/lib/filelib.php

Large files files are truncated, but you can click here to view the full file

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Functions for file handling.
 *
 * @package   core_files
 * @copyright 1999 onwards Martin Dougiamas (http://dougiamas.com)
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

/**
 * BYTESERVING_BOUNDARY - string unique string constant.
 */
define('BYTESERVING_BOUNDARY', 's1k2o3d4a5k6s7');


/**
 * Do not process file merging when working with draft area files.
 */
define('IGNORE_FILE_MERGE', -1);

/**
 * Unlimited area size constant
 */
define('FILE_AREA_MAX_BYTES_UNLIMITED', -1);

/**
 * Capacity of the draft area bucket when using the leaking bucket technique to limit the draft upload rate.
 */
define('DRAFT_AREA_BUCKET_CAPACITY', 50);

/**
 * Leaking rate of the draft area bucket when using the leaking bucket technique to limit the draft upload rate.
 */
define('DRAFT_AREA_BUCKET_LEAK', 0.2);

require_once("$CFG->libdir/filestorage/file_exceptions.php");
require_once("$CFG->libdir/filestorage/file_storage.php");
require_once("$CFG->libdir/filestorage/zip_packer.php");
require_once("$CFG->libdir/filebrowser/file_browser.php");

/**
 * Encodes file serving url
 *
 * @deprecated use moodle_url factory methods instead
 *
 * @todo MDL-31071 deprecate this function
 * @global stdClass $CFG
 * @param string $urlbase
 * @param string $path /filearea/itemid/dir/dir/file.exe
 * @param bool $forcedownload
 * @param bool $https https url required
 * @return string encoded file url
 */
function file_encode_url($urlbase, $path, $forcedownload=false, $https=false) {
    global $CFG;

//TODO: deprecate this

    if ($CFG->slasharguments) {
        $parts = explode('/', $path);
        $parts = array_map('rawurlencode', $parts);
        $path  = implode('/', $parts);
        $return = $urlbase.$path;
        if ($forcedownload) {
            $return .= '?forcedownload=1';
        }
    } else {
        $path = rawurlencode($path);
        $return = $urlbase.'?file='.$path;
        if ($forcedownload) {
            $return .= '&amp;forcedownload=1';
        }
    }

    if ($https) {
        $return = str_replace('http://', 'https://', $return);
    }

    return $return;
}

/**
 * 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
 */
function file_area_contains_subdirs(context $context, $component, $filearea, $itemid) {
    global $DB;

    if (!isset($itemid)) {
        // Not initialised yet.
        return false;
    }

    // Detect if any directories are already present, this is necessary for content upgraded from 1.x.
    $select = "contextid = :contextid AND component = :component AND filearea = :filearea AND itemid = :itemid AND filepath <> '/' AND filename = '.'";
    $params = array('contextid'=>$context->id, 'component'=>$component, 'filearea'=>$filearea, 'itemid'=>$itemid);
    return $DB->record_exists_select('files', $select, $params);
}

/**
 * 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.
 *
 * @category files
 * @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 $itemid item id, required if item exists
 * @return stdClass modified data object
 */
function file_prepare_standard_editor($data, $field, array $options, $context=null, $component=null, $filearea=null, $itemid=null) {
    $options = (array)$options;
    if (!isset($options['trusttext'])) {
        $options['trusttext'] = false;
    }
    if (!isset($options['forcehttps'])) {
        $options['forcehttps'] = false;
    }
    if (!isset($options['subdirs'])) {
        $options['subdirs'] = false;
    }
    if (!isset($options['maxfiles'])) {
        $options['maxfiles'] = 0; // no files by default
    }
    if (!isset($options['noclean'])) {
        $options['noclean'] = false;
    }

    //sanity check for passed context. This function doesn't expect $option['context'] to be set
    //But this function is called before creating editor hence, this is one of the best places to check
    //if context is used properly. This check notify developer that they missed passing context to editor.
    if (isset($context) && !isset($options['context'])) {
        //if $context is not null then make sure $option['context'] is also set.
        debugging('Context for editor is not set in editoroptions. Hence editor will not respect editor filters', DEBUG_DEVELOPER);
    } else if (isset($options['context']) && isset($context)) {
        //If both are passed then they should be equal.
        if ($options['context']->id != $context->id) {
            $exceptionmsg = 'Editor context ['.$options['context']->id.'] is not equal to passed context ['.$context->id.']';
            throw new coding_exception($exceptionmsg);
        }
    }

    if (is_null($itemid) or is_null($context)) {
        $contextid = null;
        $itemid = null;
        if (!isset($data)) {
            $data = new stdClass();
        }
        if (!isset($data->{$field})) {
            $data->{$field} = '';
        }
        if (!isset($data->{$field.'format'})) {
            $data->{$field.'format'} = editors_get_preferred_format();
        }
        if (!$options['noclean']) {
            $data->{$field} = clean_text($data->{$field}, $data->{$field.'format'});
        }

