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('http://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 = 'http://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 $destpath Relative path (from moodledata) where the .zip file will
 190      *               be expanded (default='' = moodledataitself)
 191      * @return object
 192      */
 193     function component_installer ($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      * This function will check if everything is properly set to begin
 211      * one installation. Also, it will check for required settings
 212      * and will fill everything as needed.
 213      *
 214      * @global object
 215      * @return boolean true/false (plus detailed error in errorstring)
 216      */
 217     function check_requisites() {
 218         global $CFG;
 219
 220         $this->requisitesok = false;
 221
 222     /// Check that everything we need is present
 223         if (empty($this->sourcebase) || empty($this->zippath) || empty($this->zipfilename)) {
 224             $this->errorstring='missingrequiredfield';
 225             return false;
 226         }
 227     /// Check for correct sourcebase (this will be out in the future)
 228         if ($this->sourcebase != 'http://download.moodle.org') {
 229             $this->errorstring='wrongsourcebase';
 230             return false;
 231         }
 232     /// Check the zip file is a correct one (by extension)
 233         if (stripos($this->zipfilename, '.zip') === false) {
 234             $this->errorstring='wrongzipfilename';
 235             return false;
 236         }
 237     /// Check that exists under dataroot
 238         if (!empty($this->destpath)) {
 239             if (!file_exists($CFG->dataroot.'/'.$this->destpath)) {
 240                 $this->errorstring='wrongdestpath';
 241                 return false;
 242             }
 243         }
 244     /// Calculate the componentname
 245         $pos = stripos($this->zipfilename, '.zip');
 246         $this->componentname = substr($this->zipfilename, 0, $pos);
 247     /// Calculate md5filename if it's empty
 248         if (empty($this->md5filename)) {
 249             $this->md5filename = $this->componentname.'.md5';
 250         }
 251     /// Set the requisites passed flag
 252         $this->requisitesok = true;
 253         return true;
 254     }
 255
 256     /**
 257      * This function will perform the full installation if needed, i.e.
 258      * compare md5 values, download, unzip, install and regenerate
 259      * local md5 file
 260      *
 261      * @global object
 262      * @uses COMPONENT_ERROR
 263      * @uses COMPONENT_UPTODATE
 264      * @uses COMPONENT_ERROR
 265      * @uses COMPONENT_INSTALLED
 266      * @return int COMPONENT_(ERROR | UPTODATE | INSTALLED)
 267      */
 268     function install() {
 269
 270         global $CFG;
 271
 272     /// Check requisites are passed
 273         if (!$this->requisitesok) {
 274             return COMPONENT_ERROR;
 275         }
 276     /// Confirm we need upgrade
 277         if ($this->need_upgrade() === COMPONENT_ERROR) {
 278             return COMPONENT_ERROR;
 279         } else if ($this->need_upgrade() === COMPONENT_UPTODATE) {
 280             $this->errorstring='componentisuptodate';
 281             return COMPONENT_UPTODATE;
 282         }
 283     /// Create temp directory if necesary
 284         if (!make_temp_directory('', false)) {
 285              $this->errorstring='cannotcreatetempdir';
 286              return COMPONENT_ERROR;
 287         }
 288     /// Download zip file and save it to temp
 289         $source = $this->sourcebase.'/'.$this->zippath.'/'.$this->zipfilename;
 290         $zipfile= $CFG->tempdir.'/'.$this->zipfilename;
 291
 292         if($contents = download_file_content($source)) {
 293             if ($file = fopen($zipfile, 'w')) {
 294                 if (!fwrite($file, $contents)) {
 295                     fclose($file);
