lib/componentlib.class.php

   1 <?php
   2
   3 // This file is part of Moodle - http://moodle.org/
   4 //
   5 // Moodle is free software: you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation, either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // Moodle is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 /**
  19  * This library includes all the necessary stuff to use the one-click
  20  * download and install feature of Moodle, used to keep updated some
  21  * items like languages, pear, enviroment... i.e, components.
  22  *
  23  * It has been developed harcoding some important limits that are
  24  * explained below:
  25  *    - It only can check, download and install items under moodledata.
  26  *    - Every downloadeable item must be one zip file.
  27  *    - The zip file root content must be 1 directory, i.e, everything
  28  *      is stored under 1 directory.
  29  *    - Zip file name and root directory must have the same name (but
  30  *      the .zip extension, of course).
  31  *    - Every .zip file must be defined in one .md5 file that will be
  32  *      stored in the same remote directory than the .zip file.
  33  *    - The name of such .md5 file is free, although it's recommended
  34  *      to use the same name than the .zip (that's the default
  35  *      assumption if no specified).
  36  *    - Every remote .md5 file will be a comma separated (CVS) file where each
  37  *      line will follow this format:
  38  *        - Field 1: name of the zip file (without extension). Mandatory.
  39  *        - Field 2: md5 of the zip file. Mandatory.
  40  *        - Field 3: whatever you want (or need). Optional.
  41  *    -Every local .md5 file will:
  42  *        - Have the zip file name (without the extension) plus -md5
  43  *        - Will reside inside the expanded zip file dir
  44  *        - Will contain the md5 od the latest installed component
  45  * With all these details present, the process will perform this tasks:
  46  *    - Perform security checks. Only admins are allowed to use this for now.
  47  *    - Read the .md5 file from source (1).
  48  *    - Extract the correct line for the .zip being requested.
  49  *    - Compare it with the local .md5 file (2).
  50  *    - If different:
  51  *        - Download the newer .zip file from source.
  52  *        - Calculate its md5 (3).
  53  *        - Compare (1) and (3).
  54  *        - If equal:
  55  *            - Delete old directory.
  56  *            - Uunzip the newer .zip file.
  57  *            - Create the new local .md5 file.
  58  *            - Delete the .zip file.
  59  *        - If different:
  60  *            - ERROR. Old package won't be modified. We shouldn't
  61  *              reach here ever.
  62  *    - If component download is not possible, a message text about how to do
  63  *      the process manually (remotedownloaderror) must be displayed to explain it.
  64  *
  65  * General Usage:
  66  *
  67  * To install one component:
  68  * <code>
  69  *     require_once($CFG->libdir.'/componentlib.class.php');
  70  *     if ($cd = new component_installer('https://download.moodle.org', 'langpack/2.0',
  71  *                                       'es.zip', 'languages.md5', 'lang')) {
  72  *         $status = $cd->install(); //returns COMPONENT_(ERROR | UPTODATE | INSTALLED)
  73  *         switch ($status) {
  74  *             case COMPONENT_ERROR:
  75  *                 if ($cd->get_error() == 'remotedownloaderror') {
  76  *                     $a = new stdClass();
  77  *                     $a->url = 'https://download.moodle.org/langpack/2.0/es.zip';
  78  *                     $a->dest= $CFG->dataroot.'/lang';
  79  *                     throw new \moodle_exception($cd->get_error(), 'error', '', $a);
  80  *                 } else {
  81  *                     throw new \moodle_exception($cd->get_error(), 'error');
  82  *                 }
  83  *                 break;
  84  *             case COMPONENT_UPTODATE:
  85  *                 //Print error string or whatever you want to do
  86  *                 break;
  87  *             case COMPONENT_INSTALLED:
  88  *                 //Print/do whatever you want
  89  *                 break;
  90  *             default:
  91  *                 //We shouldn't reach this point
  92  *         }
  93  *     } else {
  94  *         //We shouldn't reach this point
  95  *     }
  96  * </code>
  97  *
  98  * To switch of component (maintaining the rest of settings):
  99  * <code>
 100  *     $status = $cd->change_zip_file('en.zip'); //returns boolean false on error
 101  * </code>
 102  *
 103  * To retrieve all the components in one remote md5 file
 104  * <code>
 105  *     $components = $cd->get_all_components_md5();  //returns boolean false on error, array instead
 106  * </code>
 107  *
 108  * To check if current component needs to be updated
 109  * <code>
 110  *     $status = $cd->need_upgrade();  //returns COMPONENT_(ERROR | UPTODATE | NEEDUPDATE)
 111  * </code>
 112  *
 113  * To get the 3rd field of the md5 file (optional)
 114  * <code>
 115  *     $field = $cd->get_extra_md5_field();  //returns string (empty if not exists)
 116  * </code>
 117  *
 118  * For all the error situations the $cd->get_error() method should return always the key of the
 119  * error to be retrieved by one standard get_string() call against the error.php lang file.
