/lib/filelib.php

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<?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
 * @subpackage file
 * @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();

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

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
 *
 * @global object
 * @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;
}

/**
 * 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 object $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 object $context context of the editor
 * @param string $component
 * @param string $filearea file area name
 * @param int $itemid item id, required if item exists
 * @return object modified data object
 */
function file_prepare_standard_editor($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;
    }

    if (is_null($itemid) or is_null($context)) {
        $contextid = null;
        $itemid = null;
        if (!isset($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.
 *
 * @param object $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 object $context context, required for existing data
 * @param string component
 * @param string $filearea file area name
 * @param int $itemid item id, required if item exists
 * @return object modified data object
 */
function file_postupdate_standard_editor($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 ($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 {
        $data->{$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
 *
 * @param object $data $database entry field
 * @param string $field name of data field
 * @param array $options various options
 * @param object $context context - must already exist
 * @param string $component
 * @param string $filearea file area name
 * @param int $itemid must already exist, usually means data is in db
 * @return object modified data obejct
 */
function file_prepare_standard_filemanager($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
 *
 * @param object $data $database entry field
 * @param string $field name of data field
 * @param array $options various options
 * @param object $context context - must already exist
 * @param string $component
 * @param string $filearea file area name
 * @param int $itemid must already exist, usually means data is in db
 * @return object modified data obejct
 */
function file_postupdate_standard_filemanager($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;
}

/**
 *
 * @global object
 * @global object
 * @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 = get_context_instance(CONTEXT_USER, $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 $draftitemid by calling file_get_submitted_draft_itemid('elementname');
 *
 * @global object
 * @global object
 * @param int &$draftitemid the id of the draft area to use, or 0 to create a new one, in which case this parameter is updated.
 * @param integer $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 integer $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 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, $CFG;

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

    $usercontext = get_context_instance(CONTEXT_USER, $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;
                }
                $fs->create_file_from_storedfile($file_record, $file);
            }
        }
        if (!is_null($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->httpswwwroot/draftfile.php", "\"$CFG->httpswwwroot/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.
 *
 * @global object
 * @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 integer $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 integer $itemid helps identify the file area.
 * @param array $options text and file options ('forcehttps'=>false)
 * @return string the processed text.
 */
function file_rewrite_pluginfile_urls($text, $file, $contextid, $component, $filearea, $itemid, array $options=null) {
    global $CFG;

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

    if (!$CFG->slasharguments) {
        $file = $file . '?file=';
    }

    $baseurl = "$CFG->wwwroot/$file/$contextid/$component/$filearea/";

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

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

    return str_replace('@@PLUGINFILE@@/', $baseurl, $text);
}

/**
 * Returns information about files in a draft area.
 *
 * @global object
 * @global object
 * @param integer $draftitemid the draft area item id.
 * @return array with the following entries:
 *      'filecount' => number of files in the draft area.
 * (more information will be added as needed).
 */
function file_get_draft_area_info($draftitemid) {
    global $CFG, $USER;

    $usercontext = get_context_instance(CONTEXT_USER, $USER->id);
    $fs = get_file_storage();

    $results = array();

    // The number of files
    $draftfiles = $fs->get_area_files($usercontext->id, 'user', 'draft', $draftitemid, 'id', false);
    $results['filecount'] = count($draftfiles);
    $results['filesize'] = 0;
    foreach ($draftfiles as $file) {
        $results['filesize'] += $file->get_filesize();
    }

    return $results;
}

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

    $usercontext = get_context_instance(CONTEXT_USER, $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
 * @param string $str
 * @return string path
 */
function file_correct_filepath($str) { //TODO: what is this? (skodak)
    if ($str == '/' or empty($str)) {
        return '/';
    } else {
        return '/'.trim($str, './@#$ ').'/';
    }
}

/**
 * Generate a folder tree of draft area of current USER recursively
 * @param int $itemid
 * @param string $filepath
 * @param mixed $data //TODO: use normal return value instead, this does not fit the rest of api here (skodak)
 */
function file_get_drafarea_folders($draftitemid, $filepath, &$data) {
    global $USER, $OUTPUT, $CFG;
    $data->children = array();
    $context = get_context_instance(CONTEXT_USER, $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 $filepath
 * @return mixed
 */
function file_get_drafarea_files($draftitemid, $filepath = '/') {
    global $USER, $OUTPUT, $CFG;