 296                     $this->errorstring='cannotsavezipfile';
 297                     return COMPONENT_ERROR;
 298                 }
 299             } else {
 300                 $this->errorstring='cannotsavezipfile';
 301                 return COMPONENT_ERROR;
 302             }
 303             fclose($file);
 304         } else {
 305             $this->errorstring='cannotdownloadzipfile';
 306             return COMPONENT_ERROR;
 307         }
 308     /// Calculate its md5
 309         $new_md5 = md5($contents);
 310     /// Compare it with the remote md5 to check if we have the correct zip file
 311         if (!$remote_md5 = $this->get_component_md5()) {
 312             return COMPONENT_ERROR;
 313         }
 314         if ($new_md5 != $remote_md5) {
 315             $this->errorstring='downloadedfilecheckfailed';
 316             return COMPONENT_ERROR;
 317         }
 318     /// Move current revision to a safe place
 319         $destinationdir = $CFG->dataroot.'/'.$this->destpath;
 320         $destinationcomponent = $destinationdir.'/'.$this->componentname;
 321         @remove_dir($destinationcomponent.'_old');     //Deleting possible old components before
 322         @rename ($destinationcomponent, $destinationcomponent.'_old');  //Moving to a safe place
 323     /// Unzip new version
 324         if (!unzip_file($zipfile, $destinationdir, false)) {
 325         /// Error so, go back to the older
 326             @remove_dir($destinationcomponent);
 327             @rename ($destinationcomponent.'_old', $destinationcomponent);
 328             $this->errorstring='cannotunzipfile';
 329             return COMPONENT_ERROR;
 330         }
 331     /// Delete old component version
 332         @remove_dir($destinationcomponent.'_old');
 333     /// Create local md5
 334         if ($file = fopen($destinationcomponent.'/'.$this->componentname.'.md5', 'w')) {
 335             if (!fwrite($file, $new_md5)) {
 336                 fclose($file);
 337                 $this->errorstring='cannotsavemd5file';
 338                 return COMPONENT_ERROR;
 339             }
 340         } else  {
 341             $this->errorstring='cannotsavemd5file';
 342             return COMPONENT_ERROR;
 343         }
 344         fclose($file);
 345     /// Delete temp zip file
 346         @unlink($zipfile);
 347
 348         return COMPONENT_INSTALLED;
 349     }
 350
 351     /**
 352      * This function will detect if remote component needs to be installed
 353      * because it's different from the local one
 354      *
 355      * @uses COMPONENT_ERROR
 356      * @uses COMPONENT_UPTODATE
 357      * @uses COMPONENT_NEEDUPDATE
 358      * @return int COMPONENT_(ERROR | UPTODATE | NEEDUPDATE)
 359      */
 360     function need_upgrade() {
 361
 362     /// Check requisites are passed
 363         if (!$this->requisitesok) {
 364             return COMPONENT_ERROR;
 365         }
 366     /// Get local md5
 367         $local_md5 = $this->get_local_md5();
 368     /// Get remote md5
 369         if (!$remote_md5 = $this->get_component_md5()) {
 370             return COMPONENT_ERROR;
 371         }
 372     /// Return result
 373        if ($local_md5 == $remote_md5) {
 374            return COMPONENT_UPTODATE;
 375        } else {
 376            return COMPONENT_NEEDUPDATE;
 377        }
 378     }
 379
 380     /**
 381      * This function will change the zip file to install on the fly
 382      * to allow the class to process different components of the
 383      * same md5 file without intantiating more objects.
 384      *
 385      * @param string $newzipfilename New zip filename to process
 386      * @return boolean true/false
 387      */
 388     function change_zip_file($newzipfilename) {
 389
 390         $this->zipfilename = $newzipfilename;
 391         return $this->check_requisites();
 392     }
 393
 394     /**
 395      * This function will get the local md5 value of the installed
 396      * component.