    } else {
        if ($options['trusttext']) {
            // noclean ignored if trusttext enabled
            if (!isset($data->{$field.'trust'})) {
                $data->{$field.'trust'} = 0;
            }
            $data = trusttext_pre_edit($data, $field, $context);
        } else {
            if (!$options['noclean']) {
                $data->{$field} = clean_text($data->{$field}, $data->{$field.'format'});
            }
        }
        $contextid = $context->id;
    }

    if ($options['maxfiles'] != 0) {
        $draftid_editor = file_get_submitted_draft_itemid($field);
        $currenttext = file_prepare_draft_area($draftid_editor, $contextid, $component, $filearea, $itemid, $options, $data->{$field});
        $data->{$field.'_editor'} = array('text'=>$currenttext, 'format'=>$data->{$field.'format'}, 'itemid'=>$draftid_editor);
    } else {
        $data->{$field.'_editor'} = array('text'=>$data->{$field}, 'format'=>$data->{$field.'format'}, 'itemid'=>0);
    }

    return $data;
}

/**
 * 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.
 *
 * @category files
 * @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 $itemid item id, required if item exists
 * @return stdClass modified data object
 */
function file_postupdate_standard_editor($data, $field, array $options, $context, $component=null, $filearea=null, $itemid=null) {
    $options = (array)$options;
    if (!isset($options['trusttext'])) {
        $options['trusttext'] = false;
    }
    if (!isset($options['forcehttps'])) {
        $options['forcehttps'] = false;
    }
    if (!isset($options['subdirs'])) {
        $options['subdirs'] = false;
    }
    if (!isset($options['maxfiles'])) {
        $options['maxfiles'] = 0; // no files by default
    }
    if (!isset($options['maxbytes'])) {
        $options['maxbytes'] = 0; // unlimited
    }
    if (!isset($options['removeorphaneddrafts'])) {
        $options['removeorphaneddrafts'] = false; // Don't remove orphaned draft files by default.
    }

    if ($options['trusttext']) {
        $data->{$field.'trust'} = trusttext_trusted($context);
    } else {
        $data->{$field.'trust'} = 0;
    }

    $editor = $data->{$field.'_editor'};

    if ($options['maxfiles'] == 0 or is_null($filearea) or is_null($itemid) or empty($editor['itemid'])) {
        $data->{$field} = $editor['text'];
    } else {
        // Clean the user drafts area of any files not referenced in the editor text.
        if ($options['removeorphaneddrafts']) {
            file_remove_editor_orphaned_files($editor);
        }
        $data->{$field} = file_save_draft_area_files($editor['itemid'], $context->id, $component, $filearea, $itemid, $options, $editor['text'], $options['forcehttps']);
    }
    $data->{$field.'format'} = $editor['format'];

    return $data;
}

/**
 * Saves text and files modified by Editor formslib element
 *
 * @category files
 * @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 $itemid must already exist, usually means data is in db
 * @return stdClass modified data obejct
 */
function file_prepare_standard_filemanager($data, $field, array $options, $context=null, $component=null, $filearea=null, $itemid=null) {
    $options = (array)$options;
    if (!isset($options['subdirs'])) {
        $options['subdirs'] = false;
    }
    if (is_null($itemid) or is_null($context)) {
        $itemid = null;
        $contextid = null;
    } else {
        $contextid = $context->id;
    }

    $draftid_editor = file_get_submitted_draft_itemid($field.'_filemanager');
    file_prepare_draft_area($draftid_editor, $contextid, $component, $filearea, $itemid, $options);
    $data->{$field.'_filemanager'} = $draftid_editor;

    return $data;
}

/**
 * Saves files modified by File manager formslib element
 *
 * @todo MDL-31073 review this function
 * @category files
 * @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 $itemid must already exist, usually means data is in db
 * @return stdClass modified data obejct
 */
function file_postupdate_standard_filemanager($data, $field, array $options, $context, $component, $filearea, $itemid) {
    $options = (array)$options;
    if (!isset($options['subdirs'])) {
        $options['subdirs'] = false;
    }
    if (!isset($options['maxfiles'])) {
        $options['maxfiles'] = -1; // unlimited
    }
    if (!isset($options['maxbytes'])) {
        $options['maxbytes'] = 0; // unlimited
    }

    if (empty($data->{$field.'_filemanager'})) {
        $data->$field = '';

    } else {
        file_save_draft_area_files($data->{$field.'_filemanager'}, $context->id, $component, $filearea, $itemid, $options);
        $fs = get_file_storage();

        if ($fs->get_area_files($context->id, $component, $filearea, $itemid)) {
            $data->$field = '1'; // TODO: this is an ugly hack (skodak)
        } else {
            $data->$field = '';
        }
    }

    return $data;
}

/**
 * Generate a draft itemid
 *
 * @category files
 * @global moodle_database $DB
 * @global stdClass $USER
 * @return int a random but available draft itemid that can be used to create a new draft
 * file area.
 */
function file_get_unused_draft_itemid() {
    global $DB, $USER;

    if (isguestuser() or !isloggedin()) {
        // guests and not-logged-in users can not be allowed to upload anything!!!!!!
        print_error('noguest');
    }