    $context = get_context_instance(CONTEXT_USER, $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->filesize = $filesize ? display_size($filesize) : '';

            $icon = mimeinfo_from_type('icon', $file->get_mimetype());
            $item->icon = $OUTPUT->pix_url('f/' . $icon)->out();
            $item->sortorder = $file->get_sortorder();

            if ($icon == 'zip') {
                $item->type = 'zip';
            } else {
                $item->type = 'file';
            }

            if ($file->is_directory()) {
                $item->filesize = 0;
                $item->icon = $OUTPUT->pix_url('f/folder')->out();
                $item->type = 'folder';
                $foldername = explode('/', trim($item->filepath, '/'));
                $item->fullname = trim(array_pop($foldername), '/');
            } else {
                // do NOT use file browser here!
                $item->url = moodle_url::make_draftfile_url($draftitemid, $item->filepath, $item->filename)->out();
            }
            $list[] = $item;
        }
    }
    $data->itemid = $draftitemid;
    $data->list = $list;
    return $data;
}

/**
 * Returns draft area itemid for a given element.
 *
 * @param string $elname name of formlib editor element, or a hidden form field that stores the draft area item id, etc.
 * @return integer the itemid, or 0 if there is not one yet.
 */
function file_get_submitted_draft_itemid($elname) {
    $param = optional_param($elname, 0, PARAM_INT);
    if ($param) {
        require_sesskey();
    }
    if (is_array($param)) {
        if (!empty($param['itemid'])) {
            $param = $param['itemid'];
        } else {
            debugging('Missing itemid, maybe caused by unset maxfiles option', DEBUG_DEVELOPER);
            return false;
        }
    }
    return $param;
}

/**
 * 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.
 *
 * @global object
 * @global object
 * @param integer $draftitemid the id of the draft area to use. Normally obtained
 *      from file_get_submitted_draft_itemid('elementname') or similar.
 * @param integer $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 integer $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 boolean $forcehttps force https urls.
 * @return string 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;

    $usercontext = get_context_instance(CONTEXT_USER, $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'] = 0; // unlimited
    }

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

    if (count($draftfiles) < 2) {
        // means there are no files - one file means root dir only ;-)
        $fs->delete_area_files($contextid, $component, $filearea, $itemid);

    } else if (count($oldfiles) < 2) {
        $filecount = 0;
        // there were no files before - one file means root dir only ;-)
        $file_record = array('contextid'=>$contextid, 'component'=>$component, 'filearea'=>$filearea, 'itemid'=>$itemid);
        foreach ($draftfiles as $file) {
            if (!$options['subdirs']) {
                if ($file->get_filepath() !== '/' or $file->is_directory()) {
                    continue;
                }
            }
            if ($options['maxbytes'] and $options['maxbytes'] < $file->get_filesize()) {
                // oversized file - should not get here at all
                continue;
            }
            if ($options['maxfiles'] != -1 and $options['maxfiles'] <= $filecount) {
                // more files - should not get here at all
                break;
            }
            if (!$file->is_directory()) {
                $filecount++;
            }
            $fs->create_file_from_storedfile($file_record, $file);
        }

    } else {
        // 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
        $file_record = array('contextid'=>$contextid, 'component'=>$component, 'filearea'=>$filearea, 'itemid'=>$itemid, 'timemodified'=>time());

        $newhashes = array();
        foreach ($draftfiles as $file) {
            $newhash = $fs->get_pathname_hash($contextid, $component, $filearea, $itemid, $file->get_filepath(), $file->get_filename());
            $newhashes[$newhash] = $file;
        }
        $filecount = 0;
        foreach ($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];
            if ($oldfile->get_contenthash() != $newfile->get_contenthash() or $oldfile->get_sortorder() != $newfile->get_sortorder()
                or $oldfile->get_status() != $newfile->get_status() or $oldfile->get_license() != $newfile->get_license()
                or $oldfile->get_author() != $newfile->get_author() or $oldfile->get_source() != $newfile->get_source()) {
                // file was changed, use updated with new timemodified data
                $oldfile->delete();
                continue;
            }
            // unchanged file or directory - we keep it as is
            unset($newhashes[$oldhash]);
            if (!$oldfile->is_directory()) {
                $filecount++;
            }
        }