 120  *
 121  * That's all!
 122  *
 123  * @package   core
 124  * @copyright (C) 2001-3001 Eloy Lafuente (stronk7) {@link http://contiento.com}
 125  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 126  */
 127
 128 defined('MOODLE_INTERNAL') || die();
 129
 130  /**
 131   * @global object $CFG
 132   * @name $CFG
 133   */
 134 global $CFG;
 135 require_once($CFG->libdir.'/filelib.php');
 136
 137 // Some needed constants
 138 define('COMPONENT_ERROR',           0);
 139 define('COMPONENT_UPTODATE',        1);
 140 define('COMPONENT_NEEDUPDATE',      2);
 141 define('COMPONENT_INSTALLED',       3);
 142
 143 /**
 144  * This class is used to check, download and install items from
 145  * download.moodle.org to the moodledata directory.
 146  *
 147  * It always return true/false in all their public methods to say if
 148  * execution has ended succesfuly or not. If there is any problem
 149  * its getError() method can be called, returning one error string
 150  * to be used with the standard get/print_string() functions.
 151  *
 152  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 153  * @package moodlecore
 154  */
 155 class component_installer {
 156     /**
 157      * @var string
 158      */
 159     var $sourcebase;   /// Full http URL, base for downloadable items
 160     var $zippath;      /// Relative path (from sourcebase) where the
 161                        /// downloadeable item resides.
 162     var $zipfilename;  /// Name of the .zip file to be downloaded
 163     var $md5filename;  /// Name of the .md5 file to be read
 164     var $componentname;/// Name of the component. Must be the zip name without
 165                        /// the extension. And it defines a lot of things:
 166                        /// the md5 line to search for, the default m5 file name
 167                        /// and the name of the root dir stored inside the zip file
 168     var $destpath;     /// Relative path (from moodledata) where the .zip
 169                        /// file will be expanded.
 170     var $errorstring;  /// Latest error produced. It will contain one lang string key.
 171     var $extramd5info; /// Contents of the optional third field in the .md5 file.
 172     var $requisitesok; /// Flag to see if requisites check has been passed ok.
 173     /**
 174      * @var array
 175      */
 176     var $cachedmd5components; /// Array of cached components to avoid to
 177                               /// download the same md5 file more than once per request.
 178
 179     /**
 180      * Standard constructor of the class. It will initialize all attributes.
 181      * without performing any check at all.
 182      *
 183      * @param string $sourcebase Full http URL, base for downloadeable items
 184      * @param string $zippath Relative path (from sourcebase) where the
 185      *               downloadeable item resides
 186      * @param string $zipfilename Name of the .zip file to be downloaded
 187      * @param string $md5filename Name of the .md5 file to be read (default '' = same
 188      *               than zipfilename)
 189      * @param string $destpath Relative path (from moodledata) where the .zip file will
 190      *               be expanded (default='' = moodledataitself)
 191      * @return object
 192      */
 193     public function __construct($sourcebase, $zippath, $zipfilename, $md5filename='', $destpath='') {
 194
 195         $this->sourcebase   = $sourcebase;
 196         $this->zippath      = $zippath;
 197         $this->zipfilename  = $zipfilename;
 198         $this->md5filename  = $md5filename;
 199         $this->componentname= '';
 200         $this->destpath     = $destpath;
 201         $this->errorstring  = '';
 202         $this->extramd5info = '';
 203         $this->requisitesok = false;
 204         $this->cachedmd5components = array();
 205
 206         $this->check_requisites();
 207     }
 208
 209     /**
 210      * Old syntax of class constructor. Deprecated in PHP7.
