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= $CFG->dataroot.'/lang';
  79  *                     print_error($cd->get_error(), 'error', '', $a);
  80  *                 } else {
  81  *                     print_error($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         $this->check_requisites();
 207     }
 208
 209     /**
 210      * Old syntax of class constructor. Deprecated in PHP7.
 211      */
 212     public function component_installer($sourcebase, $zippath, $zipfilename, $md5filename='', $destpath='') {
 213         self::__construct($sourcebase, $zippath, $zipfilename, $md5filename, $destpath);
 214     }
 215
 216     /**
 217      * This function will check if everything is properly set to begin
 218      * one installation. Also, it will check for required settings
 219      * and will fill everything as needed.
 220      *
 221      * @global object
 222      * @return boolean true/false (plus detailed error in errorstring)
 223      */
 224     function check_requisites() {
 225         global $CFG;
 226
 227         $this->requisitesok = false;
 228
 229     /// Check that everything we need is present
 230         if (empty($this->sourcebase) || empty($this->zipfilename)) {
 231             $this->errorstring='missingrequiredfield';
 232             return false;
 233         }
 234     /// Check for correct sourcebase (this will be out in the future)
 235         if (!PHPUNIT_TEST and $this->sourcebase != 'https://download.moodle.org') {
 236             $this->errorstring='wrongsourcebase';
 237             return false;
 238         }
 239     /// Check the zip file is a correct one (by extension)
 240         if (stripos($this->zipfilename, '.zip') === false) {
 241             $this->errorstring='wrongzipfilename';
 242             return false;
 243         }
 244     /// Check that exists under dataroot
 245         if (!empty($this->destpath)) {
 246             if (!file_exists($CFG->dataroot.'/'.$this->destpath)) {
 247                 $this->errorstring='wrongdestpath';
 248                 return false;
 249             }
 250         }
 251     /// Calculate the componentname
 252         $pos = stripos($this->zipfilename, '.zip');
 253         $this->componentname = substr($this->zipfilename, 0, $pos);
 254     /// Calculate md5filename if it's empty
 255         if (empty($this->md5filename)) {
 256             $this->md5filename = $this->componentname.'.md5';
 257         }
 258     /// Set the requisites passed flag
 259         $this->requisitesok = true;
 260         return true;
 261     }
 262
 263     /**
 264      * This function will perform the full installation if needed, i.e.
 265      * compare md5 values, download, unzip, install and regenerate
 266      * local md5 file
 267      *
 268      * @global object
 269      * @uses COMPONENT_ERROR
 270      * @uses COMPONENT_UPTODATE
 271      * @uses COMPONENT_ERROR
 272      * @uses COMPONENT_INSTALLED
 273      * @return int COMPONENT_(ERROR | UPTODATE | INSTALLED)
 274      */
 275     function install() {
 276
 277         global $CFG;
 278
 279     /// Check requisites are passed
 280         if (!$this->requisitesok) {
 281             return COMPONENT_ERROR;
 282         }
 283     /// Confirm we need upgrade
 284         if ($this->need_upgrade() === COMPONENT_ERROR) {
 285             return COMPONENT_ERROR;
 286         } else if ($this->need_upgrade() === COMPONENT_UPTODATE) {
 287             $this->errorstring='componentisuptodate';
 288             return COMPONENT_UPTODATE;
 289         }
 290     /// Create temp directory if necesary
 291         if (!make_temp_directory('', false)) {
 292              $this->errorstring='cannotcreatetempdir';
 293              return COMPONENT_ERROR;
 294         }
 295     /// Download zip file and save it to temp
 296         if ($this->zippath) {
 297             $source = $this->sourcebase.'/'.$this->zippath.'/'.$this->zipfilename;
 298         } else {
 299             $source = $this->sourcebase.'/'.$this->zipfilename;
 300         }
 301
 302         $zipfile= $CFG->tempdir.'/'.$this->zipfilename;
 303
 304         if($contents = download_file_content($source)) {
 305             if ($file = fopen($zipfile, 'w')) {
 306                 if (!fwrite($file, $contents)) {
 307                     fclose($file);
 308                     $this->errorstring='cannotsavezipfile';
 309                     return COMPONENT_ERROR;
 310                 }
 311             } else {
 312                 $this->errorstring='cannotsavezipfile';
 313                 return COMPONENT_ERROR;
 314             }
 315             fclose($file);
 316         } else {
 317             $this->errorstring='cannotdownloadzipfile';
 318             return COMPONENT_ERROR;
 319         }
 320     /// Calculate its md5
 321         $new_md5 = md5($contents);
 322     /// Compare it with the remote md5 to check if we have the correct zip file
 323         if (!$remote_md5 = $this->get_component_md5()) {
 324             return COMPONENT_ERROR;
 325         }
 326         if ($new_md5 != $remote_md5) {
 327             $this->errorstring='downloadedfilecheckfailed';
 328             return COMPONENT_ERROR;
 329         }
 330     /// Move current revision to a safe place
 331         $destinationdir = $CFG->dataroot.'/'.$this->destpath;
 332         $destinationcomponent = $destinationdir.'/'.$this->componentname;
 333         @remove_dir($destinationcomponent.'_old');     // Deleting a possible old version.