        // now add new/changed files
        // the size and subdirectory tests are extra safety only, the UI should prevent it
        foreach ($newhashes as $file) {
            if (!$options['subdirs']) {
                if ($file->get_filepath() !== '/' or $file->is_directory()) {
                    continue;
                }
            }
            if ($options['maxbytes'] and $options['maxbytes'] < $file->get_filesize()) {
                // oversized file - should not get here at all
                continue;
            }
            if ($options['maxfiles'] != -1 and $options['maxfiles'] <= $filecount) {
                // more files - should not get here at all
                break;
            }
            if (!$file->is_directory()) {
                $filecount++;
            }
            $fs->create_file_from_storedfile($file_record, $file);
        }
    }

    // note: do not purge the draft area - we clean up areas later in cron,
    //       the reason is that user might press submit twice and they would loose the files,
    //       also sometimes we might want to use hacks that save files into two different areas

    if (is_null($text)) {
        return null;
    } else {
        return file_rewrite_urls_to_pluginfile($text, $draftitemid, $forcehttps);
    }
}

/**
 * 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 $forcehttps whether the content contains https URLs. Default false.
 * @return string the processed content.
 */
function file_rewrite_urls_to_pluginfile($text, $draftitemid, $forcehttps = false) {
    global $CFG, $USER;

    $usercontext = get_context_instance(CONTEXT_USER, $USER->id);

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

    // relink embedded files if text submitted - no absolute links allowed in database!
    $text = str_ireplace("$wwwroot/draftfile.php/$usercontext->id/user/draft/$draftitemid/", '@@PLUGINFILE@@/', $text);

    if (strpos($text, 'draftfile.php?file=') !== false) {
        $matches = array();
        preg_match_all("!$wwwroot/draftfile.php\?file=%2F{$usercontext->id}%2Fuser%2Fdraft%2F{$draftitemid}%2F[^'\",&<>|`\s:\\\\]+!iu", $text, $matches);
        if ($matches) {
            foreach ($matches[0] as $match) {
                $replace = str_ireplace('%2F', '/', $match);
                $text = str_replace($match, $replace, $text);
            }
        }
        $text = str_ireplace("$wwwroot/draftfile.php?file=/$usercontext->id/user/draft/$draftitemid/", '@@PLUGINFILE@@/', $text);
    }

    return $text;
}

/**
 * Set file sort order
 * @global object $DB
 * @param integer $contextid the context id
 * @param string $component
 * @param string $filearea file area.
 * @param integer $itemid itemid.
 * @param string $filepath file path.
 * @param string $filename file name.
 * @param integer $sortorer the sort order of file.
 * @return boolean
 */
function file_set_sortorder($contextid, $component, $filearea, $itemid, $filepath, $filename, $sortorder) {
    global $DB;
    $conditions = array('contextid'=>$contextid, 'component'=>$component, 'filearea'=>$filearea, 'itemid'=>$itemid, 'filepath'=>$filepath, 'filename'=>$filename);
    if ($file_record = $DB->get_record('files', $conditions)) {
        $sortorder = (int)$sortorder;
        $file_record->sortorder = $sortorder;
        $DB->update_record('files', $file_record);
        return true;
    }
    return false;
}

/**
 * reset file sort order number to 0
 * @global object $DB
 * @param integer $contextid the context id
 * @param string $component
 * @param string $filearea file area.
 * @param integer $itemid itemid.
 * @return boolean
 */
function file_reset_sortorder($contextid, $component, $filearea, $itemid=false) {
    global $DB;

    $conditions = array('contextid'=>$contextid, 'component'=>$component, 'filearea'=>$filearea);
    if ($itemid !== false) {
        $conditions['itemid'] = $itemid;
    }