 211      *
 212      * @deprecated since Moodle 3.1
 213      */
 214     public function component_installer($sourcebase, $zippath, $zipfilename, $md5filename='', $destpath='') {
 215         debugging('Use of class name as constructor is deprecated', DEBUG_DEVELOPER);
 216         self::__construct($sourcebase, $zippath, $zipfilename, $md5filename, $destpath);
 217     }
 218
 219     /**
 220      * This function will check if everything is properly set to begin
 221      * one installation. Also, it will check for required settings
 222      * and will fill everything as needed.
 223      *
 224      * @global object
 225      * @return boolean true/false (plus detailed error in errorstring)
 226      */
 227     function check_requisites() {
 228         global $CFG;
 229
 230         $this->requisitesok = false;
 231
 232     /// Check that everything we need is present
 233         if (empty($this->sourcebase) || empty($this->zipfilename)) {
 234             $this->errorstring='missingrequiredfield';
 235             return false;
 236         }
 237     /// Check for correct sourcebase (this will be out in the future)
 238         if (!PHPUNIT_TEST and $this->sourcebase != 'https://download.moodle.org') {
 239             $this->errorstring='wrongsourcebase';
 240             return false;
 241         }
 242     /// Check the zip file is a correct one (by extension)
 243         if (stripos($this->zipfilename, '.zip') === false) {
 244             $this->errorstring='wrongzipfilename';
 245             return false;
 246         }
 247     /// Check that exists under dataroot
 248         if (!empty($this->destpath)) {
 249             if (!file_exists($CFG->dataroot.'/'.$this->destpath)) {
 250                 $this->errorstring='wrongdestpath';
 251                 return false;
 252             }
 253         }
 254     /// Calculate the componentname
 255         $pos = stripos($this->zipfilename, '.zip');
 256         $this->componentname = substr($this->zipfilename, 0, $pos);
 257     /// Calculate md5filename if it's empty
 258         if (empty($this->md5filename)) {
 259             $this->md5filename = $this->componentname.'.md5';
 260         }
 261     /// Set the requisites passed flag
 262         $this->requisitesok = true;
 263         return true;
 264     }
 265
 266     /**
 267      * This function will perform the full installation if needed, i.e.
 268      * compare md5 values, download, unzip, install and regenerate
 269      * local md5 file
 270      *
 271      * @uses COMPONENT_ERROR
 272      * @uses COMPONENT_UPTODATE
 273      * @uses COMPONENT_ERROR
 274      * @uses COMPONENT_INSTALLED
 275      * @return int COMPONENT_(ERROR | UPTODATE | INSTALLED)
 276      */
 277     public function install() {
 278         global $CFG;
 279
 280     /// Check requisites are passed
 281         if (!$this->requisitesok) {
 282             return COMPONENT_ERROR;
 283         }
 284     /// Confirm we need upgrade
 285         if ($this->need_upgrade() === COMPONENT_ERROR) {
 286             return COMPONENT_ERROR;
 287         } else if ($this->need_upgrade() === COMPONENT_UPTODATE) {
 288             $this->errorstring='componentisuptodate';
 289             return COMPONENT_UPTODATE;
 290         }
 291     /// Create temp directory if necesary
 292         if (!make_temp_directory('', false)) {
 293              $this->errorstring='cannotcreatetempdir';
 294              return COMPONENT_ERROR;
 295         }
 296     /// Download zip file and save it to temp
 297         if ($this->zippath) {
 298             $source = $this->sourcebase.'/'.$this->zippath.'/'.$this->zipfilename;
 299         } else {
 300             $source = $this->sourcebase.'/'.$this->zipfilename;
 301         }
 302
 303         $zipfile= $CFG->tempdir.'/'.$this->zipfilename;
 304
 305         $contents = download_file_content($source, null, null, true);
 306         if ($contents->results && (int) $contents->status === 200) {
 307             if ($file = fopen($zipfile, 'w')) {
 308                 if (!fwrite($file, $contents->results)) {
 309                     fclose($file);
 310                     $this->errorstring='cannotsavezipfile';
 311                     return COMPONENT_ERROR;
 312                 }
 313             } else {
 314                 $this->errorstring='cannotsavezipfile';
 315                 return COMPONENT_ERROR;
 316             }
 317             fclose($file);
 318         } else {
 319             $this->errorstring='cannotdownloadzipfile';
 320             return COMPONENT_ERROR;
 321         }
 322     /// Calculate its md5
 323         $new_md5 = md5($contents->results);
 324     /// Compare it with the remote md5 to check if we have the correct zip file
 325         if (!$remote_md5 = $this->get_component_md5()) {
 326             return COMPONENT_ERROR;
 327         }
 328         if ($new_md5 != $remote_md5) {
 329             $this->errorstring='downloadedfilecheckfailed';
 330             return COMPONENT_ERROR;
 331         }
 332
 333         // Move current revision to a safe place.
