
 791          if ($path === '') {
 792              break;
 793          }
 794          $paths[] = $path;
 795      }
 796  
 797      $roles = array();
 798      $switchedrole = false;
 799  
 800      // Find out if role switched
 801      if (!empty($accessdata['rsw'])) {
 802          // From the bottom up...
 803          foreach ($paths as $path) {
 804              if (isset($accessdata['rsw'][$path])) {
 805                  // Found a switchrole assignment - check for that role _plus_ the default user role
 806                  $roles = array($accessdata['rsw'][$path]=>null, $CFG->defaultuserroleid=>null);
 807                  $switchedrole = true;
 808                  break;
 809              }
 810          }
 811      }
 812  
 813      if (!$switchedrole) {
 814          // get all users roles in this context and above
 815          foreach ($paths as $path) {
 816              if (isset($accessdata['ra'][$path])) {
 817                  foreach ($accessdata['ra'][$path] as $roleid) {
 818                      $roles[$roleid] = null;
 819                  }
 820              }
 821          }
 822      }
 823  
 824      // Now find out what access is given to each role, going bottom-->up direction
 825      $rdefs = get_role_definitions(array_keys($roles));
 826      $allowed = false;
 827  
 828      foreach ($roles as $roleid => $ignored) {
 829          foreach ($paths as $path) {
 830              if (isset($rdefs[$roleid][$path][$capability])) {
 831                  $perm = (int)$rdefs[$roleid][$path][$capability];
 832                  if ($perm === CAP_PROHIBIT) {
 833                      // any CAP_PROHIBIT found means no permission for the user
 834                      return false;
 835                  }
 836                  if (is_null($roles[$roleid])) {
 837                      $roles[$roleid] = $perm;
 838                  }
 839              }
 840          }
 841          // CAP_ALLOW in any role means the user has a permission, we continue only to detect prohibits
 842          $allowed = ($allowed or $roles[$roleid] === CAP_ALLOW);
 843      }
 844  
 845      return $allowed;
 846  }
 847  
 848  /**
 849   * A convenience function that tests has_capability, and displays an error if
 850   * the user does not have that capability.
 851   *
 852   * NOTE before Moodle 2.0, this function attempted to make an appropriate
 853   * require_login call before checking the capability. This is no longer the case.
 854   * You must call require_login (or one of its variants) if you want to check the
 855   * user is logged in, before you call this function.
 856   *
 857   * @see has_capability()
 858   *
 859   * @param string $capability the name of the capability to check. For example mod/forum:view
 860   * @param context $context the context to check the capability in. You normally get this with context_xxxx::instance().
 861   * @param int $userid A user id. By default (null) checks the permissions of the current user.
 862   * @param bool $doanything If false, ignore effect of admin role assignment
 863   * @param string $errormessage The error string to to user. Defaults to 'nopermissions'.
 864   * @param string $stringfile The language file to load the error string from. Defaults to 'error'.
 865   * @return void terminates with an error if the user does not have the given capability.
 866   */
 867  function require_capability($capability, context $context, $userid = null, $doanything = true,
 868                              $errormessage = 'nopermissions', $stringfile = '') {
 869      if (!has_capability($capability, $context, $userid, $doanything)) {
 870          throw new required_capability_exception($context, $capability, $errormessage, $stringfile);
 871      }
 872  }
 873  
 874  /**
 875   * A convenience function that tests has_capability for a list of capabilities, and displays an error if
 876   * the user does not have that capability.
 877   *
 878   * This is just a utility method that calls has_capability in a loop. Try to put
 879   * the capabilities that fewest users are likely to have first in the list for best
 880   * performance.
 881   *
 882   * @category access
 883   * @see has_capability()
 884   *
 885   * @param array $capabilities an array of capability names.
 886   * @param context $context the context to check the capability in. You normally get this with context_xxxx::instance().
 887   * @param int $userid A user id. By default (null) checks the permissions of the current user.
 888   * @param bool $doanything If false, ignore effect of admin role assignment
 889   * @param string $errormessage The error string to to user. Defaults to 'nopermissions'.
 890   * @param string $stringfile The language file to load the error string from. Defaults to 'error'.
 891   * @return void terminates with an error if the user does not have the given capability.
 892   */
 893  function require_all_capabilities(array $capabilities, context $context, $userid = null, $doanything = true,
 894                                    $errormessage = 'nopermissions', $stringfile = ''): void {
 895      foreach ($capabilities as $capability) {
 896          if (!has_capability($capability, $context, $userid, $doanything)) {
 897              throw new required_capability_exception($context, $capability, $errormessage, $stringfile);
 898          }
 899      }
 900  }
 901  
 902  /**
 903   * Return a nested array showing all role assignments for the user.
 904   * [ra] => [contextpath][roleid] = roleid
 905   *
 906   * @access private
 907   * @param int $userid - the id of the user
 908   * @return array access info array
 909   */
 910  function get_user_roles_sitewide_accessdata($userid) {
 911      global $CFG, $DB;
 912  
 913      $accessdata = get_empty_accessdata();
 914  
 915      // start with the default role
 916      if (!empty($CFG->defaultuserroleid)) {
 917          $syscontext = context_system::instance();
 918          $accessdata['ra'][$syscontext->path][(int)$CFG->defaultuserroleid] = (int)$CFG->defaultuserroleid;
 919      }
 920  
 921      // load the "default frontpage role"
 922      if (!empty($CFG->defaultfrontpageroleid)) {
 923          $frontpagecontext = context_course::instance(get_site()->id);
 924          if ($frontpagecontext->path) {
 925              $accessdata['ra'][$frontpagecontext->path][(int)$CFG->defaultfrontpageroleid] = (int)$CFG->defaultfrontpageroleid;
 926          }
 927      }
 928  
 929      // Preload every assigned role.
 930      $sql = "SELECT ctx.path, ra.roleid, ra.contextid
 931                FROM {role_assignments} ra
 932                JOIN {context} ctx ON ctx.id = ra.contextid
 933               WHERE ra.userid = :userid";
 934  
 935      $rs = $DB->get_recordset_sql($sql, array('userid' => $userid));
 936  
 937      foreach ($rs as $ra) {
 938          // RAs leafs are arrays to support multi-role assignments...
 939          $accessdata['ra'][$ra->path][(int)$ra->roleid] = (int)$ra->roleid;
 940      }
 941  
 942      $rs->close();
 943  
 944      return $accessdata;
 945  }
 946  
 947  /**
 948   * Returns empty accessdata structure.
 949   *
 950   * @access private
 951   * @return array empt accessdata
 952   */
 953  function get_empty_accessdata() {
 954      $accessdata               = array(); // named list
 955      $accessdata['ra']         = array();
 956      $accessdata['time']       = time();
 957      $accessdata['rsw']        = array();
 958  
 959      return $accessdata;
 960  }
 961  
 962  /**
 963   * Get accessdata for a given user.
 964   *
 965   * @access private
 966   * @param int $userid
 967   * @param bool $preloadonly true means do not return access array
 968   * @return array accessdata
 969   */
 970  function get_user_accessdata($userid, $preloadonly=false) {
 971      global $CFG, $ACCESSLIB_PRIVATE, $USER;
 972  
 973      if (isset($USER->access)) {
 974          $ACCESSLIB_PRIVATE->accessdatabyuser[$USER->id] = $USER->access;
 975      }
 976  
 977      if (!isset($ACCESSLIB_PRIVATE->accessdatabyuser[$userid])) {
 978          if (empty($userid)) {
 979              if (!empty($CFG->notloggedinroleid)) {
 980                  $accessdata = get_role_access($CFG->notloggedinroleid);
 981              } else {
 982                  // weird
 983                  return get_empty_accessdata();
 984              }
 985  
 986          } else if (isguestuser($userid)) {
 987              if ($guestrole = get_guest_role()) {
 988                  $accessdata = get_role_access($guestrole->id);
 989              } else {
 990                  //weird
 991                  return get_empty_accessdata();
 992              }
 993  
 994          } else {
 995              // Includes default role and frontpage role.
 996              $accessdata = get_user_roles_sitewide_accessdata($userid);
 997          }
 998  
 999          $ACCESSLIB_PRIVATE->accessdatabyuser[$userid] = $accessdata;
1000      }
1001  
1002      if ($preloadonly) {
1003          return;
1004      } else {
1005          return $ACCESSLIB_PRIVATE->accessdatabyuser[$userid];
1006      }
1007  }
1008  
1009  /**
1010   * A convenience function to completely load all the capabilities
1011   * for the current user. It is called from has_capability() and functions change permissions.
1012   *
1013   * Call it only _after_ you've setup $USER and called check_enrolment_plugins();
1014   * @see check_enrolment_plugins()
1015   *
1016   * @access private
1017   * @return void
1018   */
1019  function load_all_capabilities() {
1020      global $USER;
1021  
1022      // roles not installed yet - we are in the middle of installation
1023      if (during_initial_install()) {
1024          return;
1025      }
1026  
1027      if (!isset($USER->id)) {
1028          // this should not happen
1029          $USER->id = 0;
1030      }
1031  
1032      unset($USER->access);
1033      $USER->access = get_user_accessdata($USER->id);
1034  
1035      // Clear to force a refresh
1036      unset($USER->mycourses);
1037  
1038      // init/reset internal enrol caches - active course enrolments and temp access
1039      $USER->enrol = array('enrolled'=>array(), 'tempguest'=>array());
1040  }
1041  
1042  /**
1043   * A convenience function to completely reload all the capabilities
1044   * for the current user when roles have been updated in a relevant
1045   * context -- but PRESERVING switchroles and loginas.
1046   * This function resets all accesslib and context caches.
1047   *
1048   * That is - completely transparent to the user.
1049   *
1050   * Note: reloads $USER->access completely.
1051   *
1052   * @access private
1053   * @return void
1054   */
1055  function reload_all_capabilities() {
1056      global $USER, $DB, $ACCESSLIB_PRIVATE;
1057  
1058      // copy switchroles
1059      $sw = array();
1060      if (!empty($USER->access['rsw'])) {
1061          $sw = $USER->access['rsw'];
1062      }
1063  
1064      accesslib_clear_all_caches(true);
1065      unset($USER->access);
1066  
1067      // Prevent dirty flags refetching on this page.
1068      $ACCESSLIB_PRIVATE->dirtycontexts = array();
1069      $ACCESSLIB_PRIVATE->dirtyusers    = array($USER->id => false);
1070  
1071      load_all_capabilities();
1072  
1073      foreach ($sw as $path => $roleid) {
1074          if ($record = $DB->get_record('context', array('path'=>$path))) {
1075              $context = context::instance_by_id($record->id);
1076              if (has_capability('moodle/role:switchroles', $context)) {
1077                  role_switch($roleid, $context);
1078              }
1079          }
1080      }
1081  }
1082  
1083  /**
1084   * Adds a temp role to current USER->access array.
1085   *
1086   * Useful for the "temporary guest" access we grant to logged-in users.
1087   * This is useful for enrol plugins only.
1088   *
1089   * @since Moodle 2.2
1090   * @param context_course $coursecontext
1091   * @param int $roleid
1092   * @return void
1093   */
1094  function load_temp_course_role(context_course $coursecontext, $roleid) {
1095      global $USER, $SITE;
1096  
1097      if (empty($roleid)) {
1098          debugging('invalid role specified in load_temp_course_role()');
1099          return;
1100      }
1101  
1102      if ($coursecontext->instanceid == $SITE->id) {
1103          debugging('Can not use temp roles on the frontpage');
1104          return;
1105      }
1106  
1107      if (!isset($USER->access)) {
1108          load_all_capabilities();
1109      }
1110  
1111      $coursecontext->reload_if_dirty();
1112  
1113      if (isset($USER->access['ra'][$coursecontext->path][$roleid])) {
1114          return;
1115      }
1116  
1117      $USER->access['ra'][$coursecontext->path][(int)$roleid] = (int)$roleid;
1118  }
1119  
1120  /**
1121   * Removes any extra guest roles from current USER->access array.
1122   * This is useful for enrol plugins only.
1123   *
1124   * @since Moodle 2.2
1125   * @param context_course $coursecontext
1126   * @return void
1127   */
1128  function remove_temp_course_roles(context_course $coursecontext) {
1129      global $DB, $USER, $SITE;
1130  
1131      if ($coursecontext->instanceid == $SITE->id) {
1132          debugging('Can not use temp roles on the frontpage');
1133          return;
1134      }
1135  
1136      if (empty($USER->access['ra'][$coursecontext->path])) {
1137          //no roles here, weird
1138          return;
1139      }
1140  
1141      $sql = "SELECT DISTINCT ra.roleid AS id
1142                FROM {role_assignments} ra
1143               WHERE ra.contextid = :contextid AND ra.userid = :userid";
1144      $ras = $DB->get_records_sql($sql, array('contextid'=>$coursecontext->id, 'userid'=>$USER->id));
1145  
1146      $USER->access['ra'][$coursecontext->path] = array();
1147      foreach ($ras as $r) {
1148          $USER->access['ra'][$coursecontext->path][(int)$r->id] = (int)$r->id;
1149      }
1150  }
1151  
1152  /**
1153   * Returns array of all role archetypes.
1154   *
1155   * @return array
1156   */
1157  function get_role_archetypes() {
1158      return array(
1159          'manager'        => 'manager',
1160          'coursecreator'  => 'coursecreator',
1161          'editingteacher' => 'editingteacher',
1162          'teacher'        => 'teacher',
1163          'student'        => 'student',
1164          'guest'          => 'guest',
1165          'user'           => 'user',
1166          'frontpage'      => 'frontpage'
1167      );
1168  }
1169  
1170  /**
1171   * Assign the defaults found in this capability definition to roles that have
1172   * the corresponding legacy capabilities assigned to them.
1173   *
1174   * @param string $capability
1175   * @param array $legacyperms an array in the format (example):
1176   *                      'guest' => CAP_PREVENT,
1177   *                      'student' => CAP_ALLOW,
1178   *                      'teacher' => CAP_ALLOW,
1179   *                      'editingteacher' => CAP_ALLOW,
1180   *                      'coursecreator' => CAP_ALLOW,
1181   *                      'manager' => CAP_ALLOW
1182   * @return boolean success or failure.
1183   */
1184  function assign_legacy_capabilities($capability, $legacyperms) {
1185  
1186      $archetypes = get_role_archetypes();
1187  
1188      foreach ($legacyperms as $type => $perm) {
1189  
1190          $systemcontext = context_system::instance();
1191          if ($type === 'admin') {
1192              debugging('Legacy type admin in access.php was renamed to manager, please update the code.');
1193              $type = 'manager';
1194          }
1195  
1196          if (!array_key_exists($type, $archetypes)) {
1197              print_error('invalidlegacy', '', '', $type);
1198          }
1199  
1200          if ($roles = get_archetype_roles($type)) {
1201              foreach ($roles as $role) {
1202                  // Assign a site level capability.
1203                  if (!assign_capability($capability, $perm, $role->id, $systemcontext->id)) {
1204                      return false;
1205                  }
1206              }
1207          }
1208      }
1209      return true;
1210  }
1211  
1212  /**
1213   * Verify capability risks.
1214   *
1215   * @param stdClass $capability a capability - a row from the capabilities table.
1216   * @return boolean whether this capability is safe - that is, whether people with the
1217   *      safeoverrides capability should be allowed to change it.
1218   */
1219  function is_safe_capability($capability) {
1220      return !((RISK_DATALOSS | RISK_MANAGETRUST | RISK_CONFIG | RISK_XSS | RISK_PERSONAL) & $capability->riskbitmask);
1221  }
1222  
1223  /**
1224   * Get the local override (if any) for a given capability in a role in a context
1225   *
1226   * @param int $roleid
1227   * @param int $contextid
1228   * @param string $capability
1229   * @return stdClass local capability override
1230   */
1231  function get_local_override($roleid, $contextid, $capability) {
1232      global $DB;
1233  
1234      return $DB->get_record_sql("
1235          SELECT rc.*
1236            FROM {role_capabilities} rc
1237            JOIN {capability} cap ON rc.capability = cap.name
1238           WHERE rc.roleid = :roleid AND rc.capability = :capability AND rc.contextid = :contextid", [
1239              'roleid' => $roleid,
1240              'contextid' => $contextid,
1241              'capability' => $capability,
1242  
1243          ]);
1244  }
1245  
1246  /**
1247   * Returns context instance plus related course and cm instances
1248   *
1249   * @param int $contextid
1250   * @return array of ($context, $course, $cm)
1251   */
1252  function get_context_info_array($contextid) {
1253      global $DB;
1254  
1255      $context = context::instance_by_id($contextid, MUST_EXIST);
1256      $course  = null;
1257      $cm      = null;
1258  
1259      if ($context->contextlevel == CONTEXT_COURSE) {
1260          $course = $DB->get_record('course', array('id'=>$context->instanceid), '*', MUST_EXIST);
1261  
1262      } else if ($context->contextlevel == CONTEXT_MODULE) {
1263          $cm = get_coursemodule_from_id('', $context->instanceid, 0, false, MUST_EXIST);
1264          $course = $DB->get_record('course', array('id'=>$cm->course), '*', MUST_EXIST);
1265  
1266      } else if ($context->contextlevel == CONTEXT_BLOCK) {
1267          $parent = $context->get_parent_context();
1268  
1269          if ($parent->contextlevel == CONTEXT_COURSE) {
1270              $course = $DB->get_record('course', array('id'=>$parent->instanceid), '*', MUST_EXIST);
1271          } else if ($parent->contextlevel == CONTEXT_MODULE) {
1272              $cm = get_coursemodule_from_id('', $parent->instanceid, 0, false, MUST_EXIST);
1273              $course = $DB->get_record('course', array('id'=>$cm->course), '*', MUST_EXIST);
1274          }
1275      }
1276  
1277      return array($context, $course, $cm);
1278  }
1279  
1280  /**
1281   * Function that creates a role
1282   *
1283   * @param string $name role name
1284   * @param string $shortname role short name
1285   * @param string $description role description
1286   * @param string $archetype
1287   * @return int id or dml_exception
1288   */
1289  function create_role($name, $shortname, $description, $archetype = '') {
1290      global $DB;
1291  
1292      if (strpos($archetype, 'moodle/legacy:') !== false) {
1293          throw new coding_exception('Use new role archetype parameter in create_role() instead of old legacy capabilities.');
1294      }
1295  
1296      // verify role archetype actually exists
1297      $archetypes = get_role_archetypes();
1298      if (empty($archetypes[$archetype])) {
1299          $archetype = '';
1300      }
1301  
1302      // Insert the role record.
1303      $role = new stdClass();
1304      $role->name        = $name;
1305      $role->shortname   = $shortname;
1306      $role->description = $description;
1307      $role->archetype   = $archetype;
1308  
1309      //find free sortorder number
1310      $role->sortorder = $DB->get_field('role', 'MAX(sortorder) + 1', array());
1311      if (empty($role->sortorder)) {
1312          $role->sortorder = 1;
1313      }
1314      $id = $DB->insert_record('role', $role);
1315  
1316      return $id;
1317  }
1318  
1319  /**
1320   * Function that deletes a role and cleanups up after it
1321   *
1322   * @param int $roleid id of role to delete
1323   * @return bool always true
1324   */
1325  function delete_role($roleid) {
1326      global $DB;
1327  
1328      // first unssign all users
1329      role_unassign_all(array('roleid'=>$roleid));
1330  
1331      // cleanup all references to this role, ignore errors
1332      $DB->delete_records('role_capabilities',   array('roleid'=>$roleid));
1333      $DB->delete_records('role_allow_assign',   array('roleid'=>$roleid));
1334      $DB->delete_records('role_allow_assign',   array('allowassign'=>$roleid));
1335      $DB->delete_records('role_allow_override', array('roleid'=>$roleid));
1336      $DB->delete_records('role_allow_override', array('allowoverride'=>$roleid));
1337      $DB->delete_records('role_names',          array('roleid'=>$roleid));
1338      $DB->delete_records('role_context_levels', array('roleid'=>$roleid));
1339  
1340      // Get role record before it's deleted.
1341      $role = $DB->get_record('role', array('id'=>$roleid));
1342  
1343      // Finally delete the role itself.
1344      $DB->delete_records('role', array('id'=>$roleid));
1345  
1346      // Trigger event.
1347      $event = \core\event\role_deleted::create(
1348          array(
1349              'context' => context_system::instance(),
1350              'objectid' => $roleid,
1351              'other' =>
1352                  array(
1353                      'shortname' => $role->shortname,
1354                      'description' => $role->description,
1355                      'archetype' => $role->archetype
1356                  )
1357              )
1358          );
1359      $event->add_record_snapshot('role', $role);
1360      $event->trigger();
1361  
1362      // Reset any cache of this role, including MUC.
1363      accesslib_clear_role_cache($roleid);
1364  
1365      return true;
1366  }
1367  
1368  /**
1369   * Function to write context specific overrides, or default capabilities.
1370   *
1371   * @param string $capability string name
1372   * @param int $permission CAP_ constants
1373   * @param int $roleid role id
1374   * @param int|context $contextid context id
1375   * @param bool $overwrite
1376   * @return bool always true or exception
1377   */
1378  function assign_capability($capability, $permission, $roleid, $contextid, $overwrite = false) {
1379      global $USER, $DB;
1380  
1381      if ($contextid instanceof context) {
1382          $context = $contextid;
1383      } else {
1384          $context = context::instance_by_id($contextid);
1385      }
1386  
1387      // Capability must exist.
1388      if (!$capinfo = get_capability_info($capability)) {
1389          throw new coding_exception("Capability '{$capability}' was not found! This has to be fixed in code.");
1390      }
1391  
1392      if (empty($permission) || $permission == CAP_INHERIT) { // if permission is not set
1393          unassign_capability($capability, $roleid, $context->id);
1394          return true;
1395      }
1396  
1397      $existing = $DB->get_record('role_capabilities', array('contextid'=>$context->id, 'roleid'=>$roleid, 'capability'=>$capability));
1398  
1399      if ($existing and !$overwrite) {   // We want to keep whatever is there already
1400          return true;
1401      }
1402  
1403      $cap = new stdClass();
1404      $cap->contextid    = $context->id;
1405      $cap->roleid       = $roleid;
1406      $cap->capability   = $capability;
1407      $cap->permission   = $permission;
1408      $cap->timemodified = time();
1409      $cap->modifierid   = empty($USER->id) ? 0 : $USER->id;
1410  
1411      if ($existing) {
1412          $cap->id = $existing->id;
1413          $DB->update_record('role_capabilities', $cap);
1414      } else {
1415          if ($DB->record_exists('context', array('id'=>$context->id))) {
1416              $DB->insert_record('role_capabilities', $cap);
1417          }
1418      }
1419  
1420      // Trigger capability_assigned event.
1421      \core\event\capability_assigned::create([
1422          'userid' => $cap->modifierid,
1423          'context' => $context,
1424          'objectid' => $roleid,
1425          'other' => [
1426              'capability' => $capability,
1427              'oldpermission' => $existing->permission ?? CAP_INHERIT,
1428              'permission' => $permission
1429          ]
1430      ])->trigger();
1431  
1432      // Reset any cache of this role, including MUC.
1433      accesslib_clear_role_cache($roleid);
1434  
1435      return true;
1436  }
1437  
1438  /**
1439   * Unassign a capability from a role.
1440   *
1441   * @param string $capability the name of the capability
1442   * @param int $roleid the role id
1443   * @param int|context $contextid null means all contexts
1444   * @return boolean true or exception
1445   */
1446  function unassign_capability($capability, $roleid, $contextid = null) {
1447      global $DB, $USER;
1448  
1449      // Capability must exist.
1450      if (!$capinfo = get_capability_info($capability)) {
1451          throw new coding_exception("Capability '{$capability}' was not found! This has to be fixed in code.");
1452      }
1453  
1454      if (!empty($contextid)) {
1455          if ($contextid instanceof context) {
1456              $context = $contextid;
1457          } else {
1458              $context = context::instance_by_id($contextid);
1459          }
1460          // delete from context rel, if this is the last override in this context
1461          $DB->delete_records('role_capabilities', array('capability'=>$capability, 'roleid'=>$roleid, 'contextid'=>$context->id));
1462      } else {
1463          $DB->delete_records('role_capabilities', array('capability'=>$capability, 'roleid'=>$roleid));
1464      }
1465  
1466      // Trigger capability_assigned event.
1467      \core\event\capability_unassigned::create([
1468          'userid' => $USER->id,
1469          'context' => $context ?? context_system::instance(),
1470          'objectid' => $roleid,
1471          'other' => [
1472              'capability' => $capability,
1473          ]
1474      ])->trigger();
1475  
1476      // Reset any cache of this role, including MUC.
1477      accesslib_clear_role_cache($roleid);
1478  
1479      return true;
1480  }
1481  
1482  /**
1483   * Get the roles that have a given capability assigned to it
1484   *
1485   * This function does not resolve the actual permission of the capability.
1486   * It just checks for permissions and overrides.
1487   * Use get_roles_with_cap_in_context() if resolution is required.
1488   *
1489   * @param string $capability capability name (string)
1490   * @param string $permission optional, the permission defined for this capability
1491   *                      either CAP_ALLOW, CAP_PREVENT or CAP_PROHIBIT. Defaults to null which means any.
1492   * @param stdClass $context null means any
1493   * @return array of role records
1494   */
1495  function get_roles_with_capability($capability, $permission = null, $context = null) {
1496      global $DB;
1497  
1498      if ($context) {
1499          $contexts = $context->get_parent_context_ids(true);
1500          list($insql, $params) = $DB->get_in_or_equal($contexts, SQL_PARAMS_NAMED, 'ctx');
1501          $contextsql = "AND rc.contextid $insql";
1502      } else {
1503          $params = array();
1504          $contextsql = '';
1505      }
1506  
1507      if ($permission) {
1508          $permissionsql = " AND rc.permission = :permission";
1509          $params['permission'] = $permission;
1510      } else {
1511          $permissionsql = '';
1512      }
1513  
1514      $sql = "SELECT r.*
1515                FROM {role} r
1516               WHERE r.id IN (SELECT rc.roleid
1517                                FROM {role_capabilities} rc
1518                                JOIN {capabilities} cap ON rc.capability = cap.name
1519                               WHERE rc.capability = :capname
1520                                     $contextsql
1521                                     $permissionsql)";
1522      $params['capname'] = $capability;
1523  
1524  
1525      return $DB->get_records_sql($sql, $params);
1526  }
1527  
1528  /**
1529   * This function makes a role-assignment (a role for a user in a particular context)
1530   *
1531   * @param int $roleid the role of the id
1532   * @param int $userid userid
1533   * @param int|context $contextid id of the context
1534   * @param string $component example 'enrol_ldap', defaults to '' which means manual assignment,
1535   * @param int $itemid id of enrolment/auth plugin
1536   * @param string $timemodified defaults to current time
1537   * @return int new/existing id of the assignment
1538   */
1539  function role_assign($roleid, $userid, $contextid, $component = '', $itemid = 0, $timemodified = '') {
1540      global $USER, $DB;
1541  
1542      // first of all detect if somebody is using old style parameters
1543      if ($contextid === 0 or is_numeric($component)) {
1544          throw new coding_exception('Invalid call to role_assign(), code needs to be updated to use new order of parameters');
1545      }
1546  
1547      // now validate all parameters
1548      if (empty($roleid)) {
1549          throw new coding_exception('Invalid call to role_assign(), roleid can not be empty');
1550      }
1551  
1552      if (empty($userid)) {
1553          throw new coding_exception('Invalid call to role_assign(), userid can not be empty');
1554      }
1555  
1556      if ($itemid) {
1557          if (strpos($component, '_') === false) {
1558              throw new coding_exception('Invalid call to role_assign(), component must start with plugin type such as"enrol_" when itemid specified', 'component:'.$component);
1559          }
1560      } else {
1561          $itemid = 0;
1562          if ($component !== '' and strpos($component, '_') === false) {
1563              throw new coding_exception('Invalid call to role_assign(), invalid component string', 'component:'.$component);
1564          }
1565      }
1566  
1567      if (!$DB->record_exists('user', array('id'=>$userid, 'deleted'=>0))) {
1568          throw new coding_exception('User ID does not exist or is deleted!', 'userid:'.$userid);
1569      }
1570  
1571      if ($contextid instanceof context) {
1572          $context = $contextid;
1573      } else {
1574          $context = context::instance_by_id($contextid, MUST_EXIST);
1575      }
1576  
1577      if (!$timemodified) {
1578          $timemodified = time();
1579      }
1580  
1581      // Check for existing entry
1582      $ras = $DB->get_records('role_assignments', array('roleid'=>$roleid, 'contextid'=>$context->id, 'userid'=>$userid, 'component'=>$component, 'itemid'=>$itemid), 'id');
1583  
1584      if ($ras) {
1585          // role already assigned - this should not happen
1586          if (count($ras) > 1) {
1587              // very weird - remove all duplicates!
1588              $ra = array_shift($ras);
1589              foreach ($ras as $r) {
1590                  $DB->delete_records('role_assignments', array('id'=>$r->id));
1591              }
1592          } else {
1593              $ra = reset($ras);
1594          }
1595  
1596          // actually there is no need to update, reset anything or trigger any event, so just return
1597          return $ra->id;
1598      }
1599  
1600      // Create a new entry
1601      $ra = new stdClass();
1602      $ra->roleid       = $roleid;
1603      $ra->contextid    = $context->id;
1604      $ra->userid       = $userid;
1605      $ra->component    = $component;
1606      $ra->itemid       = $itemid;
1607      $ra->timemodified = $timemodified;
1608      $ra->modifierid   = empty($USER->id) ? 0 : $USER->id;
1609      $ra->sortorder    = 0;
1610  
1611      $ra->id = $DB->insert_record('role_assignments', $ra);
1612  
1613      // Role assignments have changed, so mark user as dirty.
1614      mark_user_dirty($userid);
1615  
1616      core_course_category::role_assignment_changed($roleid, $context);
1617  
1618      $event = \core\event\role_assigned::create(array(
1619          'context' => $context,
1620          'objectid' => $ra->roleid,
1621          'relateduserid' => $ra->userid,
1622          'other' => array(
1623              'id' => $ra->id,
1624              'component' => $ra->component,
1625              'itemid' => $ra->itemid
1626          )
1627      ));
1628      $event->add_record_snapshot('role_assignments', $ra);
1629      $event->trigger();
1630  
1631      return $ra->id;
1632  }
1633  
1634  /**
1635   * Removes one role assignment
1636   *
1637   * @param int $roleid
1638   * @param int  $userid
1639   * @param int  $contextid
1640   * @param string $component
1641   * @param int  $itemid
1642   * @return void
1643   */
1644  function role_unassign($roleid, $userid, $contextid, $component = '', $itemid = 0) {
1645      // first make sure the params make sense
1646      if ($roleid == 0 or $userid == 0 or $contextid == 0) {
1647          throw new coding_exception('Invalid call to role_unassign(), please use role_unassign_all() when removing multiple role assignments');
1648      }
1649  
1650      if ($itemid) {
1651          if (strpos($component, '_') === false) {
1652              throw new coding_exception('Invalid call to role_assign(), component must start with plugin type such as "enrol_" when itemid specified', 'component:'.$component);
1653          }
1654      } else {
1655          $itemid = 0;
1656          if ($component !== '' and strpos($component, '_') === false) {
1657              throw new coding_exception('Invalid call to role_assign(), invalid component string', 'component:'.$component);
1658          }
1659      }
1660  
1661      role_unassign_all(array('roleid'=>$roleid, 'userid'=>$userid, 'contextid'=>$contextid, 'component'=>$component, 'itemid'=>$itemid), false, false);
1662  }
1663  
1664  /**
1665   * Removes multiple role assignments, parameters may contain:
1666   *   'roleid', 'userid', 'contextid', 'component', 'enrolid'.