 334
 335         // Moving to a safe place.
 336         @rename($destinationcomponent, $destinationcomponent.'_old');
 337
 338     /// Unzip new version
 339         if (!unzip_file($zipfile, $destinationdir, false)) {
 340         /// Error so, go back to the older
 341             @remove_dir($destinationcomponent);
 342             @rename ($destinationcomponent.'_old', $destinationcomponent);
 343             $this->errorstring='cannotunzipfile';
 344             return COMPONENT_ERROR;
 345         }
 346     /// Delete old component version
 347         @remove_dir($destinationcomponent.'_old');
 348     /// Create local md5
 349         if ($file = fopen($destinationcomponent.'/'.$this->componentname.'.md5', 'w')) {
 350             if (!fwrite($file, $new_md5)) {
 351                 fclose($file);
 352                 $this->errorstring='cannotsavemd5file';
 353                 return COMPONENT_ERROR;
 354             }
 355         } else  {
 356             $this->errorstring='cannotsavemd5file';
 357             return COMPONENT_ERROR;
 358         }
 359         fclose($file);
 360     /// Delete temp zip file
 361         @unlink($zipfile);
 362
 363         return COMPONENT_INSTALLED;
 364     }
 365
 366     /**
 367      * This function will detect if remote component needs to be installed
 368      * because it's different from the local one
 369      *
 370      * @uses COMPONENT_ERROR
 371      * @uses COMPONENT_UPTODATE
 372      * @uses COMPONENT_NEEDUPDATE
 373      * @return int COMPONENT_(ERROR | UPTODATE | NEEDUPDATE)
 374      */
 375     function need_upgrade() {
 376
 377     /// Check requisites are passed
 378         if (!$this->requisitesok) {
 379             return COMPONENT_ERROR;
 380         }
 381     /// Get local md5
 382         $local_md5 = $this->get_local_md5();
 383     /// Get remote md5
 384         if (!$remote_md5 = $this->get_component_md5()) {
 385             return COMPONENT_ERROR;
 386         }
 387     /// Return result
 388        if ($local_md5 == $remote_md5) {
 389            return COMPONENT_UPTODATE;
 390        } else {
 391            return COMPONENT_NEEDUPDATE;
 392        }
 393     }
 394
 395     /**
 396      * This function will change the zip file to install on the fly
 397      * to allow the class to process different components of the
 398      * same md5 file without intantiating more objects.
 399      *
 400      * @param string $newzipfilename New zip filename to process
 401      * @return boolean true/false
 402      */
 403     function change_zip_file($newzipfilename) {
 404
 405         $this->zipfilename = $newzipfilename;
 406         return $this->check_requisites();
 407     }
 408
 409     /**
 410      * This function will get the local md5 value of the installed
 411      * component.
 412      *
 413      * @global object
 414      * @return bool|string md5 of the local component (false on error)
 415      */
 416     function get_local_md5() {
 417         global $CFG;
 418
 419     /// Check requisites are passed
 420         if (!$this->requisitesok) {
 421             return false;
 422         }
 423
 424         $return_value = 'needtobeinstalled';   /// Fake value to force new installation
 425
 426     /// Calculate source to read
 427        $source = $CFG->dataroot.'/'.$this->destpath.'/'.$this->componentname.'/'.$this->componentname.'.md5';
 428     /// Read md5 value stored (if exists)
 429        if (file_exists($source)) {
 430            if ($temp = file_get_contents($source)) {
 431                $return_value = $temp;
 432            }
 433         }
 434         return $return_value;
 435     }
 436
 437     /**
 438      * This function will download the specified md5 file, looking for the
 439      * current componentname, returning its md5 field and storing extramd5info
 440      * if present. Also it caches results to cachedmd5components for better
 441      * performance in the same request.