    $contextid = context_user::instance($USER->id)->id;

    $fs = get_file_storage();
    $draftitemid = rand(1, 999999999);
    while ($files = $fs->get_area_files($contextid, 'user', 'draft', $draftitemid)) {
        $draftitemid = rand(1, 999999999);
    }

    return $draftitemid;
}

/**
 * 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');
 *
 * @category files
 * @global stdClass $CFG
 * @global stdClass $USER
 * @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 $text is returned. Otherwise NULL.
 */
function file_prepare_draft_area(&$draftitemid, $contextid, $component, $filearea, $itemid, array $options=null, $text=null) {
    global $CFG, $USER;

    $options = (array)$options;
    if (!isset($options['subdirs'])) {
        $options['subdirs'] = false;
    }
    if (!isset($options['forcehttps'])) {
        $options['forcehttps'] = false;
    }

    $usercontext = context_user::instance($USER->id);
    $fs = get_file_storage();

    if (empty($draftitemid)) {
        // create a new area and copy existing files into
        $draftitemid = file_get_unused_draft_itemid();
        $file_record = array('contextid'=>$usercontext->id, 'component'=>'user', 'filearea'=>'draft', 'itemid'=>$draftitemid);
        if (!is_null($itemid) and $files = $fs->get_area_files($contextid, $component, $filearea, $itemid)) {
            foreach ($files as $file) {
                if ($file->is_directory() and $file->get_filepath() === '/') {
                    // we need a way to mark the age of each draft area,
                    // by not copying the root dir we force it to be created automatically with current timestamp
                    continue;
                }
                if (!$options['subdirs'] and ($file->is_directory() or $file->get_filepath() !== '/')) {
                    continue;
                }
                $draftfile = $fs->create_file_from_storedfile($file_record, $file);
                // XXX: This is a hack for file manager (MDL-28666)
                // File manager needs to know the original file information before copying
                // to draft area, so we append these information in mdl_files.source field
                // {@link file_storage::search_references()}
                // {@link file_storage::search_references_count()}
                $sourcefield = $file->get_source();
                $newsourcefield = new stdClass;
                $newsourcefield->source = $sourcefield;
                $original = new stdClass;
                $original->contextid = $contextid;
                $original->component = $component;
                $original->filearea  = $filearea;
                $original->itemid    = $itemid;
                $original->filename  = $file->get_filename();
                $original->filepath  = $file->get_filepath();
                $newsourcefield->original = file_storage::pack_reference($original);
                $draftfile->set_source(serialize($newsourcefield));
                // End of file manager hack
            }
        }
        if (!is_null($text)) {
            // at this point there should not be any draftfile links yet,
            // because this is a new text from database that should still contain the @@pluginfile@@ links
            // this happens when developers forget to post process the text
            $text = str_replace("\"$CFG->wwwroot/draftfile.php", "\"$CFG->wwwroot/brokenfile.php#", $text);
        }
    } else {
        // nothing to do
    }

    if (is_null($text)) {
        return null;
    }

    // relink embedded files - editor can not handle @@PLUGINFILE@@ !
    return file_rewrite_pluginfile_urls($text, 'draftfile.php', $usercontext->id, 'user', 'draft', $draftitemid, $options);
}

/**
 * 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
 *          bool    $options.forcehttps Force the user of https
 *          bool    $options.reverse Reverse the behaviour of the function
 *          mixed   $options.includetoken Use a token for authentication. True for current user, int value for other user id.
 *          string  The processed text.
 */
function file_rewrite_pluginfile_urls($text, $file, $contextid, $component, $filearea, $itemid, array $options=null) {
    global $CFG, $USER;

    $options = (array)$options;
    if (!isset($options['forcehttps'])) {
        $options['forcehttps'] = false;
    }

    $baseurl = "{$CFG->wwwroot}/{$file}";
    if (!empty($options['includetoken'])) {
        $userid = $options['includetoken'] === true ? $USER->id : $options['includetoken'];
        $token = get_user_key('core_files', $userid);
        $finalfile = basename($file);
        $tokenfile = "token{$finalfile}";
        $file = substr($file, 0, strlen($file) - strlen($finalfile)) . $tokenfile;
        $baseurl = "{$CFG->wwwroot}/{$file}";

        if (!$CFG->slasharguments) {
            $baseurl .= "?token={$token}&file=";
        } else {
            $baseurl .= "/{$token}";
        }
    }

    $baseurl .= "/{$contextid}/{$component}/{$filearea}/";

    if ($itemid !== null) {
        $baseurl .= "$itemid/";
    }

    if ($options['forcehttps']) {
        $baseurl = str_replace('http://', 'https://', $baseurl);
    }

    if (!empty($options['reverse'])) {
        return str_replace($baseurl, '@@PLUGINFILE@@/', $text);
    } else {
        return str_replace('@@PLUGINFILE@@/', $baseurl, $text);
    }
}