1667   *
1668   * @param array $params role assignment parameters
1669   * @param bool $subcontexts unassign in subcontexts too
1670   * @param bool $includemanual include manual role assignments too
1671   * @return void
1672   */
1673  function role_unassign_all(array $params, $subcontexts = false, $includemanual = false) {
1674      global $USER, $CFG, $DB;
1675  
1676      if (!$params) {
1677          throw new coding_exception('Missing parameters in role_unsassign_all() call');
1678      }
1679  
1680      $allowed = array('roleid', 'userid', 'contextid', 'component', 'itemid');
1681      foreach ($params as $key=>$value) {
1682          if (!in_array($key, $allowed)) {
1683              throw new coding_exception('Unknown role_unsassign_all() parameter key', 'key:'.$key);
1684          }
1685      }
1686  
1687      if (isset($params['component']) and $params['component'] !== '' and strpos($params['component'], '_') === false) {
1688          throw new coding_exception('Invalid component paramter in role_unsassign_all() call', 'component:'.$params['component']);
1689      }
1690  
1691      if ($includemanual) {
1692          if (!isset($params['component']) or $params['component'] === '') {
1693              throw new coding_exception('include manual parameter requires component parameter in role_unsassign_all() call');
1694          }
1695      }
1696  
1697      if ($subcontexts) {
1698          if (empty($params['contextid'])) {
1699              throw new coding_exception('subcontexts paramtere requires component parameter in role_unsassign_all() call');
1700          }
1701      }
1702  
1703      $ras = $DB->get_records('role_assignments', $params);
1704      foreach ($ras as $ra) {
1705          $DB->delete_records('role_assignments', array('id'=>$ra->id));
1706          if ($context = context::instance_by_id($ra->contextid, IGNORE_MISSING)) {
1707              // Role assignments have changed, so mark user as dirty.
1708              mark_user_dirty($ra->userid);
1709  
1710              $event = \core\event\role_unassigned::create(array(
1711                  'context' => $context,
1712                  'objectid' => $ra->roleid,
1713                  'relateduserid' => $ra->userid,
1714                  'other' => array(
1715                      'id' => $ra->id,
1716                      'component' => $ra->component,
1717                      'itemid' => $ra->itemid
1718                  )
1719              ));
1720              $event->add_record_snapshot('role_assignments', $ra);
1721              $event->trigger();
1722              core_course_category::role_assignment_changed($ra->roleid, $context);
1723          }
1724      }
1725      unset($ras);
1726  
1727      // process subcontexts
1728      if ($subcontexts and $context = context::instance_by_id($params['contextid'], IGNORE_MISSING)) {
1729          if ($params['contextid'] instanceof context) {
1730              $context = $params['contextid'];
1731          } else {
1732              $context = context::instance_by_id($params['contextid'], IGNORE_MISSING);
1733          }
1734  
1735          if ($context) {
1736              $contexts = $context->get_child_contexts();
1737              $mparams = $params;
1738              foreach ($contexts as $context) {
1739                  $mparams['contextid'] = $context->id;
1740                  $ras = $DB->get_records('role_assignments', $mparams);
1741                  foreach ($ras as $ra) {
1742                      $DB->delete_records('role_assignments', array('id'=>$ra->id));
1743                      // Role assignments have changed, so mark user as dirty.
1744                      mark_user_dirty($ra->userid);
1745  
1746                      $event = \core\event\role_unassigned::create(
1747                          array('context'=>$context, 'objectid'=>$ra->roleid, 'relateduserid'=>$ra->userid,
1748                              'other'=>array('id'=>$ra->id, 'component'=>$ra->component, 'itemid'=>$ra->itemid)));
1749                      $event->add_record_snapshot('role_assignments', $ra);
1750                      $event->trigger();
1751                      core_course_category::role_assignment_changed($ra->roleid, $context);
1752                  }
1753              }
1754          }
1755      }
1756  
1757      // do this once more for all manual role assignments
1758      if ($includemanual) {
1759          $params['component'] = '';
1760          role_unassign_all($params, $subcontexts, false);
1761      }
1762  }
1763  
1764  /**
1765   * Mark a user as dirty (with timestamp) so as to force reloading of the user session.
1766   *
1767   * @param int $userid
1768   * @return void
1769   */
1770  function mark_user_dirty($userid) {
1771      global $CFG, $ACCESSLIB_PRIVATE;
1772  
1773      if (during_initial_install()) {
1774          return;
1775      }
1776  
1777      // Throw exception if invalid userid is provided.
1778      if (empty($userid)) {
1779          throw new coding_exception('Invalid user parameter supplied for mark_user_dirty() function!');
1780      }
1781  
1782      // Set dirty flag in database, set dirty field locally, and clear local accessdata cache.
1783      set_cache_flag('accesslib/dirtyusers', $userid, 1, time() + $CFG->sessiontimeout);
1784      $ACCESSLIB_PRIVATE->dirtyusers[$userid] = 1;
1785      unset($ACCESSLIB_PRIVATE->accessdatabyuser[$userid]);
1786  }
1787  
1788  /**
1789   * Determines if a user is currently logged in
1790   *
1791   * @category   access
1792   *
1793   * @return bool
1794   */
1795  function isloggedin() {
1796      global $USER;
1797  
1798      return (!empty($USER->id));
1799  }
1800  
1801  /**
1802   * Determines if a user is logged in as real guest user with username 'guest'.
1803   *
1804   * @category   access
1805   *
1806   * @param int|object $user mixed user object or id, $USER if not specified
1807   * @return bool true if user is the real guest user, false if not logged in or other user
1808   */
1809  function isguestuser($user = null) {
1810      global $USER, $DB, $CFG;
1811  
1812      // make sure we have the user id cached in config table, because we are going to use it a lot
1813      if (empty($CFG->siteguest)) {
1814          if (!$guestid = $DB->get_field('user', 'id', array('username'=>'guest', 'mnethostid'=>$CFG->mnet_localhost_id))) {
1815              // guest does not exist yet, weird
1816              return false;
1817          }
1818          set_config('siteguest', $guestid);
1819      }
1820      if ($user === null) {
1821          $user = $USER;
1822      }
1823  
1824      if ($user === null) {
1825          // happens when setting the $USER
1826          return false;
1827  
1828      } else if (is_numeric($user)) {
1829          return ($CFG->siteguest == $user);
1830  
1831      } else if (is_object($user)) {
1832          if (empty($user->id)) {
1833              return false; // not logged in means is not be guest
1834          } else {
1835              return ($CFG->siteguest == $user->id);
1836          }
1837  
1838      } else {
1839          throw new coding_exception('Invalid user parameter supplied for isguestuser() function!');
1840      }
1841  }
1842  
1843  /**
1844   * Does user have a (temporary or real) guest access to course?
1845   *
1846   * @category   access
1847   *
1848   * @param context $context
1849   * @param stdClass|int $user
1850   * @return bool
1851   */
1852  function is_guest(context $context, $user = null) {
1853      global $USER;
1854  
1855      // first find the course context
1856      $coursecontext = $context->get_course_context();
1857  
1858      // make sure there is a real user specified
1859      if ($user === null) {
1860          $userid = isset($USER->id) ? $USER->id : 0;
1861      } else {
1862          $userid = is_object($user) ? $user->id : $user;
1863      }
1864  
1865      if (isguestuser($userid)) {
1866          // can not inspect or be enrolled
1867          return true;
1868      }
1869  
1870      if (has_capability('moodle/course:view', $coursecontext, $user)) {
1871          // viewing users appear out of nowhere, they are neither guests nor participants
1872          return false;
1873      }
1874  
1875      // consider only real active enrolments here
1876      if (is_enrolled($coursecontext, $user, '', true)) {
1877          return false;
1878      }
1879  
1880      return true;
1881  }
1882  
1883  /**
1884   * Returns true if the user has moodle/course:view capability in the course,
1885   * this is intended for admins, managers (aka small admins), inspectors, etc.
1886   *
1887   * @category   access
1888   *
1889   * @param context $context
1890   * @param int|stdClass $user if null $USER is used
1891   * @param string $withcapability extra capability name
1892   * @return bool
1893   */
1894  function is_viewing(context $context, $user = null, $withcapability = '') {
1895      // first find the course context
1896      $coursecontext = $context->get_course_context();
1897  
1898      if (isguestuser($user)) {
1899          // can not inspect
1900          return false;
1901      }
1902  
1903      if (!has_capability('moodle/course:view', $coursecontext, $user)) {
1904          // admins are allowed to inspect courses
1905          return false;
1906      }
1907  
1908      if ($withcapability and !has_capability($withcapability, $context, $user)) {
1909          // site admins always have the capability, but the enrolment above blocks
1910          return false;
1911      }
1912  
1913      return true;
1914  }
1915  
1916  /**
1917   * Returns true if the user is able to access the course.
1918   *
1919   * This function is in no way, shape, or form a substitute for require_login.
1920   * It should only be used in circumstances where it is not possible to call require_login
1921   * such as the navigation.
1922   *
1923   * This function checks many of the methods of access to a course such as the view
1924   * capability, enrollments, and guest access. It also makes use of the cache
1925   * generated by require_login for guest access.
1926   *
1927   * The flags within the $USER object that are used here should NEVER be used outside
1928   * of this function can_access_course and require_login. Doing so WILL break future
1929   * versions.
1930   *
1931   * @param stdClass $course record
1932   * @param stdClass|int|null $user user record or id, current user if null
1933   * @param string $withcapability Check for this capability as well.
1934   * @param bool $onlyactive consider only active enrolments in enabled plugins and time restrictions
1935   * @return boolean Returns true if the user is able to access the course
1936   */
1937  function can_access_course(stdClass $course, $user = null, $withcapability = '', $onlyactive = false) {
1938      global $DB, $USER;
1939  
1940      // this function originally accepted $coursecontext parameter
1941      if ($course instanceof context) {
1942          if ($course instanceof context_course) {
1943              debugging('deprecated context parameter, please use $course record');
1944              $coursecontext = $course;
1945              $course = $DB->get_record('course', array('id'=>$coursecontext->instanceid));
1946          } else {
1947              debugging('Invalid context parameter, please use $course record');
1948              return false;
1949          }
1950      } else {
1951          $coursecontext = context_course::instance($course->id);
1952      }
1953  
1954      if (!isset($USER->id)) {
1955          // should never happen
1956          $USER->id = 0;
1957          debugging('Course access check being performed on a user with no ID.', DEBUG_DEVELOPER);
1958      }
1959  
1960      // make sure there is a user specified
1961      if ($user === null) {
1962          $userid = $USER->id;
1963      } else {
1964          $userid = is_object($user) ? $user->id : $user;
1965      }
1966      unset($user);
1967  
1968      if ($withcapability and !has_capability($withcapability, $coursecontext, $userid)) {
1969          return false;
1970      }
1971  
1972      if ($userid == $USER->id) {
1973          if (!empty($USER->access['rsw'][$coursecontext->path])) {
1974              // the fact that somebody switched role means they can access the course no matter to what role they switched
1975              return true;
1976          }
1977      }
1978  
1979      if (!$course->visible and !has_capability('moodle/course:viewhiddencourses', $coursecontext, $userid)) {
1980          return false;
1981      }
1982  
1983      if (is_viewing($coursecontext, $userid)) {
1984          return true;
1985      }
1986  
1987      if ($userid != $USER->id) {
1988          // for performance reasons we do not verify temporary guest access for other users, sorry...
1989          return is_enrolled($coursecontext, $userid, '', $onlyactive);
1990      }
1991  
1992      // === from here we deal only with $USER ===
1993  
1994      $coursecontext->reload_if_dirty();
1995  
1996      if (isset($USER->enrol['enrolled'][$course->id])) {
1997          if ($USER->enrol['enrolled'][$course->id] > time()) {
1998              return true;
1999          }
2000      }
2001      if (isset($USER->enrol['tempguest'][$course->id])) {
2002          if ($USER->enrol['tempguest'][$course->id] > time()) {
2003              return true;
2004          }
2005      }
2006  
2007      if (is_enrolled($coursecontext, $USER, '', $onlyactive)) {
2008          return true;
2009      }
2010  
2011      if (!core_course_category::can_view_course_info($course)) {
2012          // No guest access if user does not have capability to browse courses.
2013          return false;
2014      }
2015  
2016      // if not enrolled try to gain temporary guest access
2017      $instances = $DB->get_records('enrol', array('courseid'=>$course->id, 'status'=>ENROL_INSTANCE_ENABLED), 'sortorder, id ASC');
2018      $enrols = enrol_get_plugins(true);
2019      foreach ($instances as $instance) {
2020          if (!isset($enrols[$instance->enrol])) {
2021              continue;
2022          }
2023          // Get a duration for the guest access, a timestamp in the future, 0 (always) or false.
2024          $until = $enrols[$instance->enrol]->try_guestaccess($instance);
2025          if ($until !== false and $until > time()) {
2026              $USER->enrol['tempguest'][$course->id] = $until;
2027              return true;
2028          }
2029      }
2030      if (isset($USER->enrol['tempguest'][$course->id])) {
2031          unset($USER->enrol['tempguest'][$course->id]);
2032          remove_temp_course_roles($coursecontext);
2033      }
2034  
2035      return false;
2036  }
2037  
2038  /**
2039   * Loads the capability definitions for the component (from file).
2040   *
2041   * Loads the capability definitions for the component (from file). If no
2042   * capabilities are defined for the component, we simply return an empty array.
2043   *
2044   * @access private
2045   * @param string $component full plugin name, examples: 'moodle', 'mod_forum'
2046   * @return array array of capabilities
2047   */
2048  function load_capability_def($component) {
2049      $defpath = core_component::get_component_directory($component).'/db/access.php';
2050  
2051      $capabilities = array();
2052      if (file_exists($defpath)) {
2053          require($defpath);
2054          if (!empty(${$component.'_capabilities'})) {
2055              // BC capability array name
2056              // since 2.0 we prefer $capabilities instead - it is easier to use and matches db/* files
2057              debugging('componentname_capabilities array is deprecated, please use $capabilities array only in access.php files');
2058              $capabilities = ${$component.'_capabilities'};
2059          }
2060      }
2061  
2062      return $capabilities;
2063  }
2064  
2065  /**
2066   * Gets the capabilities that have been cached in the database for this component.
2067   *
2068   * @access private
2069   * @param string $component - examples: 'moodle', 'mod_forum'
2070   * @return array array of capabilities
2071   */
2072  function get_cached_capabilities($component = 'moodle') {
2073      global $DB;
2074      $caps = get_all_capabilities();
2075      $componentcaps = array();
2076      foreach ($caps as $cap) {
2077          if ($cap['component'] == $component) {
2078              $componentcaps[] = (object) $cap;
2079          }
2080      }
2081      return $componentcaps;
2082  }
2083  
2084  /**
2085   * Returns default capabilities for given role archetype.
2086   *
2087   * @param string $archetype role archetype
2088   * @return array
2089   */
2090  function get_default_capabilities($archetype) {
2091      global $DB;
2092  
2093      if (!$archetype) {
2094          return array();
2095      }
2096  
2097      $alldefs = array();
2098      $defaults = array();
2099      $components = array();
2100      $allcaps = get_all_capabilities();
2101  
2102      foreach ($allcaps as $cap) {
2103          if (!in_array($cap['component'], $components)) {
2104              $components[] = $cap['component'];
2105              $alldefs = array_merge($alldefs, load_capability_def($cap['component']));
2106          }
2107      }
2108      foreach ($alldefs as $name=>$def) {
2109          // Use array 'archetypes if available. Only if not specified, use 'legacy'.
2110          if (isset($def['archetypes'])) {
2111              if (isset($def['archetypes'][$archetype])) {
2112                  $defaults[$name] = $def['archetypes'][$archetype];
2113              }
2114          // 'legacy' is for backward compatibility with 1.9 access.php
2115          } else {
2116              if (isset($def['legacy'][$archetype])) {
2117                  $defaults[$name] = $def['legacy'][$archetype];
2118              }
2119          }
2120      }
2121  
2122      return $defaults;
2123  }
2124  
2125  /**
2126   * Return default roles that can be assigned, overridden or switched
2127   * by give role archetype.
2128   *
2129   * @param string $type  assign|override|switch|view
2130   * @param string $archetype
2131   * @return array of role ids
2132   */
2133  function get_default_role_archetype_allows($type, $archetype) {
2134      global $DB;
2135  
2136      if (empty($archetype)) {
2137          return array();
2138      }
2139  
2140      $roles = $DB->get_records('role');
2141      $archetypemap = array();
2142      foreach ($roles as $role) {
2143          if ($role->archetype) {
2144              $archetypemap[$role->archetype][$role->id] = $role->id;
2145          }
2146      }
2147  
2148      $defaults = array(
2149          'assign' => array(
2150              'manager'        => array('manager', 'coursecreator', 'editingteacher', 'teacher', 'student'),
2151              'coursecreator'  => array(),
2152              'editingteacher' => array('teacher', 'student'),
2153              'teacher'        => array(),
2154              'student'        => array(),
2155              'guest'          => array(),
2156              'user'           => array(),
2157              'frontpage'      => array(),
2158          ),
2159          'override' => array(
2160              'manager'        => array('manager', 'coursecreator', 'editingteacher', 'teacher', 'student', 'guest', 'user', 'frontpage'),
2161              'coursecreator'  => array(),
2162              'editingteacher' => array('teacher', 'student', 'guest'),
2163              'teacher'        => array(),
2164              'student'        => array(),
2165              'guest'          => array(),
2166              'user'           => array(),
2167              'frontpage'      => array(),
2168          ),
2169          'switch' => array(
2170              'manager'        => array('editingteacher', 'teacher', 'student', 'guest'),
2171              'coursecreator'  => array(),
2172              'editingteacher' => array('teacher', 'student', 'guest'),
2173              'teacher'        => array('student', 'guest'),
2174              'student'        => array(),
2175              'guest'          => array(),
2176              'user'           => array(),
2177              'frontpage'      => array(),
2178          ),
2179          'view' => array(
2180              'manager'        => array('manager', 'coursecreator', 'editingteacher', 'teacher', 'student', 'guest', 'user', 'frontpage'),
2181              'coursecreator'  => array('coursecreator', 'editingteacher', 'teacher', 'student'),
2182              'editingteacher' => array('coursecreator', 'editingteacher', 'teacher', 'student'),
2183              'teacher'        => array('coursecreator', 'editingteacher', 'teacher', 'student'),
2184              'student'        => array('coursecreator', 'editingteacher', 'teacher', 'student'),
2185              'guest'          => array(),
2186              'user'           => array(),
2187              'frontpage'      => array(),
2188          ),
2189      );
2190  
2191      if (!isset($defaults[$type][$archetype])) {
2192          debugging("Unknown type '$type'' or archetype '$archetype''");
2193          return array();
2194      }
2195  
2196      $return = array();
2197      foreach ($defaults[$type][$archetype] as $at) {
2198          if (isset($archetypemap[$at])) {
2199              foreach ($archetypemap[$at] as $roleid) {
2200                  $return[$roleid] = $roleid;
2201              }
2202          }
2203      }
2204  
2205      return $return;
2206  }
2207  
2208  /**
2209   * Reset role capabilities to default according to selected role archetype.
2210   * If no archetype selected, removes all capabilities.
2211   *
2212   * This applies to capabilities that are assigned to the role (that you could
2213   * edit in the 'define roles' interface), and not to any capability overrides
2214   * in different locations.
2215   *
2216   * @param int $roleid ID of role to reset capabilities for
2217   */
2218  function reset_role_capabilities($roleid) {
2219      global $DB;
2220  
2221      $role = $DB->get_record('role', array('id'=>$roleid), '*', MUST_EXIST);
2222      $defaultcaps = get_default_capabilities($role->archetype);
2223  
2224      $systemcontext = context_system::instance();
2225  
2226      $DB->delete_records('role_capabilities',
2227              array('roleid' => $roleid, 'contextid' => $systemcontext->id));
2228  
2229      foreach ($defaultcaps as $cap=>$permission) {
2230          assign_capability($cap, $permission, $roleid, $systemcontext->id);
2231      }
2232  
2233      // Reset any cache of this role, including MUC.
2234      accesslib_clear_role_cache($roleid);
2235  }
2236  
2237  /**
2238   * Updates the capabilities table with the component capability definitions.
2239   * If no parameters are given, the function updates the core moodle
2240   * capabilities.
2241   *
2242   * Note that the absence of the db/access.php capabilities definition file
2243   * will cause any stored capabilities for the component to be removed from
2244   * the database.
2245   *
2246   * @access private
2247   * @param string $component examples: 'moodle', 'mod_forum', 'block_quiz_results'
2248   * @return boolean true if success, exception in case of any problems
2249   */
2250  function update_capabilities($component = 'moodle') {
2251      global $DB, $OUTPUT;
2252  
2253      $storedcaps = array();
2254  
2255      $filecaps = load_capability_def($component);
2256      foreach ($filecaps as $capname=>$unused) {
2257          if (!preg_match('|^[a-z]+/[a-z_0-9]+:[a-z_0-9]+$|', $capname)) {
2258              debugging("Coding problem: Invalid capability name '$capname', use 'clonepermissionsfrom' field for migration.");
2259          }
2260      }
2261  
2262      // It is possible somebody directly modified the DB (according to accesslib_test anyway).
2263      // So ensure our updating is based on fresh data.
2264      cache::make('core', 'capabilities')->delete('core_capabilities');
2265  
2266      $cachedcaps = get_cached_capabilities($component);
2267      if ($cachedcaps) {
2268          foreach ($cachedcaps as $cachedcap) {
2269              array_push($storedcaps, $cachedcap->name);
2270              // update risk bitmasks and context levels in existing capabilities if needed
2271              if (array_key_exists($cachedcap->name, $filecaps)) {
2272                  if (!array_key_exists('riskbitmask', $filecaps[$cachedcap->name])) {
2273                      $filecaps[$cachedcap->name]['riskbitmask'] = 0; // no risk if not specified
2274                  }
2275                  if ($cachedcap->captype != $filecaps[$cachedcap->name]['captype']) {
2276                      $updatecap = new stdClass();
2277                      $updatecap->id = $cachedcap->id;
2278                      $updatecap->captype = $filecaps[$cachedcap->name]['captype'];
2279                      $DB->update_record('capabilities', $updatecap);
2280                  }
2281                  if ($cachedcap->riskbitmask != $filecaps[$cachedcap->name]['riskbitmask']) {
2282                      $updatecap = new stdClass();
2283                      $updatecap->id = $cachedcap->id;
2284                      $updatecap->riskbitmask = $filecaps[$cachedcap->name]['riskbitmask'];
2285                      $DB->update_record('capabilities', $updatecap);
2286                  }
2287  
2288                  if (!array_key_exists('contextlevel', $filecaps[$cachedcap->name])) {
2289                      $filecaps[$cachedcap->name]['contextlevel'] = 0; // no context level defined
2290                  }
2291                  if ($cachedcap->contextlevel != $filecaps[$cachedcap->name]['contextlevel']) {
2292                      $updatecap = new stdClass();
2293                      $updatecap->id = $cachedcap->id;
2294                      $updatecap->contextlevel = $filecaps[$cachedcap->name]['contextlevel'];
2295                      $DB->update_record('capabilities', $updatecap);
2296                  }
2297              }
2298          }
2299      }
2300  
2301      // Flush the cached again, as we have changed DB.
2302      cache::make('core', 'capabilities')->delete('core_capabilities');
2303  
2304      // Are there new capabilities in the file definition?
2305      $newcaps = array();
2306  
2307      foreach ($filecaps as $filecap => $def) {
2308          if (!$storedcaps ||
2309                  ($storedcaps && in_array($filecap, $storedcaps) === false)) {
2310              if (!array_key_exists('riskbitmask', $def)) {
2311                  $def['riskbitmask'] = 0; // no risk if not specified
2312              }
2313              $newcaps[$filecap] = $def;
2314          }
2315      }
2316      // Add new capabilities to the stored definition.
2317      $existingcaps = $DB->get_records_menu('capabilities', array(), 'id', 'id, name');
2318      foreach ($newcaps as $capname => $capdef) {
2319          $capability = new stdClass();
2320          $capability->name         = $capname;
2321          $capability->captype      = $capdef['captype'];
2322          $capability->contextlevel = $capdef['contextlevel'];
2323          $capability->component    = $component;
2324          $capability->riskbitmask  = $capdef['riskbitmask'];
2325  
2326          $DB->insert_record('capabilities', $capability, false);
2327  
2328          // Flush the cached, as we have changed DB.
2329          cache::make('core', 'capabilities')->delete('core_capabilities');
2330  
2331          if (isset($capdef['clonepermissionsfrom']) && in_array($capdef['clonepermissionsfrom'], $existingcaps)){
2332              if ($rolecapabilities = $DB->get_records('role_capabilities', array('capability'=>$capdef['clonepermissionsfrom']))){
2333                  foreach ($rolecapabilities as $rolecapability){
2334                      //assign_capability will update rather than insert if capability exists
2335                      if (!assign_capability($capname, $rolecapability->permission,
2336                                              $rolecapability->roleid, $rolecapability->contextid, true)){
2337                           echo $OUTPUT->notification('Could not clone capabilities for '.$capname);
2338                      }
2339                  }
2340              }
2341          // we ignore archetype key if we have cloned permissions
2342          } else if (isset($capdef['archetypes']) && is_array($capdef['archetypes'])) {
2343              assign_legacy_capabilities($capname, $capdef['archetypes']);
2344          // 'legacy' is for backward compatibility with 1.9 access.php
2345          } else if (isset($capdef['legacy']) && is_array($capdef['legacy'])) {
2346              assign_legacy_capabilities($capname, $capdef['legacy']);
2347          }
2348      }
2349      // Are there any capabilities that have been removed from the file
2350      // definition that we need to delete from the stored capabilities and
2351      // role assignments?
2352      capabilities_cleanup($component, $filecaps);
2353  
2354      // reset static caches
2355      accesslib_reset_role_cache();
2356  
2357      // Flush the cached again, as we have changed DB.
2358      cache::make('core', 'capabilities')->delete('core_capabilities');
2359  
2360      return true;
2361  }
2362  
2363  /**
2364   * Deletes cached capabilities that are no longer needed by the component.
2365   * Also unassigns these capabilities from any roles that have them.
2366   * NOTE: this function is called from lib/db/upgrade.php
2367   *
2368   * @access private
2369   * @param string $component examples: 'moodle', 'mod_forum', 'block_quiz_results'
2370   * @param array $newcapdef array of the new capability definitions that will be
2371   *                     compared with the cached capabilities
2372   * @return int number of deprecated capabilities that have been removed
2373   */
2374  function capabilities_cleanup($component, $newcapdef = null) {
2375      global $DB;
2376  
2377      $removedcount = 0;
2378  
2379      if ($cachedcaps = get_cached_capabilities($component)) {
2380          foreach ($cachedcaps as $cachedcap) {
2381              if (empty($newcapdef) ||
2382                          array_key_exists($cachedcap->name, $newcapdef) === false) {
2383  
2384                  // Delete from roles.
2385                  if ($roles = get_roles_with_capability($cachedcap->name)) {
2386                      foreach ($roles as $role) {
2387                          if (!unassign_capability($cachedcap->name, $role->id)) {
2388                              print_error('cannotunassigncap', 'error', '', (object)array('cap'=>$cachedcap->name, 'role'=>$role->name));
2389                          }
2390                      }
2391                  }
2392  
2393                  // Remove from role_capabilities for any old ones.
2394                  $DB->delete_records('role_capabilities', array('capability' => $cachedcap->name));
2395  
2396                  // Remove from capabilities cache.
2397                  $DB->delete_records('capabilities', array('name' => $cachedcap->name));
2398                  $removedcount++;
2399              } // End if.
2400          }
2401      }
2402      if ($removedcount) {
2403          cache::make('core', 'capabilities')->delete('core_capabilities');
2404      }
2405      return $removedcount;
2406  }
2407  
2408  /**
2409   * Returns an array of all the known types of risk
2410   * The array keys can be used, for example as CSS class names, or in calls to
2411   * print_risk_icon. The values are the corresponding RISK_ constants.
2412   *
2413   * @return array all the known types of risk.
2414   */
2415  function get_all_risks() {
2416      return array(
2417          'riskmanagetrust' => RISK_MANAGETRUST,
2418          'riskconfig'      => RISK_CONFIG,
2419          'riskxss'         => RISK_XSS,
2420          'riskpersonal'    => RISK_PERSONAL,
2421          'riskspam'        => RISK_SPAM,
2422          'riskdataloss'    => RISK_DATALOSS,
2423      );
2424  }
2425  
2426  /**
2427   * Return a link to moodle docs for a given capability name
2428   *
2429   * @param stdClass $capability a capability - a row from the mdl_capabilities table.
2430   * @return string the human-readable capability name as a link to Moodle Docs.
2431   */
2432  function get_capability_docs_link($capability) {
2433      $url = get_docs_url('Capabilities/' . $capability->name);
2434      return '<a onclick="this.target=\'docspopup\'" href="' . $url . '">' . get_capability_string($capability->name) . '</a>';
2435  }
2436  
2437  /**
2438   * This function pulls out all the resolved capabilities (overrides and
2439   * defaults) of a role used in capability overrides in contexts at a given
2440   * context.
2441   *
2442   * @param int $roleid
2443   * @param context $context
2444   * @param string $cap capability, optional, defaults to ''
2445   * @return array Array of capabilities
2446   */
2447  function role_context_capabilities($roleid, context $context, $cap = '') {
2448      global $DB;
2449  
2450      $contexts = $context->get_parent_context_ids(true);
2451      $contexts = '('.implode(',', $contexts).')';
2452  
2453      $params = array($roleid);
2454  
2455      if ($cap) {
2456          $search = " AND rc.capability = ? ";
2457          $params[] = $cap;
2458      } else {
2459          $search = '';
2460      }
2461  
2462      $sql = "SELECT rc.*
2463                FROM {role_capabilities} rc
2464                JOIN {context} c ON rc.contextid = c.id
2465                JOIN {capabilities} cap ON rc.capability = cap.name
2466               WHERE rc.contextid in $contexts
2467                     AND rc.roleid = ?
2468                     $search
2469            ORDER BY c.contextlevel DESC, rc.capability DESC";
2470  
2471      $capabilities = array();
2472  
2473      if ($records = $DB->get_records_sql($sql, $params)) {
2474          // We are traversing via reverse order.
2475          foreach ($records as $record) {
2476              // If not set yet (i.e. inherit or not set at all), or currently we have a prohibit
2477              if (!isset($capabilities[$record->capability]) || $record->permission<-500) {
2478                  $capabilities[$record->capability] = $record->permission;
2479              }
2480          }
2481      }
2482      return $capabilities;
2483  }
2484  
2485  /**
2486   * Constructs array with contextids as first parameter and context paths,
2487   * in both cases bottom top including self.
2488   *
2489   * @access private
2490   * @param context $context
2491   * @return array
2492   */
2493  function get_context_info_list(context $context) {
2494      $contextids = explode('/', ltrim($context->path, '/'));
2495      $contextpaths = array();
2496      $contextids2 = $contextids;
2497      while ($contextids2) {
2498          $contextpaths[] = '/' . implode('/', $contextids2);
2499          array_pop($contextids2);
2500      }
2501      return array($contextids, $contextpaths);
2502  }
2503  
2504  /**
2505   * Check if context is the front page context or a context inside it
2506   *
2507   * Returns true if this context is the front page context, or a context inside it,
2508   * otherwise false.
2509   *
2510   * @param context $context a context object.
2511   * @return bool
2512   */
2513  function is_inside_frontpage(context $context) {
2514      $frontpagecontext = context_course::instance(SITEID);
2515      return strpos($context->path . '/', $frontpagecontext->path . '/') === 0;
2516  }
2517  
2518  /**
2519   * Returns capability information (cached)
2520   *
2521   * @param string $capabilityname
2522   * @return stdClass or null if capability not found
2523   */
2524  function get_capability_info($capabilityname) {
2525      $caps = get_all_capabilities();
2526  
2527      if (!isset($caps[$capabilityname])) {
2528          return null;
2529      }
2530  
2531      return (object) $caps[$capabilityname];
2532  }
2533  
2534  /**
2535   * Returns all capabilitiy records, preferably from MUC and not database.
