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See Release Notes
Long Term Support Release

  • Bug fixes for general core bugs in 3.9.x will end* 10 May 2021 (12 months).
  • Bug fixes for security issues in 3.9.x will end* 8 May 2023 (36 months).
  • PHP version: minimum PHP 7.2.0 Note: minimum PHP version has increased since Moodle 3.8. PHP 7.3.x and 7.4.x are supported too.
/lib/ -> filelib.php (source)

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

Functions for file handling.

Copyright: 1999 onwards Martin Dougiamas (http://dougiamas.com)
License: http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
File Size: 5147 lines (201 kb)
Included or required: 6 times
Referenced: 10 times
Includes or requires: 0 files

Defines 2 classes

curl:: (31 methods):
  __construct()
  resetopt()
  get_cacert()
  resetcookie()
  setopt()
  cleanopt()
  resetHeader()
  setHeader()
  getResponse()
  get_raw_response()
  formatHeader()
  apply_opt()
  download()
  get_security()
  set_security()
  multi()
  reset_request_state_vars()
  mock_response()
  request()
  head()
  patch()
  post()
  get()
  download_one()
  put()
  delete()
  trace()
  options()
  get_info()
  get_errno()
  strip_double_headers()

curl_cache:: (6 methods):
  __construct()
  get()
  set()
  cleanup()
  refresh()
  file_pluginfile()

Defines 6 functions

  file_encode_url()
  file_area_contains_subdirs()
  file_prepare_standard_editor()
  file_postupdate_standard_editor()
  file_prepare_standard_filemanager()
  file_postupdate_standard_filemanager()
  file_get_unused_draft_itemid()
  file_prepare_draft_area()
  file_rewrite_pluginfile_urls()
  file_get_draft_area_info()
  file_get_file_area_info()
  file_is_draft_area_limit_reached()
  file_is_draft_areas_limit_reached()
  file_get_user_used_space()
  file_correct_filepath()
  file_get_drafarea_folders()
  file_get_drafarea_files()
  file_get_all_files_in_draftarea()
  file_get_submitted_draft_itemid()
  file_restore_source_field_from_draft_file()
  file_remove_editor_orphaned_files()
  file_merge_draft_areas()
  file_replace_file_area_in_text()
  file_copy_file_to_file_area()
  file_save_draft_area_files()
  file_rewrite_urls_to_pluginfile()
  file_set_sortorder()
  file_reset_sortorder()
  file_get_upload_error()
  format_array_postdata_for_curlcall()
  format_postdata_for_curlcall()
  download_file_content()
  get_mimetypes_array()
  get_mimetype_for_sending()
  mimeinfo()
  mimeinfo_from_type()
  file_file_icon()
  file_folder_icon()
  file_mimetype_icon()
  file_extension_icon()
  get_mimetype_description()
  file_get_typegroup()
  file_extension_in_typegroup()
  file_mimetype_in_typegroup()
  send_file_not_found()
  send_header_404()
  readfile_allow_large()
  readfile_accel()
  readstring_accel()
  send_temp_file()
  send_temp_file_finished()
  send_content_uncached()
  file_safe_save_content()
  send_file()
  send_stored_file()
  fulldelete()
  byteserving_send_file()
  file_is_executable()
  file_overwrite_existing_draftfile()
  file_merge_files_from_draft_area_into_filearea()
  file_merge_draft_area_into_draft_area()

Class: curl  - X-Ref

RESTful cURL class

This is a wrapper class for curl, it is quite easy to use:
<code>
$c = new curl;
// enable cache
$c = new curl(array('cache'=>true));
// enable cookie
$c = new curl(array('cookie'=>true));
// enable proxy
$c = new curl(array('proxy'=>true));

// HTTP GET Method
$html = $c->get('http://example.com');
// HTTP POST Method
$html = $c->post('http://example.com/', array('q'=>'words', 'name'=>'moodle'));
// HTTP PUT Method
$html = $c->put('http://example.com/', array('file'=>'/var/www/test.txt');
</code>

__construct($settings = array()   X-Ref
Curl constructor.

Allowed settings are:
proxy: (bool) use proxy server, null means autodetect non-local from url
debug: (bool) use debug output
cookie: (string) path to cookie file, false if none
cache: (bool) use cache
module_cache: (string) type of cache
securityhelper: (\core\files\curl_security_helper_base) helper object providing URL checking for requests.
ignoresecurity: (bool) set true to override and ignore the security helper when making requests.

param: array $settings

resetopt()   X-Ref
Resets the CURL options that have already been set


get_cacert()   X-Ref
Get the location of ca certificates.

return: string absolute file path or empty if default used

resetcookie()   X-Ref
Reset Cookie


setopt($options = array()   X-Ref
Set curl options.

