[Summary view]

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

   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   * TeX filter library functions.
  19   *
  20   * @package    filter
  21   * @subpackage tex
  22   * @copyright  2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu
  23   *             Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca
  24   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25   */
  26  
  27  defined('MOODLE_INTERNAL') || die();
  28  
  29  function filter_tex_get_executable($debug=false) {
  30      global $CFG;
  31  
  32      if ((PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows")) {
  33          return "$CFG->dirroot/filter/tex/mimetex.exe";
  34      }
  35  
  36      if ($pathmimetex = get_config('filter_tex', 'pathmimetex')) {
  37          if (is_executable($pathmimetex)) {
  38              return $pathmimetex;
  39          } else {
  40              print_error('mimetexnotexecutable', 'error');
  41          }
  42      }
  43  
  44      $custom_commandpath = "$CFG->dirroot/filter/tex/mimetex";
  45      if (file_exists($custom_commandpath)) {
  46          if (is_executable($custom_commandpath)) {
  47              return $custom_commandpath;
  48          } else {
  49              print_error('mimetexnotexecutable', 'error');
  50          }
  51      }
  52  
  53      switch (PHP_OS) {
  54          case "Linux":   return "$CFG->dirroot/filter/tex/mimetex.linux";
  55          case "Darwin":  return "$CFG->dirroot/filter/tex/mimetex.darwin";
  56          case "FreeBSD": return "$CFG->dirroot/filter/tex/mimetex.freebsd";
  57      }
  58  
  59      print_error('mimetexisnotexist', 'error');
  60  }
  61  
  62  /**
  63   * Check the formula expression against the list of denied keywords.
  64   *
  65   * List of allowed could be more complete but also harder to maintain.
  66   *
  67   * @param string $texexp Formula expression to check.
  68   * @return string Formula expression with denied keywords replaced with 'forbiddenkeyword'.
  69   */
  70  function filter_tex_sanitize_formula(string $texexp): string {
  71  
  72      $denylist = [
  73          'include', 'command', 'loop', 'repeat', 'open', 'toks', 'output',
  74          'input', 'catcode', 'name', '^^',
  75          '\def', '\edef', '\gdef', '\xdef',
  76          '\every', '\errhelp', '\errorstopmode', '\scrollmode', '\nonstopmode',
  77          '\batchmode', '\read', '\write', 'csname', '\newhelp', '\uppercase',
  78          '\lowercase', '\relax', '\aftergroup',
  79          '\afterassignment', '\expandafter', '\noexpand', '\special',
  80          '\let', '\futurelet', '\else', '\fi', '\chardef', '\makeatletter', '\afterground',
  81          '\noexpand', '\line', '\mathcode', '\item', '\section', '\mbox', '\declarerobustcommand',
  82      ];
  83  
  84      $allowlist = ['inputenc'];
  85  
  86      // Prepare the denylist for regular expression.
  87      $denylist = array_map(function($value){
  88          return '/' . preg_quote($value, '/') . '/i';
  89      }, $denylist);
  90  
  91      // Prepare the allowlist for regular expression.
  92      $allowlist = array_map(function($value){
  93          return '/\bforbiddenkeyword_(' . preg_quote($value, '/') . ')\b/i';
  94      }, $allowlist);
  95  
  96      // First, mangle all denied words.
  97      $texexp = preg_replace_callback($denylist,
  98          function($matches) {
  99              return 'forbiddenkeyword_' . $matches[0];
 100          },
 101          $texexp
 102      );
 103  
 104      // Then, change back the allowed words.
 105      $texexp = preg_replace_callback($allowlist,
 106          function($matches) {
 107              return $matches[1];
 108          },
 109          $texexp
 110      );
 111  
 112      return $texexp;
 113  }
 114  
 115  function filter_tex_get_cmd($pathname, $texexp) {
 116      $texexp = filter_tex_sanitize_formula($texexp);
 117      $texexp = escapeshellarg($texexp);
 118      $executable = filter_tex_get_executable(false);
 119  
 120      if ((PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows")) {
 121          $executable = str_replace(' ', '^ ', $executable);
 122          return "$executable ++ -e  \"$pathname\" -- $texexp";
 123  
 124      } else {
 125          return "\"$executable\" -e \"$pathname\" -- $texexp";
 126      }
 127  }
 128  
 129  /**
 130   * Purge all caches when settings changed.
 131   */
 132  function filter_tex_updatedcallback($name) {
 133      global $CFG, $DB;
 134      reset_text_filters_cache();
 135  
 136      if (file_exists("$CFG->dataroot/filter/tex")) {
 137          remove_dir("$CFG->dataroot/filter/tex");
 138      }
 139      if (file_exists("$CFG->dataroot/filter/algebra")) {
 140          remove_dir("$CFG->dataroot/filter/algebra");
 141      }
 142      if (file_exists("$CFG->tempdir/latex")) {
 143          remove_dir("$CFG->tempdir/latex");
 144      }
 145  
 146      $DB->delete_records('cache_filters', array('filter'=>'tex'));
 147      $DB->delete_records('cache_filters', array('filter'=>'algebra'));
 148  
 149      $pathlatex = get_config('filter_tex', 'pathlatex');
 150      if ($pathlatex === false) {
 151          // detailed settings not present yet
 152          return;
 153      }
 154  
 155      $pathlatex = trim($pathlatex, " '\"");
 156      $pathdvips = trim(get_config('filter_tex', 'pathdvips'), " '\"");
 157      $pathconvert = trim(get_config('filter_tex', 'pathconvert'), " '\"");
 158      $pathdvisvgm = trim(get_config('filter_tex', 'pathdvisvgm'), " '\"");
 159  
 160      $supportedformats = array('gif');
 161      if ((is_file($pathlatex) && is_executable($pathlatex)) &&
 162              (is_file($pathdvips) && is_executable($pathdvips))) {
 163          if (is_file($pathconvert) && is_executable($pathconvert)) {
 164               $supportedformats[] = 'png';
 165          }
 166          if (is_file($pathdvisvgm) && is_executable($pathdvisvgm)) {
 167               $supportedformats[] = 'svg';
 168          }
 169      }
 170      if (!in_array(get_config('filter_tex', 'convertformat'), $supportedformats)) {
 171          set_config('convertformat', array_pop($supportedformats), 'filter_tex');
 172      }
 173  
 174  }
 175