/**
 * Returns information about files in a draft area.
 *
 * @global stdClass $CFG
 * @global stdClass $USER
 * @param int $draftitemid the draft area item id.
 * @param string $filepath path to the directory from which the information have to be retrieved.
 * @return array with the following entries:
 *      'filecount' => number of files in the draft area.
 *      'filesize' => total size of the files in the draft area.
 *      'foldercount' => number of folders in the draft area.
 *      'filesize_without_references' => total size of the area excluding file references.
 * (more information will be added as needed).
 */
function file_get_draft_area_info($draftitemid, $filepath = '/') {
    global $USER;

    $usercontext = context_user::instance($USER->id);
    return file_get_file_area_info($usercontext->id, 'user', 'draft', $draftitemid, $filepath);
}

/**
 * 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 $filepath path to the directory from which the information have to be retrieved.
 * @return array with the following entries:
 *      'filecount' => number of files in the area.
 *      'filesize' => total size of the files in the area.
 *      'foldercount' => number of folders in the area.
 *      'filesize_without_references' => total size of the area excluding file references.
 * @since Moodle 3.4
 */
function file_get_file_area_info($contextid, $component, $filearea, $itemid = 0, $filepath = '/') {

    $fs = get_file_storage();

    $results = array(
        'filecount' => 0,
        'foldercount' => 0,
        'filesize' => 0,
        'filesize_without_references' => 0
    );

    $draftfiles = $fs->get_directory_files($contextid, $component, $filearea, $itemid, $filepath, true, true);

    foreach ($draftfiles as $file) {
        if ($file->is_directory()) {
            $results['foldercount'] += 1;
        } else {
            $results['filecount'] += 1;
        }

        $filesize = $file->get_filesize();
        $results['filesize'] += $filesize;
        if (!$file->is_external_file()) {
            $results['filesize_without_references'] += $filesize;
        }
    }

    return $results;
}

/**
 * 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 $includereferences true to include the size of the references in the area size.
 * @return bool true if the area will/has exceeded its limit.
 * @since Moodle 2.4
 */
function file_is_draft_area_limit_reached($draftitemid, $areamaxbytes, $newfilesize = 0, $includereferences = false) {
    if ($areamaxbytes != FILE_AREA_MAX_BYTES_UNLIMITED) {
        $draftinfo = file_get_draft_area_info($draftitemid);
        $areasize = $draftinfo['filesize_without_references'];
        if ($includereferences) {
            $areasize = $draftinfo['filesize'];
        }
        if ($areasize + $newfilesize > $areamaxbytes) {
            return true;
        }
    }
    return false;
}

/**
 * Returns whether a user has reached their draft area upload rate.
 *
 * @param int $userid The user id
 * @return bool
 */
function file_is_draft_areas_limit_reached(int $userid): bool {
    global $CFG;

    $capacity = $CFG->draft_area_bucket_capacity ?? DRAFT_AREA_BUCKET_CAPACITY;
    $leak = $CFG->draft_area_bucket_leak ?? DRAFT_AREA_BUCKET_LEAK;

    $since = time() - floor($capacity / $leak); // The items that were in the bucket before this time are already leaked by now.
                                                // We are going to be a bit generous to the user when using the leaky bucket
                                                // algorithm below. We are going to assume that the bucket is empty at $since.
                                                // We have to do an assumption here unless we really want to get ALL user's draft
                                                // items without any limit and put all of them in the leaking bucket.
                                                // I decided to favour performance over accuracy here.

    $fs = get_file_storage();
    $items = $fs->get_user_draft_items($userid, $since);
    $items = array_reverse($items); // So that the items are sorted based on time in the ascending direction.

    // We only need to store the time that each element in the bucket is going to leak. So $bucket is array of leaking times.
    $bucket = [];
    foreach ($items as $item) {
        $now = $item->timemodified;
        // First let's see if items can be dropped from the bucket as a result of leakage.
        while (!empty($bucket) && ($now >= $bucket[0])) {
            array_shift($bucket);
        }

        // Calculate the time that the new item we put into the bucket will be leaked from it, and store it into the bucket.
        if ($bucket) {
            $bucket[] = max($bucket[count($bucket) - 1], $now) + (1 / $leak);
        } else {
            $bucket[] = $now + (1 / $leak);
        }
    }

    // Recalculate the bucket's content based on the leakage until now.
    $now = time();
    while (!empty($bucket) && ($now >= $bucket[0])) {
        array_shift($bucket);
    }

    return count($bucket) >= $capacity;
}

/**
 * Get used space of files
 * @global moodle_database $DB
 * @global stdClass $USER
 * @return int total bytes
 */
function file_get_user_used_space() {
    global $DB, $USER;