Do not use the curl constants to define the options, pass a string
corresponding to that constant. Ie. to set CURLOPT_MAXREDIRS, pass
array('CURLOPT_MAXREDIRS' => 10) or array('maxredirs' => 10) to this method.

param: array $options If array is null, this function will reset the options to default value.
return: void

cleanopt()   X-Ref
Reset http method


resetHeader()   X-Ref
Resets the HTTP Request headers (to prepare for the new request)


setHeader($header)   X-Ref
Set HTTP Request Header

param: array $header

getResponse()   X-Ref
Get HTTP Response Headers

return: array of arrays

get_raw_response()   X-Ref
Get raw HTTP Response Headers

return: array of strings

formatHeader($ch, $header)   X-Ref
private callback function
Formatting HTTP Response Header

We only keep the last headers returned. For example during a redirect the
redirect headers will not appear in {@link self::getResponse()}, if you need
to use those headers, refer to {@link self::get_raw_response()}.

param: resource $ch Apparently not used
param: string $header
return: int The strlen of the header

apply_opt($curl, $options)   X-Ref
Set options for individual curl instance

param: resource $curl A curl handle
param: array $options
return: resource The curl handle

download($requests, $options = array()   X-Ref
Download multiple files in parallel

Calls {@link multi()} with specific download headers

<code>
$c = new curl();
$file1 = fopen('a', 'wb');
$file2 = fopen('b', 'wb');
$c->download(array(
array('url'=>'http://localhost/', 'file'=>$file1),
array('url'=>'http://localhost/20/', 'file'=>$file2)
));
fclose($file1);
fclose($file2);
</code>

or

<code>
$c = new curl();
$c->download(array(
array('url'=>'http://localhost/', 'filepath'=>'/tmp/file1.tmp'),
array('url'=>'http://localhost/20/', 'filepath'=>'/tmp/file2.tmp')
));
</code>

param: array $requests An array of files to request {
param: array $options An array of options to set
return: array An array of results

get_security()   X-Ref
Returns the current curl security helper.

return: \core\files\curl_security_helper instance.

set_security($securityobject)   X-Ref
Sets the curl security helper.

param: \core\files\curl_security_helper $securityobject instance/subclass of the base curl_security_helper class.
return: bool true if the security helper could be set, false otherwise.

multi($requests, $options = array()   X-Ref
Multi HTTP Requests
This function could run multi-requests in parallel.

param: array $requests An array of files to request
param: array $options An array of options to set
return: array An array of results

reset_request_state_vars()   X-Ref
Helper function to reset the request state vars.

return: void.

mock_response($response)   X-Ref
For use only in unit tests - we can pre-set the next curl response.
This is useful for unit testing APIs that call external systems.

param: string $response

request($url, $options = array()   X-Ref
Single HTTP Request

param: string $url The URL to request
param: array $options
return: bool

head($url, $options = array()   X-Ref
HTTP HEAD method

param: string $url
param: array $options
return: bool

patch($url, $params = '', $options = array()   X-Ref
HTTP PATCH method

param: string $url
param: array|string $params
param: array $options
return: bool

post($url, $params = '', $options = array()   X-Ref
HTTP POST method

param: string $url
param: array|string $params
param: array $options
return: bool

get($url, $params = array()   X-Ref
HTTP GET method

param: string $url
param: array $params
param: array $options
return: bool

download_one($url, $params, $options = array()   X-Ref
Downloads one file and writes it to the specified file handler

<code>
$c = new curl();
$file = fopen('savepath', 'w');
$result = $c->download_one('http://localhost/', null,
array('file' => $file, 'timeout' => 5, 'followlocation' => true, 'maxredirs' => 3));
fclose($file);
$download_info = $c->get_info();
if ($result === true) {
// file downloaded successfully
} else {
$error_text = $result;
$error_code = $c->get_errno();
}
</code>