 334         $destinationdir = $CFG->dataroot . '/' . $this->destpath;
 335         $destinationcomponent = $destinationdir . '/' . $this->componentname;
 336         $destinationcomponentold = $destinationcomponent . '_old';
 337         @remove_dir($destinationcomponentold);     // Deleting a possible old version.
 338
 339         // Moving to a safe place.
 340         @rename($destinationcomponent, $destinationcomponentold);
 341
 342         // Unzip new version.
 343         $packer = get_file_packer('application/zip');
 344         $unzipsuccess = $packer->extract_to_pathname($zipfile, $destinationdir, null, null, true);
 345         if (!$unzipsuccess) {
 346             @remove_dir($destinationcomponent);
 347             @rename($destinationcomponentold, $destinationcomponent);
 348             $this->errorstring = 'cannotunzipfile';
 349             return COMPONENT_ERROR;
 350         }
 351
 352         // Delete old component version.
 353         @remove_dir($destinationcomponentold);
 354
 355         // Create local md5.
 356         if ($file = fopen($destinationcomponent.'/'.$this->componentname.'.md5', 'w')) {
 357             if (!fwrite($file, $new_md5)) {
 358                 fclose($file);
 359                 $this->errorstring='cannotsavemd5file';
 360                 return COMPONENT_ERROR;
 361             }
 362         } else  {
 363             $this->errorstring='cannotsavemd5file';
 364             return COMPONENT_ERROR;
 365         }
 366         fclose($file);
 367     /// Delete temp zip file
 368         @unlink($zipfile);
 369
 370         return COMPONENT_INSTALLED;
 371     }
 372
 373     /**
 374      * This function will detect if remote component needs to be installed
 375      * because it's different from the local one
 376      *
 377      * @uses COMPONENT_ERROR
 378      * @uses COMPONENT_UPTODATE
 379      * @uses COMPONENT_NEEDUPDATE
 380      * @return int COMPONENT_(ERROR | UPTODATE | NEEDUPDATE)
 381      */
 382     function need_upgrade() {
 383
 384     /// Check requisites are passed
 385         if (!$this->requisitesok) {
 386             return COMPONENT_ERROR;
 387         }
 388     /// Get local md5
 389         $local_md5 = $this->get_local_md5();
 390     /// Get remote md5
 391         if (!$remote_md5 = $this->get_component_md5()) {
 392             return COMPONENT_ERROR;
 393         }
 394     /// Return result
 395        if ($local_md5 == $remote_md5) {
 396            return COMPONENT_UPTODATE;
 397        } else {
 398            return COMPONENT_NEEDUPDATE;
 399        }
 400     }
 401
 402     /**
 403      * This function will change the zip file to install on the fly
 404      * to allow the class to process different components of the
 405      * same md5 file without intantiating more objects.
 406      *
 407      * @param string $newzipfilename New zip filename to process
 408      * @return boolean true/false
 409      */
 410     function change_zip_file($newzipfilename) {
 411
 412         $this->zipfilename = $newzipfilename;
 413         return $this->check_requisites();
 414     }
 415
 416     /**
 417      * This function will get the local md5 value of the installed
 418      * component.
 419      *
 420      * @global object
 421      * @return bool|string md5 of the local component (false on error)
 422      */
 423     function get_local_md5() {
 424         global $CFG;
 425
 426     /// Check requisites are passed
 427         if (!$this->requisitesok) {
 428             return false;
 429         }
 430
 431         $return_value = 'needtobeinstalled';   /// Fake value to force new installation
 432
 433     /// Calculate source to read
 434        $source = $CFG->dataroot.'/'.$this->destpath.'/'.$this->componentname.'/'.$this->componentname.'.md5';
 435     /// Read md5 value stored (if exists)
 436        if (file_exists($source)) {
 437            if ($temp = file_get_contents($source)) {
 438                $return_value = $temp;
 439            }
 440         }
 441         return $return_value;
 442     }
 443
 444     /**
 445      * This function will download the specified md5 file, looking for the
 446      * current componentname, returning its md5 field and storing extramd5info
 447      * if present. Also it caches results to cachedmd5components for better
 448      * performance in the same request.