 442      *
 443      * @return mixed md5 present in server (or false if error)
 444      */
 445     function get_component_md5() {
 446
 447     /// Check requisites are passed
 448         if (!$this->requisitesok) {
 449             return false;
 450         }
 451     /// Get all components of md5 file
 452         if (!$comp_arr = $this->get_all_components_md5()) {
 453             if (empty($this->errorstring)) {
 454                 $this->errorstring='cannotdownloadcomponents';
 455             }
 456             return false;
 457         }
 458     /// Search for the componentname component
 459         if (empty($comp_arr[$this->componentname]) || !$component = $comp_arr[$this->componentname]) {
 460              $this->errorstring='cannotfindcomponent';
 461              return false;
 462         }
 463     /// Check we have a valid md5
 464         if (empty($component[1]) || strlen($component[1]) != 32) {
 465             $this->errorstring='invalidmd5';
 466             return false;
 467         }
 468     /// Set the extramd5info field
 469         if (!empty($component[2])) {
 470             $this->extramd5info = $component[2];
 471         }
 472         return $component[1];
 473     }
 474
 475     /**
 476      * This function allows you to retrieve the complete array of components found in
 477      * the md5filename
 478      *
 479      * @return bool|array array of components in md5 file or false if error
 480      */
 481     function get_all_components_md5() {
 482
 483     /// Check requisites are passed
 484         if (!$this->requisitesok) {
 485             return false;
 486         }
 487
 488     /// Initialize components array
 489         $comp_arr = array();
 490
 491     /// Define and retrieve the full md5 file
 492         if ($this->zippath) {
 493             $source = $this->sourcebase.'/'.$this->zippath.'/'.$this->md5filename;
 494         } else {
 495             $source = $this->sourcebase.'/'.$this->md5filename;
 496         }
 497
 498     /// Check if we have downloaded the md5 file before (per request cache)
 499         if (!empty($this->cachedmd5components[$source])) {
 500             $comp_arr = $this->cachedmd5components[$source];
 501         } else {
 502         /// Not downloaded, let's do it now
 503             $availablecomponents = array();
 504
 505             if ($contents = download_file_content($source)) {
 506             /// Split text into lines
 507                 $lines=preg_split('/\r?\n/',$contents);
 508             /// Each line will be one component
 509                 foreach($lines as $line) {
 510                     $availablecomponents[] = explode(',', $line);
 511                 }
 512             /// If no components have been found, return error
 513                 if (empty($availablecomponents)) {
 514                     $this->errorstring='cannotdownloadcomponents';
 515                     return false;
 516                 }
 517             /// Build an associative array of components for easily search
 518             /// applying trim to avoid linefeeds and other...
 519                 $comp_arr = array();
 520                 foreach ($availablecomponents as $component) {
 521                 /// Avoid sometimes empty lines
 522                     if (empty($component[0])) {
 523                         continue;
 524                     }
 525                     $component[0]=trim($component[0]);
 526                     if (!empty($component[1])) {
 527                         $component[1]=trim($component[1]);
 528                     }
 529                     if (!empty($component[2])) {
 530                         $component[2]=trim($component[2]);
 531                     }
 532                     $comp_arr[$component[0]] = $component;
 533                 }
 534             /// Cache components
 535                 $this->cachedmd5components[$source] = $comp_arr;
 536             } else {
 537             /// Return error
 538                 $this->errorstring='remotedownloaderror';
 539                 return false;
 540             }
 541         }
 542     /// If there is no commponents or erros found, error
 543         if (!empty($this->errorstring)) {
 544              return false;
 545
 546         } else if (empty($comp_arr)) {
 547              $this->errorstring='cannotdownloadcomponents';
 548              return false;
 549         }
 550         return $comp_arr;
 551     }
 552
 553     /**
 554      * This function returns the errorstring
 555      *
 556      * @return string the error string
 557      */
 558     function get_error() {
 559         return $this->errorstring;
 560     }
 561
 562     /** This function returns the extramd5 field (optional in md5 file)
 563      *
 564      * @return string the extramd5 field
 565      */
 566     function get_extra_md5_field() {
 567         return $this->extramd5info;
 568     }
 569
 570 } /// End of component_installer class
 571
 572
 573 /**
 574  * Language packs installer
 575  *
 576  * This class wraps the functionality provided by {@link component_installer}
 577  * and adds support for installing a set of language packs.