<code>
$c = new curl();
$result = $c->download_one('http://localhost/', null,
array('filepath' => 'savepath', 'timeout' => 5, 'followlocation' => true, 'maxredirs' => 3));
// ... see above, no need to close handle and remove file if unsuccessful
</code>

param: string $url
param: array|null $params key-value pairs to be added to $url as query string
param: array $options request options. Must include either 'file' or 'filepath'
return: bool|string true on success or error string on failure

put($url, $params = array()   X-Ref
HTTP PUT method

param: string $url
param: array $params
param: array $options
return: bool

delete($url, $param = array()   X-Ref
HTTP DELETE method

param: string $url
param: array $param
param: array $options
return: bool

trace($url, $options = array()   X-Ref
HTTP TRACE method

param: string $url
param: array $options
return: bool

options($url, $options = array()   X-Ref
HTTP OPTIONS method

param: string $url
param: array $options
return: bool

get_info()   X-Ref
Get curl information

return: string

get_errno()   X-Ref
Get curl error code

return: int

strip_double_headers($input)   X-Ref
When using a proxy, an additional HTTP response code may appear at
the start of the header. For example, when using https over a proxy
there may be 'HTTP/1.0 200 Connection Established'. Other codes are
also possible and some may come with their own headers.

If using the return value containing all headers, this function can be
called to remove unwanted doubles.

Note that it is not possible to distinguish this situation from valid
data unless you know the actual response part (below the headers)
will not be included in this string, or else will not 'look like' HTTP
headers. As a result it is not safe to call this function for general
data.

param: string $input Input HTTP response
return: string HTTP response with additional headers stripped if any

Class: curl_cache  - X-Ref

This class is used by cURL class, use case:

<code>
$CFG->repositorycacheexpire = 120;
$CFG->curlcache = 120;

$c = new curl(array('cache'=>true), 'module_cache'=>'repository');
$ret = $c->get('http://www.google.com');
</code>

__construct($module = 'repository')   X-Ref
Constructor

param: string $module which module is using curl_cache

get($param)   X-Ref
Get cached value

param: mixed $param
return: bool|string

set($param, $val)   X-Ref
Set cache value

param: mixed $param
param: mixed $val

cleanup($expire)   X-Ref
Remove cache files

param: int $expire The number of seconds before expiry

refresh()   X-Ref
delete current user's cache file


file_pluginfile($relativepath, $forcedownload, $preview = null, $offline = false, $embed = false)   X-Ref
This function delegates file serving to individual plugins

param: string $relativepath
param: bool $forcedownload
param: null|string $preview the preview mode, defaults to serving the original file
param: boolean $offline If offline is requested - don't serve a redirect to an external file, return a file suitable for viewing
param: bool $embed Whether this file will be served embed into an iframe.

Functions that are not part of a class:

file_encode_url($urlbase, $path, $forcedownload=false, $https=false)   X-Ref
Encodes file serving url

param: string $urlbase
param: string $path /filearea/itemid/dir/dir/file.exe
param: bool $forcedownload
param: bool $https https url required
return: string encoded file url

file_area_contains_subdirs(context $context, $component, $filearea, $itemid)   X-Ref
Detects if area contains subdirs,
this is intended for file areas that are attached to content
migrated from 1.x where subdirs were allowed everywhere.

param: context $context
param: string $component
param: string $filearea
param: string $itemid
return: bool

file_prepare_standard_editor($data, $field, array $options, $context=null, $component=null, $filearea=null, $itemid=null)   X-Ref
Prepares 'editor' formslib element from data in database

The passed $data record must contain field foobar, foobarformat and optionally foobartrust. This
function then copies the embedded files into draft area (assigning itemids automatically),
creates the form element foobar_editor and rewrites the URLs so the embedded images can be
displayed.
In your mform definition, you must have an 'editor' element called foobar_editor. Then you call
your mform's set_data() supplying the object returned by this function.

param: stdClass $data database field that holds the html text with embedded media
param: string $field the name of the database field that holds the html text with embedded media
param: array $options editor options (like maxifiles, maxbytes etc.)
param: stdClass $context context of the editor
param: string $component
param: string $filearea file area name
param: int $itemid item id, required if item exists
return: stdClass modified data object

file_postupdate_standard_editor($data, $field, array $options, $context, $component=null, $filearea=null, $itemid=null)   X-Ref
Prepares the content of the 'editor' form element with embedded media files to be saved in database

This function moves files from draft area to the destination area and
encodes URLs to the draft files so they can be safely saved into DB. The
form has to contain the 'editor' element named foobar_editor, where 'foobar'
is the name of the database field to hold the wysiwyg editor content. The
editor data comes as an array with text, format and itemid properties. This
function automatically adds $data properties foobar, foobarformat and
foobartrust, where foobar has URL to embedded files encoded.