    $usercontext = context_user::instance($USER->id);
    $sql = "SELECT SUM(files1.filesize) AS totalbytes FROM {files} files1
            JOIN (SELECT contenthash, filename, MAX(id) AS id
            FROM {files}
            WHERE contextid = ? AND component = ? AND filearea != ?
            GROUP BY contenthash, filename) files2 ON files1.id = files2.id";
    $params = array('contextid'=>$usercontext->id, 'component'=>'user', 'filearea'=>'draft');
    $record = $DB->get_record_sql($sql, $params);
    return (int)$record->totalbytes;
}

/**
 * Convert any string to a valid filepath
 * @todo review this function
 * @param string $str
 * @return string path
 */
function file_correct_filepath($str) { //TODO: what is this? (skodak) - No idea (Fred)
    if ($str == '/' or empty($str)) {
        return '/';
    } else {
        return '/'.trim($str, '/').'/';
    }
}

/**
 * Generate a folder tree of draft area of current USER recursively
 *
 * @todo MDL-31073 use normal return value instead, this does not fit the rest of api here (skodak)
 * @param int $draftitemid
 * @param string $filepath
 * @param mixed $data
 */
function file_get_drafarea_folders($draftitemid, $filepath, &$data) {
    global $USER, $OUTPUT, $CFG;
    $data->children = array();
    $context = context_user::instance($USER->id);
    $fs = get_file_storage();
    if ($files = $fs->get_directory_files($context->id, 'user', 'draft', $draftitemid, $filepath, false)) {
        foreach ($files as $file) {
            if ($file->is_directory()) {
                $item = new stdClass();
                $item->sortorder = $file->get_sortorder();
                $item->filepath = $file->get_filepath();

                $foldername = explode('/', trim($item->filepath, '/'));
                $item->fullname = trim(array_pop($foldername), '/');

                $item->id = uniqid();
                file_get_drafarea_folders($draftitemid, $item->filepath, $item);
                $data->children[] = $item;
            } else {
                continue;
            }
        }
    }
}

/**
 * Listing all files (including folders) in current path (draft area)
 * used by file manager
 * @param int $draftitemid
 * @param string $filepath
 * @return stdClass
 */
function file_get_drafarea_files($draftitemid, $filepath = '/') {
    global $USER, $OUTPUT, $CFG;

    $context = context_user::instance($USER->id);
    $fs = get_file_storage();

    $data = new stdClass();
    $data->path = array();
    $data->path[] = array('name'=>get_string('files'), 'path'=>'/');

    // will be used to build breadcrumb
    $trail = '/';
    if ($filepath !== '/') {
        $filepath = file_correct_filepath($filepath);
        $parts = explode('/', $filepath);
        foreach ($parts as $part) {
            if ($part != '' && $part != null) {
                $trail .= ($part.'/');
                $data->path[] = array('name'=>$part, 'path'=>$trail);
            }
        }
    }

    $list = array();
    $maxlength = 12;
    if ($files = $fs->get_directory_files($context->id, 'user', 'draft', $draftitemid, $filepath, false)) {
        foreach ($files as $file) {
            $item = new stdClass();
            $item->filename = $file->get_filename();
            $item->filepath = $file->get_filepath();
            $item->fullname = trim($item->filename, '/');
            $filesize = $file->get_filesize();
            $item->size = $filesize ? $filesize : null;
            $item->filesize = $filesize ? display_size($filesize) : '';

            $item->sortorder = $file->get_sortorder();
            $item->author = $file->get_author();
            $item->license = $file->get_license();
            $item->datemodified = $file->get_timemodified();
            $item->datecreated = $file->get_timecreated();
            $item->isref = $file->is_external_file();
            if ($item->isref && $file->get_status() == 666) {
                $item->originalmissing = true;
            }
            // find the file this draft file was created from and count all references in local
            // system pointing to that file
            $source = @unserialize($file->get_source());
            if (isset($source->original)) {
                $item->refcount = $fs->search_references_count($source->original);
            }

            if ($file->is_directory()) {
                $item->filesize = 0;
                $item->icon = $OUTPUT->image_url(file_folder_icon(24))->out(false);
                $item->type = 'folder';
                $foldername = explode('/', trim($item->filepath, '/'));
                $item->fullname = trim(array_pop($foldername), '/');
                $item->thumbnail = $OUTPUT->image_url(file_folder_icon(90))->out(false);
            } else {
                // do NOT use file browser here!
                $item->mimetype = get_mimetype_description($file);
                if (file_extension_in_typegroup($file->get_filename(), 'archive')) {
                    $item->type = 'zip';
                } else {
                    $item->type = 'file';
                }
                $itemurl = moodle_url::make_draftfile_url($draftitemid, $item->filepath, $item->filename);
                $item->url = $itemurl->out();
                $item->icon = $OUTPUT->image_url(file_file_icon($file, 24))->out(false);
                $item->thumbnail = $OUTPUT->image_url(file_file_icon($file, 90))->out(false);