 397      *
 398      * @global object
 399      * @return bool|string md5 of the local component (false on error)
 400      */
 401     function get_local_md5() {
 402         global $CFG;
 403
 404     /// Check requisites are passed
 405         if (!$this->requisitesok) {
 406             return false;
 407         }
 408
 409         $return_value = 'needtobeinstalled';   /// Fake value to force new installation
 410
 411     /// Calculate source to read
 412        $source = $CFG->dataroot.'/'.$this->destpath.'/'.$this->componentname.'/'.$this->componentname.'.md5';
 413     /// Read md5 value stored (if exists)
 414        if (file_exists($source)) {
 415            if ($temp = file_get_contents($source)) {
 416                $return_value = $temp;
 417            }
 418         }
 419         return $return_value;
 420     }
 421
 422     /**
 423      * This function will download the specified md5 file, looking for the
 424      * current componentname, returning its md5 field and storing extramd5info
 425      * if present. Also it caches results to cachedmd5components for better
 426      * performance in the same request.
 427      *
 428      * @return mixed md5 present in server (or false if error)
 429      */
 430     function get_component_md5() {
 431
 432     /// Check requisites are passed
 433         if (!$this->requisitesok) {
 434             return false;
 435         }
 436     /// Get all components of md5 file
 437         if (!$comp_arr = $this->get_all_components_md5()) {
 438             if (empty($this->errorstring)) {
 439                 $this->errorstring='cannotdownloadcomponents';
 440             }
 441             return false;
 442         }
 443     /// Search for the componentname component
 444         if (empty($comp_arr[$this->componentname]) || !$component = $comp_arr[$this->componentname]) {
 445              $this->errorstring='cannotfindcomponent';
 446              return false;
 447         }
 448     /// Check we have a valid md5
 449         if (empty($component[1]) || strlen($component[1]) != 32) {
 450             $this->errorstring='invalidmd5';
 451             return false;
 452         }
 453     /// Set the extramd5info field
 454         if (!empty($component[2])) {
 455             $this->extramd5info = $component[2];
 456         }
 457         return $component[1];
 458     }
 459
 460     /**
 461      * This function allows you to retrieve the complete array of components found in
 462      * the md5filename
 463      *
 464      * @return bool|array array of components in md5 file or false if error
 465      */
 466     function get_all_components_md5() {
 467
 468     /// Check requisites are passed
 469         if (!$this->requisitesok) {
 470             return false;
 471         }
 472
 473     /// Initialize components array
 474         $comp_arr = array();
 475
 476     /// Define and retrieve the full md5 file
 477         $source = $this->sourcebase.'/'.$this->zippath.'/'.$this->md5filename;
 478
 479     /// Check if we have downloaded the md5 file before (per request cache)
 480         if (!empty($this->cachedmd5components[$source])) {
 481             $comp_arr = $this->cachedmd5components[$source];
 482         } else {
 483         /// Not downloaded, let's do it now
 484             $availablecomponents = array();
 485
 486             if ($contents = download_file_content($source)) {
 487             /// Split text into lines
 488                 $lines=preg_split('/\r?\n/',$contents);
 489             /// Each line will be one component
 490                 foreach($lines as $line) {
 491                     $availablecomponents[] = explode(',', $line);
 492                 }
 493             /// If no components have been found, return error
 494                 if (empty($availablecomponents)) {
 495                     $this->errorstring='cannotdownloadcomponents';
 496                     return false;
 497                 }
 498             /// Build an associative array of components for easily search
 499             /// applying trim to avoid linefeeds and other...
 500                 $comp_arr = array();
 501                 foreach ($availablecomponents as $component) {
 502                 /// Avoid sometimes empty lines
 503                     if (empty($component[0])) {
 504                         continue;
 505                     }
 506                     $component[0]=trim($component[0]);
 507                     if (!empty($component[1])) {
 508                         $component[1]=trim($component[1]);
 509                     }
 510                     if (!empty($component[2])) {
 511                         $component[2]=trim($component[2]);
 512                     }
 513                     $comp_arr[$component[0]] = $component;
 514                 }
 515             /// Cache components
 516                 $this->cachedmd5components[$source] = $comp_arr;
 517             } else {
 518             /// Return error
 519                 $this->errorstring='remotedownloaderror';
 520                 return false;
 521             }
 522         }
 523     /// If there is no commponents or erros found, error
 524         if (!empty($this->errorstring)) {
 525              return false;
 526
 527         } else if (empty($comp_arr)) {
 528              $this->errorstring='cannotdownloadcomponents';
 529              return false;
 530         }
 531         return $comp_arr;
 532     }
 533
 534     /**
 535      * This function returns the errorstring
 536      *
 537      * @return string the error string
 538      */
 539     function get_error() {
 540         return $this->errorstring;
 541     }
 542
 543     /** This function returns the extramd5 field (optional in md5 file)
 544      *
 545      * @return string the extramd5 field
 546      */
 547     function get_extra_md5_field() {
 548         return $this->extramd5info;
 549     }
 550
 551 } /// End of component_installer class
 552
 553
 554 /**
 555  * Language packs installer
 556  *
 557  * This class wraps the functionality provided by {@link component_installer}
 558  * and adds support for installing a set of language packs.