param: stdClass $data raw data submitted by the form
param: string $field name of the database field containing the html with embedded media files
param: array $options editor options (trusttext, subdirs, maxfiles, maxbytes etc.)
param: stdClass $context context, required for existing data
param: string $component file component
param: string $filearea file area name
param: int $itemid item id, required if item exists
return: stdClass modified data object

file_prepare_standard_filemanager($data, $field, array $options, $context=null, $component=null, $filearea=null, $itemid=null)   X-Ref
Saves text and files modified by Editor formslib element

param: stdClass $data $database entry field
param: string $field name of data field
param: array $options various options
param: stdClass $context context - must already exist
param: string $component
param: string $filearea file area name
param: int $itemid must already exist, usually means data is in db
return: stdClass modified data obejct

file_postupdate_standard_filemanager($data, $field, array $options, $context, $component, $filearea, $itemid)   X-Ref
Saves files modified by File manager formslib element

param: stdClass $data $database entry field
param: string $field name of data field
param: array $options various options
param: stdClass $context context - must already exist
param: string $component
param: string $filearea file area name
param: int $itemid must already exist, usually means data is in db
return: stdClass modified data obejct

file_get_unused_draft_itemid()   X-Ref
Generate a draft itemid

return: int a random but available draft itemid that can be used to create a new draft

file_prepare_draft_area(&$draftitemid, $contextid, $component, $filearea, $itemid, array $options=null, $text=null)   X-Ref
Initialise a draft file area from a real one by copying the files. A draft
area will be created if one does not already exist. Normally you should
get $draftitemid by calling file_get_submitted_draft_itemid('elementname');

param: int $draftitemid the id of the draft area to use, or 0 to create a new one, in which case this parameter is updated.
param: int $contextid This parameter and the next two identify the file area to copy files from.
param: string $component
param: string $filearea helps indentify the file area.
param: int $itemid helps identify the file area. Can be null if there are no files yet.
param: array $options text and file options ('subdirs'=>false, 'forcehttps'=>false)
param: string $text some html content that needs to have embedded links rewritten to point to the draft area.
return: string|null returns string if $text was passed in, the rewritten $text is returned. Otherwise NULL.

file_rewrite_pluginfile_urls($text, $file, $contextid, $component, $filearea, $itemid, array $options=null)   X-Ref
Convert encoded URLs in $text from the @@PLUGINFILE@@/... form to an actual URL.
Passing a new option reverse = true in the $options var will make the function to convert actual URLs in $text to encoded URLs
in the @@PLUGINFILE@@ form.

param: string  $text The content that may contain ULRs in need of rewriting.
param: string  $file The script that should be used to serve these files. pluginfile.php, draftfile.php, etc.
param: int     $contextid This parameter and the next two identify the file area to use.
param: string  $component
param: string  $filearea helps identify the file area.
param: int     $itemid helps identify the file area.
param: array   $options

file_get_draft_area_info($draftitemid, $filepath = '/')   X-Ref
Returns information about files in a draft area.

param: int $draftitemid the draft area item id.
param: string $filepath path to the directory from which the information have to be retrieved.
return: array with the following entries:

file_get_file_area_info($contextid, $component, $filearea, $itemid = 0, $filepath = '/')   X-Ref
Returns information about files in an area.

param: int $contextid context id
param: string $component component
param: string $filearea file area name
param: int $itemid item id or all files if not specified
param: string $filepath path to the directory from which the information have to be retrieved.
return: array with the following entries:

file_is_draft_area_limit_reached($draftitemid, $areamaxbytes, $newfilesize = 0, $includereferences = false)   X-Ref
Returns whether a draft area has exceeded/will exceed its size limit.

Please note that the unlimited value for $areamaxbytes is -1 {@link FILE_AREA_MAX_BYTES_UNLIMITED}, not 0.

param: int $draftitemid the draft area item id.
param: int $areamaxbytes the maximum size allowed in this draft area.
param: int $newfilesize the size that would be added to the current area.
param: bool $includereferences true to include the size of the references in the area size.
return: bool true if the area will/has exceeded its limit.

file_is_draft_areas_limit_reached(int $userid)   X-Ref
Returns whether a user has reached their draft area upload rate.

param: int $userid The user id
return: bool

file_get_user_used_space()   X-Ref
Get used space of files

return: int total bytes

file_correct_filepath($str)   X-Ref
Convert any string to a valid filepath

param: string $str
return: string path

file_get_drafarea_folders($draftitemid, $filepath, &$data)   X-Ref
Generate a folder tree of draft area of current USER recursively

param: int $draftitemid
param: string $filepath
param: mixed $data

file_get_drafarea_files($draftitemid, $filepath = '/')   X-Ref
Listing all files (including folders) in current path (draft area)
used by file manager

param: int $draftitemid
param: string $filepath
return: stdClass

file_get_all_files_in_draftarea(int $draftitemid, string $filepath = '/')   X-Ref
Returns all of the files in the draftarea.