2536   *
2537   * @return array All capability records indexed by capability name
2538   */
2539  function get_all_capabilities() {
2540      global $DB;
2541      $cache = cache::make('core', 'capabilities');
2542      if (!$allcaps = $cache->get('core_capabilities')) {
2543          $rs = $DB->get_recordset('capabilities');
2544          $allcaps = array();
2545          foreach ($rs as $capability) {
2546              $capability->riskbitmask = (int) $capability->riskbitmask;
2547              $allcaps[$capability->name] = (array) $capability;
2548          }
2549          $rs->close();
2550          $cache->set('core_capabilities', $allcaps);
2551      }
2552      return $allcaps;
2553  }
2554  
2555  /**
2556   * Returns the human-readable, translated version of the capability.
2557   * Basically a big switch statement.
2558   *
2559   * @param string $capabilityname e.g. mod/choice:readresponses
2560   * @return string
2561   */
2562  function get_capability_string($capabilityname) {
2563  
2564      // Typical capability name is 'plugintype/pluginname:capabilityname'
2565      list($type, $name, $capname) = preg_split('|[/:]|', $capabilityname);
2566  
2567      if ($type === 'moodle') {
2568          $component = 'core_role';
2569      } else if ($type === 'quizreport') {
2570          //ugly hack!!
2571          $component = 'quiz_'.$name;
2572      } else {
2573          $component = $type.'_'.$name;
2574      }
2575  
2576      $stringname = $name.':'.$capname;
2577  
2578      if ($component === 'core_role' or get_string_manager()->string_exists($stringname, $component)) {
2579          return get_string($stringname, $component);
2580      }
2581  
2582      $dir = core_component::get_component_directory($component);
2583      if (!file_exists($dir)) {
2584          // plugin broken or does not exist, do not bother with printing of debug message
2585          return $capabilityname.' ???';
2586      }
2587  
2588      // something is wrong in plugin, better print debug
2589      return get_string($stringname, $component);
2590  }
2591  
2592  /**
2593   * This gets the mod/block/course/core etc strings.
2594   *
2595   * @param string $component
2596   * @param int $contextlevel
2597   * @return string|bool String is success, false if failed
2598   */
2599  function get_component_string($component, $contextlevel) {
2600  
2601      if ($component === 'moodle' || $component === 'core') {
2602          return context_helper::get_level_name($contextlevel);
2603      }
2604  
2605      list($type, $name) = core_component::normalize_component($component);
2606      $dir = core_component::get_plugin_directory($type, $name);
2607      if (!file_exists($dir)) {
2608          // plugin not installed, bad luck, there is no way to find the name
2609          return $component . ' ???';
2610      }
2611  
2612      // Some plugin types need an extra prefix to make the name easy to understand.
2613      switch ($type) {
2614          case 'quiz':
2615              $prefix = get_string('quizreport', 'quiz') . ': ';
2616              break;
2617          case 'repository':
2618              $prefix = get_string('repository', 'repository') . ': ';
2619              break;
2620          case 'gradeimport':
2621              $prefix = get_string('gradeimport', 'grades') . ': ';
2622              break;
2623          case 'gradeexport':
2624              $prefix = get_string('gradeexport', 'grades') . ': ';
2625              break;
2626          case 'gradereport':
2627              $prefix = get_string('gradereport', 'grades') . ': ';
2628              break;
2629          case 'webservice':
2630              $prefix = get_string('webservice', 'webservice') . ': ';
2631              break;
2632          case 'block':
2633              $prefix = get_string('block') . ': ';
2634              break;
2635          case 'mod':
2636              $prefix = get_string('activity') . ': ';
2637              break;
2638  
2639          // Default case, just use the plugin name.
2640          default:
2641              $prefix = '';
2642      }
2643      return $prefix . get_string('pluginname', $component);
2644  }
2645  
2646  /**
2647   * Gets the list of roles assigned to this context and up (parents)
2648   * from the aggregation of:
2649   * a) the list of roles that are visible on user profile page and participants page (profileroles setting) and;
2650   * b) if applicable, those roles that are assigned in the context.
2651   *
2652   * @param context $context
2653   * @return array
2654   */
2655  function get_profile_roles(context $context) {
2656      global $CFG, $DB;
2657      // If the current user can assign roles, then they can see all roles on the profile and participants page,
2658      // provided the roles are assigned to at least 1 user in the context. If not, only the policy-defined roles.
2659      if (has_capability('moodle/role:assign', $context)) {
2660          $rolesinscope = array_keys(get_all_roles($context));
2661      } else {
2662          $rolesinscope = empty($CFG->profileroles) ? [] : array_map('trim', explode(',', $CFG->profileroles));
2663      }
2664  
2665      if (empty($rolesinscope)) {
2666          return [];
2667      }
2668  
2669      list($rallowed, $params) = $DB->get_in_or_equal($rolesinscope, SQL_PARAMS_NAMED, 'a');
2670      list($contextlist, $cparams) = $DB->get_in_or_equal($context->get_parent_context_ids(true), SQL_PARAMS_NAMED, 'p');
2671      $params = array_merge($params, $cparams);
2672  
2673      if ($coursecontext = $context->get_course_context(false)) {
2674          $params['coursecontext'] = $coursecontext->id;
2675      } else {
2676          $params['coursecontext'] = 0;
2677      }
2678  
2679      $sql = "SELECT DISTINCT r.id, r.name, r.shortname, r.sortorder, rn.name AS coursealias
2680                FROM {role_assignments} ra, {role} r
2681           LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = r.id)
2682               WHERE r.id = ra.roleid
2683                     AND ra.contextid $contextlist
2684                     AND r.id $rallowed
2685            ORDER BY r.sortorder ASC";
2686  
2687      return $DB->get_records_sql($sql, $params);
2688  }
2689  
2690  /**
2691   * Gets the list of roles assigned to this context and up (parents)
2692   *
2693   * @param context $context
2694   * @param boolean $includeparents, false means without parents.
2695   * @return array
2696   */
2697  function get_roles_used_in_context(context $context, $includeparents = true) {
2698      global $DB;
2699  
2700      if ($includeparents === true) {
2701          list($contextlist, $params) = $DB->get_in_or_equal($context->get_parent_context_ids(true), SQL_PARAMS_NAMED, 'cl');
2702      } else {
2703          list($contextlist, $params) = $DB->get_in_or_equal($context->id, SQL_PARAMS_NAMED, 'cl');
2704      }
2705  
2706      if ($coursecontext = $context->get_course_context(false)) {
2707          $params['coursecontext'] = $coursecontext->id;
2708      } else {
2709          $params['coursecontext'] = 0;
2710      }
2711  
2712      $sql = "SELECT DISTINCT r.id, r.name, r.shortname, r.sortorder, rn.name AS coursealias
2713                FROM {role_assignments} ra, {role} r
2714           LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = r.id)
2715               WHERE r.id = ra.roleid
2716                     AND ra.contextid $contextlist
2717            ORDER BY r.sortorder ASC";
2718  
2719      return $DB->get_records_sql($sql, $params);
2720  }
2721  
2722  /**
2723   * This function is used to print roles column in user profile page.
2724   * It is using the CFG->profileroles to limit the list to only interesting roles.
2725   * (The permission tab has full details of user role assignments.)
2726   *
2727   * @param int $userid
2728   * @param int $courseid
2729   * @return string
2730   */
2731  function get_user_roles_in_course($userid, $courseid) {
2732      global $CFG, $DB;
2733      if ($courseid == SITEID) {
2734          $context = context_system::instance();
2735      } else {
2736          $context = context_course::instance($courseid);
2737      }
2738      // If the current user can assign roles, then they can see all roles on the profile and participants page,
2739      // provided the roles are assigned to at least 1 user in the context. If not, only the policy-defined roles.
2740      if (has_capability('moodle/role:assign', $context)) {
2741          $rolesinscope = array_keys(get_all_roles($context));
2742      } else {
2743          $rolesinscope = empty($CFG->profileroles) ? [] : array_map('trim', explode(',', $CFG->profileroles));
2744      }
2745      if (empty($rolesinscope)) {
2746          return '';
2747      }
2748  
2749      list($rallowed, $params) = $DB->get_in_or_equal($rolesinscope, SQL_PARAMS_NAMED, 'a');
2750      list($contextlist, $cparams) = $DB->get_in_or_equal($context->get_parent_context_ids(true), SQL_PARAMS_NAMED, 'p');
2751      $params = array_merge($params, $cparams);
2752  
2753      if ($coursecontext = $context->get_course_context(false)) {
2754          $params['coursecontext'] = $coursecontext->id;
2755      } else {
2756          $params['coursecontext'] = 0;
2757      }
2758  
2759      $sql = "SELECT DISTINCT r.id, r.name, r.shortname, r.sortorder, rn.name AS coursealias
2760                FROM {role_assignments} ra, {role} r
2761           LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = r.id)
2762               WHERE r.id = ra.roleid
2763                     AND ra.contextid $contextlist
2764                     AND r.id $rallowed
2765                     AND ra.userid = :userid
2766            ORDER BY r.sortorder ASC";
2767      $params['userid'] = $userid;
2768  
2769      $rolestring = '';
2770  
2771      if ($roles = $DB->get_records_sql($sql, $params)) {
2772          $viewableroles = get_viewable_roles($context, $userid);
2773  
2774          $rolenames = array();
2775          foreach ($roles as $roleid => $unused) {
2776              if (isset($viewableroles[$roleid])) {
2777                  $url = new moodle_url('/user/index.php', ['contextid' => $context->id, 'roleid' => $roleid]);
2778                  $rolenames[] = '<a href="' . $url . '">' . $viewableroles[$roleid] . '</a>';
2779              }
2780          }
2781          $rolestring = implode(', ', $rolenames);
2782      }
2783  
2784      return $rolestring;
2785  }
2786  
2787  /**
2788   * Checks if a user can assign users to a particular role in this context
2789   *
2790   * @param context $context
2791   * @param int $targetroleid - the id of the role you want to assign users to
2792   * @return boolean
2793   */
2794  function user_can_assign(context $context, $targetroleid) {
2795      global $DB;
2796  
2797      // First check to see if the user is a site administrator.
2798      if (is_siteadmin()) {
2799          return true;
2800      }
2801  
2802      // Check if user has override capability.
2803      // If not return false.
2804      if (!has_capability('moodle/role:assign', $context)) {
2805          return false;
2806      }
2807      // pull out all active roles of this user from this context(or above)
2808      if ($userroles = get_user_roles($context)) {
2809          foreach ($userroles as $userrole) {
2810              // if any in the role_allow_override table, then it's ok
2811              if ($DB->get_record('role_allow_assign', array('roleid'=>$userrole->roleid, 'allowassign'=>$targetroleid))) {
2812                  return true;
2813              }
2814          }
2815      }
2816  
2817      return false;
2818  }
2819  
2820  /**
2821   * Returns all site roles in correct sort order.
2822   *
2823   * Note: this method does not localise role names or descriptions,
2824   *       use role_get_names() if you need role names.
2825   *
2826   * @param context $context optional context for course role name aliases
2827   * @return array of role records with optional coursealias property
2828   */
2829  function get_all_roles(context $context = null) {
2830      global $DB;
2831  
2832      if (!$context or !$coursecontext = $context->get_course_context(false)) {
2833          $coursecontext = null;
2834      }
2835  
2836      if ($coursecontext) {
2837          $sql = "SELECT r.*, rn.name AS coursealias
2838                    FROM {role} r
2839               LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = r.id)
2840                ORDER BY r.sortorder ASC";
2841          return $DB->get_records_sql($sql, array('coursecontext'=>$coursecontext->id));
2842  
2843      } else {
2844          return $DB->get_records('role', array(), 'sortorder ASC');
2845      }
2846  }
2847  
2848  /**
2849   * Returns roles of a specified archetype
2850   *
2851   * @param string $archetype
2852   * @return array of full role records
2853   */
2854  function get_archetype_roles($archetype) {
2855      global $DB;
2856      return $DB->get_records('role', array('archetype'=>$archetype), 'sortorder ASC');
2857  }
2858  
2859  /**
2860   * Gets all the user roles assigned in this context, or higher contexts for a list of users.
2861   *
2862   * If you try using the combination $userids = [], $checkparentcontexts = true then this is likely
2863   * to cause an out-of-memory error on large Moodle sites, so this combination is deprecated and
2864   * outputs a warning, even though it is the default.
2865   *
2866   * @param context $context
2867   * @param array $userids. An empty list means fetch all role assignments for the context.
2868   * @param bool $checkparentcontexts defaults to true
2869   * @param string $order defaults to 'c.contextlevel DESC, r.sortorder ASC'
2870   * @return array
2871   */
2872  function get_users_roles(context $context, $userids = [], $checkparentcontexts = true, $order = 'c.contextlevel DESC, r.sortorder ASC') {
2873      global $DB;
2874  
2875      if (!$userids && $checkparentcontexts) {
2876          debugging('Please do not call get_users_roles() with $checkparentcontexts = true ' .
2877                  'and $userids array not set. This combination causes large Moodle sites ' .
2878                  'with lots of site-wide role assignemnts to run out of memory.', DEBUG_DEVELOPER);
2879      }
2880  
2881      if ($checkparentcontexts) {
2882          $contextids = $context->get_parent_context_ids();
2883      } else {
2884          $contextids = array();
2885      }
2886      $contextids[] = $context->id;
2887  
2888      list($contextids, $params) = $DB->get_in_or_equal($contextids, SQL_PARAMS_NAMED, 'con');
2889  
2890      // If userids was passed as an empty array, we fetch all role assignments for the course.
2891      if (empty($userids)) {
2892          $useridlist = ' IS NOT NULL ';
2893          $uparams = [];
2894      } else {
2895          list($useridlist, $uparams) = $DB->get_in_or_equal($userids, SQL_PARAMS_NAMED, 'uids');
2896      }
2897  
2898      $sql = "SELECT ra.*, r.name, r.shortname, ra.userid
2899                FROM {role_assignments} ra, {role} r, {context} c
2900               WHERE ra.userid $useridlist
2901                     AND ra.roleid = r.id
2902                     AND ra.contextid = c.id
2903                     AND ra.contextid $contextids
2904            ORDER BY $order";
2905  
2906      $all = $DB->get_records_sql($sql , array_merge($params, $uparams));
2907  
2908      // Return results grouped by userid.
2909      $result = [];
2910      foreach ($all as $id => $record) {
2911          if (!isset($result[$record->userid])) {
2912              $result[$record->userid] = [];
2913          }
2914          $result[$record->userid][$record->id] = $record;
2915      }
2916  
2917      // Make sure all requested users are included in the result, even if they had no role assignments.
2918      foreach ($userids as $id) {
2919          if (!isset($result[$id])) {
2920              $result[$id] = [];
2921          }
2922      }
2923  
2924      return $result;
2925  }
2926  
2927  
2928  /**
2929   * Gets all the user roles assigned in this context, or higher contexts
2930   * this is mainly used when checking if a user can assign a role, or overriding a role
2931   * i.e. we need to know what this user holds, in order to verify against allow_assign and
2932   * allow_override tables
2933   *
2934   * @param context $context
2935   * @param int $userid
2936   * @param bool $checkparentcontexts defaults to true
2937   * @param string $order defaults to 'c.contextlevel DESC, r.sortorder ASC'
2938   * @return array
2939   */
2940  function get_user_roles(context $context, $userid = 0, $checkparentcontexts = true, $order = 'c.contextlevel DESC, r.sortorder ASC') {
2941      global $USER, $DB;
2942  
2943      if (empty($userid)) {
2944          if (empty($USER->id)) {
2945              return array();
2946          }
2947          $userid = $USER->id;
2948      }
2949  
2950      if ($checkparentcontexts) {
2951          $contextids = $context->get_parent_context_ids();
2952      } else {
2953          $contextids = array();
2954      }
2955      $contextids[] = $context->id;
2956  
2957      list($contextids, $params) = $DB->get_in_or_equal($contextids, SQL_PARAMS_QM);
2958  
2959      array_unshift($params, $userid);
2960  
2961      $sql = "SELECT ra.*, r.name, r.shortname
2962                FROM {role_assignments} ra, {role} r, {context} c
2963               WHERE ra.userid = ?
2964                     AND ra.roleid = r.id
2965                     AND ra.contextid = c.id
2966                     AND ra.contextid $contextids
2967            ORDER BY $order";
2968  
2969      return $DB->get_records_sql($sql ,$params);
2970  }
2971  
2972  /**
2973   * Like get_user_roles, but adds in the authenticated user role, and the front
2974   * page roles, if applicable.
2975   *
2976   * @param context $context the context.
2977   * @param int $userid optional. Defaults to $USER->id
2978   * @return array of objects with fields ->userid, ->contextid and ->roleid.
2979   */
2980  function get_user_roles_with_special(context $context, $userid = 0) {
2981      global $CFG, $USER;
2982  
2983      if (empty($userid)) {
2984          if (empty($USER->id)) {
2985              return array();
2986          }
2987          $userid = $USER->id;
2988      }
2989  
2990      $ras = get_user_roles($context, $userid);
2991  
2992      // Add front-page role if relevant.
2993      $defaultfrontpageroleid = isset($CFG->defaultfrontpageroleid) ? $CFG->defaultfrontpageroleid : 0;
2994      $isfrontpage = ($context->contextlevel == CONTEXT_COURSE && $context->instanceid == SITEID) ||
2995              is_inside_frontpage($context);
2996      if ($defaultfrontpageroleid && $isfrontpage) {
2997          $frontpagecontext = context_course::instance(SITEID);
2998          $ra = new stdClass();
2999          $ra->userid = $userid;
3000          $ra->contextid = $frontpagecontext->id;
3001          $ra->roleid = $defaultfrontpageroleid;
3002          $ras[] = $ra;
3003      }
3004  
3005      // Add authenticated user role if relevant.
3006      $defaultuserroleid      = isset($CFG->defaultuserroleid) ? $CFG->defaultuserroleid : 0;
3007      if ($defaultuserroleid && !isguestuser($userid)) {
3008          $systemcontext = context_system::instance();
3009          $ra = new stdClass();
3010          $ra->userid = $userid;
3011          $ra->contextid = $systemcontext->id;
3012          $ra->roleid = $defaultuserroleid;
3013          $ras[] = $ra;
3014      }
3015  
3016      return $ras;
3017  }
3018  
3019  /**
3020   * Creates a record in the role_allow_override table
3021   *
3022   * @param int $fromroleid source roleid
3023   * @param int $targetroleid target roleid
3024   * @return void
3025   */
3026  function core_role_set_override_allowed($fromroleid, $targetroleid) {
3027      global $DB;
3028  
3029      $record = new stdClass();
3030      $record->roleid        = $fromroleid;
3031      $record->allowoverride = $targetroleid;
3032      $DB->insert_record('role_allow_override', $record);
3033  }
3034  
3035  /**
3036   * Creates a record in the role_allow_assign table
3037   *
3038   * @param int $fromroleid source roleid
3039   * @param int $targetroleid target roleid
3040   * @return void
3041   */
3042  function core_role_set_assign_allowed($fromroleid, $targetroleid) {
3043      global $DB;
3044  
3045      $record = new stdClass();
3046      $record->roleid      = $fromroleid;
3047      $record->allowassign = $targetroleid;
3048      $DB->insert_record('role_allow_assign', $record);
3049  }
3050  
3051  /**
3052   * Creates a record in the role_allow_switch table
3053   *
3054   * @param int $fromroleid source roleid
3055   * @param int $targetroleid target roleid
3056   * @return void
3057   */
3058  function core_role_set_switch_allowed($fromroleid, $targetroleid) {
3059      global $DB;
3060  
3061      $record = new stdClass();
3062      $record->roleid      = $fromroleid;
3063      $record->allowswitch = $targetroleid;
3064      $DB->insert_record('role_allow_switch', $record);
3065  }
3066  
3067  /**
3068   * Creates a record in the role_allow_view table
3069   *
3070   * @param int $fromroleid source roleid
3071   * @param int $targetroleid target roleid
3072   * @return void
3073   */
3074  function core_role_set_view_allowed($fromroleid, $targetroleid) {
3075      global $DB;
3076  
3077      $record = new stdClass();
3078      $record->roleid      = $fromroleid;
3079      $record->allowview = $targetroleid;
3080      $DB->insert_record('role_allow_view', $record);
3081  }
3082  
3083  /**
3084   * Gets a list of roles that this user can assign in this context
3085   *
3086   * @param context $context the context.
3087   * @param int $rolenamedisplay the type of role name to display. One of the
3088   *      ROLENAME_X constants. Default ROLENAME_ALIAS.
3089   * @param bool $withusercounts if true, count the number of users with each role.
3090   * @param integer|object $user A user id or object. By default (null) checks the permissions of the current user.
3091   * @return array if $withusercounts is false, then an array $roleid => $rolename.
3092   *      if $withusercounts is true, returns a list of three arrays,
3093   *      $rolenames, $rolecounts, and $nameswithcounts.
3094   */
3095  function get_assignable_roles(context $context, $rolenamedisplay = ROLENAME_ALIAS, $withusercounts = false, $user = null) {
3096      global $USER, $DB;
3097  
3098      // make sure there is a real user specified
3099      if ($user === null) {
3100          $userid = isset($USER->id) ? $USER->id : 0;
3101      } else {
3102          $userid = is_object($user) ? $user->id : $user;
3103      }
3104  
3105      if (!has_capability('moodle/role:assign', $context, $userid)) {
3106          if ($withusercounts) {
3107              return array(array(), array(), array());
3108          } else {
3109              return array();
3110          }
3111      }
3112  
3113      $params = array();
3114      $extrafields = '';
3115  
3116      if ($withusercounts) {
3117          $extrafields = ', (SELECT COUNT(DISTINCT u.id)
3118                               FROM {role_assignments} cra JOIN {user} u ON cra.userid = u.id
3119                              WHERE cra.roleid = r.id AND cra.contextid = :conid AND u.deleted = 0
3120                            ) AS usercount';
3121          $params['conid'] = $context->id;
3122      }
3123  
3124      if (is_siteadmin($userid)) {
3125          // show all roles allowed in this context to admins
3126          $assignrestriction = "";
3127      } else {
3128          $parents = $context->get_parent_context_ids(true);
3129          $contexts = implode(',' , $parents);
3130          $assignrestriction = "JOIN (SELECT DISTINCT raa.allowassign AS id
3131                                        FROM {role_allow_assign} raa
3132                                        JOIN {role_assignments} ra ON ra.roleid = raa.roleid
3133                                       WHERE ra.userid = :userid AND ra.contextid IN ($contexts)
3134                                     ) ar ON ar.id = r.id";
3135          $params['userid'] = $userid;
3136      }
3137      $params['contextlevel'] = $context->contextlevel;
3138  
3139      if ($coursecontext = $context->get_course_context(false)) {
3140          $params['coursecontext'] = $coursecontext->id;
3141      } else {
3142          $params['coursecontext'] = 0; // no course aliases
3143          $coursecontext = null;
3144      }
3145      $sql = "SELECT r.id, r.name, r.shortname, rn.name AS coursealias $extrafields
3146                FROM {role} r
3147                $assignrestriction
3148                JOIN {role_context_levels} rcl ON (rcl.contextlevel = :contextlevel AND r.id = rcl.roleid)
3149           LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = r.id)
3150            ORDER BY r.sortorder ASC";
3151      $roles = $DB->get_records_sql($sql, $params);
3152  
3153      $rolenames = role_fix_names($roles, $coursecontext, $rolenamedisplay, true);
3154  
3155      if (!$withusercounts) {
3156          return $rolenames;
3157      }
3158  
3159      $rolecounts = array();
3160      $nameswithcounts = array();
3161      foreach ($roles as $role) {
3162          $nameswithcounts[$role->id] = $rolenames[$role->id] . ' (' . $roles[$role->id]->usercount . ')';
3163          $rolecounts[$role->id] = $roles[$role->id]->usercount;
3164      }
3165      return array($rolenames, $rolecounts, $nameswithcounts);
3166  }
3167  
3168  /**
3169   * Gets a list of roles that this user can switch to in a context
3170   *
3171   * Gets a list of roles that this user can switch to in a context, for the switchrole menu.
3172   * This function just process the contents of the role_allow_switch table. You also need to
3173   * test the moodle/role:switchroles to see if the user is allowed to switch in the first place.
3174   *
3175   * @param context $context a context.
3176   * @param int $rolenamedisplay the type of role name to display. One of the
3177   *      ROLENAME_X constants. Default ROLENAME_ALIAS.
3178   * @return array an array $roleid => $rolename.
3179   */
3180  function get_switchable_roles(context $context, $rolenamedisplay = ROLENAME_ALIAS) {
3181      global $USER, $DB;
3182  
3183      // You can't switch roles without this capability.
3184      if (!has_capability('moodle/role:switchroles', $context)) {
3185          return [];
3186      }
3187  
3188      $params = array();
3189      $extrajoins = '';
3190      $extrawhere = '';
3191      if (!is_siteadmin()) {
3192          // Admins are allowed to switch to any role with.
3193          // Others are subject to the additional constraint that the switch-to role must be allowed by
3194          // 'role_allow_switch' for some role they have assigned in this context or any parent.
3195          $parents = $context->get_parent_context_ids(true);
3196          $contexts = implode(',' , $parents);
3197  
3198          $extrajoins = "JOIN {role_allow_switch} ras ON ras.allowswitch = rc.roleid
3199          JOIN {role_assignments} ra ON ra.roleid = ras.roleid";
3200          $extrawhere = "WHERE ra.userid = :userid AND ra.contextid IN ($contexts)";
3201          $params['userid'] = $USER->id;
3202      }
3203  
3204      if ($coursecontext = $context->get_course_context(false)) {
3205          $params['coursecontext'] = $coursecontext->id;
3206      } else {
3207          $params['coursecontext'] = 0; // no course aliases
3208          $coursecontext = null;
3209      }
3210  
3211      $query = "
3212          SELECT r.id, r.name, r.shortname, rn.name AS coursealias
3213            FROM (SELECT DISTINCT rc.roleid
3214                    FROM {role_capabilities} rc
3215  
3216                    $extrajoins
3217                    $extrawhere) idlist
3218            JOIN {role} r ON r.id = idlist.roleid
3219       LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = r.id)
3220        ORDER BY r.sortorder";
3221      $roles = $DB->get_records_sql($query, $params);
3222  
3223      return role_fix_names($roles, $context, $rolenamedisplay, true);
3224  }
3225  
3226  /**
3227   * Gets a list of roles that this user can view in a context
3228   *
3229   * @param context $context a context.
3230   * @param int $userid id of user.
3231   * @param int $rolenamedisplay the type of role name to display. One of the
3232   *      ROLENAME_X constants. Default ROLENAME_ALIAS.
3233   * @return array an array $roleid => $rolename.
3234   */
3235  function get_viewable_roles(context $context, $userid = null, $rolenamedisplay = ROLENAME_ALIAS) {
3236      global $USER, $DB;
3237  
3238      if ($userid == null) {
3239          $userid = $USER->id;
3240      }
3241  
3242      $params = array();
3243      $extrajoins = '';
3244      $extrawhere = '';
3245      if (!is_siteadmin()) {
3246          // Admins are allowed to view any role.
3247          // Others are subject to the additional constraint that the view role must be allowed by
3248          // 'role_allow_view' for some role they have assigned in this context or any parent.
3249          $contexts = $context->get_parent_context_ids(true);
3250          list($insql, $inparams) = $DB->get_in_or_equal($contexts, SQL_PARAMS_NAMED);
3251  
3252          $extrajoins = "JOIN {role_allow_view} ras ON ras.allowview = r.id
3253                         JOIN {role_assignments} ra ON ra.roleid = ras.roleid";
3254          $extrawhere = "WHERE ra.userid = :userid AND ra.contextid $insql";
3255  
3256          $params += $inparams;
3257          $params['userid'] = $userid;
3258      }
3259  
3260      if ($coursecontext = $context->get_course_context(false)) {
3261          $params['coursecontext'] = $coursecontext->id;
3262      } else {
3263          $params['coursecontext'] = 0; // No course aliases.
3264          $coursecontext = null;
3265      }
3266  
3267      $query = "
3268          SELECT r.id, r.name, r.shortname, rn.name AS coursealias, r.sortorder
3269            FROM {role} r
3270            $extrajoins
3271       LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = r.id)
3272            $extrawhere
3273        GROUP BY r.id, r.name, r.shortname, rn.name, r.sortorder
3274        ORDER BY r.sortorder";
3275      $roles = $DB->get_records_sql($query, $params);
3276  
3277      return role_fix_names($roles, $context, $rolenamedisplay, true);
3278  }
3279  
3280  /**
3281   * Gets a list of roles that this user can override in this context.
3282   *
3283   * @param context $context the context.
3284   * @param int $rolenamedisplay the type of role name to display. One of the
3285   *      ROLENAME_X constants. Default ROLENAME_ALIAS.
3286   * @param bool $withcounts if true, count the number of overrides that are set for each role.
3287   * @return array if $withcounts is false, then an array $roleid => $rolename.
3288   *      if $withusercounts is true, returns a list of three arrays,
3289   *      $rolenames, $rolecounts, and $nameswithcounts.
3290   */
3291  function get_overridable_roles(context $context, $rolenamedisplay = ROLENAME_ALIAS, $withcounts = false) {
3292      global $USER, $DB;
3293  
3294      if (!has_any_capability(array('moodle/role:safeoverride', 'moodle/role:override'), $context)) {
3295          if ($withcounts) {
3296              return array(array(), array(), array());
3297          } else {
3298              return array();
3299          }
3300      }
3301  
3302      $parents = $context->get_parent_context_ids(true);
3303      $contexts = implode(',' , $parents);
3304  
3305      $params = array();
3306      $extrafields = '';
3307  
3308      $params['userid'] = $USER->id;
3309      if ($withcounts) {
3310          $extrafields = ', (SELECT COUNT(rc.id) FROM {role_capabilities} rc
3311                  WHERE rc.roleid = ro.id AND rc.contextid = :conid) AS overridecount';
3312          $params['conid'] = $context->id;
3313      }
3314  
3315      if ($coursecontext = $context->get_course_context(false)) {
3316          $params['coursecontext'] = $coursecontext->id;
3317      } else {
3318          $params['coursecontext'] = 0; // no course aliases
3319          $coursecontext = null;
3320      }
3321  
3322      if (is_siteadmin()) {
3323          // show all roles to admins
3324          $roles = $DB->get_records_sql("
3325              SELECT ro.id, ro.name, ro.shortname, rn.name AS coursealias $extrafields
3326                FROM {role} ro
3327           LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = ro.id)
3328            ORDER BY ro.sortorder ASC", $params);
3329  
3330      } else {
3331          $roles = $DB->get_records_sql("
3332              SELECT ro.id, ro.name, ro.shortname, rn.name AS coursealias $extrafields
3333                FROM {role} ro
3334                JOIN (SELECT DISTINCT r.id
3335                        FROM {role} r
3336                        JOIN {role_allow_override} rao ON r.id = rao.allowoverride
3337                        JOIN {role_assignments} ra ON rao.roleid = ra.roleid
3338                       WHERE ra.userid = :userid AND ra.contextid IN ($contexts)
3339                     ) inline_view ON ro.id = inline_view.id
3340           LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = ro.id)
3341            ORDER BY ro.sortorder ASC", $params);
3342      }
3343  
3344      $rolenames = role_fix_names($roles, $context, $rolenamedisplay, true);
3345  
3346      if (!$withcounts) {
3347          return $rolenames;
3348      }
3349  
3350      $rolecounts = array();
3351      $nameswithcounts = array();
3352      foreach ($roles as $role) {
3353          $nameswithcounts[$role->id] = $rolenames[$role->id] . ' (' . $roles[$role->id]->overridecount . ')';
3354          $rolecounts[$role->id] = $roles[$role->id]->overridecount;
3355      }
3356      return array($rolenames, $rolecounts, $nameswithcounts);
3357  }
3358  
3359  /**
3360   * Create a role menu suitable for default role selection in enrol plugins.