    $file_records = $DB->get_records('files', $conditions);
    foreach ($file_records as $file_record) {
        $file_record->sortorder = 0;
        $DB->update_record('files', $file_record);
    }
    return true;
}

/**
 * Returns description of upload error
 *
 * @param int $errorcode found in $_FILES['filename.ext']['error']
 * @return string error description string, '' if ok
 */
function file_get_upload_error($errorcode) {

    switch ($errorcode) {
    case 0: // UPLOAD_ERR_OK - no error
        $errmessage = '';
        break;

    case 1: // UPLOAD_ERR_INI_SIZE
        $errmessage = get_string('uploadserverlimit');
        break;

    case 2: // UPLOAD_ERR_FORM_SIZE
        $errmessage = get_string('uploadformlimit');
        break;

    case 3: // UPLOAD_ERR_PARTIAL
        $errmessage = get_string('uploadpartialfile');
        break;

    case 4: // UPLOAD_ERR_NO_FILE
        $errmessage = get_string('uploadnofilefound');
        break;

    // Note: there is no error with a value of 5

    case 6: // UPLOAD_ERR_NO_TMP_DIR
        $errmessage = get_string('uploadnotempdir');
        break;

    case 7: // UPLOAD_ERR_CANT_WRITE
        $errmessage = get_string('uploadcantwrite');
        break;

    case 8: // UPLOAD_ERR_EXTENSION
        $errmessage = get_string('uploadextension');
        break;

    default:
        $errmessage = get_string('uploadproblem');
    }

    return $errmessage;
}

/**
 * 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
 *                when finish, it's assign to $data under this format: name[keyname][][]...[]='value'
 * @param array $data - the final data array containing all POST parameters : 1 row = 1 parameter
 */
function format_array_postdata_for_curlcall($arraydata, $currentdata, &$data) {
        foreach ($arraydata as $k=>$v) {
            $newcurrentdata = $currentdata;
            if (is_array($v)) { //the value is an array, call the function recursively
                $newcurrentdata = $newcurrentdata.'['.urlencode($k).']';
                format_array_postdata_for_curlcall($v, $newcurrentdata, $data);
            }  else { //add the POST parameter to the $data array
                $data[] = $newcurrentdata.'['.urlencode($k).']='.urlencode($v);
            }
        }
}

/**
 * Transform a PHP array into POST parameter
 * (see the recursive function format_array_postdata_for_curlcall)
 * @param array $postdata
 * @return array containing all POST parameters  (1 row = 1 POST parameter)
 */
function format_postdata_for_curlcall($postdata) {
        $data = array();
        foreach ($postdata as $k=>$v) {
            if (is_array($v)) {
                $currentdata = urlencode($k);
                format_array_postdata_for_curlcall($v, $currentdata, $data);
            }  else {
                $data[] = urlencode($k).'='.urlencode($v);
            }
        }
        $convertedpostdata = implode('&', $data);
        return $convertedpostdata;
}




/**
 * 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.
 *
 * @global object
 * @param string $url file url starting with http(s)://
 * @param array $headers http headers, null if none. If set, should be an
 *   associative array of header name => value pairs.
 * @param array $postdata array means use POST request with given parameters
 * @param bool $fullresponse return headers, responses, etc in a similar way snoopy does
 *   (if false, just returns content)
 * @param int $timeout timeout for complete download process including all file transfer
 *   (default 5 minutes)
 * @param int $connecttimeout timeout for connection to server; this is the timeout that
 *   usually happens if the remote server is completely down (default 20 seconds);
 *   may not work when using proxy
 * @param bool $skipcertverify If true, the peer's SSL certificate will not be checked. Only use this when already in a trusted location.
 * @param string $tofile store the downloaded content to file instead of returning it
 * @return mixed false if request failed or content of the file as string if ok. true if file downloaded into $tofile successfully.
 */
function download_file_content($url, $headers=null, $postdata=null, $fullresponse=false, $timeout=300, $connecttimeout=20, $skipcertverify=false, $tofile=NULL) {
    global $CFG;