param: int $draftitemid The draft item ID
param: string $filepath path for the uploaded files.
return: array An array of files associated with this draft item id.

file_get_submitted_draft_itemid($elname)   X-Ref
Returns draft area itemid for a given element.

param: string $elname name of formlib editor element, or a hidden form field that stores the draft area item id, etc.
return: int the itemid, or 0 if there is not one yet.

file_restore_source_field_from_draft_file($storedfile)   X-Ref
Restore the original source field from draft files

Do not use this function because it makes field files.source inconsistent
for draft area files. This function will be deprecated in 2.6

param: stored_file $storedfile This only works with draft files
return: stored_file

file_remove_editor_orphaned_files($editor)   X-Ref
Removes those files from the user drafts filearea which are not referenced in the editor text.

param: stdClass $editor The online text editor element from the submitted form data.

file_merge_draft_areas($draftitemid, $usercontextid, $text, $forcehttps = false)   X-Ref
Finds all draft areas used in a textarea and copies the files into the primary textarea. If a user copies and pastes
content from another draft area it's possible for a single textarea to reference multiple draft areas.

param: int $draftitemid the id of the primary draft area.
param: int $usercontextid the user's context id.
param: string $text some html content that needs to have files copied to the correct draft area.
param: bool $forcehttps force https urls.
return: string $text html content modified with new draft links

file_replace_file_area_in_text($file, $newid, $text, $forcehttps = false)   X-Ref
Rewrites a file area in arbitrary text.

param: array $file General information about the file.
param: int $newid The new file area itemid.
param: string $text The text to rewrite.
param: bool $forcehttps force https urls.
return: string The rewritten text.

file_copy_file_to_file_area($file, $filename, $itemid)   X-Ref
Copies a file from one file area to another.

param: array $file Information about the file to be copied.
param: string $filename The filename.
param: int $itemid The new file area.

file_save_draft_area_files($draftitemid, $contextid, $component, $filearea, $itemid, array $options=null, $text=null, $forcehttps=false)   X-Ref
Saves files from a draft file area to a real one (merging the list of files).
Can rewrite URLs in some content at the same time if desired.

param: int $draftitemid the id of the draft area to use. Normally obtained
param: int $contextid This parameter and the next two identify the file area to save to.
param: string $component
param: string $filearea indentifies the file area.
param: int $itemid helps identifies the file area.
param: array $options area options (subdirs=>false, maxfiles=-1, maxbytes=0)
param: string $text some html content that needs to have embedded links rewritten
param: bool $forcehttps force https urls.
return: string|null if $text was passed in, the rewritten $text is returned. Otherwise NULL.

file_rewrite_urls_to_pluginfile($text, $draftitemid, $forcehttps = false)   X-Ref
Convert the draft file area URLs in some content to @@PLUGINFILE@@ tokens
ready to be saved in the database. Normally, this is done automatically by
{@link file_save_draft_area_files()}.

param: string $text the content to process.
param: int $draftitemid the draft file area the content was using.
param: bool $forcehttps whether the content contains https URLs. Default false.
return: string the processed content.

file_set_sortorder($contextid, $component, $filearea, $itemid, $filepath, $filename, $sortorder)   X-Ref
Set file sort order

param: int $contextid the context id
param: string $component file component
param: string $filearea file area.
param: int $itemid itemid.
param: string $filepath file path.
param: string $filename file name.
param: int $sortorder the sort order of file.
return: bool

file_reset_sortorder($contextid, $component, $filearea, $itemid=false)   X-Ref
reset file sort order number to 0

param: int $contextid the context id
param: string $component
param: string $filearea file area.
param: int|bool $itemid itemid.
return: bool

file_get_upload_error($errorcode)   X-Ref
Returns description of upload error

param: int $errorcode found in $_FILES['filename.ext']['error']
return: string error description string, '' if ok

format_array_postdata_for_curlcall($arraydata, $currentdata, &$data)   X-Ref
Recursive function formating an array in POST parameter

param: array $arraydata - the array that we are going to format and add into &$data array
param: string $currentdata - a row of the final postdata array at instant T
param: array $data - the final data array containing all POST parameters : 1 row = 1 parameter

format_postdata_for_curlcall($postdata)   X-Ref
Transform a PHP array into POST parameter
(see the recursive function format_array_postdata_for_curlcall)

param: array $postdata
return: array containing all POST parameters  (1 row = 1 POST parameter)

download_file_content($url, $headers=null, $postdata=null, $fullresponse=false, $timeout=300, $connecttimeout=20, $skipcertverify=false, $tofile=NULL, $calctimeout=false)   X-Ref
Fetches content of file from Internet (using proxy if defined). Uses cURL extension if present.
Due to security concerns only downloads from http(s) sources are supported.