3361   *
3362   * @package    core_enrol
3363   *
3364   * @param context $context
3365   * @param int $addroleid current or default role - always added to list
3366   * @return array roleid=>localised role name
3367   */
3368  function get_default_enrol_roles(context $context, $addroleid = null) {
3369      global $DB;
3370  
3371      $params = array('contextlevel'=>CONTEXT_COURSE);
3372  
3373      if ($coursecontext = $context->get_course_context(false)) {
3374          $params['coursecontext'] = $coursecontext->id;
3375      } else {
3376          $params['coursecontext'] = 0; // no course names
3377          $coursecontext = null;
3378      }
3379  
3380      if ($addroleid) {
3381          $addrole = "OR r.id = :addroleid";
3382          $params['addroleid'] = $addroleid;
3383      } else {
3384          $addrole = "";
3385      }
3386  
3387      $sql = "SELECT r.id, r.name, r.shortname, rn.name AS coursealias
3388                FROM {role} r
3389           LEFT JOIN {role_context_levels} rcl ON (rcl.roleid = r.id AND rcl.contextlevel = :contextlevel)
3390           LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = r.id)
3391               WHERE rcl.id IS NOT NULL $addrole
3392            ORDER BY sortorder DESC";
3393  
3394      $roles = $DB->get_records_sql($sql, $params);
3395  
3396      return role_fix_names($roles, $context, ROLENAME_BOTH, true);
3397  }
3398  
3399  /**
3400   * Return context levels where this role is assignable.
3401   *
3402   * @param integer $roleid the id of a role.
3403   * @return array list of the context levels at which this role may be assigned.
3404   */
3405  function get_role_contextlevels($roleid) {
3406      global $DB;
3407      return $DB->get_records_menu('role_context_levels', array('roleid' => $roleid),
3408              'contextlevel', 'id,contextlevel');
3409  }
3410  
3411  /**
3412   * Return roles suitable for assignment at the specified context level.
3413   *
3414   * NOTE: this function name looks like a typo, should be probably get_roles_for_contextlevel()
3415   *
3416   * @param integer $contextlevel a contextlevel.
3417   * @return array list of role ids that are assignable at this context level.
3418   */
3419  function get_roles_for_contextlevels($contextlevel) {
3420      global $DB;
3421      return $DB->get_records_menu('role_context_levels', array('contextlevel' => $contextlevel),
3422              '', 'id,roleid');
3423  }
3424  
3425  /**
3426   * Returns default context levels where roles can be assigned.
3427   *
3428   * @param string $rolearchetype one of the role archetypes - that is, one of the keys
3429   *      from the array returned by get_role_archetypes();
3430   * @return array list of the context levels at which this type of role may be assigned by default.
3431   */
3432  function get_default_contextlevels($rolearchetype) {
3433      static $defaults = array(
3434          'manager'        => array(CONTEXT_SYSTEM, CONTEXT_COURSECAT, CONTEXT_COURSE),
3435          'coursecreator'  => array(CONTEXT_SYSTEM, CONTEXT_COURSECAT),
3436          'editingteacher' => array(CONTEXT_COURSE, CONTEXT_MODULE),
3437          'teacher'        => array(CONTEXT_COURSE, CONTEXT_MODULE),
3438          'student'        => array(CONTEXT_COURSE, CONTEXT_MODULE),
3439          'guest'          => array(),
3440          'user'           => array(),
3441          'frontpage'      => array());
3442  
3443      if (isset($defaults[$rolearchetype])) {
3444          return $defaults[$rolearchetype];
3445      } else {
3446          return array();
3447      }
3448  }
3449  
3450  /**
3451   * Set the context levels at which a particular role can be assigned.
3452   * Throws exceptions in case of error.
3453   *
3454   * @param integer $roleid the id of a role.
3455   * @param array $contextlevels the context levels at which this role should be assignable,
3456   *      duplicate levels are removed.
3457   * @return void
3458   */
3459  function set_role_contextlevels($roleid, array $contextlevels) {
3460      global $DB;
3461      $DB->delete_records('role_context_levels', array('roleid' => $roleid));
3462      $rcl = new stdClass();
3463      $rcl->roleid = $roleid;
3464      $contextlevels = array_unique($contextlevels);
3465      foreach ($contextlevels as $level) {
3466          $rcl->contextlevel = $level;
3467          $DB->insert_record('role_context_levels', $rcl, false, true);
3468      }
3469  }
3470  
3471  /**
3472   * Gets sql joins for finding users with capability in the given context.
3473   *
3474   * @param context $context Context for the join.
3475   * @param string|array $capability Capability name or array of names.
3476   *      If an array is provided then this is the equivalent of a logical 'OR',
3477   *      i.e. the user needs to have one of these capabilities.
3478   * @param string $useridcolumn e.g. 'u.id'.
3479   * @return \core\dml\sql_join Contains joins, wheres, params.
3480   *      This function will set ->cannotmatchanyrows if applicable.
3481   *      This may let you skip doing a DB query.
3482   */
3483  function get_with_capability_join(context $context, $capability, $useridcolumn) {
3484      global $CFG, $DB;
3485  
3486      // Add a unique prefix to param names to ensure they are unique.
3487      static $i = 0;
3488      $i++;
3489      $paramprefix = 'eu' . $i . '_';
3490  
3491      $defaultuserroleid      = isset($CFG->defaultuserroleid) ? $CFG->defaultuserroleid : 0;
3492      $defaultfrontpageroleid = isset($CFG->defaultfrontpageroleid) ? $CFG->defaultfrontpageroleid : 0;
3493  
3494      $ctxids = trim($context->path, '/');
3495      $ctxids = str_replace('/', ',', $ctxids);
3496  
3497      // Context is the frontpage
3498      $isfrontpage = $context->contextlevel == CONTEXT_COURSE && $context->instanceid == SITEID;
3499      $isfrontpage = $isfrontpage || is_inside_frontpage($context);
3500  
3501      $caps = (array) $capability;
3502  
3503      // Construct list of context paths bottom --> top.
3504      list($contextids, $paths) = get_context_info_list($context);
3505  
3506      // We need to find out all roles that have these capabilities either in definition or in overrides.
3507      $defs = [];
3508      list($incontexts, $params) = $DB->get_in_or_equal($contextids, SQL_PARAMS_NAMED, $paramprefix . 'con');
3509      list($incaps, $params2) = $DB->get_in_or_equal($caps, SQL_PARAMS_NAMED, $paramprefix . 'cap');
3510  
3511      // Check whether context locking is enabled.
3512      // Filter out any write capability if this is the case.
3513      $excludelockedcaps = '';
3514      $excludelockedcapsparams = [];
3515      if (!empty($CFG->contextlocking) && $context->locked) {
3516          $excludelockedcaps = 'AND (cap.captype = :capread OR cap.name = :managelockscap)';
3517          $excludelockedcapsparams['capread'] = 'read';
3518          $excludelockedcapsparams['managelockscap'] = 'moodle/site:managecontextlocks';
3519      }
3520  
3521      $params = array_merge($params, $params2, $excludelockedcapsparams);
3522      $sql = "SELECT rc.id, rc.roleid, rc.permission, rc.capability, ctx.path
3523                FROM {role_capabilities} rc
3524                JOIN {capabilities} cap ON rc.capability = cap.name
3525                JOIN {context} ctx on rc.contextid = ctx.id
3526               WHERE rc.contextid $incontexts AND rc.capability $incaps $excludelockedcaps";
3527  
3528      $rcs = $DB->get_records_sql($sql, $params);
3529      foreach ($rcs as $rc) {
3530          $defs[$rc->capability][$rc->path][$rc->roleid] = $rc->permission;
3531      }
3532  
3533      // Go through the permissions bottom-->top direction to evaluate the current permission,
3534      // first one wins (prohibit is an exception that always wins).
3535      $access = [];
3536      foreach ($caps as $cap) {
3537          foreach ($paths as $path) {
3538              if (empty($defs[$cap][$path])) {
3539                  continue;
3540              }
3541              foreach ($defs[$cap][$path] as $roleid => $perm) {
3542                  if ($perm == CAP_PROHIBIT) {
3543                      $access[$cap][$roleid] = CAP_PROHIBIT;
3544                      continue;
3545                  }
3546                  if (!isset($access[$cap][$roleid])) {
3547                      $access[$cap][$roleid] = (int)$perm;
3548                  }
3549              }
3550          }
3551      }
3552  
3553      // Make lists of roles that are needed and prohibited in this context.
3554      $needed = []; // One of these is enough.
3555      $prohibited = []; // Must not have any of these.
3556      foreach ($caps as $cap) {
3557          if (empty($access[$cap])) {
3558              continue;
3559          }
3560          foreach ($access[$cap] as $roleid => $perm) {
3561              if ($perm == CAP_PROHIBIT) {
3562                  unset($needed[$cap][$roleid]);
3563                  $prohibited[$cap][$roleid] = true;
3564              } else if ($perm == CAP_ALLOW and empty($prohibited[$cap][$roleid])) {
3565                  $needed[$cap][$roleid] = true;
3566              }
3567          }
3568          if (empty($needed[$cap]) or !empty($prohibited[$cap][$defaultuserroleid])) {
3569              // Easy, nobody has the permission.
3570              unset($needed[$cap]);
3571              unset($prohibited[$cap]);
3572          } else if ($isfrontpage and !empty($prohibited[$cap][$defaultfrontpageroleid])) {
3573              // Everybody is disqualified on the frontpage.
3574              unset($needed[$cap]);
3575              unset($prohibited[$cap]);
3576          }
3577          if (empty($prohibited[$cap])) {
3578              unset($prohibited[$cap]);
3579          }
3580      }
3581  
3582      if (empty($needed)) {
3583          // There can not be anybody if no roles match this request.
3584          return new \core\dml\sql_join('', '1 = 2', [], true);
3585      }
3586  
3587      if (empty($prohibited)) {
3588          // We can compact the needed roles.
3589          $n = [];
3590          foreach ($needed as $cap) {
3591              foreach ($cap as $roleid => $unused) {
3592                  $n[$roleid] = true;
3593              }
3594          }
3595          $needed = ['any' => $n];
3596          unset($n);
3597      }
3598  
3599      // Prepare query clauses.
3600      $wherecond = [];
3601      $params    = [];
3602      $joins     = [];
3603      $cannotmatchanyrows = false;
3604  
3605      // We never return deleted users or guest account.
3606      // Use a hack to get the deleted user column without an API change.
3607      $deletedusercolumn = substr($useridcolumn, 0, -2) . 'deleted';
3608      $wherecond[] = "$deletedusercolumn = 0 AND $useridcolumn <> :{$paramprefix}guestid";
3609      $params[$paramprefix . 'guestid'] = $CFG->siteguest;
3610  
3611      // Now add the needed and prohibited roles conditions as joins.
3612      if (!empty($needed['any'])) {
3613          // Simple case - there are no prohibits involved.
3614          if (!empty($needed['any'][$defaultuserroleid]) ||
3615                  ($isfrontpage && !empty($needed['any'][$defaultfrontpageroleid]))) {
3616              // Everybody.
3617          } else {
3618              $joins[] = "JOIN (SELECT DISTINCT userid
3619                                  FROM {role_assignments}
3620                                 WHERE contextid IN ($ctxids)
3621                                       AND roleid IN (" . implode(',', array_keys($needed['any'])) . ")
3622                               ) ra ON ra.userid = $useridcolumn";
3623          }
3624      } else {
3625          $unions = [];
3626          $everybody = false;
3627          foreach ($needed as $cap => $unused) {
3628              if (empty($prohibited[$cap])) {
3629                  if (!empty($needed[$cap][$defaultuserroleid]) ||
3630                          ($isfrontpage && !empty($needed[$cap][$defaultfrontpageroleid]))) {
3631                      $everybody = true;
3632                      break;
3633                  } else {
3634                      $unions[] = "SELECT userid
3635                                     FROM {role_assignments}
3636                                    WHERE contextid IN ($ctxids)
3637                                          AND roleid IN (".implode(',', array_keys($needed[$cap])) .")";
3638                  }
3639              } else {
3640                  if (!empty($prohibited[$cap][$defaultuserroleid]) ||
3641                          ($isfrontpage && !empty($prohibited[$cap][$defaultfrontpageroleid]))) {
3642                      // Nobody can have this cap because it is prohibited in default roles.
3643                      continue;
3644  
3645                  } else if (!empty($needed[$cap][$defaultuserroleid]) ||
3646                          ($isfrontpage && !empty($needed[$cap][$defaultfrontpageroleid]))) {
3647                      // Everybody except the prohibited - hiding does not matter.
3648                      $unions[] = "SELECT id AS userid
3649                                     FROM {user}
3650                                    WHERE id NOT IN (SELECT userid
3651                                                       FROM {role_assignments}
3652                                                      WHERE contextid IN ($ctxids)
3653                                                            AND roleid IN (" . implode(',', array_keys($prohibited[$cap])) . "))";
3654  
3655                  } else {
3656                      $unions[] = "SELECT userid
3657                                     FROM {role_assignments}
3658                                    WHERE contextid IN ($ctxids) AND roleid IN (" . implode(',', array_keys($needed[$cap])) . ")
3659                                          AND userid NOT IN (
3660                                              SELECT userid
3661                                                FROM {role_assignments}
3662                                               WHERE contextid IN ($ctxids)
3663                                                     AND roleid IN (" . implode(',', array_keys($prohibited[$cap])) . "))";
3664                  }
3665              }
3666          }
3667  
3668          if (!$everybody) {
3669              if ($unions) {
3670                  $joins[] = "JOIN (
3671                                    SELECT DISTINCT userid
3672                                      FROM (
3673                                              " . implode("\n UNION \n", $unions) . "
3674                                           ) us
3675                                   ) ra ON ra.userid = $useridcolumn";
3676              } else {
3677                  // Only prohibits found - nobody can be matched.
3678                  $wherecond[] = "1 = 2";
3679                  $cannotmatchanyrows = true;
3680              }
3681          }
3682      }
3683  
3684      return new \core\dml\sql_join(implode("\n", $joins), implode(" AND ", $wherecond), $params, $cannotmatchanyrows);
3685  }
3686  
3687  /**
3688   * Who has this capability in this context?
3689   *
3690   * This can be a very expensive call - use sparingly and keep
3691   * the results if you are going to need them again soon.
3692   *
3693   * Note if $fields is empty this function attempts to get u.*
3694   * which can get rather large - and has a serious perf impact
3695   * on some DBs.
3696   *
3697   * @param context $context
3698   * @param string|array $capability - capability name(s)
3699   * @param string $fields - fields to be pulled. The user table is aliased to 'u'. u.id MUST be included.
3700   * @param string $sort - the sort order. Default is lastaccess time.
3701   * @param mixed $limitfrom - number of records to skip (offset)
3702   * @param mixed $limitnum - number of records to fetch
3703   * @param string|array $groups - single group or array of groups - only return
3704   *               users who are in one of these group(s).
3705   * @param string|array $exceptions - list of users to exclude, comma separated or array
3706   * @param bool $notuseddoanything not used any more, admin accounts are never returned
3707   * @param bool $notusedview - use get_enrolled_sql() instead
3708   * @param bool $useviewallgroups if $groups is set the return users who
3709   *               have capability both $capability and moodle/site:accessallgroups
3710   *               in this context, as well as users who have $capability and who are
3711   *               in $groups.
3712   * @return array of user records
3713   */
3714  function get_users_by_capability(context $context, $capability, $fields = '', $sort = '', $limitfrom = '', $limitnum = '',
3715          $groups = '', $exceptions = '', $notuseddoanything = null, $notusedview = null, $useviewallgroups = false) {
3716      global $CFG, $DB;
3717  
3718      // Context is a course page other than the frontpage.
3719      $iscoursepage = $context->contextlevel == CONTEXT_COURSE && $context->instanceid != SITEID;
3720  
3721      // Set up default fields list if necessary.
3722      if (empty($fields)) {
3723          if ($iscoursepage) {
3724              $fields = 'u.*, ul.timeaccess AS lastaccess';
3725          } else {
3726              $fields = 'u.*';
3727          }
3728      } else {
3729          if ($CFG->debugdeveloper && strpos($fields, 'u.*') === false && strpos($fields, 'u.id') === false) {
3730              debugging('u.id must be included in the list of fields passed to get_users_by_capability().', DEBUG_DEVELOPER);
3731          }
3732      }
3733  
3734      // Set up default sort if necessary.
3735      if (empty($sort)) { // default to course lastaccess or just lastaccess
3736          if ($iscoursepage) {
3737              $sort = 'ul.timeaccess';
3738          } else {
3739              $sort = 'u.lastaccess';
3740          }
3741      }
3742  
3743      // Get the bits of SQL relating to capabilities.
3744      $sqljoin = get_with_capability_join($context, $capability, 'u.id');
3745      if ($sqljoin->cannotmatchanyrows) {
3746          return [];
3747      }
3748  
3749      // Prepare query clauses.
3750      $wherecond = [$sqljoin->wheres];
3751      $params    = $sqljoin->params;
3752      $joins     = [$sqljoin->joins];
3753  
3754      // Add user lastaccess JOIN, if required.
3755      if ((strpos($sort, 'ul.timeaccess') === false) and (strpos($fields, 'ul.timeaccess') === false)) {
3756           // Here user_lastaccess is not required MDL-13810.
3757      } else {
3758          if ($iscoursepage) {
3759              $joins[] = "LEFT OUTER JOIN {user_lastaccess} ul ON (ul.userid = u.id AND ul.courseid = {$context->instanceid})";
3760          } else {
3761              throw new coding_exception('Invalid sort in get_users_by_capability(), ul.timeaccess allowed only for course contexts.');
3762          }
3763      }
3764  
3765      // Groups.
3766      if ($groups) {
3767          $groups = (array)$groups;
3768          list($grouptest, $grpparams) = $DB->get_in_or_equal($groups, SQL_PARAMS_NAMED, 'grp');
3769          $joins[] = "LEFT OUTER JOIN (SELECT DISTINCT userid
3770                                         FROM {groups_members}
3771                                        WHERE groupid $grouptest
3772                                      ) gm ON gm.userid = u.id";
3773  
3774          $params = array_merge($params, $grpparams);
3775  
3776          $grouptest = 'gm.userid IS NOT NULL';
3777          if ($useviewallgroups) {
3778              $viewallgroupsusers = get_users_by_capability($context, 'moodle/site:accessallgroups', 'u.id, u.id', '', '', '', '', $exceptions);
3779              if (!empty($viewallgroupsusers)) {
3780                  $grouptest .= ' OR u.id IN (' . implode(',', array_keys($viewallgroupsusers)) . ')';
3781              }
3782          }
3783          $wherecond[] = "($grouptest)";
3784      }
3785  
3786      // User exceptions.
3787      if (!empty($exceptions)) {
3788          $exceptions = (array)$exceptions;
3789          list($exsql, $exparams) = $DB->get_in_or_equal($exceptions, SQL_PARAMS_NAMED, 'exc', false);
3790          $params = array_merge($params, $exparams);
3791          $wherecond[] = "u.id $exsql";
3792      }
3793  
3794      // Collect WHERE conditions and needed joins.
3795      $where = implode(' AND ', $wherecond);
3796      if ($where !== '') {
3797          $where = 'WHERE ' . $where;
3798      }
3799      $joins = implode("\n", $joins);
3800  
3801      // Finally! we have all the bits, run the query.
3802      $sql = "SELECT $fields
3803                FROM {user} u
3804              $joins
3805              $where
3806            ORDER BY $sort";
3807  
3808      return $DB->get_records_sql($sql, $params, $limitfrom, $limitnum);
3809  }
3810  
3811  /**
3812   * Re-sort a users array based on a sorting policy
3813   *
3814   * Will re-sort a $users results array (from get_users_by_capability(), usually)
3815   * based on a sorting policy. This is to support the odd practice of
3816   * sorting teachers by 'authority', where authority was "lowest id of the role
3817   * assignment".
3818   *
3819   * Will execute 1 database query. Only suitable for small numbers of users, as it
3820   * uses an u.id IN() clause.
3821   *
3822   * Notes about the sorting criteria.
3823   *
3824   * As a default, we cannot rely on role.sortorder because then
3825   * admins/coursecreators will always win. That is why the sane
3826   * rule "is locality matters most", with sortorder as 2nd
3827   * consideration.
3828   *
3829   * If you want role.sortorder, use the 'sortorder' policy, and
3830   * name explicitly what roles you want to cover. It's probably
3831   * a good idea to see what roles have the capabilities you want
3832   * (array_diff() them against roiles that have 'can-do-anything'
3833   * to weed out admin-ish roles. Or fetch a list of roles from
3834   * variables like $CFG->coursecontact .
3835   *
3836   * @param array $users Users array, keyed on userid
3837   * @param context $context
3838   * @param array $roles ids of the roles to include, optional
3839   * @param string $sortpolicy defaults to locality, more about
3840   * @return array sorted copy of the array
3841   */
3842  function sort_by_roleassignment_authority($users, context $context, $roles = array(), $sortpolicy = 'locality') {
3843      global $DB;
3844  
3845      $userswhere = ' ra.userid IN (' . implode(',',array_keys($users)) . ')';
3846      $contextwhere = 'AND ra.contextid IN ('.str_replace('/', ',',substr($context->path, 1)).')';
3847      if (empty($roles)) {
3848          $roleswhere = '';
3849      } else {
3850          $roleswhere = ' AND ra.roleid IN ('.implode(',',$roles).')';
3851      }
3852  
3853      $sql = "SELECT ra.userid
3854                FROM {role_assignments} ra
3855                JOIN {role} r
3856                     ON ra.roleid=r.id
3857                JOIN {context} ctx
3858                     ON ra.contextid=ctx.id
3859               WHERE $userswhere
3860                     $contextwhere
3861                     $roleswhere";
3862  
3863      // Default 'locality' policy -- read PHPDoc notes
3864      // about sort policies...
3865      $orderby = 'ORDER BY '
3866                      .'ctx.depth DESC, '  /* locality wins */
3867                      .'r.sortorder ASC, ' /* rolesorting 2nd criteria */
3868                      .'ra.id';            /* role assignment order tie-breaker */
3869      if ($sortpolicy === 'sortorder') {
3870          $orderby = 'ORDER BY '
3871                          .'r.sortorder ASC, ' /* rolesorting 2nd criteria */
3872                          .'ra.id';            /* role assignment order tie-breaker */
3873      }
3874  
3875      $sortedids = $DB->get_fieldset_sql($sql . $orderby);
3876      $sortedusers = array();
3877      $seen = array();
3878  
3879      foreach ($sortedids as $id) {
3880          // Avoid duplicates
3881          if (isset($seen[$id])) {
3882              continue;
3883          }
3884          $seen[$id] = true;
3885  
3886          // assign
3887          $sortedusers[$id] = $users[$id];
3888      }
3889      return $sortedusers;
3890  }
3891  
3892  /**
3893   * Gets all the users assigned this role in this context or higher
3894   *
3895   * Note that moodle is based on capabilities and it is usually better
3896   * to check permissions than to check role ids as the capabilities
3897   * system is more flexible. If you really need, you can to use this
3898   * function but consider has_capability() as a possible substitute.
3899   *
3900   * All $sort fields are added into $fields if not present there yet.
3901   *
3902   * If $roleid is an array or is empty (all roles) you need to set $fields
3903   * (and $sort by extension) params according to it, as the first field
3904   * returned by the database should be unique (ra.id is the best candidate).
3905   *
3906   * @param int $roleid (can also be an array of ints!)
3907   * @param context $context
3908   * @param bool $parent if true, get list of users assigned in higher context too
3909   * @param string $fields fields from user (u.) , role assignment (ra) or role (r.)
3910   * @param string $sort sort from user (u.) , role assignment (ra.) or role (r.).
3911   *      null => use default sort from users_order_by_sql.
3912   * @param bool $all true means all, false means limit to enrolled users
3913   * @param string $group defaults to ''
3914   * @param mixed $limitfrom defaults to ''
3915   * @param mixed $limitnum defaults to ''
3916   * @param string $extrawheretest defaults to ''
3917   * @param array $whereorsortparams any paramter values used by $sort or $extrawheretest.
3918   * @return array
3919   */
3920  function get_role_users($roleid, context $context, $parent = false, $fields = '',
3921          $sort = null, $all = true, $group = '',
3922          $limitfrom = '', $limitnum = '', $extrawheretest = '', $whereorsortparams = array()) {
3923      global $DB;
3924  
3925      if (empty($fields)) {
3926          $userfieldsapi = \core_user\fields::for_name();
3927          $allnames = $userfieldsapi->get_sql('u', false, '', '', false)->selects;
3928          $fields = 'u.id, u.confirmed, u.username, '. $allnames . ', ' .
3929                    'u.maildisplay, u.mailformat, u.maildigest, u.email, u.emailstop, u.city, '.
3930                    'u.country, u.picture, u.idnumber, u.department, u.institution, '.
3931                    'u.lang, u.timezone, u.lastaccess, u.mnethostid, r.name AS rolename, r.sortorder, '.
3932                    'r.shortname AS roleshortname, rn.name AS rolecoursealias';
3933      }
3934  
3935      // Prevent wrong function uses.
3936      if ((empty($roleid) || is_array($roleid)) && strpos($fields, 'ra.id') !== 0) {
3937          debugging('get_role_users() without specifying one single roleid needs to be called prefixing ' .
3938              'role assignments id (ra.id) as unique field, you can use $fields param for it.');
3939  
3940          if (!empty($roleid)) {
3941              // Solving partially the issue when specifying multiple roles.
3942              $users = array();
3943              foreach ($roleid as $id) {
3944                  // Ignoring duplicated keys keeping the first user appearance.
3945                  $users = $users + get_role_users($id, $context, $parent, $fields, $sort, $all, $group,
3946                      $limitfrom, $limitnum, $extrawheretest, $whereorsortparams);
3947              }
3948              return $users;
3949          }
3950      }
3951  
3952      $parentcontexts = '';
3953      if ($parent) {
3954          $parentcontexts = substr($context->path, 1); // kill leading slash
3955          $parentcontexts = str_replace('/', ',', $parentcontexts);
3956          if ($parentcontexts !== '') {
3957              $parentcontexts = ' OR ra.contextid IN ('.$parentcontexts.' )';
3958          }
3959      }
3960  
3961      if ($roleid) {
3962          list($rids, $params) = $DB->get_in_or_equal($roleid, SQL_PARAMS_NAMED, 'r');
3963          $roleselect = "AND ra.roleid $rids";
3964      } else {
3965          $params = array();
3966          $roleselect = '';
3967      }
3968  
3969      if ($coursecontext = $context->get_course_context(false)) {
3970          $params['coursecontext'] = $coursecontext->id;
3971      } else {
3972          $params['coursecontext'] = 0;
3973      }
3974  
3975      if ($group) {
3976          $groupjoin   = "JOIN {groups_members} gm ON gm.userid = u.id";
3977          $groupselect = " AND gm.groupid = :groupid ";
3978          $params['groupid'] = $group;
3979      } else {
3980          $groupjoin   = '';
3981          $groupselect = '';
3982      }
3983  
3984      $params['contextid'] = $context->id;
3985  
3986      if ($extrawheretest) {
3987          $extrawheretest = ' AND ' . $extrawheretest;
3988      }
3989  
3990      if ($whereorsortparams) {
3991          $params = array_merge($params, $whereorsortparams);
3992      }
3993  
3994      if (!$sort) {
3995          list($sort, $sortparams) = users_order_by_sql('u');
3996          $params = array_merge($params, $sortparams);
3997      }
3998  
3999      // Adding the fields from $sort that are not present in $fields.
4000      $sortarray = preg_split('/,\s*/', $sort);
4001      $fieldsarray = preg_split('/,\s*/', $fields);
4002  
4003      // Discarding aliases from the fields.
4004      $fieldnames = array();
4005      foreach ($fieldsarray as $key => $field) {
4006          list($fieldnames[$key]) = explode(' ', $field);
4007      }
4008  
4009      $addedfields = array();
4010      foreach ($sortarray as $sortfield) {
4011          // Throw away any additional arguments to the sort (e.g. ASC/DESC).
4012          list($sortfield) = explode(' ', $sortfield);
4013          list($tableprefix) = explode('.', $sortfield);
4014          $fieldpresent = false;
4015          foreach ($fieldnames as $fieldname) {
4016              if ($fieldname === $sortfield || $fieldname === $tableprefix.'.*') {
4017                  $fieldpresent = true;
4018                  break;
4019              }
4020          }
4021  
4022          if (!$fieldpresent) {
4023              $fieldsarray[] = $sortfield;
4024              $addedfields[] = $sortfield;
4025          }
4026      }
4027  
4028      $fields = implode(', ', $fieldsarray);
4029      if (!empty($addedfields)) {
4030          $addedfields = implode(', ', $addedfields);
4031          debugging('get_role_users() adding '.$addedfields.' to the query result because they were required by $sort but missing in $fields');
4032      }
4033  
4034      if ($all === null) {
4035          // Previously null was used to indicate that parameter was not used.
4036          $all = true;
4037      }
4038      if (!$all and $coursecontext) {
4039          // Do not use get_enrolled_sql() here for performance reasons.
4040          $ejoin = "JOIN {user_enrolments} ue ON ue.userid = u.id
4041                    JOIN {enrol} e ON (e.id = ue.enrolid AND e.courseid = :ecourseid)";
4042          $params['ecourseid'] = $coursecontext->instanceid;
4043      } else {
4044          $ejoin = "";
4045      }
4046  
4047      $sql = "SELECT DISTINCT $fields, ra.roleid
4048                FROM {role_assignments} ra
4049                JOIN {user} u ON u.id = ra.userid
4050                JOIN {role} r ON ra.roleid = r.id
4051              $ejoin
4052           LEFT JOIN {role_names} rn ON (rn.contextid = :coursecontext AND rn.roleid = r.id)
4053          $groupjoin
4054               WHERE (ra.contextid = :contextid $parentcontexts)
4055                     $roleselect
4056                     $groupselect
4057                     $extrawheretest
4058            ORDER BY $sort";                  // join now so that we can just use fullname() later
4059  
4060      return $DB->get_records_sql($sql, $params, $limitfrom, $limitnum);
4061  }
4062  
4063  /**
4064   * Counts all the users assigned this role in this context or higher
4065   *
4066   * @param int|array $roleid either int or an array of ints
4067   * @param context $context
4068   * @param bool $parent if true, get list of users assigned in higher context too
4069   * @return int Returns the result count
4070   */
4071  function count_role_users($roleid, context $context, $parent = false) {
4072      global $DB;
4073  
4074      if ($parent) {
4075          if ($contexts = $context->get_parent_context_ids()) {
4076              $parentcontexts = ' OR r.contextid IN ('.implode(',', $contexts).')';
4077          } else {
4078              $parentcontexts = '';
4079          }
4080      } else {
4081          $parentcontexts = '';
4082      }
4083  
4084      if ($roleid) {
4085          list($rids, $params) = $DB->get_in_or_equal($roleid, SQL_PARAMS_QM);
4086          $roleselect = "AND r.roleid $rids";
4087      } else {
4088          $params = array();
4089          $roleselect = '';
4090      }
4091  
4092      array_unshift($params, $context->id);
4093  
4094      $sql = "SELECT COUNT(DISTINCT u.id)
4095                FROM {role_assignments} r
4096                JOIN {user} u ON u.id = r.userid
4097               WHERE (r.contextid = ? $parentcontexts)
4098                     $roleselect
4099                     AND u.deleted = 0";
4100  
4101      return $DB->count_records_sql($sql, $params);
4102  }
4103  
4104  /**
4105   * This function gets the list of courses that this user has a particular capability in.
4106   *
4107   * It is now reasonably efficient, but bear in mind that if there are users who have the capability
4108   * everywhere, it may return an array of all courses.
4109   *
4110   * @param string $capability Capability in question
4111   * @param int $userid User ID or null for current user
4112   * @param bool $doanything True if 'doanything' is permitted (default)
4113   * @param string $fieldsexceptid Leave blank if you only need 'id' in the course records;
4114   *   otherwise use a comma-separated list of the fields you require, not including id.