 559  *
 560  * Given an array of required language packs, this class fetches them all
 561  * and installs them. It detects eventual dependencies and installs
 562  * all parent languages, too.
 563  *
 564  * @copyright 2011 David Mudrak <david@moodle.com>
 565  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 566  */
 567 class lang_installer {
 568
 569     /** lang pack was successfully downloaded and deployed */
 570     const RESULT_INSTALLED      = 'installed';
 571     /** lang pack was up-to-date so no download was needed */
 572     const RESULT_UPTODATE       = 'uptodate';
 573     /** there was a problem with downloading the lang pack */
 574     const RESULT_DOWNLOADERROR  = 'downloaderror';
 575
 576     /** @var array of languages to install */
 577     protected $queue = array();
 578     /** @var string the code of language being currently installed */
 579     protected $current;
 580     /** @var array of languages already installed by this instance */
 581     protected $done = array();
 582     /** @var string this Moodle major version */
 583     protected $version;
 584
 585     /**
 586      * Prepare the installer
 587      *
 588      * @param string|array $langcode a code of the language to install
 589      */
 590     public function __construct($langcode = '') {
 591         global $CFG;
 592
 593         $this->set_queue($langcode);
 594         $this->version = moodle_major_version(true);
 595
 596         if (!empty($CFG->langotherroot) and $CFG->langotherroot !== $CFG->dataroot . '/lang') {
 597             debugging('The in-built language pack installer does not support alternative location ' .
 598                 'of languages root directory. You are supposed to install and update your language '.
 599                 'packs on your own.');
 600         }
 601     }
 602
 603     /**
 604      * Sets the queue of language packs to be installed
 605      *
 606      * @param string|array $langcodes language code like 'cs' or a list of them
 607      */
 608     public function set_queue($langcodes) {
 609         if (is_array($langcodes)) {
 610             $this->queue = $langcodes;
 611         } else if (!empty($langcodes)) {
 612             $this->queue = array($langcodes);
 613         }
 614     }
 615
 616     /**
 617      * Runs the installer
 618      *
 619      * This method calls {@link self::install_language_pack} for every language in the
 620      * queue. If a dependency is detected, the parent language is added to the queue.
 621      *
 622      * @return array results, array of self::RESULT_xxx constants indexed by language code
 623      */
 624     public function run() {
 625
 626         $results = array();
 627
 628         while ($this->current = array_shift($this->queue)) {
 629
 630             if ($this->was_processed($this->current)) {
 631                 // do not repeat yourself
 632                 continue;
 633             }
 634
 635             if ($this->current === 'en') {
 636                 $this->mark_processed($this->current);
 637                 continue;
 638             }
 639
 640             $results[$this->current] = $this->install_language_pack($this->current);
 641
 642             if (in_array($results[$this->current], array(self::RESULT_INSTALLED, self::RESULT_UPTODATE))) {
 643                 if ($parentlang = $this->get_parent_language($this->current)) {
 644                     if (!$this->is_queued($parentlang) and !$this->was_processed($parentlang)) {
 645                         $this->add_to_queue($parentlang);
 646                     }
 647                 }
 648             }
 649
 650             $this->mark_processed($this->current);
 651         }
 652
 653         return $results;
 654     }
 655
 656     /**
 657      * Returns the URL where a given language pack can be downloaded
 658      *
 659      * Alternatively, if the parameter is empty, returns URL of the page with the
 660      * list of all available language packs.