 578  *
 579  * Given an array of required language packs, this class fetches them all
 580  * and installs them. It detects eventual dependencies and installs
 581  * all parent languages, too.
 582  *
 583  * @copyright 2011 David Mudrak <david@moodle.com>
 584  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 585  */
 586 class lang_installer {
 587
 588     /** lang pack was successfully downloaded and deployed */
 589     const RESULT_INSTALLED      = 'installed';
 590     /** lang pack was up-to-date so no download was needed */
 591     const RESULT_UPTODATE       = 'uptodate';
 592     /** there was a problem with downloading the lang pack */
 593     const RESULT_DOWNLOADERROR  = 'downloaderror';
 594
 595     /** @var array of languages to install */
 596     protected $queue = array();
 597     /** @var string the code of language being currently installed */
 598     protected $current;
 599     /** @var array of languages already installed by this instance */
 600     protected $done = array();
 601     /** @var string this Moodle major version */
 602     protected $version;
 603
 604     /**
 605      * Prepare the installer
 606      *
 607      * @param string|array $langcode a code of the language to install
 608      */
 609     public function __construct($langcode = '') {
 610         global $CFG;
 611
 612         $this->set_queue($langcode);
 613         $this->version = moodle_major_version(true);
 614
 615         if (!empty($CFG->langotherroot) and $CFG->langotherroot !== $CFG->dataroot . '/lang') {
 616             debugging('The in-built language pack installer does not support alternative location ' .
 617                 'of languages root directory. You are supposed to install and update your language '.
 618                 'packs on your own.');
 619         }
 620     }
 621
 622     /**
 623      * Sets the queue of language packs to be installed
 624      *
 625      * @param string|array $langcodes language code like 'cs' or a list of them
 626      */
 627     public function set_queue($langcodes) {
 628         if (is_array($langcodes)) {
 629             $this->queue = $langcodes;
 630         } else if (!empty($langcodes)) {
 631             $this->queue = array($langcodes);
 632         }
 633     }
 634
 635     /**
 636      * Runs the installer
 637      *
 638      * This method calls {@link self::install_language_pack} for every language in the
 639      * queue. If a dependency is detected, the parent language is added to the queue.
 640      *
 641      * @return array results, array of self::RESULT_xxx constants indexed by language code
 642      */
 643     public function run() {
 644
 645         $results = array();
 646
 647         while ($this->current = array_shift($this->queue)) {
 648
 649             if ($this->was_processed($this->current)) {
 650                 // do not repeat yourself
 651                 continue;
 652             }
 653
 654             if ($this->current === 'en') {
 655                 $this->mark_processed($this->current);
 656                 continue;
 657             }
 658
 659             $results[$this->current] = $this->install_language_pack($this->current);
 660
 661             if (in_array($results[$this->current], array(self::RESULT_INSTALLED, self::RESULT_UPTODATE))) {
 662                 if ($parentlang = $this->get_parent_language($this->current)) {
 663                     if (!$this->is_queued($parentlang) and !$this->was_processed($parentlang)) {
 664                         $this->add_to_queue($parentlang);
 665                     }
 666                 }
 667             }
 668
 669             $this->mark_processed($this->current);
 670         }
 671
 672         return $results;
 673     }
 674
 675     /**
 676      * Returns the URL where a given language pack can be downloaded
 677      *
 678      * Alternatively, if the parameter is empty, returns URL of the page with the
 679      * list of all available language packs.