4115   *   Add ctxid, ctxpath, ctxdepth etc to return course context information for preloading.
4116   * @param string $orderby If set, use a comma-separated list of fields from course
4117   *   table with sql modifiers (DESC) if needed
4118   * @param int $limit Limit the number of courses to return on success. Zero equals all entries.
4119   * @return array|bool Array of courses, if none found false is returned.
4120   */
4121  function get_user_capability_course($capability, $userid = null, $doanything = true, $fieldsexceptid = '', $orderby = '',
4122          $limit = 0) {
4123      global $DB, $USER;
4124  
4125      // Default to current user.
4126      if (!$userid) {
4127          $userid = $USER->id;
4128      }
4129  
4130      if ($doanything && is_siteadmin($userid)) {
4131          // If the user is a site admin and $doanything is enabled then there is no need to restrict
4132          // the list of courses.
4133          $contextlimitsql = '';
4134          $contextlimitparams = [];
4135      } else {
4136          // Gets SQL to limit contexts ('x' table) to those where the user has this capability.
4137          list ($contextlimitsql, $contextlimitparams) = \core\access\get_user_capability_course_helper::get_sql(
4138                  $userid, $capability);
4139          if (!$contextlimitsql) {
4140              // If the does not have this capability in any context, return false without querying.
4141              return false;
4142          }
4143  
4144          $contextlimitsql = 'WHERE' . $contextlimitsql;
4145      }
4146  
4147      // Convert fields list and ordering
4148      $fieldlist = '';
4149      if ($fieldsexceptid) {
4150          $fields = array_map('trim', explode(',', $fieldsexceptid));
4151          foreach ($fields as $field) {
4152              // Context fields have a different alias.
4153              if (strpos($field, 'ctx') === 0) {
4154                  switch($field) {
4155                      case 'ctxlevel' :
4156                          $realfield = 'contextlevel';
4157                          break;
4158                      case 'ctxinstance' :
4159                          $realfield = 'instanceid';
4160                          break;
4161                      default:
4162                          $realfield = substr($field, 3);
4163                          break;
4164                  }
4165                  $fieldlist .= ',x.' . $realfield . ' AS ' . $field;
4166              } else {
4167                  $fieldlist .= ',c.'.$field;
4168              }
4169          }
4170      }
4171      if ($orderby) {
4172          $fields = explode(',', $orderby);
4173          $orderby = '';
4174          foreach ($fields as $field) {
4175              if ($orderby) {
4176                  $orderby .= ',';
4177              }
4178              $orderby .= 'c.'.$field;
4179          }
4180          $orderby = 'ORDER BY '.$orderby;
4181      }
4182  
4183      $courses = array();
4184      $rs = $DB->get_recordset_sql("
4185              SELECT c.id $fieldlist
4186                FROM {course} c
4187                JOIN {context} x ON c.id = x.instanceid AND x.contextlevel = ?
4188              $contextlimitsql
4189              $orderby", array_merge([CONTEXT_COURSE], $contextlimitparams));
4190      foreach ($rs as $course) {
4191          $courses[] = $course;
4192          $limit--;
4193          if ($limit == 0) {
4194              break;
4195          }
4196      }
4197      $rs->close();
4198      return empty($courses) ? false : $courses;
4199  }
4200  
4201  /**
4202   * Switches the current user to another role for the current session and only
4203   * in the given context.
4204   *
4205   * The caller *must* check
4206   * - that this op is allowed
4207   * - that the requested role can be switched to in this context (use get_switchable_roles)
4208   * - that the requested role is NOT $CFG->defaultuserroleid
4209   *
4210   * To "unswitch" pass 0 as the roleid.
4211   *
4212   * This function *will* modify $USER->access - beware
4213   *
4214   * @param integer $roleid the role to switch to.
4215   * @param context $context the context in which to perform the switch.
4216   * @return bool success or failure.
4217   */
4218  function role_switch($roleid, context $context) {
4219      global $USER;
4220  
4221      // Add the ghost RA to $USER->access as $USER->access['rsw'][$path] = $roleid.
4222      // To un-switch just unset($USER->access['rsw'][$path]).
4223      //
4224      // Note: it is not possible to switch to roles that do not have course:view
4225  
4226      if (!isset($USER->access)) {
4227          load_all_capabilities();
4228      }
4229  
4230      // Add the switch RA
4231      if ($roleid == 0) {
4232          unset($USER->access['rsw'][$context->path]);
4233          return true;
4234      }
4235  
4236      $USER->access['rsw'][$context->path] = $roleid;
4237  
4238      return true;
4239  }
4240  
4241  /**
4242   * Checks if the user has switched roles within the given course.
4243   *
4244   * Note: You can only switch roles within the course, hence it takes a course id
4245   * rather than a context. On that note Petr volunteered to implement this across
4246   * all other contexts, all requests for this should be forwarded to him ;)
4247   *
4248   * @param int $courseid The id of the course to check
4249   * @return bool True if the user has switched roles within the course.
4250   */
4251  function is_role_switched($courseid) {
4252      global $USER;
4253      $context = context_course::instance($courseid, MUST_EXIST);
4254      return (!empty($USER->access['rsw'][$context->path]));
4255  }
4256  
4257  /**
4258   * Get any role that has an override on exact context
4259   *
4260   * @param context $context The context to check
4261   * @return array An array of roles
4262   */
4263  function get_roles_with_override_on_context(context $context) {
4264      global $DB;
4265  
4266      return $DB->get_records_sql("SELECT r.*
4267                                     FROM {role_capabilities} rc, {role} r
4268                                    WHERE rc.roleid = r.id AND rc.contextid = ?",
4269                                  array($context->id));
4270  }
4271  
4272  /**
4273   * Get all capabilities for this role on this context (overrides)
4274   *
4275   * @param stdClass $role
4276   * @param context $context
4277   * @return array
4278   */
4279  function get_capabilities_from_role_on_context($role, context $context) {
4280      global $DB;
4281  
4282      return $DB->get_records_sql("SELECT *
4283                                     FROM {role_capabilities}
4284                                    WHERE contextid = ? AND roleid = ?",
4285                                  array($context->id, $role->id));
4286  }
4287  
4288  /**
4289   * Find all user assignment of users for this role, on this context
4290   *
4291   * @param stdClass $role
4292   * @param context $context
4293   * @return array
4294   */
4295  function get_users_from_role_on_context($role, context $context) {
4296      global $DB;
4297  
4298      return $DB->get_records_sql("SELECT *
4299                                     FROM {role_assignments}
4300                                    WHERE contextid = ? AND roleid = ?",
4301                                  array($context->id, $role->id));
4302  }
4303  
4304  /**
4305   * Simple function returning a boolean true if user has roles
4306   * in context or parent contexts, otherwise false.
4307   *
4308   * @param int $userid
4309   * @param int $roleid
4310   * @param int $contextid empty means any context
4311   * @return bool
4312   */
4313  function user_has_role_assignment($userid, $roleid, $contextid = 0) {
4314      global $DB;
4315  
4316      if ($contextid) {
4317          if (!$context = context::instance_by_id($contextid, IGNORE_MISSING)) {
4318              return false;
4319          }
4320          $parents = $context->get_parent_context_ids(true);
4321          list($contexts, $params) = $DB->get_in_or_equal($parents, SQL_PARAMS_NAMED, 'r');
4322          $params['userid'] = $userid;
4323          $params['roleid'] = $roleid;
4324  
4325          $sql = "SELECT COUNT(ra.id)
4326                    FROM {role_assignments} ra
4327                   WHERE ra.userid = :userid AND ra.roleid = :roleid AND ra.contextid $contexts";
4328  
4329          $count = $DB->get_field_sql($sql, $params);
4330          return ($count > 0);
4331  
4332      } else {
4333          return $DB->record_exists('role_assignments', array('userid'=>$userid, 'roleid'=>$roleid));
4334      }
4335  }
4336  
4337  /**
4338   * Get localised role name or alias if exists and format the text.
4339   *
4340   * @param stdClass $role role object
4341   *      - optional 'coursealias' property should be included for performance reasons if course context used
4342   *      - description property is not required here
4343   * @param context|bool $context empty means system context
4344   * @param int $rolenamedisplay type of role name
4345   * @return string localised role name or course role name alias
4346   */
4347  function role_get_name(stdClass $role, $context = null, $rolenamedisplay = ROLENAME_ALIAS) {
4348      global $DB;
4349  
4350      if ($rolenamedisplay == ROLENAME_SHORT) {
4351          return $role->shortname;
4352      }
4353  
4354      if (!$context or !$coursecontext = $context->get_course_context(false)) {
4355          $coursecontext = null;
4356      }
4357  
4358      if ($coursecontext and !property_exists($role, 'coursealias') and ($rolenamedisplay == ROLENAME_ALIAS or $rolenamedisplay == ROLENAME_BOTH or $rolenamedisplay == ROLENAME_ALIAS_RAW)) {
4359          $role = clone($role); // Do not modify parameters.
4360          if ($r = $DB->get_record('role_names', array('roleid'=>$role->id, 'contextid'=>$coursecontext->id))) {
4361              $role->coursealias = $r->name;
4362          } else {
4363              $role->coursealias = null;
4364          }
4365      }
4366  
4367      if ($rolenamedisplay == ROLENAME_ALIAS_RAW) {
4368          if ($coursecontext) {
4369              return $role->coursealias;
4370          } else {
4371              return null;
4372          }
4373      }
4374  
4375      if (trim($role->name) !== '') {
4376          // For filtering always use context where was the thing defined - system for roles here.
4377          $original = format_string($role->name, true, array('context'=>context_system::instance()));
4378  
4379      } else {
4380          // Empty role->name means we want to see localised role name based on shortname,
4381          // only default roles are supposed to be localised.
4382          switch ($role->shortname) {
4383              case 'manager':         $original = get_string('manager', 'role'); break;
4384              case 'coursecreator':   $original = get_string('coursecreators'); break;
4385              case 'editingteacher':  $original = get_string('defaultcourseteacher'); break;
4386              case 'teacher':         $original = get_string('noneditingteacher'); break;
4387              case 'student':         $original = get_string('defaultcoursestudent'); break;
4388              case 'guest':           $original = get_string('guest'); break;
4389              case 'user':            $original = get_string('authenticateduser'); break;
4390              case 'frontpage':       $original = get_string('frontpageuser', 'role'); break;
4391              // We should not get here, the role UI should require the name for custom roles!
4392              default:                $original = $role->shortname; break;
4393          }
4394      }
4395  
4396      if ($rolenamedisplay == ROLENAME_ORIGINAL) {
4397          return $original;
4398      }
4399  
4400      if ($rolenamedisplay == ROLENAME_ORIGINALANDSHORT) {
4401          return "$original ($role->shortname)";
4402      }
4403  
4404      if ($rolenamedisplay == ROLENAME_ALIAS) {
4405          if ($coursecontext and trim($role->coursealias) !== '') {
4406              return format_string($role->coursealias, true, array('context'=>$coursecontext));
4407          } else {
4408              return $original;
4409          }
4410      }
4411  
4412      if ($rolenamedisplay == ROLENAME_BOTH) {
4413          if ($coursecontext and trim($role->coursealias) !== '') {
4414              return format_string($role->coursealias, true, array('context'=>$coursecontext)) . " ($original)";
4415          } else {
4416              return $original;
4417          }
4418      }
4419  
4420      throw new coding_exception('Invalid $rolenamedisplay parameter specified in role_get_name()');
4421  }
4422  
4423  /**
4424   * Returns localised role description if available.
4425   * If the name is empty it tries to find the default role name using
4426   * hardcoded list of default role names or other methods in the future.
4427   *
4428   * @param stdClass $role
4429   * @return string localised role name
4430   */
4431  function role_get_description(stdClass $role) {
4432      if (!html_is_blank($role->description)) {
4433          return format_text($role->description, FORMAT_HTML, array('context'=>context_system::instance()));
4434      }
4435  
4436      switch ($role->shortname) {
4437          case 'manager':         return get_string('managerdescription', 'role');
4438          case 'coursecreator':   return get_string('coursecreatorsdescription');
4439          case 'editingteacher':  return get_string('defaultcourseteacherdescription');
4440          case 'teacher':         return get_string('noneditingteacherdescription');
4441          case 'student':         return get_string('defaultcoursestudentdescription');
4442          case 'guest':           return get_string('guestdescription');
4443          case 'user':            return get_string('authenticateduserdescription');
4444          case 'frontpage':       return get_string('frontpageuserdescription', 'role');
4445          default:                return '';
4446      }
4447  }
4448  
4449  /**
4450   * Get all the localised role names for a context.
4451   *
4452   * In new installs default roles have empty names, this function
4453   * add localised role names using current language pack.
4454   *
4455   * @param context $context the context, null means system context
4456   * @param array of role objects with a ->localname field containing the context-specific role name.
4457   * @param int $rolenamedisplay
4458   * @param bool $returnmenu true means id=>localname, false means id=>rolerecord
4459   * @return array Array of context-specific role names, or role objects with a ->localname field added.
4460   */
4461  function role_get_names(context $context = null, $rolenamedisplay = ROLENAME_ALIAS, $returnmenu = null) {
4462      return role_fix_names(get_all_roles($context), $context, $rolenamedisplay, $returnmenu);
4463  }
4464  
4465  /**
4466   * Prepare list of roles for display, apply aliases and localise default role names.
4467   *
4468   * @param array $roleoptions array roleid => roleobject (with optional coursealias), strings are accepted for backwards compatibility only
4469   * @param context $context the context, null means system context
4470   * @param int $rolenamedisplay
4471   * @param bool $returnmenu null means keep the same format as $roleoptions, true means id=>localname, false means id=>rolerecord
4472   * @return array Array of context-specific role names, or role objects with a ->localname field added.
4473   */
4474  function role_fix_names($roleoptions, context $context = null, $rolenamedisplay = ROLENAME_ALIAS, $returnmenu = null) {
4475      global $DB;
4476  
4477      if (empty($roleoptions)) {
4478          return array();
4479      }
4480  
4481      if (!$context or !$coursecontext = $context->get_course_context(false)) {
4482          $coursecontext = null;
4483      }
4484  
4485      // We usually need all role columns...
4486      $first = reset($roleoptions);
4487      if ($returnmenu === null) {
4488          $returnmenu = !is_object($first);
4489      }
4490  
4491      if (!is_object($first) or !property_exists($first, 'shortname')) {
4492          $allroles = get_all_roles($context);
4493          foreach ($roleoptions as $rid => $unused) {
4494              $roleoptions[$rid] = $allroles[$rid];
4495          }
4496      }
4497  
4498      // Inject coursealias if necessary.
4499      if ($coursecontext and ($rolenamedisplay == ROLENAME_ALIAS_RAW or $rolenamedisplay == ROLENAME_ALIAS or $rolenamedisplay == ROLENAME_BOTH)) {
4500          $first = reset($roleoptions);
4501          if (!property_exists($first, 'coursealias')) {
4502              $aliasnames = $DB->get_records('role_names', array('contextid'=>$coursecontext->id));
4503              foreach ($aliasnames as $alias) {
4504                  if (isset($roleoptions[$alias->roleid])) {
4505                      $roleoptions[$alias->roleid]->coursealias = $alias->name;
4506                  }
4507              }
4508          }
4509      }
4510  
4511      // Add localname property.
4512      foreach ($roleoptions as $rid => $role) {
4513          $roleoptions[$rid]->localname = role_get_name($role, $coursecontext, $rolenamedisplay);
4514      }
4515  
4516      if (!$returnmenu) {
4517          return $roleoptions;
4518      }
4519  
4520      $menu = array();
4521      foreach ($roleoptions as $rid => $role) {
4522          $menu[$rid] = $role->localname;
4523      }
4524  
4525      return $menu;
4526  }
4527  
4528  /**
4529   * Aids in detecting if a new line is required when reading a new capability
4530   *
4531   * This function helps admin/roles/manage.php etc to detect if a new line should be printed
4532   * when we read in a new capability.
4533   * Most of the time, if the 2 components are different we should print a new line, (e.g. course system->rss client)
4534   * but when we are in grade, all reports/import/export capabilities should be together
4535   *
4536   * @param string $cap component string a
4537   * @param string $comp component string b
4538   * @param int $contextlevel
4539   * @return bool whether 2 component are in different "sections"
4540   */
4541  function component_level_changed($cap, $comp, $contextlevel) {
4542  
4543      if (strstr($cap->component, '/') && strstr($comp, '/')) {
4544          $compsa = explode('/', $cap->component);
4545          $compsb = explode('/', $comp);
4546  
4547          // list of system reports
4548          if (($compsa[0] == 'report') && ($compsb[0] == 'report')) {
4549              return false;
4550          }
4551  
4552          // we are in gradebook, still
4553          if (($compsa[0] == 'gradeexport' || $compsa[0] == 'gradeimport' || $compsa[0] == 'gradereport') &&
4554              ($compsb[0] == 'gradeexport' || $compsb[0] == 'gradeimport' || $compsb[0] == 'gradereport')) {
4555              return false;
4556          }
4557  
4558          if (($compsa[0] == 'coursereport') && ($compsb[0] == 'coursereport')) {
4559              return false;
4560          }
4561      }
4562  
4563      return ($cap->component != $comp || $cap->contextlevel != $contextlevel);
4564  }
4565  
4566  /**
4567   * Fix the roles.sortorder field in the database, so it contains sequential integers,
4568   * and return an array of roleids in order.
4569   *
4570   * @param array $allroles array of roles, as returned by get_all_roles();
4571   * @return array $role->sortorder =-> $role->id with the keys in ascending order.
4572   */
4573  function fix_role_sortorder($allroles) {
4574      global $DB;
4575  
4576      $rolesort = array();
4577      $i = 0;
4578      foreach ($allroles as $role) {
4579          $rolesort[$i] = $role->id;
4580          if ($role->sortorder != $i) {
4581              $r = new stdClass();
4582              $r->id = $role->id;
4583              $r->sortorder = $i;
4584              $DB->update_record('role', $r);
4585              $allroles[$role->id]->sortorder = $i;
4586          }
4587          $i++;
4588      }
4589      return $rolesort;
4590  }
4591  
4592  /**
4593   * Switch the sort order of two roles (used in admin/roles/manage.php).
4594   *
4595   * @param stdClass $first The first role. Actually, only ->sortorder is used.
4596   * @param stdClass $second The second role. Actually, only ->sortorder is used.
4597   * @return boolean success or failure
4598   */
4599  function switch_roles($first, $second) {
4600      global $DB;
4601      $temp = $DB->get_field('role', 'MAX(sortorder) + 1', array());
4602      $result = $DB->set_field('role', 'sortorder', $temp, array('sortorder' => $first->sortorder));
4603      $result = $result && $DB->set_field('role', 'sortorder', $first->sortorder, array('sortorder' => $second->sortorder));
4604      $result = $result && $DB->set_field('role', 'sortorder', $second->sortorder, array('sortorder' => $temp));
4605      return $result;
4606  }
4607  
4608  /**
4609   * Duplicates all the base definitions of a role
4610   *
4611   * @param stdClass $sourcerole role to copy from
4612   * @param int $targetrole id of role to copy to
4613   */
4614  function role_cap_duplicate($sourcerole, $targetrole) {
4615      global $DB;
4616  
4617      $systemcontext = context_system::instance();
4618      $caps = $DB->get_records_sql("SELECT *
4619                                      FROM {role_capabilities}
4620                                     WHERE roleid = ? AND contextid = ?",
4621                                   array($sourcerole->id, $systemcontext->id));
4622      // adding capabilities
4623      foreach ($caps as $cap) {
4624          unset($cap->id);
4625          $cap->roleid = $targetrole;
4626          $DB->insert_record('role_capabilities', $cap);
4627      }
4628  
4629      // Reset any cache of this role, including MUC.
4630      accesslib_clear_role_cache($targetrole);
4631  }
4632  
4633  /**
4634   * Returns two lists, this can be used to find out if user has capability.
4635   * Having any needed role and no forbidden role in this context means
4636   * user has this capability in this context.
4637   * Use get_role_names_with_cap_in_context() if you need role names to display in the UI
4638   *
4639   * @param stdClass $context
4640   * @param string $capability
4641   * @return array($neededroles, $forbiddenroles)
4642   */
4643  function get_roles_with_cap_in_context($context, $capability) {
4644      global $DB;
4645  
4646      $ctxids = trim($context->path, '/'); // kill leading slash
4647      $ctxids = str_replace('/', ',', $ctxids);
4648  
4649      $sql = "SELECT rc.id, rc.roleid, rc.permission, ctx.depth
4650                FROM {role_capabilities} rc
4651                JOIN {context} ctx ON ctx.id = rc.contextid
4652                JOIN {capabilities} cap ON rc.capability = cap.name
4653               WHERE rc.capability = :cap AND ctx.id IN ($ctxids)
4654            ORDER BY rc.roleid ASC, ctx.depth DESC";
4655      $params = array('cap'=>$capability);
4656  
4657      if (!$capdefs = $DB->get_records_sql($sql, $params)) {
4658          // no cap definitions --> no capability
4659          return array(array(), array());
4660      }
4661  
4662      $forbidden = array();
4663      $needed    = array();
4664      foreach ($capdefs as $def) {
4665          if (isset($forbidden[$def->roleid])) {
4666              continue;
4667          }
4668          if ($def->permission == CAP_PROHIBIT) {
4669              $forbidden[$def->roleid] = $def->roleid;
4670              unset($needed[$def->roleid]);
4671              continue;
4672          }
4673          if (!isset($needed[$def->roleid])) {
4674              if ($def->permission == CAP_ALLOW) {
4675                  $needed[$def->roleid] = true;
4676              } else if ($def->permission == CAP_PREVENT) {
4677                  $needed[$def->roleid] = false;
4678              }
4679          }
4680      }
4681      unset($capdefs);
4682  
4683      // remove all those roles not allowing
4684      foreach ($needed as $key=>$value) {
4685          if (!$value) {
4686              unset($needed[$key]);
4687          } else {
4688              $needed[$key] = $key;
4689          }
4690      }
4691  
4692      return array($needed, $forbidden);
4693  }
4694  
4695  /**
4696   * Returns an array of role IDs that have ALL of the the supplied capabilities
4697   * Uses get_roles_with_cap_in_context(). Returns $allowed minus $forbidden
4698   *
4699   * @param stdClass $context
4700   * @param array $capabilities An array of capabilities
4701   * @return array of roles with all of the required capabilities
4702   */
4703  function get_roles_with_caps_in_context($context, $capabilities) {
4704      $neededarr = array();
4705      $forbiddenarr = array();
4706      foreach ($capabilities as $caprequired) {
4707          list($neededarr[], $forbiddenarr[]) = get_roles_with_cap_in_context($context, $caprequired);
4708      }
4709  
4710      $rolesthatcanrate = array();
4711      if (!empty($neededarr)) {
4712          foreach ($neededarr as $needed) {
4713              if (empty($rolesthatcanrate)) {
4714                  $rolesthatcanrate = $needed;
4715              } else {
4716                  //only want roles that have all caps
4717                  $rolesthatcanrate = array_intersect_key($rolesthatcanrate,$needed);
4718              }
4719          }
4720      }
4721      if (!empty($forbiddenarr) && !empty($rolesthatcanrate)) {
4722          foreach ($forbiddenarr as $forbidden) {
4723             //remove any roles that are forbidden any of the caps
4724             $rolesthatcanrate = array_diff($rolesthatcanrate, $forbidden);
4725          }
4726      }
4727      return $rolesthatcanrate;
4728  }
4729  
4730  /**
4731   * Returns an array of role names that have ALL of the the supplied capabilities
4732   * Uses get_roles_with_caps_in_context(). Returns $allowed minus $forbidden
4733   *
4734   * @param stdClass $context
4735   * @param array $capabilities An array of capabilities
4736   * @return array of roles with all of the required capabilities
4737   */
4738  function get_role_names_with_caps_in_context($context, $capabilities) {
4739      global $DB;
4740  
4741      $rolesthatcanrate = get_roles_with_caps_in_context($context, $capabilities);
4742      $allroles = $DB->get_records('role', null, 'sortorder DESC');
4743  
4744      $roles = array();
4745      foreach ($rolesthatcanrate as $r) {
4746          $roles[$r] = $allroles[$r];
4747      }
4748  
4749      return role_fix_names($roles, $context, ROLENAME_ALIAS, true);
4750  }
4751  
4752  /**
4753   * This function verifies the prohibit comes from this context
4754   * and there are no more prohibits in parent contexts.
4755   *
4756   * @param int $roleid
4757   * @param context $context
4758   * @param string $capability name
4759   * @return bool
4760   */
4761  function prohibit_is_removable($roleid, context $context, $capability) {
4762      global $DB;
4763  
4764      $ctxids = trim($context->path, '/'); // kill leading slash
4765      $ctxids = str_replace('/', ',', $ctxids);
4766  
4767      $params = array('roleid'=>$roleid, 'cap'=>$capability, 'prohibit'=>CAP_PROHIBIT);
4768  
4769      $sql = "SELECT ctx.id
4770                FROM {role_capabilities} rc
4771                JOIN {context} ctx ON ctx.id = rc.contextid
4772                JOIN {capabilities} cap ON rc.capability = cap.name
4773               WHERE rc.roleid = :roleid AND rc.permission = :prohibit AND rc.capability = :cap AND ctx.id IN ($ctxids)
4774            ORDER BY ctx.depth DESC";
4775  
4776      if (!$prohibits = $DB->get_records_sql($sql, $params)) {
4777          // no prohibits == nothing to remove
4778          return true;
4779      }
4780  
4781      if (count($prohibits) > 1) {
4782          // more prohibits can not be removed
4783          return false;
4784      }
4785  
4786      return !empty($prohibits[$context->id]);
4787  }
4788  
4789  /**
4790   * More user friendly role permission changing,
4791   * it should produce as few overrides as possible.
4792   *
4793   * @param int $roleid
4794   * @param stdClass $context
4795   * @param string $capname capability name
4796   * @param int $permission
4797   * @return void
4798   */
4799  function role_change_permission($roleid, $context, $capname, $permission) {
4800      global $DB;
4801  
4802      if ($permission == CAP_INHERIT) {
4803          unassign_capability($capname, $roleid, $context->id);
4804          return;
4805      }
4806  
4807      $ctxids = trim($context->path, '/'); // kill leading slash
4808      $ctxids = str_replace('/', ',', $ctxids);
4809  
4810      $params = array('roleid'=>$roleid, 'cap'=>$capname);
4811  
4812      $sql = "SELECT ctx.id, rc.permission, ctx.depth
4813                FROM {role_capabilities} rc
4814                JOIN {context} ctx ON ctx.id = rc.contextid
4815                JOIN {capabilities} cap ON rc.capability = cap.name
4816               WHERE rc.roleid = :roleid AND rc.capability = :cap AND ctx.id IN ($ctxids)
4817            ORDER BY ctx.depth DESC";
4818  
4819      if ($existing = $DB->get_records_sql($sql, $params)) {
4820          foreach ($existing as $e) {
4821              if ($e->permission == CAP_PROHIBIT) {
4822                  // prohibit can not be overridden, no point in changing anything
4823                  return;
4824              }
4825          }
4826          $lowest = array_shift($existing);
4827          if ($lowest->permission == $permission) {
4828              // permission already set in this context or parent - nothing to do
4829              return;
4830          }
4831          if ($existing) {
4832              $parent = array_shift($existing);
4833              if ($parent->permission == $permission) {
4834                  // permission already set in parent context or parent - just unset in this context
4835                  // we do this because we want as few overrides as possible for performance reasons
4836                  unassign_capability($capname, $roleid, $context->id);
4837                  return;
4838              }
4839          }
4840  
4841      } else {
4842          if ($permission == CAP_PREVENT) {
4843              // nothing means role does not have permission
4844              return;
4845          }
4846      }
4847  
4848      // assign the needed capability
4849      assign_capability($capname, $permission, $roleid, $context->id, true);
4850  }
4851  
4852  
4853  /**
4854   * Basic moodle context abstraction class.
4855   *
4856   * Google confirms that no other important framework is using "context" class,
4857   * we could use something else like mcontext or moodle_context, but we need to type
4858   * this very often which would be annoying and it would take too much space...
4859   *
4860   * This class is derived from stdClass for backwards compatibility with
4861   * odl $context record that was returned from DML $DB->get_record()
4862   *
4863   * @package   core_access
4864   * @category  access
4865   * @copyright Petr Skoda {@link http://skodak.org}
4866   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
4867   * @since     Moodle 2.2
4868   *
4869   * @property-read int $id context id
4870   * @property-read int $contextlevel CONTEXT_SYSTEM, CONTEXT_COURSE, etc.
4871   * @property-read int $instanceid id of related instance in each context
4872   * @property-read string $path path to context, starts with system context
4873   * @property-read int $depth
4874   */
4875  abstract class context extends stdClass implements IteratorAggregate {
4876  
4877      /** @var string Default sorting of capabilities in {@see get_capabilities} */
4878      protected const DEFAULT_CAPABILITY_SORT = 'contextlevel, component, name';
4879  
4880      /**
4881       * The context id
4882       * Can be accessed publicly through $context->id
4883       * @var int
4884       */
4885      protected $_id;
4886  
4887      /**
4888       * The context level
4889       * Can be accessed publicly through $context->contextlevel
4890       * @var int One of CONTEXT_* e.g. CONTEXT_COURSE, CONTEXT_MODULE
4891       */
4892      protected $_contextlevel;
4893  
4894      /**
4895       * Id of the item this context is related to e.g. COURSE_CONTEXT => course.id
4896       * Can be accessed publicly through $context->instanceid
4897       * @var int
4898       */
4899      protected $_instanceid;
4900  
4901      /**
4902       * The path to the context always starting from the system context
4903       * Can be accessed publicly through $context->path
4904       * @var string
4905       */
4906      protected $_path;
4907  
4908      /**
4909       * The depth of the context in relation to parent contexts
4910       * Can be accessed publicly through $context->depth
4911       * @var int
4912       */
4913      protected $_depth;
4914  
4915      /**
4916       * Whether this context is locked or not.
4917       *
4918       * Can be accessed publicly through $context->locked.
4919       *
4920       * @var int
4921       */
4922      protected $_locked;
4923  
4924      /**
4925       * @var array Context caching info
4926       */
4927      private static $cache_contextsbyid = array();
4928  
4929      /**
4930       * @var array Context caching info
4931       */
4932      private static $cache_contexts     = array();
4933  
4934      /**
4935       * Context count
4936       * Why do we do count contexts? Because count($array) is horribly slow for large arrays
4937       * @var int
4938       */
4939      protected static $cache_count      = 0;
4940  
4941      /**
4942       * @var array Context caching info
4943       */
4944      protected static $cache_preloaded  = array();
4945  
4946      /**
4947       * @var context_system The system context once initialised
4948       */
4949      protected static $systemcontext    = null;
4950  
4951      /**
4952       * Resets the cache to remove all data.
4953       * @static
4954       */
4955      protected static function reset_caches() {
4956          self::$cache_contextsbyid = array();
4957          self::$cache_contexts     = array();
4958          self::$cache_count        = 0;
4959          self::$cache_preloaded    = array();
4960  
4961          self::$systemcontext = null;
4962      }
4963  
4964      /**
4965       * Adds a context to the cache. If the cache is full, discards a batch of
4966       * older entries.