                // The call to $file->get_imageinfo() fails with an exception if the file can't be read on the file system.
                // We still want to add such files to the list, so the owner can view and delete them if needed. So, we only call
                // get_imageinfo() on files that can be read, and we also spoof the file status based on whether it was found.
                // We'll use the same status types used by stored_file->get_status(), where 0 = OK. 1 = problem, as these will be
                // used by the widget to display a warning about the problem files.
                // The value of stored_file->get_status(), and the file record are unaffected by this. It's only superficially set.
                $item->status = $fs->get_file_system()->is_file_readable_remotely_by_storedfile($file) ? 0 : 1;
                if ($item->status == 0) {
                    if ($imageinfo = $file->get_imageinfo()) {
                        $item->realthumbnail = $itemurl->out(false, array('preview' => 'thumb',
                            'oid' => $file->get_timemodified()));
                        $item->realicon = $itemurl->out(false, array('preview' => 'tinyicon', 'oid' => $file->get_timemodified()));
                        $item->image_width = $imageinfo['width'];
                        $item->image_height = $imageinfo['height'];
                    }
                }
            }
            $list[] = $item;
        }
    }
    $data->itemid = $draftitemid;
    $data->list = $list;
    return $data;
}

/**
 * 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.
 */
function file_get_all_files_in_draftarea(int $draftitemid, string $filepath = '/') : array {
    $files = [];
    $draftfiles = file_get_drafarea_files($draftitemid, $filepath);
    file_get_drafarea_folders($draftitemid, $filepath, $draftfiles);

    if (!empty($draftfiles)) {
        foreach ($draftfiles->list as $draftfile) {
            if ($draftfile->type == 'file') {
                $files[] = $draftfile;
            }
        }

        if (isset($draftfiles->children)) {
            foreach ($draftfiles->children as $draftfile) {
                $files = array_merge($files, file_get_all_files_in_draftarea($draftitemid, $draftfile->filepath));
            }
        }
    }
    return $files;
}

/**
 * Returns draft area itemid for a given element.
 *
 * @category files
 * @param string $elname name of formlib editor element, or a hidden form field that stores the draft area item id, etc.
 * @return int the itemid, or 0 if there is not one yet.
 */
function file_get_submitted_draft_itemid($elname) {
    // this is a nasty hack, ideally all new elements should use arrays here or there should be a new parameter
    if (!isset($_REQUEST[$elname])) {
        return 0;
    }
    if (is_array($_REQUEST[$elname])) {
        $param = optional_param_array($elname, 0, PARAM_INT);
        if (!empty($param['itemid'])) {
            $param = $param['itemid'];
        } else {
            debugging('Missing itemid, maybe caused by unset maxfiles option', DEBUG_DEVELOPER);
            return false;
        }

    } else {
        $param = optional_param($elname, 0, PARAM_INT);
    }

    if ($param) {
        require_sesskey();
    }

    return $param;
}

/**
 * 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 $storedfile This only works with draft files
 * @return stored_file
 */
function file_restore_source_field_from_draft_file($storedfile) {
    $source = @unserialize($storedfile->get_source());
    if (!empty($source)) {
        if (is_object($source)) {
            $restoredsource = $source->source;
            $storedfile->set_source($restoredsource);
        } else {
            throw new moodle_exception('invalidsourcefield', 'error');
        }
    }
    return $storedfile;
}

/**
 * Removes those files from the user drafts filearea which are not referenced in the editor text.
 *
 * @param stdClass $editor The online text editor element from the submitted form data.
 */
function file_remove_editor_orphaned_files($editor) {
    global $CFG, $USER;

    // Find those draft files included in the text, and generate their hashes.
    $context = context_user::instance($USER->id);
    $baseurl = $CFG->wwwroot . '/draftfile.php/' . $context->id . '/user/draft/' . $editor['itemid'] . '/';
    $pattern = "/" . preg_quote($baseurl, '/') . "(.+?)[\?\"']/";
    preg_match_all($pattern, $editor['text'], $matches);
    $usedfilehashes = [];
    foreach ($matches[1] as $matchedfilename) {
        $matchedfilename = urldecode($matchedfilename);
        $usedfilehashes[] = \file_storage::get_pathname_hash($context->id, 'user', 'draft', $editor['itemid'], '/',
                                                             $matchedfilename);
    }

    // Now, compare the hashes of all draft files, and remove those which don't match used files.
    $fs = get_file_storage();
    $files = $fs->get_area_files($context->id, 'user', 'draft', $editor['itemid'], 'id', false);
    foreach ($files as $file) {
        $tmphash = $file->get_pathnamehash();
        if (!in_array($tmphash, $usedfilehashes)) {
            $file->delete();
        }
    }
}

/**
 * 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.
 *
 * @category files
 * @param int $draftitemid the id of the primary draft area.
 *            When set to -1 (probably, by a WebService) it won't process file merging, keeping the original state of the file 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 $text html content modified with new draft links
 */
function file_merge_draft_areas($draftitemid, $usercontextid, $text, $forcehttps = false) {
    if (is_null($text)) {
        return null;
    }