    // some extra security
    $newlines = array("\r", "\n");
    if (is_array($headers) ) {
        foreach ($headers as $key => $value) {
            $headers[$key] = str_replace($newlines, '', $value);
        }
    }
    $url = str_replace($newlines, '', $url);
    if (!preg_match('|^https?://|i', $url)) {
        if ($fullresponse) {
            $response = new stdClass();
            $response->status        = 0;
            $response->headers       = array();
            $response->response_code = 'Invalid protocol specified in url';
            $response->results       = '';
            $response->error         = 'Invalid protocol specified in url';
            return $response;
        } else {
            return false;
        }
    }

    // check if proxy (if used) should be bypassed for this url
    $proxybypass = is_proxybypass($url);

    if (!$ch = curl_init($url)) {
        debugging('Can not init curl.');
        return false;
    }

    // set extra headers
    if (is_array($headers) ) {
        $headers2 = array();
        foreach ($headers as $key => $value) {
            $headers2[] = "$key: $value";
        }
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers2);
    }


    if ($skipcertverify) {
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    }

    // use POST if requested
    if (is_array($postdata)) {
        $postdata = format_postdata_for_curlcall($postdata);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $postdata);
    }

    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HEADER, false);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $connecttimeout);
    curl_setopt($ch, CURLOPT_TIMEOUT, $timeout);
    if (!ini_get('open_basedir') and !ini_get('safe_mode')) {
        // TODO: add version test for '7.10.5'
        curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
        curl_setopt($ch, CURLOPT_MAXREDIRS, 5);
    }

    if (!empty($CFG->proxyhost) and !$proxybypass) {
        // SOCKS supported in PHP5 only
        if (!empty($CFG->proxytype) and ($CFG->proxytype == 'SOCKS5')) {
            if (defined('CURLPROXY_SOCKS5')) {
                curl_setopt($ch, CURLOPT_PROXYTYPE, CURLPROXY_SOCKS5);
            } else {
                curl_close($ch);
                if ($fullresponse) {
                    $response = new stdClass();
                    $response->status        = '0';
                    $response->headers       = array();
                    $response->response_code = 'SOCKS5 proxy is not supported in PHP4';
                    $response->results       = '';
                    $response->error         = 'SOCKS5 proxy is not supported in PHP4';
                    return $response;
                } else {
                    debugging("SOCKS5 proxy is not supported in PHP4.", DEBUG_ALL);
                    return false;
                }
            }
        }

        curl_setopt($ch, CURLOPT_HTTPPROXYTUNNEL, false);

        if (empty($CFG->proxyport)) {
            curl_setopt($ch, CURLOPT_PROXY, $CFG->proxyhost);
        } else {
            curl_setopt($ch, CURLOPT_PROXY, $CFG->proxyhost.':'.$CFG->proxyport);
        }

        if (!empty($CFG->proxyuser) and !empty($CFG->proxypassword)) {
            curl_setopt($ch, CURLOPT_PROXYUSERPWD, $CFG->proxyuser.':'.$CFG->proxypassword);
            if (defined('CURLOPT_PROXYAUTH')) {
                // any proxy authentication if PHP 5.1
                curl_setopt($ch, CURLOPT_PROXYAUTH, CURLAUTH_BASIC | CURLAUTH_NTLM);
            }
        }
    }

    // set up header and content handlers
    $received = new stdClass();
    $received->headers = array(); // received headers array
    $received->tofile  = $tofile;
    $received->fh      = null;
    curl_setopt($ch, CURLOPT_HEADERFUNCTION, partial('download_file_content_header_handler', $received));
    if ($tofile) {
        curl_setopt($ch, CURLOPT_WRITEFUNCTION, partial('download_file_content_write_handler', $received));
    }

    $result = curl_exec($ch);