4967       *
4968       * @static
4969       * @param context $context New context to add
4970       * @return void
4971       */
4972      protected static function cache_add(context $context) {
4973          if (isset(self::$cache_contextsbyid[$context->id])) {
4974              // already cached, no need to do anything - this is relatively cheap, we do all this because count() is slow
4975              return;
4976          }
4977  
4978          if (self::$cache_count >= CONTEXT_CACHE_MAX_SIZE) {
4979              $i = 0;
4980              foreach (self::$cache_contextsbyid as $ctx) {
4981                  $i++;
4982                  if ($i <= 100) {
4983                      // we want to keep the first contexts to be loaded on this page, hopefully they will be needed again later
4984                      continue;
4985                  }
4986                  if ($i > (CONTEXT_CACHE_MAX_SIZE / 3)) {
4987                      // we remove oldest third of the contexts to make room for more contexts
4988                      break;
4989                  }
4990                  unset(self::$cache_contextsbyid[$ctx->id]);
4991                  unset(self::$cache_contexts[$ctx->contextlevel][$ctx->instanceid]);
4992                  self::$cache_count--;
4993              }
4994          }
4995  
4996          self::$cache_contexts[$context->contextlevel][$context->instanceid] = $context;
4997          self::$cache_contextsbyid[$context->id] = $context;
4998          self::$cache_count++;
4999      }
5000  
5001      /**
5002       * Removes a context from the cache.
5003       *
5004       * @static
5005       * @param context $context Context object to remove
5006       * @return void
5007       */
5008      protected static function cache_remove(context $context) {
5009          if (!isset(self::$cache_contextsbyid[$context->id])) {
5010              // not cached, no need to do anything - this is relatively cheap, we do all this because count() is slow
5011              return;
5012          }
5013          unset(self::$cache_contexts[$context->contextlevel][$context->instanceid]);
5014          unset(self::$cache_contextsbyid[$context->id]);
5015  
5016          self::$cache_count--;
5017  
5018          if (self::$cache_count < 0) {
5019              self::$cache_count = 0;
5020          }
5021      }
5022  
5023      /**
5024       * Gets a context from the cache.
5025       *
5026       * @static
5027       * @param int $contextlevel Context level
5028       * @param int $instance Instance ID
5029       * @return context|bool Context or false if not in cache
5030       */
5031      protected static function cache_get($contextlevel, $instance) {
5032          if (isset(self::$cache_contexts[$contextlevel][$instance])) {
5033              return self::$cache_contexts[$contextlevel][$instance];
5034          }
5035          return false;
5036      }
5037  
5038      /**
5039       * Gets a context from the cache based on its id.
5040       *
5041       * @static
5042       * @param int $id Context ID
5043       * @return context|bool Context or false if not in cache
5044       */
5045      protected static function cache_get_by_id($id) {
5046          if (isset(self::$cache_contextsbyid[$id])) {
5047              return self::$cache_contextsbyid[$id];
5048          }
5049          return false;
5050      }
5051  
5052      /**
5053       * Preloads context information from db record and strips the cached info.
5054       *
5055       * @static
5056       * @param stdClass $rec
5057       * @return void (modifies $rec)
5058       */
5059      protected static function preload_from_record(stdClass $rec) {
5060          $notenoughdata = false;
5061          $notenoughdata = $notenoughdata || empty($rec->ctxid);
5062          $notenoughdata = $notenoughdata || empty($rec->ctxlevel);
5063          $notenoughdata = $notenoughdata || !isset($rec->ctxinstance);
5064          $notenoughdata = $notenoughdata || empty($rec->ctxpath);
5065          $notenoughdata = $notenoughdata || empty($rec->ctxdepth);
5066          $notenoughdata = $notenoughdata || !isset($rec->ctxlocked);
5067          if ($notenoughdata) {
5068              // The record does not have enough data, passed here repeatedly or context does not exist yet.
5069              if (isset($rec->ctxid) && !isset($rec->ctxlocked)) {
5070                  debugging('Locked value missing. Code is possibly not usings the getter properly.', DEBUG_DEVELOPER);
5071              }
5072              return;
5073          }
5074  
5075          $record = (object) [
5076              'id'            => $rec->ctxid,
5077              'contextlevel'  => $rec->ctxlevel,
5078              'instanceid'    => $rec->ctxinstance,
5079              'path'          => $rec->ctxpath,
5080              'depth'         => $rec->ctxdepth,
5081              'locked'        => $rec->ctxlocked,
5082          ];
5083  
5084          unset($rec->ctxid);
5085          unset($rec->ctxlevel);
5086          unset($rec->ctxinstance);
5087          unset($rec->ctxpath);
5088          unset($rec->ctxdepth);
5089          unset($rec->ctxlocked);
5090  
5091          return context::create_instance_from_record($record);
5092      }
5093  
5094  
5095      // ====== magic methods =======
5096  
5097      /**
5098       * Magic setter method, we do not want anybody to modify properties from the outside
5099       * @param string $name
5100       * @param mixed $value
5101       */
5102      public function __set($name, $value) {
5103          debugging('Can not change context instance properties!');
5104      }
5105  
5106      /**
5107       * Magic method getter, redirects to read only values.
5108       * @param string $name
5109       * @return mixed
5110       */
5111      public function __get($name) {
5112          switch ($name) {
5113              case 'id':
5114                  return $this->_id;
5115              case 'contextlevel':
5116                  return $this->_contextlevel;
5117              case 'instanceid':
5118                  return $this->_instanceid;
5119              case 'path':
5120                  return $this->_path;
5121              case 'depth':
5122                  return $this->_depth;
5123              case 'locked':
5124                  return $this->is_locked();
5125  
5126              default:
5127                  debugging('Invalid context property accessed! '.$name);
5128                  return null;
5129          }
5130      }
5131  
5132      /**
5133       * Full support for isset on our magic read only properties.
5134       * @param string $name
5135       * @return bool
5136       */
5137      public function __isset($name) {
5138          switch ($name) {
5139              case 'id':
5140                  return isset($this->_id);
5141              case 'contextlevel':
5142                  return isset($this->_contextlevel);
5143              case 'instanceid':
5144                  return isset($this->_instanceid);
5145              case 'path':
5146                  return isset($this->_path);
5147              case 'depth':
5148                  return isset($this->_depth);
5149              case 'locked':
5150                  // Locked is always set.
5151                  return true;
5152              default:
5153                  return false;
5154          }
5155      }
5156  
5157      /**
5158       * All properties are read only, sorry.
5159       * @param string $name
5160       */
5161      public function __unset($name) {
5162          debugging('Can not unset context instance properties!');
5163      }
5164  
5165      // ====== implementing method from interface IteratorAggregate ======
5166  
5167      /**
5168       * Create an iterator because magic vars can't be seen by 'foreach'.
5169       *
5170       * Now we can convert context object to array using convert_to_array(),
5171       * and feed it properly to json_encode().
5172       */
5173      public function getIterator() {
5174          $ret = array(
5175              'id'           => $this->id,
5176              'contextlevel' => $this->contextlevel,
5177              'instanceid'   => $this->instanceid,
5178              'path'         => $this->path,
5179              'depth'        => $this->depth,
5180              'locked'       => $this->locked,
5181          );
5182          return new ArrayIterator($ret);
5183      }
5184  
5185      // ====== general context methods ======
5186  
5187      /**
5188       * Constructor is protected so that devs are forced to
5189       * use context_xxx::instance() or context::instance_by_id().
5190       *
5191       * @param stdClass $record
5192       */
5193      protected function __construct(stdClass $record) {
5194          $this->_id           = (int)$record->id;
5195          $this->_contextlevel = (int)$record->contextlevel;
5196          $this->_instanceid   = $record->instanceid;
5197          $this->_path         = $record->path;
5198          $this->_depth        = $record->depth;
5199  
5200          if (isset($record->locked)) {
5201              $this->_locked = $record->locked;
5202          } else if (!during_initial_install() && !moodle_needs_upgrading()) {
5203              debugging('Locked value missing. Code is possibly not usings the getter properly.', DEBUG_DEVELOPER);
5204          }
5205      }
5206  
5207      /**
5208       * This function is also used to work around 'protected' keyword problems in context_helper.
5209       * @static
5210       * @param stdClass $record
5211       * @return context instance
5212       */
5213      protected static function create_instance_from_record(stdClass $record) {
5214          $classname = context_helper::get_class_for_level($record->contextlevel);
5215  
5216          if ($context = context::cache_get_by_id($record->id)) {
5217              return $context;
5218          }
5219  
5220          $context = new $classname($record);
5221          context::cache_add($context);
5222  
5223          return $context;
5224      }
5225  
5226      /**
5227       * Copy prepared new contexts from temp table to context table,
5228       * we do this in db specific way for perf reasons only.
5229       * @static
5230       */
5231      protected static function merge_context_temp_table() {
5232          global $DB;
5233  
5234          /* MDL-11347:
5235           *  - mysql does not allow to use FROM in UPDATE statements
5236           *  - using two tables after UPDATE works in mysql, but might give unexpected
5237           *    results in pg 8 (depends on configuration)
5238           *  - using table alias in UPDATE does not work in pg < 8.2
5239           *
5240           * Different code for each database - mostly for performance reasons
5241           */
5242  
5243          $dbfamily = $DB->get_dbfamily();
5244          if ($dbfamily == 'mysql') {
5245              $updatesql = "UPDATE {context} ct, {context_temp} temp
5246                               SET ct.path     = temp.path,
5247                                   ct.depth    = temp.depth,
5248                                   ct.locked   = temp.locked
5249                             WHERE ct.id = temp.id";
5250          } else if ($dbfamily == 'oracle') {
5251              $updatesql = "UPDATE {context} ct
5252                               SET (ct.path, ct.depth, ct.locked) =
5253                                   (SELECT temp.path, temp.depth, temp.locked
5254                                      FROM {context_temp} temp
5255                                     WHERE temp.id=ct.id)
5256                             WHERE EXISTS (SELECT 'x'
5257                                             FROM {context_temp} temp
5258                                             WHERE temp.id = ct.id)";
5259          } else if ($dbfamily == 'postgres' or $dbfamily == 'mssql') {
5260              $updatesql = "UPDATE {context}
5261                               SET path     = temp.path,
5262                                   depth    = temp.depth,
5263                                   locked   = temp.locked
5264                              FROM {context_temp} temp
5265                             WHERE temp.id={context}.id";
5266          } else {
5267              // sqlite and others
5268              $updatesql = "UPDATE {context}
5269                               SET path     = (SELECT path FROM {context_temp} WHERE id = {context}.id),
5270                                   depth    = (SELECT depth FROM {context_temp} WHERE id = {context}.id),
5271                                   locked   = (SELECT locked FROM {context_temp} WHERE id = {context}.id)
5272                               WHERE id IN (SELECT id FROM {context_temp})";
5273          }
5274  
5275          $DB->execute($updatesql);
5276      }
5277  
5278     /**
5279      * Get a context instance as an object, from a given context id.
5280      *
5281      * @static
5282      * @param int $id context id
5283      * @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
5284      *                        MUST_EXIST means throw exception if no record found
5285      * @return context|bool the context object or false if not found
5286      */
5287      public static function instance_by_id($id, $strictness = MUST_EXIST) {
5288          global $DB;
5289  
5290          if (get_called_class() !== 'context' and get_called_class() !== 'context_helper') {
5291              // some devs might confuse context->id and instanceid, better prevent these mistakes completely
5292              throw new coding_exception('use only context::instance_by_id() for real context levels use ::instance() methods');
5293          }
5294  
5295          if ($id == SYSCONTEXTID) {
5296              return context_system::instance(0, $strictness);
5297          }
5298  
5299          if (is_array($id) or is_object($id) or empty($id)) {
5300              throw new coding_exception('Invalid context id specified context::instance_by_id()');
5301          }
5302  
5303          if ($context = context::cache_get_by_id($id)) {
5304              return $context;
5305          }
5306  
5307          if ($record = $DB->get_record('context', array('id'=>$id), '*', $strictness)) {
5308              return context::create_instance_from_record($record);
5309          }
5310  
5311          return false;
5312      }
5313  
5314      /**
5315       * Update context info after moving context in the tree structure.
5316       *
5317       * @param context $newparent
5318       * @return void
5319       */
5320      public function update_moved(context $newparent) {
5321          global $DB;
5322  
5323          $frompath = $this->_path;
5324          $newpath  = $newparent->path . '/' . $this->_id;
5325  
5326          $trans = $DB->start_delegated_transaction();
5327  
5328          $setdepth = '';
5329          if (($newparent->depth +1) != $this->_depth) {
5330              $diff = $newparent->depth - $this->_depth + 1;
5331              $setdepth = ", depth = depth + $diff";
5332          }
5333          $sql = "UPDATE {context}
5334                     SET path = ?
5335                         $setdepth
5336                   WHERE id = ?";
5337          $params = array($newpath, $this->_id);
5338          $DB->execute($sql, $params);
5339  
5340          $this->_path  = $newpath;
5341          $this->_depth = $newparent->depth + 1;
5342  
5343          $sql = "UPDATE {context}
5344                     SET path = ".$DB->sql_concat("?", $DB->sql_substr("path", strlen($frompath)+1))."
5345                         $setdepth
5346                   WHERE path LIKE ?";
5347          $params = array($newpath, "{$frompath}/%");
5348          $DB->execute($sql, $params);
5349  
5350          $this->mark_dirty();
5351  
5352          context::reset_caches();
5353  
5354          $trans->allow_commit();
5355      }
5356  
5357      /**
5358       * Set whether this context has been locked or not.
5359       *
5360       * @param   bool    $locked
5361       * @return  $this
5362       */
5363      public function set_locked(bool $locked) {
5364          global $DB;
5365  
5366          if ($this->_locked == $locked) {
5367              return $this;
5368          }
5369  
5370          $this->_locked = $locked;
5371          $DB->set_field('context', 'locked', (int) $locked, ['id' => $this->id]);
5372          $this->mark_dirty();
5373  
5374          if ($locked) {
5375              $eventname = '\\core\\event\\context_locked';
5376          } else {
5377              $eventname = '\\core\\event\\context_unlocked';
5378          }
5379          $event = $eventname::create(['context' => $this, 'objectid' => $this->id]);
5380          $event->trigger();
5381  
5382          self::reset_caches();
5383  
5384          return $this;
5385      }
5386  
5387      /**
5388       * Remove all context path info and optionally rebuild it.
5389       *
5390       * @param bool $rebuild
5391       * @return void
5392       */
5393      public function reset_paths($rebuild = true) {
5394          global $DB;
5395  
5396          if ($this->_path) {
5397              $this->mark_dirty();
5398          }
5399          $DB->set_field_select('context', 'depth', 0, "path LIKE '%/$this->_id/%'");
5400          $DB->set_field_select('context', 'path', NULL, "path LIKE '%/$this->_id/%'");
5401          if ($this->_contextlevel != CONTEXT_SYSTEM) {
5402              $DB->set_field('context', 'depth', 0, array('id'=>$this->_id));
5403              $DB->set_field('context', 'path', NULL, array('id'=>$this->_id));
5404              $this->_depth = 0;
5405              $this->_path = null;
5406          }
5407  
5408          if ($rebuild) {
5409              context_helper::build_all_paths(false);
5410          }
5411  
5412          context::reset_caches();
5413      }
5414  
5415      /**
5416       * Delete all data linked to content, do not delete the context record itself
5417       */
5418      public function delete_content() {
5419          global $CFG, $DB;
5420  
5421          blocks_delete_all_for_context($this->_id);
5422          filter_delete_all_for_context($this->_id);
5423  
5424          require_once($CFG->dirroot . '/comment/lib.php');
5425          comment::delete_comments(array('contextid'=>$this->_id));
5426  
5427          require_once($CFG->dirroot.'/rating/lib.php');
5428          $delopt = new stdclass();
5429          $delopt->contextid = $this->_id;
5430          $rm = new rating_manager();
5431          $rm->delete_ratings($delopt);
5432  
5433          // delete all files attached to this context
5434          $fs = get_file_storage();
5435          $fs->delete_area_files($this->_id);
5436  
5437          // Delete all repository instances attached to this context.
5438          require_once($CFG->dirroot . '/repository/lib.php');
5439          repository::delete_all_for_context($this->_id);
5440  
5441          // delete all advanced grading data attached to this context
5442          require_once($CFG->dirroot.'/grade/grading/lib.php');
5443          grading_manager::delete_all_for_context($this->_id);
5444  
5445          // now delete stuff from role related tables, role_unassign_all
5446          // and unenrol should be called earlier to do proper cleanup
5447          $DB->delete_records('role_assignments', array('contextid'=>$this->_id));
5448          $DB->delete_records('role_names', array('contextid'=>$this->_id));
5449          $this->delete_capabilities();
5450      }
5451  
5452      /**
5453       * Unassign all capabilities from a context.
5454       */
5455      public function delete_capabilities() {
5456          global $DB;
5457  
5458          $ids = $DB->get_fieldset_select('role_capabilities', 'DISTINCT roleid', 'contextid = ?', array($this->_id));
5459          if ($ids) {
5460              $DB->delete_records('role_capabilities', array('contextid' => $this->_id));
5461  
5462              // Reset any cache of these roles, including MUC.
5463              accesslib_clear_role_cache($ids);
5464          }
5465      }
5466  
5467      /**
5468       * Delete the context content and the context record itself
5469       */
5470      public function delete() {
5471          global $DB;
5472  
5473          if ($this->_contextlevel <= CONTEXT_SYSTEM) {
5474              throw new coding_exception('Cannot delete system context');
5475          }
5476  
5477          // double check the context still exists
5478          if (!$DB->record_exists('context', array('id'=>$this->_id))) {
5479              context::cache_remove($this);
5480              return;
5481          }
5482  
5483          $this->delete_content();
5484          $DB->delete_records('context', array('id'=>$this->_id));
5485          // purge static context cache if entry present
5486          context::cache_remove($this);
5487  
5488          // Inform search engine to delete data related to this context.
5489          \core_search\manager::context_deleted($this);
5490      }
5491  
5492      // ====== context level related methods ======
5493  
5494      /**
5495       * Utility method for context creation
5496       *
5497       * @static
5498       * @param int $contextlevel
5499       * @param int $instanceid
5500       * @param string $parentpath
5501       * @return stdClass context record
5502       */
5503      protected static function insert_context_record($contextlevel, $instanceid, $parentpath) {
5504          global $DB;
5505  
5506          $record = new stdClass();
5507          $record->contextlevel = $contextlevel;
5508          $record->instanceid   = $instanceid;
5509          $record->depth        = 0;
5510          $record->path         = null; //not known before insert
5511          $record->locked       = 0;
5512  
5513          $record->id = $DB->insert_record('context', $record);
5514  
5515          // now add path if known - it can be added later
5516          if (!is_null($parentpath)) {
5517              $record->path = $parentpath.'/'.$record->id;
5518              $record->depth = substr_count($record->path, '/');
5519              $DB->update_record('context', $record);
5520          }
5521  
5522          return $record;
5523      }
5524  
5525      /**
5526       * Returns human readable context identifier.
5527       *
5528       * @param boolean $withprefix whether to prefix the name of the context with the
5529       *      type of context, e.g. User, Course, Forum, etc.
5530       * @param boolean $short whether to use the short name of the thing. Only applies
5531       *      to course contexts
5532       * @param boolean $escape Whether the returned name of the thing is to be
5533       *      HTML escaped or not.
5534       * @return string the human readable context name.
5535       */
5536      public function get_context_name($withprefix = true, $short = false, $escape = true) {
5537          // must be implemented in all context levels
5538          throw new coding_exception('can not get name of abstract context');
5539      }
5540  
5541      /**
5542       * Whether the current context is locked.
5543       *
5544       * @return  bool
5545       */
5546      public function is_locked() {
5547          if ($this->_locked) {
5548              return true;
5549          }
5550  
5551          if ($parent = $this->get_parent_context()) {
5552              return $parent->is_locked();
5553          }
5554  
5555          return false;
5556      }
5557  
5558      /**
5559       * Returns the most relevant URL for this context.
5560       *
5561       * @return moodle_url
5562       */
5563      public abstract function get_url();
5564  
5565      /**
5566       * Returns array of relevant context capability records.
5567       *
5568       * @param string $sort SQL order by snippet for sorting returned capabilities sensibly for display
5569       * @return array
5570       */
5571      public abstract function get_capabilities(string $sort = self::DEFAULT_CAPABILITY_SORT);
5572  
5573      /**
5574       * Recursive function which, given a context, find all its children context ids.
5575       *
5576       * For course category contexts it will return immediate children and all subcategory contexts.
5577       * It will NOT recurse into courses or subcategories categories.
5578       * If you want to do that, call it on the returned courses/categories.
5579       *
5580       * When called for a course context, it will return the modules and blocks
5581       * displayed in the course page and blocks displayed on the module pages.
5582       *
5583       * If called on a user/course/module context it _will_ populate the cache with the appropriate
5584       * contexts ;-)
5585       *
5586       * @return array Array of child records
5587       */
5588      public function get_child_contexts() {
5589          global $DB;
5590  
5591          if (empty($this->_path) or empty($this->_depth)) {
5592              debugging('Can not find child contexts of context '.$this->_id.' try rebuilding of context paths');
5593              return array();
5594          }
5595  
5596          $sql = "SELECT ctx.*
5597                    FROM {context} ctx
5598                   WHERE ctx.path LIKE ?";
5599          $params = array($this->_path.'/%');
5600          $records = $DB->get_records_sql($sql, $params);
5601  
5602          $result = array();
5603          foreach ($records as $record) {
5604              $result[$record->id] = context::create_instance_from_record($record);
5605          }
5606  
5607          return $result;
5608      }
5609  
5610      /**
5611       * Determine if the current context is a parent of the possible child.
5612       *
5613       * @param   context $possiblechild
5614       * @param   bool $includeself Whether to check the current context
5615       * @return  bool
5616       */
5617      public function is_parent_of(context $possiblechild, bool $includeself): bool {
5618          // A simple substring check is used on the context path.
5619          // The possible child's path is used as a haystack, with the current context as the needle.
5620          // The path is prefixed with '+' to ensure that the parent always starts at the top.
5621          // It is suffixed with '+' to ensure that parents are not included.
5622          // The needle always suffixes with a '/' to ensure that the contextid uses a complete match (i.e. 142/ instead of 14).
5623          // The haystack is suffixed with '/+' if $includeself is true to allow the current context to match.
5624          // The haystack is suffixed with '+' if $includeself is false to prevent the current context from matching.
5625          $haystacksuffix = $includeself ? '/+' : '+';
5626  
5627          $strpos = strpos(
5628              "+{$possiblechild->path}{$haystacksuffix}",
5629              "+{$this->path}/"
5630          );
5631          return $strpos === 0;
5632      }
5633  
5634      /**
5635       * Returns parent contexts of this context in reversed order, i.e. parent first,
5636       * then grand parent, etc.
5637       *
5638       * @param bool $includeself true means include self too
5639       * @return array of context instances
5640       */
5641      public function get_parent_contexts($includeself = false) {
5642          if (!$contextids = $this->get_parent_context_ids($includeself)) {
5643              return array();
5644          }
5645  
5646          // Preload the contexts to reduce DB calls.
5647          context_helper::preload_contexts_by_id($contextids);
5648  
5649          $result = array();
5650          foreach ($contextids as $contextid) {
5651              $parent = context::instance_by_id($contextid, MUST_EXIST);
5652              $result[$parent->id] = $parent;
5653          }
5654  
5655          return $result;
5656      }
5657  
5658      /**
5659       * Determine if the current context is a child of the possible parent.
5660       *
5661       * @param   context $possibleparent
5662       * @param   bool $includeself Whether to check the current context
5663       * @return  bool
5664       */
5665      public function is_child_of(context $possibleparent, bool $includeself): bool {
5666          // A simple substring check is used on the context path.
5667          // The current context is used as a haystack, with the possible parent as the needle.
5668          // The path is prefixed with '+' to ensure that the parent always starts at the top.
5669          // It is suffixed with '+' to ensure that children are not included.
5670          // The needle always suffixes with a '/' to ensure that the contextid uses a complete match (i.e. 142/ instead of 14).
5671          // The haystack is suffixed with '/+' if $includeself is true to allow the current context to match.
5672          // The haystack is suffixed with '+' if $includeself is false to prevent the current context from matching.
5673          $haystacksuffix = $includeself ? '/+' : '+';
5674  
5675          $strpos = strpos(
5676              "+{$this->path}{$haystacksuffix}",
5677              "+{$possibleparent->path}/"
5678          );
5679          return $strpos === 0;
5680      }
5681  
5682      /**
5683       * Returns parent context ids of this context in reversed order, i.e. parent first,
5684       * then grand parent, etc.
5685       *
5686       * @param bool $includeself true means include self too
5687       * @return array of context ids
5688       */
5689      public function get_parent_context_ids($includeself = false) {
5690          if (empty($this->_path)) {
5691              return array();
5692          }
5693  
5694          $parentcontexts = trim($this->_path, '/'); // kill leading slash
5695          $parentcontexts = explode('/', $parentcontexts);
5696          if (!$includeself) {
5697              array_pop($parentcontexts); // and remove its own id
5698          }
5699  
5700          return array_reverse($parentcontexts);
5701      }
5702  
5703      /**
5704       * Returns parent context paths of this context.
5705       *
5706       * @param bool $includeself true means include self too
5707       * @return array of context paths
5708       */
5709      public function get_parent_context_paths($includeself = false) {
5710          if (empty($this->_path)) {
5711              return array();
5712          }
5713  
5714          $contextids = explode('/', $this->_path);
5715  
5716          $path = '';
5717          $paths = array();
5718          foreach ($contextids as $contextid) {
5719              if ($contextid) {
5720                  $path .= '/' . $contextid;
5721                  $paths[$contextid] = $path;
5722              }
5723          }
5724  
5725          if (!$includeself) {
5726              unset($paths[$this->_id]);
5727          }
5728  
5729          return $paths;
5730      }
5731  
5732      /**
5733       * Returns parent context
5734       *
5735       * @return context
5736       */
5737      public function get_parent_context() {
5738          if (empty($this->_path) or $this->_id == SYSCONTEXTID) {
5739              return false;
5740          }
5741  
5742          $parentcontexts = trim($this->_path, '/'); // kill leading slash
5743          $parentcontexts = explode('/', $parentcontexts);
5744          array_pop($parentcontexts); // self
5745          $contextid = array_pop($parentcontexts); // immediate parent
5746  
5747          return context::instance_by_id($contextid, MUST_EXIST);
5748      }
5749  
5750      /**
5751       * Is this context part of any course? If yes return course context.
5752       *
5753       * @param bool $strict true means throw exception if not found, false means return false if not found
5754       * @return context_course context of the enclosing course, null if not found or exception
5755       */
5756      public function get_course_context($strict = true) {
5757          if ($strict) {
5758              throw new coding_exception('Context does not belong to any course.');
5759          } else {
5760              return false;
5761          }
5762      }
5763  
5764      /**
5765       * Returns sql necessary for purging of stale context instances.
5766       *
5767       * @static
5768       * @return string cleanup SQL
5769       */
5770      protected static function get_cleanup_sql() {
5771          throw new coding_exception('get_cleanup_sql() method must be implemented in all context levels');
5772      }
5773  
5774      /**
5775       * Rebuild context paths and depths at context level.
5776       *
5777       * @static
5778       * @param bool $force
5779       * @return void
5780       */
5781      protected static function build_paths($force) {
5782          throw new coding_exception('build_paths() method must be implemented in all context levels');
5783      }
5784  
5785      /**
5786       * Create missing context instances at given level
5787       *
5788       * @static
5789       * @return void
5790       */
5791      protected static function create_level_instances() {
5792          throw new coding_exception('create_level_instances() method must be implemented in all context levels');
5793      }
5794  
5795      /**
5796       * Reset all cached permissions and definitions if the necessary.
5797       * @return void
5798       */
5799      public function reload_if_dirty() {
5800          global $ACCESSLIB_PRIVATE, $USER;
5801  
5802          // Load dirty contexts list if needed
5803          if (CLI_SCRIPT) {
5804              if (!isset($ACCESSLIB_PRIVATE->dirtycontexts)) {
5805                  // we do not load dirty flags in CLI and cron
5806                  $ACCESSLIB_PRIVATE->dirtycontexts = array();
5807              }
5808          } else {
5809              if (!isset($USER->access['time'])) {
5810                  // Nothing has been loaded yet, so we do not need to check dirty flags now.
5811                  return;
5812              }
5813  
5814              // From skodak: No idea why -2 is there, server cluster time difference maybe...
5815              $changedsince = $USER->access['time'] - 2;
5816  
5817              if (!isset($ACCESSLIB_PRIVATE->dirtycontexts)) {
5818                  $ACCESSLIB_PRIVATE->dirtycontexts = get_cache_flags('accesslib/dirtycontexts', $changedsince);
5819              }
5820  
5821              if (!isset($ACCESSLIB_PRIVATE->dirtyusers[$USER->id])) {
5822                  $ACCESSLIB_PRIVATE->dirtyusers[$USER->id] = get_cache_flag('accesslib/dirtyusers', $USER->id, $changedsince);
5823              }
5824          }
5825  
5826          $dirty = false;
5827  
5828          if (!empty($ACCESSLIB_PRIVATE->dirtyusers[$USER->id])) {
5829              $dirty = true;
5830          } else if (!empty($ACCESSLIB_PRIVATE->dirtycontexts)) {
5831              $paths = $this->get_parent_context_paths(true);
5832  
5833              foreach ($paths as $path) {
5834                  if (isset($ACCESSLIB_PRIVATE->dirtycontexts[$path])) {
5835                      $dirty = true;
5836                      break;
5837                  }
5838              }
5839          }
5840  
5841          if ($dirty) {
5842              // Reload all capabilities of USER and others - preserving loginas, roleswitches, etc.
5843              // Then cleanup any marks of dirtyness... at least from our short term memory!
5844              reload_all_capabilities();
5845          }
5846      }
5847  
5848      /**
5849       * Mark a context as dirty (with timestamp) so as to force reloading of the context.
5850       */
5851      public function mark_dirty() {
5852          global $CFG, $USER, $ACCESSLIB_PRIVATE;
5853  
5854          if (during_initial_install()) {
5855              return;
5856          }
5857  
5858          // only if it is a non-empty string
5859          if (is_string($this->_path) && $this->_path !== '') {
5860              set_cache_flag('accesslib/dirtycontexts', $this->_path, 1, time()+$CFG->sessiontimeout);
5861              if (isset($ACCESSLIB_PRIVATE->dirtycontexts)) {
5862                  $ACCESSLIB_PRIVATE->dirtycontexts[$this->_path] = 1;
5863              } else {
5864                  if (CLI_SCRIPT) {
5865                      $ACCESSLIB_PRIVATE->dirtycontexts = array($this->_path => 1);
5866                  } else {
5867                      if (isset($USER->access['time'])) {
5868                          $ACCESSLIB_PRIVATE->dirtycontexts = get_cache_flags('accesslib/dirtycontexts', $USER->access['time']-2);
5869                      } else {
5870                          $ACCESSLIB_PRIVATE->dirtycontexts = array($this->_path => 1);
5871                      }
5872                      // flags not loaded yet, it will be done later in $context->reload_if_dirty()
5873                  }
5874              }
5875          }
5876      }
5877  }
5878  
5879  
5880  /**
5881   * Context maintenance and helper methods.
5882   *
5883   * This is "extends context" is a bloody hack that tires to work around the deficiencies
5884   * in the "protected" keyword in PHP, this helps us to hide all the internals of context
5885   * level implementation from the rest of code, the code completion returns what developers need.
5886   *
5887   * Thank you Tim Hunt for helping me with this nasty trick.
5888   *
5889   * @package   core_access
5890   * @category  access
5891   * @copyright Petr Skoda {@link http://skodak.org}
5892   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
5893   * @since     Moodle 2.2
5894   */
5895  class context_helper extends context {
5896  
5897      /**
5898       * @var array An array mapping context levels to classes
5899       */
5900      private static $alllevels;
5901  
5902      /**
5903       * Instance does not make sense here, only static use
5904       */
5905      protected function __construct() {
5906      }
5907  
5908      /**
5909       * Reset internal context levels array.
5910       */
5911      public static function reset_levels() {
5912          self::$alllevels = null;
5913      }
5914  
5915      /**
5916       * Initialise context levels, call before using self::$alllevels.