param: string $url file url starting with http(s)://
param: array $headers http headers, null if none. If set, should be an
param: array $postdata array means use POST request with given parameters
param: bool $fullresponse return headers, responses, etc in a similar way snoopy does
param: int $timeout timeout for complete download process including all file transfer
param: int $connecttimeout timeout for connection to server; this is the timeout that
param: bool $skipcertverify If true, the peer's SSL certificate will not be checked.
param: string $tofile store the downloaded content to file instead of returning it.
param: bool $calctimeout false by default, true enables an extra head request to try and determine
return: stdClass|string|bool stdClass object if $fullresponse is true, false if request failed, true

get_mimetypes_array()   X-Ref
Returns a list of information about file types based on extensions.

The following elements expected in value array for each extension:
'type' - mimetype
'icon' - location of the icon file. If value is FILENAME, then either pix/f/FILENAME.gif
or pix/f/FILENAME.png must be present in moodle and contain 16x16 filetype icon;
also files with bigger sizes under names
FILENAME-24, FILENAME-32, FILENAME-64, FILENAME-128, FILENAME-256 are recommended.
'groups' (optional) - array of filetype groups this filetype extension is part of;
commonly used in moodle the following groups:
- web_image - image that can be included as <img> in HTML
- image - image that we can parse using GD to find it's dimensions, also used for portfolio format
- optimised_image - image that will be processed and optimised
- video - file that can be imported as video in text editor
- audio - file that can be imported as audio in text editor
- archive - we can extract files from this archive
- spreadsheet - used for portfolio format
- document - used for portfolio format
- presentation - used for portfolio format
'string' (optional) - the name of the string from lang/en/mimetypes.php that displays
human-readable description for this filetype;
Function {@link get_mimetype_description()} first looks at the presence of string for
particular mimetype (value of 'type'), if not found looks for string specified in 'string'
attribute, if not found returns the value of 'type';
'defaulticon' (boolean, optional) - used by function {@link file_mimetype_icon()} to find
an icon for mimetype. If an entry with 'defaulticon' is not found for a particular mimetype,
this function will return first found icon; Especially usefull for types such as 'text/plain'

return: array List of information about file types based on extensions.

get_mimetype_for_sending($filename = '')   X-Ref
Determine a file's MIME type based on the given filename using the function mimeinfo.

This function retrieves a file's MIME type for a file that will be sent to the user.
This should only be used for file-sending purposes just like in send_stored_file, send_file, and send_temp_file.
Should the file's MIME type cannot be determined by mimeinfo, it will return 'application/octet-stream' as a default
MIME type which should tell the browser "I don't know what type of file this is, so just download it.".

param: string $filename The file's filename.
return: string The file's MIME type or 'application/octet-stream' if it cannot be determined.

mimeinfo($element, $filename)   X-Ref
Obtains information about a filetype based on its extension. Will
use a default if no information is present about that particular
extension.

param: string $element Desired information (usually 'icon'
param: string $filename Filename we're looking up
return: string Requested piece of information from array

mimeinfo_from_type($element, $mimetype)   X-Ref
Obtains information about a filetype based on the MIME type rather than
the other way around.

param: string $element Desired information ('extension', 'icon', 'icon-24', etc.)
param: string $mimetype MIME type we're looking up
return: string Requested piece of information from array

file_file_icon($file, $size = null)   X-Ref
Return the relative icon path for a given file

Usage:
<code>
// $file - instance of stored_file or file_info
$icon = $OUTPUT->image_url(file_file_icon($file))->out();
echo html_writer::empty_tag('img', array('src' => $icon, 'alt' => get_mimetype_description($file)));
</code>
or
<code>
echo $OUTPUT->pix_icon(file_file_icon($file), get_mimetype_description($file));
</code>

param: stored_file|file_info|stdClass|array $file (in case of object attributes $file->filename
param: int $size The size of the icon. Defaults to 16 can also be 24, 32, 64, 128, 256
return: string

file_folder_icon($iconsize = null)   X-Ref
Return the relative icon path for a folder image

Usage:
<code>
$icon = $OUTPUT->image_url(file_folder_icon())->out();
echo html_writer::empty_tag('img', array('src' => $icon));
</code>
or
<code>
echo $OUTPUT->pix_icon(file_folder_icon(32), '');
</code>

param: int $iconsize The size of the icon. Defaults to 16 can also be 24, 32, 48, 64, 72, 80, 96, 128, 256
return: string

file_mimetype_icon($mimetype, $size = NULL)   X-Ref
Returns the relative icon path for a given mime type

This function should be used in conjunction with $OUTPUT->image_url to produce
a return the full path to an icon.