    // Do not merge files, leave it as it was.
    if ($draftitemid === IGNORE_FILE_MERGE) {
        return null;
    }

    $urls = extract_draft_file_urls_from_text($text, $forcehttps, $usercontextid, 'user', 'draft');

    // No draft areas to rewrite.
    if (empty($urls)) {
        return $text;
    }

    foreach ($urls as $url) {
        // Do not process the "home" draft area.
        if ($url['itemid'] == $draftitemid) {
            continue;
        }

        // Decode the filename.
        $filename = urldecode($url['filename']);

        // Copy the file.
        file_copy_file_to_file_area($url, $filename, $draftitemid);

        // Rewrite draft area.
        $text = file_replace_file_area_in_text($url, $draftitemid, $text, $forcehttps);
    }
    return $text;
}

/**
 * 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 $forcehttps force https urls.
 * @return string The rewritten text.
 */
function file_replace_file_area_in_text($file, $newid, $text, $forcehttps = false) {
    global $CFG;

    $wwwroot = $CFG->wwwroot;
    if ($forcehttps) {
        $wwwroot = str_replace('http://', 'https://', $wwwroot);
    }

    $search = [
        $wwwroot,
        $file['urlbase'],
        $file['contextid'],
        $file['component'],
        $file['filearea'],
        $file['itemid'],
        $file['filename']
    ];
    $replace = [
        $wwwroot,
        $file['urlbase'],
        $file['contextid'],
        $file['component'],
        $file['filearea'],
        $newid,
        $file['filename']
    ];

    $text = str_ireplace( implode('/', $search), implode('/', $replace), $text);
    return $text;
}

/**
 * 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 $itemid The new file area.
 */
function file_copy_file_to_file_area($file, $filename, $itemid) {
    $fs = get_file_storage();

    // Load the current file in the old draft area.
    $fileinfo = array(
        'component' => $file['component'],
        'filearea' => $file['filearea'],
        'itemid' => $file['itemid'],
        'contextid' => $file['contextid'],
        'filepath' => '/',
        'filename' => $filename
    );
    $oldfile = $fs->get_file($fileinfo['contextid'], $fileinfo['component'], $fileinfo['filearea'],
        $fileinfo['itemid'], $fileinfo['filepath'], $fileinfo['filename']);
    $newfileinfo = array(
        'component' => $file['component'],
        'filearea' => $file['filearea'],
        'itemid' => $itemid,
        'contextid' => $file['contextid'],
        'filepath' => '/',
        'filename' => $filename
    );

    $newcontextid = $newfileinfo['contextid'];
    $newcomponent = $newfileinfo['component'];
    $newfilearea = $newfileinfo['filearea'];
    $newitemid = $newfileinfo['itemid'];
    $newfilepath = $newfileinfo['filepath'];
    $newfilename = $newfileinfo['filename'];

    // Check if the file exists.
    if (!$fs->file_exists($newcontextid, $newcomponent, $newfilearea, $newitemid, $newfilepath, $newfilename)) {
        $fs->create_file_from_storedfile($newfileinfo, $oldfile);
    }
}

/**
 * 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.
 *
 * @category files
 * @global stdClass $USER
 * @param int $draftitemid the id of the draft area to use. Normally obtained
 *      from file_get_submitted_draft_itemid('elementname') or similar.
 *      When set to -1 (probably, by a WebService) it won't process file merging, keeping the original state of the file area.
 * @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
 *      to the @@PLUGINFILE@@ form for saving in the database.
 * @param bool $forcehttps force https urls.
 * @return string|null if $text was passed in, the rewritten $text is returned. Otherwise NULL.
 */
function file_save_draft_area_files($draftitemid, $contextid, $component, $filearea, $itemid, array $options=null, $text=null, $forcehttps=false) {
    global $USER;

    // Do not merge files, leave it as it was.
    if ($draftitemid === IGNORE_FILE_MERGE) {
        // Safely return $text, no need to rewrite pluginfile because this is mostly comming from an external client like the app.
        return $text;
    }

    if ($itemid === false) {
        // Catch a potentially dangerous coding error.
        throw new coding_exception('file_save_draft_area_files was called with $itemid false. ' .
                "This suggests a bug, because it would wipe all ($contextid, $component, $filearea) files.");
    }

    $usercontext = context_user::instance($USER->id);
    $fs = get_file_storage();

    $options = (array)$options;
    if (!isset($options['subdirs'])) {
        $options['subdirs'] = false;
    }
    if (!isset($options['maxfiles'])) {
        $options['maxfiles'] = -1; // unlimited
    }
    if (!isset($options['maxbytes']) || $options['maxbytes'] == USER_CAN_IGNORE_FILE_SIZE_LIMITS) {
        $options['maxbytes'] = 0; // unlimited
    }
    if (!isset($options['areamaxbytes'])) {
        $options['areamaxbytes'] = FILE_AREA_MAX_BYTES_UNLIMITED; // Unlimited.
    }
    $allowreferences = true;
    if (isset($options['return_types']) && !($options['return_types'] & (FILE_REFERENCE | FILE_CONTROLLED_LINK))) {
        // we assume that if $options['return_types'] is NOT specified, we DO allow references.
        // this is not exactly right. BUT there are many places in code where filemanager options
        // are not passed to file_save_draft_area_files()
        $allowreferences = false;
    }