    // try to detect encoding problems
    if ((curl_errno($ch) == 23 or curl_errno($ch) == 61) and defined('CURLOPT_ENCODING')) {
        curl_setopt($ch, CURLOPT_ENCODING, 'none');
        $result = curl_exec($ch);
    }

    if ($received->fh) {
        fclose($received->fh);
    }

    if (curl_errno($ch)) {
        $error    = curl_error($ch);
        $error_no = curl_errno($ch);
        curl_close($ch);

        if ($fullresponse) {
            $response = new stdClass();
            if ($error_no == 28) {
                $response->status    = '-100'; // mimic snoopy
            } else {
                $response->status    = '0';
            }
            $response->headers       = array();
            $response->response_code = $error;
            $response->results       = false;
            $response->error         = $error;
            return $response;
        } else {
            debugging("cURL request for \"$url\" failed with: $error ($error_no)", DEBUG_ALL);
            return false;
        }

    } else {
        $info = curl_getinfo($ch);
        curl_close($ch);

        if (empty($info['http_code'])) {
            // for security reasons we support only true http connections (Location: file:// exploit prevention)
            $response = new stdClass();
            $response->status        = '0';
            $response->headers       = array();
            $response->response_code = 'Unknown cURL error';
            $response->results       = false; // do NOT change this, we really want to ignore the result!
            $response->error         = 'Unknown cURL error';

        } else {
            $response = new stdClass();;
            $response->status        = (string)$info['http_code'];
            $response->headers       = $received->headers;
            $response->response_code = $received->headers[0];
            $response->results       = $result;
            $response->error         = '';
        }

        if ($fullresponse) {
            return $response;
        } else if ($info['http_code'] != 200) {
            debugging("cURL request for \"$url\" failed, HTTP response code: ".$response->response_code, DEBUG_ALL);
            return false;
        } else {
            return $response->results;
        }
    }
}

/**
 * internal implementation
 */
function download_file_content_header_handler($received, $ch, $header) {
    $received->headers[] = $header;
    return strlen($header);
}

/**
 * internal implementation
 */
function download_file_content_write_handler($received, $ch, $data) {
    if (!$received->fh) {
        $received->fh = fopen($received->tofile, 'w');
        if ($received->fh === false) {
            // bad luck, file creation or overriding failed
            return 0;
        }
    }
    if (fwrite($received->fh, $data) === false) {
        // bad luck, write failed, let's abort completely
        return 0;
    }
    return strlen($data);
}

/**
 * @return array List of information about file types based on extensions.
 *   Associative array of extension (lower-case) to associative array
 *   from 'element name' to data. Current element names are 'type' and 'icon'.
 *   Unknown types should use the 'xxx' entry which includes defaults.
 */
function get_mimetypes_array() {
    static $mimearray = array (
        'xxx'  => array ('type'=>'document/unknown', 'icon'=>'unknown'),
        '3gp'  => array ('type'=>'video/quicktime', 'icon'=>'video'),
        'aac'  => array ('type'=>'audio/aac', 'icon'=>'audio'),
        'ai'   => array ('type'=>'application/postscript', 'icon'=>'image'),
        'aif'  => array ('type'=>'audio/x-aiff', 'icon'=>'audio'),
        'aiff' => array ('type'=>'audio/x-aiff', 'icon'=>'audio'),
        'aifc' => array ('type'=>'audio/x-aiff', 'icon'=>'audio'),
        'applescript'  => array ('type'=>'text/plain', 'icon'=>'text'),
        'asc'  => array ('type'=>'text/plain', 'icon'=>'text'),
        'asm'  => array ('type'=>'text/plain', 'icon'=>'text'),
        'au'   => array ('type'=>'audio/au', 'icon'=>'audio'),
        'avi'  => array ('type'=>'video/x-ms-wm', 'icon'=>'avi'),
        'bmp'  => array ('type'=>'image/bmp', 'icon'=>'image'),
        'c'    => array ('type'=>'text/plain', 'icon'=>'text'),
        'cct'  => array ('type'=>'shockwave/director', 'icon'=>'flash'),
        'cpp'  => array ('type'=>'text/plain', 'icon'=>'text'),
        'cs'   => array ('type'=>'application/x-csh', 'icon'=>'text'),
        'css'  => array ('type'=>'text/css', 'icon'=>'text'),
        'csv'  => array ('type'=>'text/csv', 'icon'=>'excel'),
        'dv'   => array ('type'=>'video/x-dv', 'icon'=>'video'),
        'dmg'  => array ('type'=>'application/octet-stream', 'icon'=>'dmg'),