 449      *
 450      * @return mixed md5 present in server (or false if error)
 451      */
 452     function get_component_md5() {
 453
 454     /// Check requisites are passed
 455         if (!$this->requisitesok) {
 456             return false;
 457         }
 458     /// Get all components of md5 file
 459         if (!$comp_arr = $this->get_all_components_md5()) {
 460             if (empty($this->errorstring)) {
 461                 $this->errorstring='cannotdownloadcomponents';
 462             }
 463             return false;
 464         }
 465     /// Search for the componentname component
 466         if (empty($comp_arr[$this->componentname]) || !$component = $comp_arr[$this->componentname]) {
 467              $this->errorstring='cannotfindcomponent';
 468              return false;
 469         }
 470     /// Check we have a valid md5
 471         if (empty($component[1]) || strlen($component[1]) != 32) {
 472             $this->errorstring='invalidmd5';
 473             return false;
 474         }
 475     /// Set the extramd5info field
 476         if (!empty($component[2])) {
 477             $this->extramd5info = $component[2];
 478         }
 479         return $component[1];
 480     }
 481
 482     /**
 483      * This function allows you to retrieve the complete array of components found in
 484      * the md5filename
 485      *
 486      * @return bool|array array of components in md5 file or false if error
 487      */
 488     function get_all_components_md5() {
 489
 490     /// Check requisites are passed
 491         if (!$this->requisitesok) {
 492             return false;
 493         }
 494
 495     /// Initialize components array
 496         $comp_arr = array();
 497
 498     /// Define and retrieve the full md5 file
 499         if ($this->zippath) {
 500             $source = $this->sourcebase.'/'.$this->zippath.'/'.$this->md5filename;
 501         } else {
 502             $source = $this->sourcebase.'/'.$this->md5filename;
 503         }
 504
 505     /// Check if we have downloaded the md5 file before (per request cache)
 506         if (!empty($this->cachedmd5components[$source])) {
 507             $comp_arr = $this->cachedmd5components[$source];
 508         } else {
 509         /// Not downloaded, let's do it now
 510             $availablecomponents = array();
 511
 512             $contents = download_file_content($source, null, null, true);
 513             if ($contents->results && (int) $contents->status === 200) {
 514             /// Split text into lines
 515                 $lines = preg_split('/\r?\n/', $contents->results);
 516             /// Each line will be one component
 517                 foreach($lines as $line) {
 518                     $availablecomponents[] = explode(',', $line);
 519                 }
 520             /// If no components have been found, return error
 521                 if (empty($availablecomponents)) {
 522                     $this->errorstring='cannotdownloadcomponents';
 523                     return false;
 524                 }
 525             /// Build an associative array of components for easily search
 526             /// applying trim to avoid linefeeds and other...
 527                 $comp_arr = array();
 528                 foreach ($availablecomponents as $component) {
 529                 /// Avoid sometimes empty lines
 530                     if (empty($component[0])) {
 531                         continue;
 532                     }
 533                     $component[0]=trim($component[0]);
 534                     if (!empty($component[1])) {
 535                         $component[1]=trim($component[1]);
 536                     }
 537                     if (!empty($component[2])) {
 538                         $component[2]=trim($component[2]);
 539                     }
 540                     $comp_arr[$component[0]] = $component;
 541                 }
 542             /// Cache components
 543                 $this->cachedmd5components[$source] = $comp_arr;
 544             } else {
 545             /// Return error
 546                 $this->errorstring='remotedownloaderror';
 547                 return false;
 548             }
 549         }
 550     /// If there is no commponents or erros found, error
 551         if (!empty($this->errorstring)) {
 552              return false;
 553
 554         } else if (empty($comp_arr)) {
 555              $this->errorstring='cannotdownloadcomponents';
 556              return false;
 557         }
 558         return $comp_arr;
 559     }
 560
 561     /**
 562      * This function returns the errorstring
 563      *
 564      * @return string the error string
 565      */
 566     function get_error() {
 567         return $this->errorstring;
 568     }
 569
 570     /** This function returns the extramd5 field (optional in md5 file)
 571      *
 572      * @return string the extramd5 field
 573      */
 574     function get_extra_md5_field() {
 575         return $this->extramd5info;
 576     }
 577
 578 } /// End of component_installer class
 579
 580
 581 /**
 582  * Language packs installer
 583  *
 584  * This class wraps the functionality provided by {@link component_installer}
 585  * and adds support for installing a set of language packs.