 680      *
 681      * @param string $langcode language code like 'cs' or empty for unknown
 682      * @return string URL
 683      */
 684     public function lang_pack_url($langcode = '') {
 685
 686         if (empty($langcode)) {
 687             return 'https://download.moodle.org/langpack/'.$this->version.'/';
 688         } else {
 689             return 'https://download.moodle.org/download.php/langpack/'.$this->version.'/'.$langcode.'.zip';
 690         }
 691     }
 692
 693     /**
 694      * Returns the list of available language packs from download.moodle.org
 695      *
 696      * @return array|bool false if can not download
 697      */
 698     public function get_remote_list_of_languages() {
 699         $source = 'https://download.moodle.org/langpack/' . $this->version . '/languages.md5';
 700         $availablelangs = array();
 701
 702         if ($content = download_file_content($source)) {
 703             $alllines = explode("\n", $content);
 704             foreach($alllines as $line) {
 705                 if (!empty($line)){
 706                     $availablelangs[] = explode(',', $line);
 707                 }
 708             }
 709             return $availablelangs;
 710
 711         } else {
 712             return false;
 713         }
 714     }
 715
 716     // Internal implementation /////////////////////////////////////////////////
 717
 718     /**
 719      * Adds a language pack (or a list of them) to the queue
 720      *
 721      * @param string|array $langcodes code of the language to install or a list of them
 722      */
 723     protected function add_to_queue($langcodes) {
 724         if (is_array($langcodes)) {
 725             $this->queue = array_merge($this->queue, $langcodes);
 726         } else if (!empty($langcodes)) {
 727             $this->queue[] = $langcodes;
 728         }
 729     }
 730
 731     /**
 732      * Checks if the given language is queued or if the queue is empty
 733      *
 734      * @example $installer->is_queued('es');    // is Spanish going to be installed?
 735      * @example $installer->is_queued();        // is there a language queued?
 736      *
 737      * @param string $langcode language code or empty string for "any"
 738      * @return boolean
 739      */
 740     protected function is_queued($langcode = '') {
 741
 742         if (empty($langcode)) {
 743             return !empty($this->queue);
 744
 745         } else {
 746             return in_array($langcode, $this->queue);
 747         }
 748     }
 749
 750     /**
 751      * Checks if the given language has already been processed by this instance
 752      *
 753      * @see self::mark_processed()
 754      * @param string $langcode
 755      * @return boolean
 756      */
 757     protected function was_processed($langcode) {
 758         return isset($this->done[$langcode]);
 759     }
 760
 761     /**
 762      * Mark the given language pack as processed
 763      *
 764      * @see self::was_processed()
 765      * @param string $langcode
 766      */
 767     protected function mark_processed($langcode) {
 768         $this->done[$langcode] = 1;
 769     }
 770
 771     /**
 772      * Returns a parent language of the given installed language
 773      *
 774      * @param string $langcode
 775      * @return string parent language's code
 776      */
 777     protected function get_parent_language($langcode) {
 778         return get_parent_language($langcode);
 779     }
 780
 781     /**
 782      * Perform the actual language pack installation
 783      *
 784      * @uses component_installer
 785      * @param string $langcode
 786      * @return int return status
 787      */
 788     protected function install_language_pack($langcode) {
 789
 790         // initialise new component installer to process this language
 791         $installer = new component_installer('https://download.moodle.org', 'download.php/direct/langpack/' . $this->version,
 792             $langcode . '.zip', 'languages.md5', 'lang');
 793
 794         if (!$installer->requisitesok) {
 795             throw new lang_installer_exception('installer_requisites_check_failed');
 796         }
 797
 798         $status = $installer->install();
 799
 800         if ($status == COMPONENT_ERROR) {
 801             if ($installer->get_error() === 'remotedownloaderror') {
 802                 return self::RESULT_DOWNLOADERROR;
 803             } else {
 804                 throw new lang_installer_exception($installer->get_error(), $langcode);
 805             }
 806
 807         } else if ($status == COMPONENT_UPTODATE) {
 808             return self::RESULT_UPTODATE;
 809
 810         } else if ($status == COMPONENT_INSTALLED) {
 811             return self::RESULT_INSTALLED;
 812
 813         } else {
 814             throw new lang_installer_exception('unexpected_installer_result', $status);
 815         }
 816     }
 817 }
 818
 819
 820 /**
 821  * Exception thrown by {@link lang_installer}
 822  *
 823  * @copyright 2011 David Mudrak <david@moodle.com>
 824  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 825  */
 826 class lang_installer_exception extends moodle_exception {
 827
 828     public function __construct($errorcode, $debuginfo = null) {
 829         parent::__construct($errorcode, 'error', '', null, $debuginfo);
 830     }
 831 }