        'doc'  => array ('type'=>'application/msword', 'icon'=>'word'),
        'docx' => array ('type'=>'application/vnd.openxmlformats-officedocument.wordprocessingml.document', 'icon'=>'docx'),
        'docm' => array ('type'=>'application/vnd.ms-word.document.macroEnabled.12', 'icon'=>'docm'),
        'dotx' => array ('type'=>'application/vnd.openxmlformats-officedocument.wordprocessingml.template', 'icon'=>'dotx'),
        'dotm' => array ('type'=>'application/vnd.ms-word.template.macroEnabled.12', 'icon'=>'dotm'),

        'dcr'  => array ('type'=>'application/x-director', 'icon'=>'flash'),
        'dif'  => array ('type'=>'video/x-dv', 'icon'=>'video'),
        'dir'  => array ('type'=>'application/x-director', 'icon'=>'flash'),
        'dxr'  => array ('type'=>'application/x-director', 'icon'=>'flash'),
        'eps'  => array ('type'=>'application/postscript', 'icon'=>'pdf'),
        'fdf'  => array ('type'=>'application/pdf', 'icon'=>'pdf'),
        'flv'  => array ('type'=>'video/x-flv', 'icon'=>'video'),
        'f4v'  => array ('type'=>'video/mp4', 'icon'=>'video'),
        'gif'  => array ('type'=>'image/gif', 'icon'=>'image'),
        'gtar' => array ('type'=>'application/x-gtar', 'icon'=>'zip'),
        'tgz'  => array ('type'=>'application/g-zip', 'icon'=>'zip'),
        'gz'   => array ('type'=>'application/g-zip', 'icon'=>'zip'),
        'gzip' => array ('type'=>'application/g-zip', 'icon'=>'zip'),
        'h'    => array ('type'=>'text/plain', 'icon'=>'text'),
        'hpp'  => array ('type'=>'text/plain', 'icon'=>'text'),
        'hqx'  => array ('type'=>'application/mac-binhex40', 'icon'=>'zip'),
        'htc'  => array ('type'=>'text/x-component', 'icon'=>'text'),
        'html' => array ('type'=>'text/html', 'icon'=>'html'),
        'xhtml'=> array ('type'=>'application/xhtml+xml', 'icon'=>'html'),
        'htm'  => array ('type'=>'text/html', 'icon'=>'html'),
        'ico'  => array ('type'=>'image/vnd.microsoft.icon', 'icon'=>'image'),
        'ics'  => array ('type'=>'text/calendar', 'icon'=>'text'),
        'isf'  => array ('type'=>'application/inspiration', 'icon'=>'isf'),
        'ist'  => array ('type'=>'application/inspiration.template', 'icon'=>'isf'),
        'java' => array ('type'=>'text/plain', 'icon'=>'text'),
        'jcb'  => array ('type'=>'text/xml', 'icon'=>'jcb'),
        'jcl'  => array ('type'=>'text/xml', 'icon'=>'jcl'),
        'jcw'  => array ('type'=>'text/xml', 'icon'=>'jcw'),
        'jmt'  => array ('type'=>'text/xml', 'icon'=>'jmt'),
        'jmx'  => array ('type'=>'text/xml', 'icon'=>'jmx'),
        'jpe'  => array ('type'=>'image/jpeg', 'icon'=>'image'),
        'jpeg' => array ('type'=>'image/jpeg', 'icon'=>'image'),
        'jpg'  => array ('type'=>'image/jpeg', 'icon'=>'image'),
        'jqz'  => array ('type'=>'text/xml', 'icon'=>'jqz'),
        'js'   => array ('type'=>'application/x-javascript', 'icon'=>'text'),
        'latex'=> array ('type'=>'application/x-latex', 'icon'=>'text'),
        'm'    => array ('type'=>'text/plain', 'icon'=>'text'),
        'mbz'  => array ('type'=>'application/vnd.moodle.backup', 'icon'=>'moodle'),
        'mov'  => array ('type'=>'video/quicktime', 'icon'=>'video'),
        'movie'=> array ('type'=>'video/x-sgi-movie', 'icon'=>'video'),
        'm3u'  => array ('type'=>'audio/x-mpegurl', 'icon'=>'audio'),
        'mp3'  => array ('type'=>'audio/mp3', 'icon'=>'audio'),
        'mp4'  => array ('type'=>'video/mp4', 'icon'=>'video'),
        'm4v'  => array ('type'=>'video/mp4', 'icon'=>'video'),
        'm4a'  => array ('type'=>'audio/mp4', 'icon'=>'audio'),
        'mpeg' => array ('type'=>'video/mpeg', 'icon'=>'video'),
        'mpe'  => array ('type'=>'video/mpeg', 'icon'=>'video'),
        'mpg'  => array ('type'=>'video/mpeg', 'icon'=>'video'),