 586  *
 587  * Given an array of required language packs, this class fetches them all
 588  * and installs them. It detects eventual dependencies and installs
 589  * all parent languages, too.
 590  *
 591  * @copyright 2011 David Mudrak <david@moodle.com>
 592  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 593  */
 594 class lang_installer {
 595
 596     /** lang pack was successfully downloaded and deployed */
 597     const RESULT_INSTALLED      = 'installed';
 598     /** lang pack was up-to-date so no download was needed */
 599     const RESULT_UPTODATE       = 'uptodate';
 600     /** there was a problem with downloading the lang pack */
 601     const RESULT_DOWNLOADERROR  = 'downloaderror';
 602
 603     /** @var array of languages to install */
 604     protected $queue = array();
 605     /** @var string the code of language being currently installed */
 606     protected $current;
 607     /** @var array of languages already installed by this instance */
 608     protected $done = array();
 609     /** @var string this Moodle major version */
 610     protected $version;
 611
 612     /**
 613      * Prepare the installer
 614      *
 615      * @param string|array $langcode a code of the language to install
 616      */
 617     public function __construct($langcode = '') {
 618         global $CFG;
 619
 620         $this->set_queue($langcode);
 621         $this->version = moodle_major_version(true);
 622
 623         if (!empty($CFG->langotherroot) and $CFG->langotherroot !== $CFG->dataroot . '/lang') {
 624             debugging('The in-built language pack installer does not support alternative location ' .
 625                 'of languages root directory. You are supposed to install and update your language '.
 626                 'packs on your own.');
 627         }
 628     }
 629
 630     /**
 631      * Sets the queue of language packs to be installed
 632      *
 633      * @param string|array $langcodes language code like 'cs' or a list of them
 634      */
 635     public function set_queue($langcodes) {
 636         if (is_array($langcodes)) {
 637             $this->queue = $langcodes;
 638         } else if (!empty($langcodes)) {
 639             $this->queue = array($langcodes);
 640         }
 641     }
 642
 643     /**
 644      * Runs the installer
 645      *
 646      * This method calls {@link self::install_language_pack} for every language in the
 647      * queue. If a dependency is detected, the parent language is added to the queue.
 648      *
 649      * @return array results, array of self::RESULT_xxx constants indexed by language code
 650      */
 651     public function run() {
 652
 653         $results = array();
 654
 655         while ($this->current = array_shift($this->queue)) {
 656
 657             if ($this->was_processed($this->current)) {
 658                 // do not repeat yourself
 659                 continue;
 660             }
 661
 662             if ($this->current === 'en') {
 663                 $this->mark_processed($this->current);
 664                 continue;
 665             }
 666
 667             $results[$this->current] = $this->install_language_pack($this->current);
 668
 669             if (in_array($results[$this->current], array(self::RESULT_INSTALLED, self::RESULT_UPTODATE))) {
 670                 if ($parentlang = $this->get_parent_language($this->current)) {
 671                     if (!$this->is_queued($parentlang) and !$this->was_processed($parentlang)) {
 672                         $this->add_to_queue($parentlang);
 673                     }
 674                 }
 675             }
 676
 677             $this->mark_processed($this->current);
 678         }
 679
 680         return $results;
 681     }
 682
 683     /**
 684      * Returns the URL where a given language pack can be downloaded
 685      *
 686      * Alternatively, if the parameter is empty, returns URL of the page with the
 687      * list of all available language packs.