<code>
$mimetype = 'image/jpg';
$icon = $OUTPUT->image_url(file_mimetype_icon($mimetype))->out();
echo html_writer::empty_tag('img', array('src' => $icon, 'alt' => get_mimetype_description($mimetype)));
</code>

param: string $mimetype The mimetype to fetch an icon for
param: int $size The size of the icon. Defaults to 16 can also be 24, 32, 64, 128, 256
return: string The relative path to the icon

file_extension_icon($filename, $size = NULL)   X-Ref
Returns the relative icon path for a given file name

This function should be used in conjunction with $OUTPUT->image_url to produce
a return the full path to an icon.

<code>
$filename = '.jpg';
$icon = $OUTPUT->image_url(file_extension_icon($filename))->out();
echo html_writer::empty_tag('img', array('src' => $icon, 'alt' => '...'));
</code>

param: string $filename The filename to get the icon for
param: int $size The size of the icon. Defaults to 16 can also be 24, 32, 64, 128, 256
return: string

get_mimetype_description($obj, $capitalise=false)   X-Ref
Obtains descriptions for file types (e.g. 'Microsoft Word document') from the
mimetypes.php language file.

param: mixed $obj - instance of stored_file or file_info or array/stdClass with field
param: bool $capitalise If true, capitalises first character of result
return: string Text description

file_get_typegroup($element, $groups)   X-Ref
Returns array of elements of type $element in type group(s)

param: string $element name of the element we are interested in, usually 'type' or 'extension'
param: string|array $groups one group or array of groups/extensions/mimetypes
return: array

file_extension_in_typegroup($filename, $groups, $checktype = false)   X-Ref
Checks if file with name $filename has one of the extensions in groups $groups

param: string $filename name of the file to check
param: string|array $groups one group or array of groups to check
param: bool $checktype if true and extension check fails, find the mimetype and check if
return: bool

file_mimetype_in_typegroup($mimetype, $groups)   X-Ref
Checks if mimetype $mimetype belongs to one of the groups $groups

param: string $mimetype
param: string|array $groups one group or array of groups to check
return: bool

send_file_not_found()   X-Ref
Requested file is not found or not accessible, does not return, terminates script


send_header_404()   X-Ref
Helper function to send correct 404 for server.


readfile_allow_large($path, $filesize = -1)   X-Ref
The readfile function can fail when files are larger than 2GB (even on 64-bit
platforms). This wrapper uses readfile for small files and custom code for
large ones.

param: string $path Path to file
param: int $filesize Size of file (if left out, will get it automatically)
return: int|bool Size read (will always be $filesize) or false if failed

readfile_accel($file, $mimetype, $accelerate)   X-Ref
Enhanced readfile() with optional acceleration.

param: string|stored_file $file
param: string $mimetype
param: bool $accelerate
return: void

readstring_accel($string, $mimetype, $accelerate = false)   X-Ref
Similar to readfile_accel() but designed for strings.

param: string $string
param: string $mimetype
param: bool $accelerate Ignored
return: void

send_temp_file($path, $filename, $pathisstring=false)   X-Ref
Handles the sending of temporary file to user, download is forced.
File is deleted after abort or successful sending, does not return, script terminated

param: string $path path to file, preferably from moodledata/temp/something; or content of file itself
param: string $filename proposed file name when saving file
param: bool $pathisstring If the path is string

send_temp_file_finished($path)   X-Ref
Internal callback function used by send_temp_file()

param: string $path

send_content_uncached($content, $filename)   X-Ref
Serve content which is not meant to be cached.

This is only intended to be used for volatile public files, for instance
when development is enabled, or when caching is not required on a public resource.

param: string $content Raw content.
param: string $filename The file name.
return: void

file_safe_save_content($content, $destination)   X-Ref
Safely save content to a certain path.

This function tries hard to be atomic by first copying the content
to a separate file, and then moving the file across. It also prevents
the user to abort a request to prevent half-safed files.