5917       */
5918      private static function init_levels() {
5919          global $CFG;
5920  
5921          if (isset(self::$alllevels)) {
5922              return;
5923          }
5924          self::$alllevels = array(
5925              CONTEXT_SYSTEM    => 'context_system',
5926              CONTEXT_USER      => 'context_user',
5927              CONTEXT_COURSECAT => 'context_coursecat',
5928              CONTEXT_COURSE    => 'context_course',
5929              CONTEXT_MODULE    => 'context_module',
5930              CONTEXT_BLOCK     => 'context_block',
5931          );
5932  
5933          if (empty($CFG->custom_context_classes)) {
5934              return;
5935          }
5936  
5937          $levels = $CFG->custom_context_classes;
5938          if (!is_array($levels)) {
5939              $levels = @unserialize($levels);
5940          }
5941          if (!is_array($levels)) {
5942              debugging('Invalid $CFG->custom_context_classes detected, value ignored.', DEBUG_DEVELOPER);
5943              return;
5944          }
5945  
5946          // Unsupported custom levels, use with care!!!
5947          foreach ($levels as $level => $classname) {
5948              self::$alllevels[$level] = $classname;
5949          }
5950          ksort(self::$alllevels);
5951      }
5952  
5953      /**
5954       * Returns a class name of the context level class
5955       *
5956       * @static
5957       * @param int $contextlevel (CONTEXT_SYSTEM, etc.)
5958       * @return string class name of the context class
5959       */
5960      public static function get_class_for_level($contextlevel) {
5961          self::init_levels();
5962          if (isset(self::$alllevels[$contextlevel])) {
5963              return self::$alllevels[$contextlevel];
5964          } else {
5965              throw new coding_exception('Invalid context level specified');
5966          }
5967      }
5968  
5969      /**
5970       * Returns a list of all context levels
5971       *
5972       * @static
5973       * @return array int=>string (level=>level class name)
5974       */
5975      public static function get_all_levels() {
5976          self::init_levels();
5977          return self::$alllevels;
5978      }
5979  
5980      /**
5981       * Remove stale contexts that belonged to deleted instances.
5982       * Ideally all code should cleanup contexts properly, unfortunately accidents happen...
5983       *
5984       * @static
5985       * @return void
5986       */
5987      public static function cleanup_instances() {
5988          global $DB;
5989          self::init_levels();
5990  
5991          $sqls = array();
5992          foreach (self::$alllevels as $level=>$classname) {
5993              $sqls[] = $classname::get_cleanup_sql();
5994          }
5995  
5996          $sql = implode(" UNION ", $sqls);
5997  
5998          // it is probably better to use transactions, it might be faster too
5999          $transaction = $DB->start_delegated_transaction();
6000  
6001          $rs = $DB->get_recordset_sql($sql);
6002          foreach ($rs as $record) {
6003              $context = context::create_instance_from_record($record);
6004              $context->delete();
6005          }
6006          $rs->close();
6007  
6008          $transaction->allow_commit();
6009      }
6010  
6011      /**
6012       * Create all context instances at the given level and above.
6013       *
6014       * @static
6015       * @param int $contextlevel null means all levels
6016       * @param bool $buildpaths
6017       * @return void
6018       */
6019      public static function create_instances($contextlevel = null, $buildpaths = true) {
6020          self::init_levels();
6021          foreach (self::$alllevels as $level=>$classname) {
6022              if ($contextlevel and $level > $contextlevel) {
6023                  // skip potential sub-contexts
6024                  continue;
6025              }
6026              $classname::create_level_instances();
6027              if ($buildpaths) {
6028                  $classname::build_paths(false);
6029              }
6030          }
6031      }
6032  
6033      /**
6034       * Rebuild paths and depths in all context levels.
6035       *
6036       * @static
6037       * @param bool $force false means add missing only
6038       * @return void
6039       */
6040      public static function build_all_paths($force = false) {
6041          self::init_levels();
6042          foreach (self::$alllevels as $classname) {
6043              $classname::build_paths($force);
6044          }
6045  
6046          // reset static course cache - it might have incorrect cached data
6047          accesslib_clear_all_caches(true);
6048      }
6049  
6050      /**
6051       * Resets the cache to remove all data.
6052       * @static
6053       */
6054      public static function reset_caches() {
6055          context::reset_caches();
6056      }
6057  
6058      /**
6059       * Returns all fields necessary for context preloading from user $rec.
6060       *
6061       * This helps with performance when dealing with hundreds of contexts.
6062       *
6063       * @static
6064       * @param string $tablealias context table alias in the query
6065       * @return array (table.column=>alias, ...)
6066       */
6067      public static function get_preload_record_columns($tablealias) {
6068          return [
6069              "$tablealias.id" => "ctxid",
6070              "$tablealias.path" => "ctxpath",
6071              "$tablealias.depth" => "ctxdepth",
6072              "$tablealias.contextlevel" => "ctxlevel",
6073              "$tablealias.instanceid" => "ctxinstance",
6074              "$tablealias.locked" => "ctxlocked",
6075          ];
6076      }
6077  
6078      /**
6079       * Returns all fields necessary for context preloading from user $rec.
6080       *
6081       * This helps with performance when dealing with hundreds of contexts.
6082       *
6083       * @static
6084       * @param string $tablealias context table alias in the query
6085       * @return string
6086       */
6087      public static function get_preload_record_columns_sql($tablealias) {
6088          return "$tablealias.id AS ctxid, " .
6089                 "$tablealias.path AS ctxpath, " .
6090                 "$tablealias.depth AS ctxdepth, " .
6091                 "$tablealias.contextlevel AS ctxlevel, " .
6092                 "$tablealias.instanceid AS ctxinstance, " .
6093                 "$tablealias.locked AS ctxlocked";
6094      }
6095  
6096      /**
6097       * Preloads context information from db record and strips the cached info.
6098       *
6099       * The db request has to contain all columns from context_helper::get_preload_record_columns().
6100       *
6101       * @static
6102       * @param stdClass $rec
6103       * @return void (modifies $rec)
6104       */
6105       public static function preload_from_record(stdClass $rec) {
6106           context::preload_from_record($rec);
6107       }
6108  
6109      /**
6110       * Preload a set of contexts using their contextid.
6111       *
6112       * @param   array $contextids
6113       */
6114      public static function preload_contexts_by_id(array $contextids) {
6115          global $DB;
6116  
6117          // Determine which contexts are not already cached.
6118          $tofetch = [];
6119          foreach ($contextids as $contextid) {
6120              if (!self::cache_get_by_id($contextid)) {
6121                  $tofetch[] = $contextid;
6122              }
6123          }
6124  
6125          if (count($tofetch) > 1) {
6126              // There are at least two to fetch.
6127              // There is no point only fetching a single context as this would be no more efficient than calling the existing code.
6128              list($insql, $inparams) = $DB->get_in_or_equal($tofetch, SQL_PARAMS_NAMED);
6129              $ctxs = $DB->get_records_select('context', "id {$insql}", $inparams, '',
6130                      \context_helper::get_preload_record_columns_sql('{context}'));
6131              foreach ($ctxs as $ctx) {
6132                  self::preload_from_record($ctx);
6133              }
6134          }
6135      }
6136  
6137      /**
6138       * Preload all contexts instances from course.
6139       *
6140       * To be used if you expect multiple queries for course activities...
6141       *
6142       * @static
6143       * @param int $courseid
6144       */
6145      public static function preload_course($courseid) {
6146          // Users can call this multiple times without doing any harm
6147          if (isset(context::$cache_preloaded[$courseid])) {
6148              return;
6149          }
6150          $coursecontext = context_course::instance($courseid);
6151          $coursecontext->get_child_contexts();
6152  
6153          context::$cache_preloaded[$courseid] = true;
6154      }
6155  
6156      /**
6157       * Delete context instance
6158       *
6159       * @static
6160       * @param int $contextlevel
6161       * @param int $instanceid
6162       * @return void
6163       */
6164      public static function delete_instance($contextlevel, $instanceid) {
6165          global $DB;
6166  
6167          // double check the context still exists
6168          if ($record = $DB->get_record('context', array('contextlevel'=>$contextlevel, 'instanceid'=>$instanceid))) {
6169              $context = context::create_instance_from_record($record);
6170              $context->delete();
6171          } else {
6172              // we should try to purge the cache anyway
6173          }
6174      }
6175  
6176      /**
6177       * Returns the name of specified context level
6178       *
6179       * @static
6180       * @param int $contextlevel
6181       * @return string name of the context level
6182       */
6183      public static function get_level_name($contextlevel) {
6184          $classname = context_helper::get_class_for_level($contextlevel);
6185          return $classname::get_level_name();
6186      }
6187  
6188      /**
6189       * Gets the current context to be used for navigation tree filtering.
6190       *
6191       * @param context|null $context The current context to be checked against.
6192       * @return context|null the context that navigation tree filtering should use.
6193       */
6194      public static function get_navigation_filter_context(?context $context): ?context {
6195          global $CFG;
6196          if (!empty($CFG->filternavigationwithsystemcontext)) {
6197              return context_system::instance();
6198          } else {
6199              return $context;
6200          }
6201      }
6202  
6203      /**
6204       * not used
6205       */
6206      public function get_url() {
6207      }
6208  
6209      /**
6210       * not used
6211       *
6212       * @param string $sort
6213       */
6214      public function get_capabilities(string $sort = self::DEFAULT_CAPABILITY_SORT) {
6215      }
6216  }
6217  
6218  
6219  /**
6220   * System context class
6221   *
6222   * @package   core_access
6223   * @category  access
6224   * @copyright Petr Skoda {@link http://skodak.org}
6225   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
6226   * @since     Moodle 2.2
6227   */
6228  class context_system extends context {
6229      /**
6230       * Please use context_system::instance() if you need the instance of context.
6231       *
6232       * @param stdClass $record
6233       */
6234      protected function __construct(stdClass $record) {
6235          parent::__construct($record);
6236          if ($record->contextlevel != CONTEXT_SYSTEM) {
6237              throw new coding_exception('Invalid $record->contextlevel in context_system constructor.');
6238          }
6239      }
6240  
6241      /**
6242       * Returns human readable context level name.
6243       *
6244       * @static
6245       * @return string the human readable context level name.
6246       */
6247      public static function get_level_name() {
6248          return get_string('coresystem');
6249      }
6250  
6251      /**
6252       * Returns human readable context identifier.
6253       *
6254       * @param boolean $withprefix does not apply to system context
6255       * @param boolean $short does not apply to system context
6256       * @param boolean $escape does not apply to system context
6257       * @return string the human readable context name.
6258       */
6259      public function get_context_name($withprefix = true, $short = false, $escape = true) {
6260          return self::get_level_name();
6261      }
6262  
6263      /**
6264       * Returns the most relevant URL for this context.
6265       *
6266       * @return moodle_url
6267       */
6268      public function get_url() {
6269          return new moodle_url('/');
6270      }
6271  
6272      /**
6273       * Returns array of relevant context capability records.
6274       *
6275       * @param string $sort
6276       * @return array
6277       */
6278      public function get_capabilities(string $sort = self::DEFAULT_CAPABILITY_SORT) {
6279          global $DB;
6280  
6281          return $DB->get_records('capabilities', [], $sort);
6282      }
6283  
6284      /**
6285       * Create missing context instances at system context
6286       * @static
6287       */
6288      protected static function create_level_instances() {
6289          // nothing to do here, the system context is created automatically in installer
6290          self::instance(0);
6291      }
6292  
6293      /**
6294       * Returns system context instance.
6295       *
6296       * @static
6297       * @param int $instanceid should be 0
6298       * @param int $strictness
6299       * @param bool $cache
6300       * @return context_system context instance
6301       */
6302      public static function instance($instanceid = 0, $strictness = MUST_EXIST, $cache = true) {
6303          global $DB;
6304  
6305          if ($instanceid != 0) {
6306              debugging('context_system::instance(): invalid $id parameter detected, should be 0');
6307          }
6308  
6309          if (defined('SYSCONTEXTID') and $cache) { // dangerous: define this in config.php to eliminate 1 query/page
6310              if (!isset(context::$systemcontext)) {
6311                  $record = new stdClass();
6312                  $record->id           = SYSCONTEXTID;
6313                  $record->contextlevel = CONTEXT_SYSTEM;
6314                  $record->instanceid   = 0;
6315                  $record->path         = '/'.SYSCONTEXTID;
6316                  $record->depth        = 1;
6317                  $record->locked       = 0;
6318                  context::$systemcontext = new context_system($record);
6319              }
6320              return context::$systemcontext;
6321          }
6322  
6323          try {
6324              // We ignore the strictness completely because system context must exist except during install.
6325              $record = $DB->get_record('context', array('contextlevel'=>CONTEXT_SYSTEM), '*', MUST_EXIST);
6326          } catch (dml_exception $e) {
6327              //table or record does not exist
6328              if (!during_initial_install()) {
6329                  // do not mess with system context after install, it simply must exist
6330                  throw $e;
6331              }
6332              $record = null;
6333          }
6334  
6335          if (!$record) {
6336              $record = new stdClass();
6337              $record->contextlevel = CONTEXT_SYSTEM;
6338              $record->instanceid   = 0;
6339              $record->depth        = 1;
6340              $record->path         = null; // Not known before insert.
6341              $record->locked       = 0;
6342  
6343              try {
6344                  if ($DB->count_records('context')) {
6345                      // contexts already exist, this is very weird, system must be first!!!
6346                      return null;
6347                  }
6348                  if (defined('SYSCONTEXTID')) {
6349                      // this would happen only in unittest on sites that went through weird 1.7 upgrade
6350                      $record->id = SYSCONTEXTID;
6351                      $DB->import_record('context', $record);
6352                      $DB->get_manager()->reset_sequence('context');
6353                  } else {
6354                      $record->id = $DB->insert_record('context', $record);
6355                  }
6356              } catch (dml_exception $e) {
6357                  // can not create context - table does not exist yet, sorry
6358                  return null;
6359              }
6360          }
6361  
6362          if ($record->instanceid != 0) {
6363              // this is very weird, somebody must be messing with context table
6364              debugging('Invalid system context detected');
6365          }
6366  
6367          if ($record->depth != 1 or $record->path != '/'.$record->id) {
6368              // fix path if necessary, initial install or path reset
6369              $record->depth = 1;
6370              $record->path  = '/'.$record->id;
6371              $DB->update_record('context', $record);
6372          }
6373  
6374          if (empty($record->locked)) {
6375              $record->locked = 0;
6376          }
6377  
6378          if (!defined('SYSCONTEXTID')) {
6379              define('SYSCONTEXTID', $record->id);
6380          }
6381  
6382          context::$systemcontext = new context_system($record);
6383          return context::$systemcontext;
6384      }
6385  
6386      /**
6387       * Returns all site contexts except the system context, DO NOT call on production servers!!
6388       *
6389       * Contexts are not cached.
6390       *
6391       * @return array
6392       */
6393      public function get_child_contexts() {
6394          global $DB;
6395  
6396          debugging('Fetching of system context child courses is strongly discouraged on production servers (it may eat all available memory)!');
6397  
6398          // Just get all the contexts except for CONTEXT_SYSTEM level
6399          // and hope we don't OOM in the process - don't cache
6400          $sql = "SELECT c.*
6401                    FROM {context} c
6402                   WHERE contextlevel > ".CONTEXT_SYSTEM;
6403          $records = $DB->get_records_sql($sql);
6404  
6405          $result = array();
6406          foreach ($records as $record) {
6407              $result[$record->id] = context::create_instance_from_record($record);
6408          }
6409  
6410          return $result;
6411      }
6412  
6413      /**
6414       * Returns sql necessary for purging of stale context instances.
6415       *
6416       * @static
6417       * @return string cleanup SQL
6418       */
6419      protected static function get_cleanup_sql() {
6420          $sql = "
6421                    SELECT c.*
6422                      FROM {context} c
6423                     WHERE 1=2
6424                 ";
6425  
6426          return $sql;
6427      }
6428  
6429      /**
6430       * Rebuild context paths and depths at system context level.
6431       *
6432       * @static
6433       * @param bool $force
6434       */
6435      protected static function build_paths($force) {
6436          global $DB;
6437  
6438          /* note: ignore $force here, we always do full test of system context */
6439  
6440          // exactly one record must exist
6441          $record = $DB->get_record('context', array('contextlevel'=>CONTEXT_SYSTEM), '*', MUST_EXIST);
6442  
6443          if ($record->instanceid != 0) {
6444              debugging('Invalid system context detected');
6445          }
6446  
6447          if (defined('SYSCONTEXTID') and $record->id != SYSCONTEXTID) {
6448              debugging('Invalid SYSCONTEXTID detected');
6449          }
6450  
6451          if ($record->depth != 1 or $record->path != '/'.$record->id) {
6452              // fix path if necessary, initial install or path reset
6453              $record->depth    = 1;
6454              $record->path     = '/'.$record->id;
6455              $DB->update_record('context', $record);
6456          }
6457      }
6458  
6459      /**
6460       * Set whether this context has been locked or not.
6461       *
6462       * @param   bool    $locked
6463       * @return  $this
6464       */
6465      public function set_locked(bool $locked) {
6466          throw new \coding_exception('It is not possible to lock the system context');
6467  
6468          return $this;
6469      }
6470  }
6471  
6472  
6473  /**
6474   * User context class
6475   *
6476   * @package   core_access
6477   * @category  access
6478   * @copyright Petr Skoda {@link http://skodak.org}
6479   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
6480   * @since     Moodle 2.2
6481   */
6482  class context_user extends context {
6483      /**
6484       * Please use context_user::instance($userid) if you need the instance of context.
6485       * Alternatively if you know only the context id use context::instance_by_id($contextid)
6486       *
6487       * @param stdClass $record
6488       */
6489      protected function __construct(stdClass $record) {
6490          parent::__construct($record);
6491          if ($record->contextlevel != CONTEXT_USER) {
6492              throw new coding_exception('Invalid $record->contextlevel in context_user constructor.');
6493          }
6494      }
6495  
6496      /**
6497       * Returns human readable context level name.
6498       *
6499       * @static
6500       * @return string the human readable context level name.
6501       */
6502      public static function get_level_name() {
6503          return get_string('user');
6504      }
6505  
6506      /**
6507       * Returns human readable context identifier.
6508       *
6509       * @param boolean $withprefix whether to prefix the name of the context with User
6510       * @param boolean $short does not apply to user context
6511       * @param boolean $escape does not apply to user context
6512       * @return string the human readable context name.
6513       */
6514      public function get_context_name($withprefix = true, $short = false, $escape = true) {
6515          global $DB;
6516  
6517          $name = '';
6518          if ($user = $DB->get_record('user', array('id'=>$this->_instanceid, 'deleted'=>0))) {
6519              if ($withprefix){
6520                  $name = get_string('user').': ';
6521              }
6522              $name .= fullname($user);
6523          }
6524          return $name;
6525      }
6526  
6527      /**
6528       * Returns the most relevant URL for this context.
6529       *
6530       * @return moodle_url
6531       */
6532      public function get_url() {
6533          global $COURSE;
6534  
6535          if ($COURSE->id == SITEID) {
6536              $url = new moodle_url('/user/profile.php', array('id'=>$this->_instanceid));
6537          } else {
6538              $url = new moodle_url('/user/view.php', array('id'=>$this->_instanceid, 'courseid'=>$COURSE->id));
6539          }
6540          return $url;
6541      }
6542  
6543      /**
6544       * Returns array of relevant context capability records.
6545       *
6546       * @param string $sort
6547       * @return array
6548       */
6549      public function get_capabilities(string $sort = self::DEFAULT_CAPABILITY_SORT) {
6550          global $DB;
6551  
6552          $extracaps = array('moodle/grade:viewall');
6553          list($extra, $params) = $DB->get_in_or_equal($extracaps, SQL_PARAMS_NAMED, 'cap');
6554  
6555          return $DB->get_records_select('capabilities', "contextlevel = :level OR name {$extra}",
6556              $params + ['level' => CONTEXT_USER], $sort);
6557      }
6558  
6559      /**
6560       * Returns user context instance.
6561       *
6562       * @static
6563       * @param int $userid id from {user} table
6564       * @param int $strictness
6565       * @return context_user context instance
6566       */
6567      public static function instance($userid, $strictness = MUST_EXIST) {
6568          global $DB;
6569  
6570          if ($context = context::cache_get(CONTEXT_USER, $userid)) {
6571              return $context;
6572          }
6573  
6574          if (!$record = $DB->get_record('context', array('contextlevel' => CONTEXT_USER, 'instanceid' => $userid))) {
6575              if ($user = $DB->get_record('user', array('id' => $userid, 'deleted' => 0), 'id', $strictness)) {
6576                  $record = context::insert_context_record(CONTEXT_USER, $user->id, '/'.SYSCONTEXTID, 0);
6577              }
6578          }
6579  
6580          if ($record) {
6581              $context = new context_user($record);
6582              context::cache_add($context);
6583              return $context;
6584          }
6585  
6586          return false;
6587      }
6588  
6589      /**
6590       * Create missing context instances at user context level
6591       * @static
6592       */
6593      protected static function create_level_instances() {
6594          global $DB;
6595  
6596          $sql = "SELECT ".CONTEXT_USER.", u.id
6597                    FROM {user} u
6598                   WHERE u.deleted = 0
6599                         AND NOT EXISTS (SELECT 'x'
6600                                           FROM {context} cx
6601                                          WHERE u.id = cx.instanceid AND cx.contextlevel=".CONTEXT_USER.")";
6602          $contextdata = $DB->get_recordset_sql($sql);
6603          foreach ($contextdata as $context) {
6604              context::insert_context_record(CONTEXT_USER, $context->id, null);
6605          }
6606          $contextdata->close();
6607      }
6608  
6609      /**
6610       * Returns sql necessary for purging of stale context instances.
6611       *
6612       * @static
6613       * @return string cleanup SQL
6614       */
6615      protected static function get_cleanup_sql() {
6616          $sql = "
6617                    SELECT c.*
6618                      FROM {context} c
6619           LEFT OUTER JOIN {user} u ON (c.instanceid = u.id AND u.deleted = 0)
6620                     WHERE u.id IS NULL AND c.contextlevel = ".CONTEXT_USER."
6621                 ";
6622  
6623          return $sql;
6624      }
6625  
6626      /**
6627       * Rebuild context paths and depths at user context level.
6628       *
6629       * @static
6630       * @param bool $force
6631       */
6632      protected static function build_paths($force) {
6633          global $DB;
6634  
6635          // First update normal users.
6636          $path = $DB->sql_concat('?', 'id');
6637          $pathstart = '/' . SYSCONTEXTID . '/';
6638          $params = array($pathstart);
6639  
6640          if ($force) {
6641              $where = "depth <> 2 OR path IS NULL OR path <> ({$path})";
6642              $params[] = $pathstart;
6643          } else {
6644              $where = "depth = 0 OR path IS NULL";
6645          }
6646  
6647          $sql = "UPDATE {context}
6648                     SET depth = 2,
6649                         path = {$path}
6650                   WHERE contextlevel = " . CONTEXT_USER . "
6651                     AND ($where)";
6652          $DB->execute($sql, $params);
6653      }
6654  }
6655  
6656  
6657  /**
6658   * Course category context class
6659   *
6660   * @package   core_access
6661   * @category  access
6662   * @copyright Petr Skoda {@link http://skodak.org}
6663   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
6664   * @since     Moodle 2.2
6665   */
6666  class context_coursecat extends context {
6667      /**
6668       * Please use context_coursecat::instance($coursecatid) if you need the instance of context.
6669       * Alternatively if you know only the context id use context::instance_by_id($contextid)
6670       *
6671       * @param stdClass $record
6672       */
6673      protected function __construct(stdClass $record) {
6674          parent::__construct($record);
6675          if ($record->contextlevel != CONTEXT_COURSECAT) {
6676              throw new coding_exception('Invalid $record->contextlevel in context_coursecat constructor.');
6677          }
6678      }
6679  
6680      /**
6681       * Returns human readable context level name.
6682       *
6683       * @static
6684       * @return string the human readable context level name.
6685       */
6686      public static function get_level_name() {
6687          return get_string('category');
6688      }
6689  
6690      /**
6691       * Returns human readable context identifier.
6692       *
6693       * @param boolean $withprefix whether to prefix the name of the context with Category
6694       * @param boolean $short does not apply to course categories
6695       * @param boolean $escape Whether the returned name of the context is to be HTML escaped or not.
6696       * @return string the human readable context name.
6697       */
6698      public function get_context_name($withprefix = true, $short = false, $escape = true) {
6699          global $DB;
6700  
6701          $name = '';
6702          if ($category = $DB->get_record('course_categories', array('id'=>$this->_instanceid))) {
6703              if ($withprefix){
6704                  $name = get_string('category').': ';
6705              }
6706              if (!$escape) {
6707                  $name .= format_string($category->name, true, array('context' => $this, 'escape' => false));
6708              } else {
6709                  $name .= format_string($category->name, true, array('context' => $this));
6710              }
6711          }
6712          return $name;
6713      }
6714  
6715      /**
6716       * Returns the most relevant URL for this context.
6717       *
6718       * @return moodle_url
6719       */
6720      public function get_url() {
6721          return new moodle_url('/course/index.php', array('categoryid' => $this->_instanceid));
6722      }
6723  
6724      /**
6725       * Returns array of relevant context capability records.
6726       *
6727       * @param string $sort
6728       * @return array
6729       */
6730      public function get_capabilities(string $sort = self::DEFAULT_CAPABILITY_SORT) {
6731          global $DB;
6732  
6733          return $DB->get_records_list('capabilities', 'contextlevel', [
6734              CONTEXT_COURSECAT,
6735              CONTEXT_COURSE,
6736              CONTEXT_MODULE,
6737              CONTEXT_BLOCK,
6738          ], $sort);
6739      }
6740  
6741      /**
6742       * Returns course category context instance.
6743       *
6744       * @static
6745       * @param int $categoryid id from {course_categories} table
6746       * @param int $strictness
6747       * @return context_coursecat context instance
6748       */
6749      public static function instance($categoryid, $strictness = MUST_EXIST) {
6750          global $DB;
6751  
6752          if ($context = context::cache_get(CONTEXT_COURSECAT, $categoryid)) {
6753              return $context;
6754          }
6755  
6756          if (!$record = $DB->get_record('context', array('contextlevel' => CONTEXT_COURSECAT, 'instanceid' => $categoryid))) {
6757              if ($category = $DB->get_record('course_categories', array('id' => $categoryid), 'id,parent', $strictness)) {
6758                  if ($category->parent) {
6759                      $parentcontext = context_coursecat::instance($category->parent);
6760                      $record = context::insert_context_record(CONTEXT_COURSECAT, $category->id, $parentcontext->path);
6761                  } else {
6762                      $record = context::insert_context_record(CONTEXT_COURSECAT, $category->id, '/'.SYSCONTEXTID, 0);
6763                  }
6764              }
6765          }
6766  
6767          if ($record) {
6768              $context = new context_coursecat($record);
6769              context::cache_add($context);
6770              return $context;
6771          }
6772  
6773          return false;
6774      }
6775  
6776      /**
6777       * Returns immediate child contexts of category and all subcategories,
6778       * children of subcategories and courses are not returned.
6779       *
6780       * @return array
6781       */
6782      public function get_child_contexts() {
6783          global $DB;
6784  
6785          if (empty($this->_path) or empty($this->_depth)) {
6786              debugging('Can not find child contexts of context '.$this->_id.' try rebuilding of context paths');
6787              return array();
6788          }
6789  
6790          $sql = "SELECT ctx.*
6791                    FROM {context} ctx
6792                   WHERE ctx.path LIKE ? AND (ctx.depth = ? OR ctx.contextlevel = ?)";
6793          $params = array($this->_path.'/%', $this->depth+1, CONTEXT_COURSECAT);
6794          $records = $DB->get_records_sql($sql, $params);
6795  
6796          $result = array();
6797          foreach ($records as $record) {
6798              $result[$record->id] = context::create_instance_from_record($record);
6799          }
6800  
6801          return $result;
6802      }
6803  
6804      /**
6805       * Create missing context instances at course category context level
6806       * @static
6807       */
6808      protected static function create_level_instances() {
6809          global $DB;
6810  
6811          $sql = "SELECT ".CONTEXT_COURSECAT.", cc.id
6812                    FROM {course_categories} cc
6813                   WHERE NOT EXISTS (SELECT 'x'
6814                                       FROM {context} cx
6815                                      WHERE cc.id = cx.instanceid AND cx.contextlevel=".CONTEXT_COURSECAT.")";
6816          $contextdata = $DB->get_recordset_sql($sql);
6817          foreach ($contextdata as $context) {
6818              context::insert_context_record(CONTEXT_COURSECAT, $context->id, null);
6819          }
6820          $contextdata->close();
6821      }
6822  
6823      /**
6824       * Returns sql necessary for purging of stale context instances.
6825       *
6826       * @static
6827       * @return string cleanup SQL
6828       */
6829      protected static function get_cleanup_sql() {
6830          $sql = "
6831                    SELECT c.*
6832                      FROM {context} c
6833           LEFT OUTER JOIN {course_categories} cc ON c.instanceid = cc.id
6834                     WHERE cc.id IS NULL AND c.contextlevel = ".CONTEXT_COURSECAT."
6835                 ";
6836  
6837          return $sql;
6838      }
6839  
6840      /**
6841       * Rebuild context paths and depths at course category context level.
6842       *
6843       * @static
6844       * @param bool $force
6845       */
6846      protected static function build_paths($force) {
6847          global $DB;
6848  
6849          if ($force or $DB->record_exists_select('context', "contextlevel = ".CONTEXT_COURSECAT." AND (depth = 0 OR path IS NULL)")) {
6850              if ($force) {
6851                  $ctxemptyclause = $emptyclause = '';
6852              } else {
6853                  $ctxemptyclause = "AND (ctx.path IS NULL OR ctx.depth = 0)";
6854                  $emptyclause    = "AND ({context}.path IS NULL OR {context}.depth = 0)";
6855              }
6856  
6857              $base = '/'.SYSCONTEXTID;
6858  
6859              // Normal top level categories
6860              $sql = "UPDATE {context}
6861                         SET depth=2,
6862                             path=".$DB->sql_concat("'$base/'", 'id')."
6863                       WHERE contextlevel=".CONTEXT_COURSECAT."
6864                             AND EXISTS (SELECT 'x'
6865                                           FROM {course_categories} cc
6866                                          WHERE cc.id = {context}.instanceid AND cc.depth=1)
6867                             $emptyclause";
6868              $DB->execute($sql);
6869  
6870              // Deeper categories - one query per depthlevel
6871              $maxdepth = $DB->get_field_sql("SELECT MAX(depth) FROM {course_categories}");
6872              for ($n=2; $n<=$maxdepth; $n++) {
6873                  $sql = "INSERT INTO {context_temp} (id, path, depth, locked)
6874                          SELECT ctx.id, ".$DB->sql_concat('pctx.path', "'/'", 'ctx.id').", pctx.depth+1, ctx.locked
6875                            FROM {context} ctx
6876                            JOIN {course_categories} cc ON (cc.id = ctx.instanceid AND ctx.contextlevel = ".CONTEXT_COURSECAT." AND cc.depth = $n)
6877                            JOIN {context} pctx ON (pctx.instanceid = cc.parent AND pctx.contextlevel = ".CONTEXT_COURSECAT.")
6878                           WHERE pctx.path IS NOT NULL AND pctx.depth > 0
6879                                 $ctxemptyclause";
6880                  $trans = $DB->start_delegated_transaction();
6881                  $DB->delete_records('context_temp');
6882                  $DB->execute($sql);
6883                  context::merge_context_temp_table();
6884                  $DB->delete_records('context_temp');
6885                  $trans->allow_commit();
6886  
6887              }
6888          }
6889      }
6890  }
6891  
6892  
6893  /**
6894   * Course context class
6895   *
6896   * @package   core_access
6897   * @category  access
6898   * @copyright Petr Skoda {@link http://skodak.org}
6899   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
6900   * @since     Moodle 2.2
6901   */
6902  class context_course extends context {
6903      /**
6904       * Please use context_course::instance($courseid) if you need the instance of context.