 688      *
 689      * @param string $langcode language code like 'cs' or empty for unknown
 690      * @return string URL
 691      */
 692     public function lang_pack_url($langcode = '') {
 693
 694         if (empty($langcode)) {
 695             return 'https://download.moodle.org/langpack/'.$this->version.'/';
 696         } else {
 697             return 'https://download.moodle.org/download.php/langpack/'.$this->version.'/'.$langcode.'.zip';
 698         }
 699     }
 700
 701     /**
 702      * Returns the list of available language packs from download.moodle.org
 703      *
 704      * @return array|bool false if can not download
 705      */
 706     public function get_remote_list_of_languages() {
 707         $source = 'https://download.moodle.org/langpack/' . $this->version . '/languages.md5';
 708         $availablelangs = array();
 709
 710         $contents = download_file_content($source, null, null, true);
 711         if ($contents->results && (int) $contents->status === 200) {
 712             $alllines = explode("\n", $contents->results);
 713             foreach($alllines as $line) {
 714                 if (!empty($line)){
 715                     $availablelangs[] = explode(',', $line);
 716                 }
 717             }
 718             return $availablelangs;
 719
 720         } else {
 721             return false;
 722         }
 723     }
 724
 725     // Internal implementation /////////////////////////////////////////////////
 726
 727     /**
 728      * Adds a language pack (or a list of them) to the queue
 729      *
 730      * @param string|array $langcodes code of the language to install or a list of them
 731      */
 732     protected function add_to_queue($langcodes) {
 733         if (is_array($langcodes)) {
 734             $this->queue = array_merge($this->queue, $langcodes);
 735         } else if (!empty($langcodes)) {
 736             $this->queue[] = $langcodes;
 737         }
 738     }
 739
 740     /**
 741      * Checks if the given language is queued or if the queue is empty
 742      *
 743      * @example $installer->is_queued('es');    // is Spanish going to be installed?
 744      * @example $installer->is_queued();        // is there a language queued?
 745      *
 746      * @param string $langcode language code or empty string for "any"
 747      * @return boolean
 748      */
 749     protected function is_queued($langcode = '') {
 750
 751         if (empty($langcode)) {
 752             return !empty($this->queue);
 753
 754         } else {
 755             return in_array($langcode, $this->queue);
 756         }
 757     }
 758
 759     /**
 760      * Checks if the given language has already been processed by this instance
 761      *
 762      * @see self::mark_processed()
 763      * @param string $langcode
 764      * @return boolean
 765      */
 766     protected function was_processed($langcode) {
 767         return isset($this->done[$langcode]);
 768     }
 769
 770     /**
 771      * Mark the given language pack as processed
 772      *
 773      * @see self::was_processed()
 774      * @param string $langcode
 775      */
 776     protected function mark_processed($langcode) {
 777         $this->done[$langcode] = 1;
 778     }
 779
 780     /**
 781      * Returns a parent language of the given installed language
 782      *
 783      * @param string $langcode
 784      * @return string parent language's code
 785      */
 786     protected function get_parent_language($langcode) {
 787         return get_parent_language($langcode);
 788     }
 789
 790     /**
 791      * Perform the actual language pack installation
 792      *
 793      * @uses component_installer
 794      * @param string $langcode
 795      * @return int return status
 796      */
 797     protected function install_language_pack($langcode) {
 798
 799         // initialise new component installer to process this language
 800         $installer = new component_installer('https://download.moodle.org', 'download.php/direct/langpack/' . $this->version,
 801             $langcode . '.zip', 'languages.md5', 'lang');
 802
 803         if (!$installer->requisitesok) {
 804             throw new lang_installer_exception('installer_requisites_check_failed');
 805         }
 806
 807         $status = $installer->install();
 808
 809         if ($status == COMPONENT_ERROR) {
 810             if ($installer->get_error() === 'remotedownloaderror') {
 811                 return self::RESULT_DOWNLOADERROR;
 812             } else {
 813                 throw new lang_installer_exception($installer->get_error(), $langcode);
 814             }
 815
 816         } else if ($status == COMPONENT_UPTODATE) {
 817             return self::RESULT_UPTODATE;
 818
 819         } else if ($status == COMPONENT_INSTALLED) {
 820             return self::RESULT_INSTALLED;
 821
 822         } else {
 823             throw new lang_installer_exception('unexpected_installer_result', $status);
 824         }
 825     }
 826 }
 827
 828
 829 /**
 830  * Exception thrown by {@link lang_installer}
 831  *
 832  * @copyright 2011 David Mudrak <david@moodle.com>
 833  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 834  */
 835 class lang_installer_exception extends moodle_exception {
 836
 837     public function __construct($errorcode, $debuginfo = null) {
 838         parent::__construct($errorcode, 'error', '', null, $debuginfo);
 839     }
 840 }