This function is intended to be used when saving some content to cache like
$CFG->localcachedir. If you're not caching a file you should use the File API.

param: string $content The file content.
param: string $destination The absolute path of the final file.
return: void

send_file($path, $filename, $lifetime = null , $filter=0, $pathisstring=false, $forcedownload=false, $mimetype='',$dontdie=false, array $options = array()   X-Ref
Handles the sending of file data to the user's browser, including support for
byteranges etc.

param: string|stored_file $path Path of file on disk (including real filename),
param: string $filename Filename to send
param: int $lifetime Number of seconds before the file should expire from caches (null means $CFG->filelifetime)
param: int $filter 0 (default)=no filtering, 1=all files, 2=html files only
param: bool $pathisstring If true (default false), $path is the content to send and not the pathname.
param: bool $forcedownload If true (default false), forces download of file rather than view in browser/plugin
param: string $mimetype Include to specify the MIME type; leave blank to have it guess the type from $filename
param: bool $dontdie - return control to caller afterwards. this is not recommended and only used for cleanup tasks.
param: array $options An array of options, currently accepts:
return: null script execution stopped unless $dontdie is true

send_stored_file($stored_file, $lifetime=null, $filter=0, $forcedownload=false, array $options=array()   X-Ref
Handles the sending of file data to the user's browser, including support for
byteranges etc.

The $options parameter supports the following keys:
(string|null) preview - send the preview of the file (e.g. "thumb" for a thumbnail)
(string|null) filename - overrides the implicit filename
(bool) dontdie - return control to caller afterwards. this is not recommended and only used for cleanup tasks.
if this is passed as true, ignore_user_abort is called.  if you don't want your processing to continue on cancel,
you must detect this case when control is returned using connection_aborted. Please not that session is closed
and should not be reopened
(string|null) cacheability - force the cacheability setting of the HTTP response, "private" or "public",
when $lifetime is greater than 0. Cacheability defaults to "private" when logged in as other than guest; otherwise,
defaults to "public".
(string|null) immutable - set the immutable cache setting in the HTTP response, when served under HTTPS.
Note: it's up to the consumer to set it properly i.e. when serving a "versioned" URL.

param: stored_file $stored_file local file object
param: int $lifetime Number of seconds before the file should expire from caches (null means $CFG->filelifetime)
param: int $filter 0 (default)=no filtering, 1=all files, 2=html files only
param: bool $forcedownload If true (default false), forces download of file rather than view in browser/plugin
param: array $options additional options affecting the file serving
return: null script execution stopped unless $options['dontdie'] is true

fulldelete($location)   X-Ref
Recursively delete the file or folder with path $location. That is,
if it is a file delete it. If it is a folder, delete all its content
then delete it. If $location does not exist to start, that is not
considered an error.

param: string $location the path to remove.
return: bool

byteserving_send_file($handle, $mimetype, $ranges, $filesize)   X-Ref
Send requested byterange of file.

param: resource $handle A file handle
param: string $mimetype The mimetype for the output
param: array $ranges An array of ranges to send
param: string $filesize The size of the content if only one range is used

file_is_executable($filename)   X-Ref
Tells whether the filename is executable.

param: string $filename Path to the file.
return: bool True if the filename exists and is executable; otherwise, false.

file_overwrite_existing_draftfile(stored_file $newfile, stored_file $existingfile)   X-Ref
Overwrite an existing file in a draft area.

param: stored_file $newfile      the new file with the new content and meta-data
param: stored_file $existingfile the file that will be overwritten

file_merge_files_from_draft_area_into_filearea($draftitemid, $contextid, $component, $filearea, $itemid,array $options = null)   X-Ref
Add files from a draft area into a final area.

Most of the time you do not want to use this. It is intended to be used
by asynchronous services which cannot direcly manipulate a final
area through a draft area. Instead they add files to a new draft
area and merge that new draft into the final area when ready.

param: int $draftitemid the id of the draft area to use.
param: int $contextid this parameter and the next two identify the file area to save to.
param: string $component component name
param: string $filearea indentifies the file area
param: int $itemid identifies the item id or false for all items in the file area
param: array $options area options (subdirs=false, maxfiles=-1, maxbytes=0, areamaxbytes=FILE_AREA_MAX_BYTES_UNLIMITED)

file_merge_draft_area_into_draft_area($getfromdraftid, $mergeintodraftid)   X-Ref
Merge files from two draftarea areas.

This does not handle conflict resolution, files in the destination area which appear
to be more recent will be kept disregarding the intended ones.

param: int $getfromdraftid the id of the draft area where are the files to merge.
param: int $mergeintodraftid the id of the draft area where new files will be merged.