6905       * Alternatively if you know only the context id use context::instance_by_id($contextid)
6906       *
6907       * @param stdClass $record
6908       */
6909      protected function __construct(stdClass $record) {
6910          parent::__construct($record);
6911          if ($record->contextlevel != CONTEXT_COURSE) {
6912              throw new coding_exception('Invalid $record->contextlevel in context_course constructor.');
6913          }
6914      }
6915  
6916      /**
6917       * Returns human readable context level name.
6918       *
6919       * @static
6920       * @return string the human readable context level name.
6921       */
6922      public static function get_level_name() {
6923          return get_string('course');
6924      }
6925  
6926      /**
6927       * Returns human readable context identifier.
6928       *
6929       * @param boolean $withprefix whether to prefix the name of the context with Course
6930       * @param boolean $short whether to use the short name of the thing.
6931       * @param bool $escape Whether the returned category name is to be HTML escaped or not.
6932       * @return string the human readable context name.
6933       */
6934      public function get_context_name($withprefix = true, $short = false, $escape = true) {
6935          global $DB;
6936  
6937          $name = '';
6938          if ($this->_instanceid == SITEID) {
6939              $name = get_string('frontpage', 'admin');
6940          } else {
6941              if ($course = $DB->get_record('course', array('id'=>$this->_instanceid))) {
6942                  if ($withprefix){
6943                      $name = get_string('course').': ';
6944                  }
6945                  if ($short){
6946                      if (!$escape) {
6947                          $name .= format_string($course->shortname, true, array('context' => $this, 'escape' => false));
6948                      } else {
6949                          $name .= format_string($course->shortname, true, array('context' => $this));
6950                      }
6951                  } else {
6952                      if (!$escape) {
6953                          $name .= format_string(get_course_display_name_for_list($course), true, array('context' => $this,
6954                              'escape' => false));
6955                      } else {
6956                          $name .= format_string(get_course_display_name_for_list($course), true, array('context' => $this));
6957                      }
6958                 }
6959              }
6960          }
6961          return $name;
6962      }
6963  
6964      /**
6965       * Returns the most relevant URL for this context.
6966       *
6967       * @return moodle_url
6968       */
6969      public function get_url() {
6970          if ($this->_instanceid != SITEID) {
6971              return new moodle_url('/course/view.php', array('id'=>$this->_instanceid));
6972          }
6973  
6974          return new moodle_url('/');
6975      }
6976  
6977      /**
6978       * Returns array of relevant context capability records.
6979       *
6980       * @param string $sort
6981       * @return array
6982       */
6983      public function get_capabilities(string $sort = self::DEFAULT_CAPABILITY_SORT) {
6984          global $DB;
6985  
6986          return $DB->get_records_list('capabilities', 'contextlevel', [
6987              CONTEXT_COURSE,
6988              CONTEXT_MODULE,
6989              CONTEXT_BLOCK,
6990          ], $sort);
6991      }
6992  
6993      /**
6994       * Is this context part of any course? If yes return course context.
6995       *
6996       * @param bool $strict true means throw exception if not found, false means return false if not found
6997       * @return context_course context of the enclosing course, null if not found or exception
6998       */
6999      public function get_course_context($strict = true) {
7000          return $this;
7001      }
7002  
7003      /**
7004       * Returns course context instance.
7005       *
7006       * @static
7007       * @param int $courseid id from {course} table
7008       * @param int $strictness
7009       * @return context_course context instance
7010       */
7011      public static function instance($courseid, $strictness = MUST_EXIST) {
7012          global $DB;
7013  
7014          if ($context = context::cache_get(CONTEXT_COURSE, $courseid)) {
7015              return $context;
7016          }
7017  
7018          if (!$record = $DB->get_record('context', array('contextlevel' => CONTEXT_COURSE, 'instanceid' => $courseid))) {
7019              if ($course = $DB->get_record('course', array('id' => $courseid), 'id,category', $strictness)) {
7020                  if ($course->category) {
7021                      $parentcontext = context_coursecat::instance($course->category);
7022                      $record = context::insert_context_record(CONTEXT_COURSE, $course->id, $parentcontext->path);
7023                  } else {
7024                      $record = context::insert_context_record(CONTEXT_COURSE, $course->id, '/'.SYSCONTEXTID, 0);
7025                  }
7026              }
7027          }
7028  
7029          if ($record) {
7030              $context = new context_course($record);
7031              context::cache_add($context);
7032              return $context;
7033          }
7034  
7035          return false;
7036      }
7037  
7038      /**
7039       * Create missing context instances at course context level
7040       * @static
7041       */
7042      protected static function create_level_instances() {
7043          global $DB;
7044  
7045          $sql = "SELECT ".CONTEXT_COURSE.", c.id
7046                    FROM {course} c
7047                   WHERE NOT EXISTS (SELECT 'x'
7048                                       FROM {context} cx
7049                                      WHERE c.id = cx.instanceid AND cx.contextlevel=".CONTEXT_COURSE.")";
7050          $contextdata = $DB->get_recordset_sql($sql);
7051          foreach ($contextdata as $context) {
7052              context::insert_context_record(CONTEXT_COURSE, $context->id, null);
7053          }
7054          $contextdata->close();
7055      }
7056  
7057      /**
7058       * Returns sql necessary for purging of stale context instances.
7059       *
7060       * @static
7061       * @return string cleanup SQL
7062       */
7063      protected static function get_cleanup_sql() {
7064          $sql = "
7065                    SELECT c.*
7066                      FROM {context} c
7067           LEFT OUTER JOIN {course} co ON c.instanceid = co.id
7068                     WHERE co.id IS NULL AND c.contextlevel = ".CONTEXT_COURSE."
7069                 ";
7070  
7071          return $sql;
7072      }
7073  
7074      /**
7075       * Rebuild context paths and depths at course context level.
7076       *
7077       * @static
7078       * @param bool $force
7079       */
7080      protected static function build_paths($force) {
7081          global $DB;
7082  
7083          if ($force or $DB->record_exists_select('context', "contextlevel = ".CONTEXT_COURSE." AND (depth = 0 OR path IS NULL)")) {
7084              if ($force) {
7085                  $ctxemptyclause = $emptyclause = '';
7086              } else {
7087                  $ctxemptyclause = "AND (ctx.path IS NULL OR ctx.depth = 0)";
7088                  $emptyclause    = "AND ({context}.path IS NULL OR {context}.depth = 0)";
7089              }
7090  
7091              $base = '/'.SYSCONTEXTID;
7092  
7093              // Standard frontpage
7094              $sql = "UPDATE {context}
7095                         SET depth = 2,
7096                             path = ".$DB->sql_concat("'$base/'", 'id')."
7097                       WHERE contextlevel = ".CONTEXT_COURSE."
7098                             AND EXISTS (SELECT 'x'
7099                                           FROM {course} c
7100                                          WHERE c.id = {context}.instanceid AND c.category = 0)
7101                             $emptyclause";
7102              $DB->execute($sql);
7103  
7104              // standard courses
7105              $sql = "INSERT INTO {context_temp} (id, path, depth, locked)
7106                      SELECT ctx.id, ".$DB->sql_concat('pctx.path', "'/'", 'ctx.id').", pctx.depth+1, ctx.locked
7107                        FROM {context} ctx
7108                        JOIN {course} c ON (c.id = ctx.instanceid AND ctx.contextlevel = ".CONTEXT_COURSE." AND c.category <> 0)
7109                        JOIN {context} pctx ON (pctx.instanceid = c.category AND pctx.contextlevel = ".CONTEXT_COURSECAT.")
7110                       WHERE pctx.path IS NOT NULL AND pctx.depth > 0
7111                             $ctxemptyclause";
7112              $trans = $DB->start_delegated_transaction();
7113              $DB->delete_records('context_temp');
7114              $DB->execute($sql);
7115              context::merge_context_temp_table();
7116              $DB->delete_records('context_temp');
7117              $trans->allow_commit();
7118          }
7119      }
7120  }
7121  
7122  
7123  /**
7124   * Course module context class
7125   *
7126   * @package   core_access
7127   * @category  access
7128   * @copyright Petr Skoda {@link http://skodak.org}
7129   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
7130   * @since     Moodle 2.2
7131   */
7132  class context_module extends context {
7133      /**
7134       * Please use context_module::instance($cmid) if you need the instance of context.
7135       * Alternatively if you know only the context id use context::instance_by_id($contextid)
7136       *
7137       * @param stdClass $record
7138       */
7139      protected function __construct(stdClass $record) {
7140          parent::__construct($record);
7141          if ($record->contextlevel != CONTEXT_MODULE) {
7142              throw new coding_exception('Invalid $record->contextlevel in context_module constructor.');
7143          }
7144      }
7145  
7146      /**
7147       * Returns human readable context level name.
7148       *
7149       * @static
7150       * @return string the human readable context level name.
7151       */
7152      public static function get_level_name() {
7153          return get_string('activitymodule');
7154      }
7155  
7156      /**
7157       * Returns human readable context identifier.
7158       *
7159       * @param boolean $withprefix whether to prefix the name of the context with the
7160       *      module name, e.g. Forum, Glossary, etc.
7161       * @param boolean $short does not apply to module context
7162       * @param boolean $escape Whether the returned name of the context is to be HTML escaped or not.
7163       * @return string the human readable context name.
7164       */
7165      public function get_context_name($withprefix = true, $short = false, $escape = true) {
7166          global $DB;
7167  
7168          $name = '';
7169          if ($cm = $DB->get_record_sql("SELECT cm.*, md.name AS modname
7170                                           FROM {course_modules} cm
7171                                           JOIN {modules} md ON md.id = cm.module
7172                                          WHERE cm.id = ?", array($this->_instanceid))) {
7173              if ($mod = $DB->get_record($cm->modname, array('id' => $cm->instance))) {
7174                      if ($withprefix){
7175                          $name = get_string('modulename', $cm->modname).': ';
7176                      }
7177                      if (!$escape) {
7178                          $name .= format_string($mod->name, true, array('context' => $this, 'escape' => false));
7179                      } else {
7180                          $name .= format_string($mod->name, true, array('context' => $this));
7181                      }
7182                  }
7183              }
7184          return $name;
7185      }
7186  
7187      /**
7188       * Returns the most relevant URL for this context.
7189       *
7190       * @return moodle_url
7191       */
7192      public function get_url() {
7193          global $DB;
7194  
7195          if ($modname = $DB->get_field_sql("SELECT md.name AS modname
7196                                               FROM {course_modules} cm
7197                                               JOIN {modules} md ON md.id = cm.module
7198                                              WHERE cm.id = ?", array($this->_instanceid))) {
7199              return new moodle_url('/mod/' . $modname . '/view.php', array('id'=>$this->_instanceid));
7200          }
7201  
7202          return new moodle_url('/');
7203      }
7204  
7205      /**
7206       * Returns array of relevant context capability records.
7207       *
7208       * @param string $sort
7209       * @return array
7210       */
7211      public function get_capabilities(string $sort = self::DEFAULT_CAPABILITY_SORT) {
7212          global $DB, $CFG;
7213  
7214          $cm = $DB->get_record('course_modules', array('id'=>$this->_instanceid));
7215          $module = $DB->get_record('modules', array('id'=>$cm->module));
7216  
7217          $subcaps = array();
7218  
7219          $modulepath = "{$CFG->dirroot}/mod/{$module->name}";
7220          if (file_exists("{$modulepath}/db/subplugins.json")) {
7221              $subplugins = (array) json_decode(file_get_contents("{$modulepath}/db/subplugins.json"))->plugintypes;
7222          } else if (file_exists("{$modulepath}/db/subplugins.php")) {
7223              debugging('Use of subplugins.php has been deprecated. ' .
7224                      'Please update your plugin to provide a subplugins.json file instead.',
7225                      DEBUG_DEVELOPER);
7226              $subplugins = array();  // should be redefined in the file
7227              include("{$modulepath}/db/subplugins.php");
7228          }
7229  
7230          if (!empty($subplugins)) {
7231              foreach (array_keys($subplugins) as $subplugintype) {
7232                  foreach (array_keys(core_component::get_plugin_list($subplugintype)) as $subpluginname) {
7233                      $subcaps = array_merge($subcaps, array_keys(load_capability_def($subplugintype.'_'.$subpluginname)));
7234                  }
7235              }
7236          }
7237  
7238          $modfile = "{$modulepath}/lib.php";
7239          $extracaps = array();
7240          if (file_exists($modfile)) {
7241              include_once($modfile);
7242              $modfunction = $module->name.'_get_extra_capabilities';
7243              if (function_exists($modfunction)) {
7244                  $extracaps = $modfunction();
7245              }
7246          }
7247  
7248          $extracaps = array_merge($subcaps, $extracaps);
7249          $extra = '';
7250          list($extra, $params) = $DB->get_in_or_equal(
7251              $extracaps, SQL_PARAMS_NAMED, 'cap0', true, '');
7252          if (!empty($extra)) {
7253              $extra = "OR name $extra";
7254          }
7255  
7256          // Fetch the list of modules, and remove this one.
7257          $components = \core_component::get_component_list();
7258          $componentnames = $components['mod'];
7259          unset($componentnames["mod_{$module->name}"]);
7260          $componentnames = array_keys($componentnames);
7261  
7262          // Exclude all other modules.
7263          list($notcompsql, $notcompparams) = $DB->get_in_or_equal($componentnames, SQL_PARAMS_NAMED, 'notcomp', false);
7264          $params = array_merge($params, $notcompparams);
7265  
7266  
7267          // Exclude other component submodules.
7268          $i = 0;
7269          $ignorecomponents = [];
7270          foreach ($componentnames as $mod) {
7271              if ($subplugins = \core_component::get_subplugins($mod)) {
7272                  foreach (array_keys($subplugins) as $subplugintype) {
7273                      $paramname = "notlike{$i}";
7274                      $ignorecomponents[] = $DB->sql_like('component', ":{$paramname}", true, true, true);
7275                      $params[$paramname] = "{$subplugintype}_%";
7276                      $i++;
7277                  }
7278              }
7279          }
7280          $notlikesql = "(" . implode(' AND ', $ignorecomponents) . ")";
7281  
7282          $sql = "SELECT *
7283                    FROM {capabilities}
7284                   WHERE (contextlevel = ".CONTEXT_MODULE."
7285                     AND component {$notcompsql}
7286                     AND {$notlikesql})
7287                         $extra
7288                ORDER BY $sort";
7289  
7290          return $DB->get_records_sql($sql, $params);
7291      }
7292  
7293      /**
7294       * Is this context part of any course? If yes return course context.
7295       *
7296       * @param bool $strict true means throw exception if not found, false means return false if not found
7297       * @return context_course context of the enclosing course, null if not found or exception
7298       */
7299      public function get_course_context($strict = true) {
7300          return $this->get_parent_context();
7301      }
7302  
7303      /**
7304       * Returns module context instance.
7305       *
7306       * @static
7307       * @param int $cmid id of the record from {course_modules} table; pass cmid there, NOT id in the instance column
7308       * @param int $strictness
7309       * @return context_module context instance
7310       */
7311      public static function instance($cmid, $strictness = MUST_EXIST) {
7312          global $DB;
7313  
7314          if ($context = context::cache_get(CONTEXT_MODULE, $cmid)) {
7315              return $context;
7316          }
7317  
7318          if (!$record = $DB->get_record('context', array('contextlevel' => CONTEXT_MODULE, 'instanceid' => $cmid))) {
7319              if ($cm = $DB->get_record('course_modules', array('id' => $cmid), 'id,course', $strictness)) {
7320                  $parentcontext = context_course::instance($cm->course);
7321                  $record = context::insert_context_record(CONTEXT_MODULE, $cm->id, $parentcontext->path);
7322              }
7323          }
7324  
7325          if ($record) {
7326              $context = new context_module($record);
7327              context::cache_add($context);
7328              return $context;
7329          }
7330  
7331          return false;
7332      }
7333  
7334      /**
7335       * Create missing context instances at module context level
7336       * @static
7337       */
7338      protected static function create_level_instances() {
7339          global $DB;
7340  
7341          $sql = "SELECT ".CONTEXT_MODULE.", cm.id
7342                    FROM {course_modules} cm
7343                   WHERE NOT EXISTS (SELECT 'x'
7344                                       FROM {context} cx
7345                                      WHERE cm.id = cx.instanceid AND cx.contextlevel=".CONTEXT_MODULE.")";
7346          $contextdata = $DB->get_recordset_sql($sql);
7347          foreach ($contextdata as $context) {
7348              context::insert_context_record(CONTEXT_MODULE, $context->id, null);
7349          }
7350          $contextdata->close();
7351      }
7352  
7353      /**
7354       * Returns sql necessary for purging of stale context instances.
7355       *
7356       * @static
7357       * @return string cleanup SQL
7358       */
7359      protected static function get_cleanup_sql() {
7360          $sql = "
7361                    SELECT c.*
7362                      FROM {context} c
7363           LEFT OUTER JOIN {course_modules} cm ON c.instanceid = cm.id
7364                     WHERE cm.id IS NULL AND c.contextlevel = ".CONTEXT_MODULE."
7365                 ";
7366  
7367          return $sql;
7368      }
7369  
7370      /**
7371       * Rebuild context paths and depths at module context level.
7372       *
7373       * @static
7374       * @param bool $force
7375       */
7376      protected static function build_paths($force) {
7377          global $DB;
7378  
7379          if ($force or $DB->record_exists_select('context', "contextlevel = ".CONTEXT_MODULE." AND (depth = 0 OR path IS NULL)")) {
7380              if ($force) {
7381                  $ctxemptyclause = '';
7382              } else {
7383                  $ctxemptyclause = "AND (ctx.path IS NULL OR ctx.depth = 0)";
7384              }
7385  
7386              $sql = "INSERT INTO {context_temp} (id, path, depth, locked)
7387                      SELECT ctx.id, ".$DB->sql_concat('pctx.path', "'/'", 'ctx.id').", pctx.depth+1, ctx.locked
7388                        FROM {context} ctx
7389                        JOIN {course_modules} cm ON (cm.id = ctx.instanceid AND ctx.contextlevel = ".CONTEXT_MODULE.")
7390                        JOIN {context} pctx ON (pctx.instanceid = cm.course AND pctx.contextlevel = ".CONTEXT_COURSE.")
7391                       WHERE pctx.path IS NOT NULL AND pctx.depth > 0
7392                             $ctxemptyclause";
7393              $trans = $DB->start_delegated_transaction();
7394              $DB->delete_records('context_temp');
7395              $DB->execute($sql);
7396              context::merge_context_temp_table();
7397              $DB->delete_records('context_temp');
7398              $trans->allow_commit();
7399          }
7400      }
7401  }
7402  
7403  
7404  /**
7405   * Block context class
7406   *
7407   * @package   core_access
7408   * @category  access
7409   * @copyright Petr Skoda {@link http://skodak.org}
7410   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
7411   * @since     Moodle 2.2
7412   */
7413  class context_block extends context {
7414      /**
7415       * Please use context_block::instance($blockinstanceid) if you need the instance of context.
7416       * Alternatively if you know only the context id use context::instance_by_id($contextid)
7417       *
7418       * @param stdClass $record
7419       */
7420      protected function __construct(stdClass $record) {
7421          parent::__construct($record);
7422          if ($record->contextlevel != CONTEXT_BLOCK) {
7423              throw new coding_exception('Invalid $record->contextlevel in context_block constructor');
7424          }
7425      }
7426  
7427      /**
7428       * Returns human readable context level name.
7429       *
7430       * @static
7431       * @return string the human readable context level name.
7432       */
7433      public static function get_level_name() {
7434          return get_string('block');
7435      }
7436  
7437      /**
7438       * Returns human readable context identifier.
7439       *
7440       * @param boolean $withprefix whether to prefix the name of the context with Block
7441       * @param boolean $short does not apply to block context
7442       * @param boolean $escape does not apply to block context
7443       * @return string the human readable context name.
7444       */
7445      public function get_context_name($withprefix = true, $short = false, $escape = true) {
7446          global $DB, $CFG;
7447  
7448          $name = '';
7449          if ($blockinstance = $DB->get_record('block_instances', array('id'=>$this->_instanceid))) {
7450              global $CFG;
7451              require_once("$CFG->dirroot/blocks/moodleblock.class.php");
7452              require_once("$CFG->dirroot/blocks/$blockinstance->blockname/block_$blockinstance->blockname.php");
7453              $blockname = "block_$blockinstance->blockname";
7454              if ($blockobject = new $blockname()) {
7455                  if ($withprefix){
7456                      $name = get_string('block').': ';
7457                  }
7458                  $name .= $blockobject->title;
7459              }
7460          }
7461  
7462          return $name;
7463      }
7464  
7465      /**
7466       * Returns the most relevant URL for this context.
7467       *
7468       * @return moodle_url
7469       */
7470      public function get_url() {
7471          $parentcontexts = $this->get_parent_context();
7472          return $parentcontexts->get_url();
7473      }
7474  
7475      /**
7476       * Returns array of relevant context capability records.
7477       *
7478       * @param string $sort
7479       * @return array
7480       */
7481      public function get_capabilities(string $sort = self::DEFAULT_CAPABILITY_SORT) {
7482          global $DB;
7483  
7484          $bi = $DB->get_record('block_instances', array('id' => $this->_instanceid));
7485  
7486          $select = '(contextlevel = :level AND component = :component)';
7487          $params = [
7488              'level' => CONTEXT_BLOCK,
7489              'component' => 'block_' . $bi->blockname,
7490          ];
7491  
7492          $extracaps = block_method_result($bi->blockname, 'get_extra_capabilities');
7493          if ($extracaps) {
7494              list($extra, $extraparams) = $DB->get_in_or_equal($extracaps, SQL_PARAMS_NAMED, 'cap');
7495              $select .= " OR name $extra";
7496              $params = array_merge($params, $extraparams);
7497          }
7498  
7499          return $DB->get_records_select('capabilities', $select, $params, $sort);
7500      }
7501  
7502      /**
7503       * Is this context part of any course? If yes return course context.
7504       *
7505       * @param bool $strict true means throw exception if not found, false means return false if not found
7506       * @return context_course context of the enclosing course, null if not found or exception
7507       */
7508      public function get_course_context($strict = true) {
7509          $parentcontext = $this->get_parent_context();
7510          return $parentcontext->get_course_context($strict);
7511      }
7512  
7513      /**
7514       * Returns block context instance.
7515       *
7516       * @static
7517       * @param int $blockinstanceid id from {block_instances} table.
7518       * @param int $strictness
7519       * @return context_block context instance
7520       */
7521      public static function instance($blockinstanceid, $strictness = MUST_EXIST) {
7522          global $DB;
7523  
7524          if ($context = context::cache_get(CONTEXT_BLOCK, $blockinstanceid)) {
7525              return $context;
7526          }
7527  
7528          if (!$record = $DB->get_record('context', array('contextlevel' => CONTEXT_BLOCK, 'instanceid' => $blockinstanceid))) {
7529              if ($bi = $DB->get_record('block_instances', array('id' => $blockinstanceid), 'id,parentcontextid', $strictness)) {
7530                  $parentcontext = context::instance_by_id($bi->parentcontextid);
7531                  $record = context::insert_context_record(CONTEXT_BLOCK, $bi->id, $parentcontext->path);
7532              }
7533          }
7534  
7535          if ($record) {
7536              $context = new context_block($record);
7537              context::cache_add($context);
7538              return $context;
7539          }
7540  
7541          return false;
7542      }
7543  
7544      /**
7545       * Block do not have child contexts...
7546       * @return array
7547       */
7548      public function get_child_contexts() {
7549          return array();
7550      }
7551  
7552      /**
7553       * Create missing context instances at block context level
7554       * @static
7555       */
7556      protected static function create_level_instances() {
7557          global $DB;
7558  
7559          $sql = "SELECT ".CONTEXT_BLOCK.", bi.id
7560                    FROM {block_instances} bi
7561                   WHERE NOT EXISTS (SELECT 'x'
7562                                       FROM {context} cx
7563                                      WHERE bi.id = cx.instanceid AND cx.contextlevel=".CONTEXT_BLOCK.")";
7564          $contextdata = $DB->get_recordset_sql($sql);
7565          foreach ($contextdata as $context) {
7566              context::insert_context_record(CONTEXT_BLOCK, $context->id, null);
7567          }
7568          $contextdata->close();
7569      }
7570  
7571      /**
7572       * Returns sql necessary for purging of stale context instances.
7573       *
7574       * @static
7575       * @return string cleanup SQL
7576       */
7577      protected static function get_cleanup_sql() {
7578          $sql = "
7579                    SELECT c.*
7580                      FROM {context} c
7581           LEFT OUTER JOIN {block_instances} bi ON c.instanceid = bi.id
7582                     WHERE bi.id IS NULL AND c.contextlevel = ".CONTEXT_BLOCK."
7583                 ";
7584  
7585          return $sql;
7586      }
7587  
7588      /**
7589       * Rebuild context paths and depths at block context level.
7590       *
7591       * @static
7592       * @param bool $force
7593       */
7594      protected static function build_paths($force) {
7595          global $DB;
7596  
7597          if ($force or $DB->record_exists_select('context', "contextlevel = ".CONTEXT_BLOCK." AND (depth = 0 OR path IS NULL)")) {
7598              if ($force) {
7599                  $ctxemptyclause = '';
7600              } else {
7601                  $ctxemptyclause = "AND (ctx.path IS NULL OR ctx.depth = 0)";
7602              }
7603  
7604              // pctx.path IS NOT NULL prevents fatal problems with broken block instances that point to invalid context parent
7605              $sql = "INSERT INTO {context_temp} (id, path, depth, locked)
7606                      SELECT ctx.id, ".$DB->sql_concat('pctx.path', "'/'", 'ctx.id').", pctx.depth+1, ctx.locked
7607                        FROM {context} ctx
7608                        JOIN {block_instances} bi ON (bi.id = ctx.instanceid AND ctx.contextlevel = ".CONTEXT_BLOCK.")
7609                        JOIN {context} pctx ON (pctx.id = bi.parentcontextid)
7610                       WHERE (pctx.path IS NOT NULL AND pctx.depth > 0)
7611                             $ctxemptyclause";
7612              $trans = $DB->start_delegated_transaction();
7613              $DB->delete_records('context_temp');
7614              $DB->execute($sql);
7615              context::merge_context_temp_table();
7616              $DB->delete_records('context_temp');
7617              $trans->allow_commit();
7618          }
7619      }
7620  }
7621  
7622  
7623  // ============== DEPRECATED FUNCTIONS ==========================================
7624  // Old context related functions were deprecated in 2.0, it is recommended
7625  // to use context classes in new code. Old function can be used when
7626  // creating patches that are supposed to be backported to older stable branches.
7627  // These deprecated functions will not be removed in near future,
7628  // before removing devs will be warned with a debugging message first,
7629  // then we will add error message and only after that we can remove the functions
7630  // completely.
7631  
7632  /**
7633   * Runs get_records select on context table and returns the result
7634   * Does get_records_select on the context table, and returns the results ordered
7635   * by contextlevel, and then the natural sort order within each level.
7636   * for the purpose of $select, you need to know that the context table has been
7637   * aliased to ctx, so for example, you can call get_sorted_contexts('ctx.depth = 3');
7638   *
7639   * @param string $select the contents of the WHERE clause. Remember to do ctx.fieldname.
7640   * @param array $params any parameters required by $select.
7641   * @return array the requested context records.
7642   */
7643  function get_sorted_contexts($select, $params = array()) {
7644  
7645      //TODO: we should probably rewrite all the code that is using this thing, the trouble is we MUST NOT modify the context instances...
7646  
7647      global $DB;
7648      if ($select) {
7649          $select = 'WHERE ' . $select;
7650      }
7651      return $DB->get_records_sql("
7652              SELECT ctx.*
7653                FROM {context} ctx
7654                LEFT JOIN {user} u ON ctx.contextlevel = " . CONTEXT_USER . " AND u.id = ctx.instanceid
7655                LEFT JOIN {course_categories} cat ON ctx.contextlevel = " . CONTEXT_COURSECAT . " AND cat.id = ctx.instanceid
7656                LEFT JOIN {course} c ON ctx.contextlevel = " . CONTEXT_COURSE . " AND c.id = ctx.instanceid
7657                LEFT JOIN {course_modules} cm ON ctx.contextlevel = " . CONTEXT_MODULE . " AND cm.id = ctx.instanceid
7658                LEFT JOIN {block_instances} bi ON ctx.contextlevel = " . CONTEXT_BLOCK . " AND bi.id = ctx.instanceid
7659             $select
7660            ORDER BY ctx.contextlevel, bi.defaultregion, COALESCE(cat.sortorder, c.sortorder, cm.section, bi.defaultweight), u.lastname, u.firstname, cm.id
7661              ", $params);
7662  }
7663  
7664  /**
7665   * Given context and array of users, returns array of users whose enrolment status is suspended,
7666   * or enrolment has expired or has not started. Also removes those users from the given array
7667   *
7668   * @param context $context context in which suspended users should be extracted.
7669   * @param array $users list of users.
7670   * @param array $ignoreusers array of user ids to ignore, e.g. guest
7671   * @return array list of suspended users.
7672   */
7673  function extract_suspended_users($context, &$users, $ignoreusers=array()) {
7674      global $DB;
7675  
7676      // Get active enrolled users.
7677      list($sql, $params) = get_enrolled_sql($context, null, null, true);
7678      $activeusers = $DB->get_records_sql($sql, $params);
7679  
7680      // Move suspended users to a separate array & remove from the initial one.
7681      $susers = array();
7682      if (sizeof($activeusers)) {
7683          foreach ($users as $userid => $user) {
7684              if (!array_key_exists($userid, $activeusers) && !in_array($userid, $ignoreusers)) {
7685                  $susers[$userid] = $user;
7686                  unset($users[$userid]);
7687              }
7688          }
7689      }
7690      return $susers;
7691  }
7692  
7693  /**
7694   * Given context and array of users, returns array of user ids whose enrolment status is suspended,
7695   * or enrolment has expired or not started.
7696   *
7697   * @param context $context context in which user enrolment is checked.
7698   * @param bool $usecache Enable or disable (default) the request cache
7699   * @return array list of suspended user id's.
7700   */
7701  function get_suspended_userids(context $context, $usecache = false) {
7702      global $DB;
7703  
7704      if ($usecache) {
7705          $cache = cache::make('core', 'suspended_userids');
7706          $susers = $cache->get($context->id);
7707          if ($susers !== false) {
7708              return $susers;
7709          }
7710      }
7711  
7712      $coursecontext = $context->get_course_context();
7713      $susers = array();
7714  
7715      // Front page users are always enrolled, so suspended list is empty.
7716      if ($coursecontext->instanceid != SITEID) {
7717          list($sql, $params) = get_enrolled_sql($context, null, null, false, true);
7718          $susers = $DB->get_fieldset_sql($sql, $params);
7719          $susers = array_combine($susers, $susers);
7720      }
7721  
7722      // Cache results for the remainder of this request.
7723      if ($usecache) {
7724          $cache->set($context->id, $susers);
7725      }
7726  
7727      return $susers;
7728  }
7729  
7730  /**
7731   * Gets sql for finding users with capability in the given context
7732   *
7733   * @param context $context
7734   * @param string|array $capability Capability name or array of names.
7735   *      If an array is provided then this is the equivalent of a logical 'OR',
7736   *      i.e. the user needs to have one of these capabilities.
7737   * @return array($sql, $params)
7738   */
7739  function get_with_capability_sql(context $context, $capability) {
7740      static $i = 0;
7741      $i++;
7742      $prefix = 'cu' . $i . '_';
7743  
7744      $capjoin = get_with_capability_join($context, $capability, $prefix . 'u.id');
7745  
7746      $sql = "SELECT DISTINCT {$prefix}u.id
7747                FROM {user} {$prefix}u
7748              $capjoin->joins
7749               WHERE {$prefix}u.deleted = 0 AND $capjoin->wheres";
7750  
7751      return array($sql, $capjoin->params);
7752  }