        'odt'  => array ('type'=>'application/vnd.oasis.opendocument.text', 'icon'=>'odt'),
        'ott'  => array ('type'=>'application/vnd.oasis.opendocument.text-template', 'icon'=>'odt'),
        'oth'  => array ('type'=>'application/vnd.oasis.opendocument.text-web', 'icon'=>'odt'),
        'odm'  => array ('type'=>'application/vnd.oasis.opendocument.text-master', 'icon'=>'odm'),
        'odg'  => array ('type'=>'application/vnd.oasis.opendocument.graphics', 'icon'=>'odg'),
        'otg'  => array ('type'=>'application/vnd.oasis.opendocument.graphics-template', 'icon'=>'odg'),
        'odp'  => array ('type'=>'application/vnd.oasis.opendocument.presentation', 'icon'=>'odp'),
        'otp'  => array ('type'=>'application/vnd.oasis.opendocument.presentation-template', 'icon'=>'odp'),
        'ods'  => array ('type'=>'application/vnd.oasis.opendocument.spreadsheet', 'icon'=>'ods'),
        'ots'  => array ('type'=>'application/vnd.oasis.opendocument.spreadsheet-template', 'icon'=>'ods'),
        'odc'  => array ('type'=>'application/vnd.oasis.opendocument.chart', 'icon'=>'odc'),
        'odf'  => array ('type'=>'application/vnd.oasis.opendocument.formula', 'icon'=>'odf'),
        'odb'  => array ('type'=>'application/vnd.oasis.opendocument.database', 'icon'=>'odb'),
        'odi'  => array ('type'=>'application/vnd.oasis.opendocument.image', 'icon'=>'odi'),
        'oga'  => array ('type'=>'audio/ogg', 'icon'=>'audio'),
        'ogg'  => array ('type'=>'audio/ogg', 'icon'=>'audio'),
        'ogv'  => array ('type'=>'video/ogg', 'icon'=>'video'),

        'pct'  => array ('type'=>'image/pict', 'icon'=>'image'),
        'pdf'  => array ('type'=>'application/pdf', 'icon'=>'pdf'),
        'php'  => array ('type'=>'text/plain', 'icon'=>'text'),
        'pic'  => array ('type'=>'image/pict', 'icon'=>'image'),
        'pict' => array ('type'=>'image/pict', 'icon'=>'image'),
        'png'  => array ('type'=>'image/png', 'icon'=>'image'),

        'pps'  => array ('type'=>'application/vnd.ms-powerpoint', 'icon'=>'powerpoint'),
        'ppt'  => array ('type'=>'application/vnd.ms-powerpoint', 'icon'=>'powerpoint'),
        'pptx' => array ('type'=>'application/vnd.openxmlformats-officedocument.presentationml.presentation', 'icon'=>'pptx'),
        'pptm' => array ('type'=>'application/vnd.ms-powerpoint.presentation.macroEnabled.12', 'icon'=>'pptm'),
        'potx' => array ('type'=>'application/vnd.openxmlformats-officedocument.presentationml.template', 'icon'=>'potx'),
        'potm' => array ('type'=>'application/vnd.ms-powerpoint.template.macroEnabled.12', 'icon'=>'potm'),
       …