    // Check if the user has copy-pasted from other draft areas. Those files will be located in different draft
    // areas and need to be copied into the current draft area.
    $text = file_merge_draft_areas($draftitemid, $usercontext->id, $text, $forcehttps);

    // Check if the draft area has exceeded the authorised limit. This should never happen as validation
    // should have taken place before, unless the user is doing something nauthly. If so, let's just not save
    // anything at all in the next area.
    if (file_is_draft_area_limit_reached($draftitemid, $options['areamaxbytes'])) {
        return null;
    }

    $draftfiles = $fs->get_area_files($usercontext->id, 'user', 'draft', $draftitemid, 'id');
    $oldfiles   = $fs->get_area_files($contextid, $component, $filearea, $itemid, 'id');

    // One file in filearea means it is empty (it has only top-level directory '.').
    if (count($draftfiles) > 1 || count($oldfiles) > 1) {
        // we have to merge old and new files - we want to keep file ids for files that were not changed
        // we change time modified for all new and changed files, we keep time created as is

        $newhashes = array();
        $filecount = 0;
        $context = context::instance_by_id($contextid, MUST_EXIST);
        foreach ($draftfiles as $file) {
            if (!$options['subdirs'] && $file->get_filepath() !== '/') {
                continue;
            }
            if (!$allowreferences && $file->is_external_file()) {
                continue;
            }
            if (!$file->is_directory()) {
                // Check to see if this file was uploaded by someone who can ignore the file size limits.
                $fileusermaxbytes = get_user_max_upload_file_size($context, $options['maxbytes'], 0, 0, $file->get_userid());
                if ($fileusermaxbytes != USER_CAN_IGNORE_FILE_SIZE_LIMITS
                        && ($options['maxbytes'] and $options['maxbytes'] < $file->get_filesize())) {
                    // Oversized file.
                    continue;
                }
                if ($options['maxfiles'] != -1 and $options['maxfiles'] <= $filecount) {
                    // more files - should not get here at all
                    continue;
                }
                $filecount++;
            }
            $newhash = $fs->get_pathname_hash($contextid, $component, $filearea, $itemid, $file->get_filepath(), $file->get_filename());
            $newhashes[$newhash] = $file;
        }

        // Loop through oldfiles and decide which we need to delete and which to update.
        // After this cycle the array $newhashes will only contain the files that need to be added.
        foreach ($oldfiles as $oldfile) {
            $oldhash = $oldfile->get_pathnamehash();
            if (!isset($newhashes[$oldhash])) {
                // delete files not needed any more - deleted by user
                $oldfile->delete();
                continue;
            }

            $newfile = $newhashes[$oldhash];
            // Now we know that we have $oldfile and $newfile for the same path.
            // Let's check if we can update this file or we need to delete and create.
            if ($newfile->is_directory()) {
                // Directories are always ok to just update.
            } else if (($source = @unserialize($newfile->get_source())) && isset($source->original)) {
                // File has the 'original' - we need to update the file (it may even have not been changed at all).
                $original = file_storage::unpack_reference($source->original);
                if ($original['filename'] !== $oldfile->get_filename() || $original['filepath'] !== $oldfile->get_filepath()) {
                    // Very odd, original points to another file. Delete and create file.
                    $oldfile->delete();
                    continue;
                }
            } else {
                // The same file name but absence of 'original' means that file was deteled and uploaded again.
                // By deleting and creating new file we properly manage all existing references.
                $oldfile->delete();
                continue;
            }

            // status changed, we delete old file, and create a new one
            if ($oldfile->get_status() != $newfile->get_status()) {
                // file was changed, use updated with new timemodified data
                $oldfile->delete();
                // This file will be added later
                continue;
            }

            // Updated author
            if ($oldfile->get_author() != $newfile->get_author()) {
                $oldfile->set_author($newfile->get_author());
            }
            // Updated license
            if ($oldfile->get_license() != $newfile->get_license()) {
                $oldfile->set_license($newfile->get_license());
            }

            // Updated file source
            // Field files.source for draftarea files contains serialised object with source and original information.
            // We only store the source part of it for non-draft file area.
            $newsource = $newfile->get_source();
            if ($source = @unserialize($newfile->get_source())) {
                $newsource = $source->source;
            }
            if ($oldfile->get_source() !== $newsource) {
                $oldfile->set_source($newsource);
            }

            // Updated sort order
            if ($oldfile->get_sortorder() != $newfile->get_sortorder()) {
                $oldfile->set_sortorder($newfile->get_sortorder());
            }

            // Update file timemodified
            if ($oldfile->get_…