 661      *
 662      * @param string $langcode language code like 'cs' or empty for unknown
 663      * @return string URL
 664      */
 665     public function lang_pack_url($langcode = '') {
 666
 667         if (empty($langcode)) {
 668             return 'http://download.moodle.org/langpack/'.$this->version.'/';
 669         } else {
 670             return 'http://download.moodle.org/download.php/langpack/'.$this->version.'/'.$langcode.'.zip';
 671         }
 672     }
 673
 674     /**
 675      * Returns the list of available language packs from download.moodle.org
 676      *
 677      * @return array|bool false if can not download
 678      */
 679     public function get_remote_list_of_languages() {
 680         $source = 'http://download.moodle.org/langpack/' . $this->version . '/languages.md5';
 681         $availablelangs = array();
 682
 683         if ($content = download_file_content($source)) {
 684             $alllines = explode("\n", $content);
 685             foreach($alllines as $line) {
 686                 if (!empty($line)){
 687                     $availablelangs[] = explode(',', $line);
 688                 }
 689             }
 690             return $availablelangs;
 691
 692         } else {
 693             return false;
 694         }
 695     }
 696
 697     // Internal implementation /////////////////////////////////////////////////
 698
 699     /**
 700      * Adds a language pack (or a list of them) to the queue
 701      *
 702      * @param string|array $langcodes code of the language to install or a list of them
 703      */
 704     protected function add_to_queue($langcodes) {
 705         if (is_array($langcodes)) {
 706             $this->queue = array_merge($this->queue, $langcodes);
 707         } else if (!empty($langcodes)) {
 708             $this->queue[] = $langcodes;
 709         }
 710     }
 711
 712     /**
 713      * Checks if the given language is queued or if the queue is empty
 714      *
 715      * @example $installer->is_queued('es');    // is Spanish going to be installed?
 716      * @example $installer->is_queued();        // is there a language queued?
 717      *
 718      * @param string $langcode language code or empty string for "any"
 719      * @return boolean
 720      */
 721     protected function is_queued($langcode = '') {
 722
 723         if (empty($langcode)) {
 724             return !empty($this->queue);
 725
 726         } else {
 727             return in_array($langcode, $this->queue);
 728         }
 729     }
 730
 731     /**
 732      * Checks if the given language has already been processed by this instance
 733      *
 734      * @see self::mark_processed()
 735      * @param string $langcode
 736      * @return boolean
 737      */
 738     protected function was_processed($langcode) {
 739         return isset($this->done[$langcode]);
 740     }
 741
 742     /**
 743      * Mark the given language pack as processed
 744      *
 745      * @see self::was_processed()
 746      * @param string $langcode
 747      */
 748     protected function mark_processed($langcode) {
 749         $this->done[$langcode] = 1;
 750     }
 751
 752     /**
 753      * Returns a parent language of the given installed language
 754      *
 755      * @param string $langcode
 756      * @return string parent language's code
 757      */
 758     protected function get_parent_language($langcode) {
 759         return get_parent_language($langcode);
 760     }
 761
 762     /**
 763      * Perform the actual language pack installation
 764      *
 765      * @uses component_installer
 766      * @param string $langcode
 767      * @return int return status
 768      */
 769     protected function install_language_pack($langcode) {
 770
 771         // initialise new component installer to process this language
 772         $installer = new component_installer('http://download.moodle.org', 'download.php/direct/langpack/' . $this->version,
 773             $langcode . '.zip', 'languages.md5', 'lang');
 774
 775         if (!$installer->requisitesok) {
 776             throw new lang_installer_exception('installer_requisites_check_failed');
 777         }
 778
 779         $status = $installer->install();
 780
 781         if ($status == COMPONENT_ERROR) {
 782             if ($installer->get_error() === 'remotedownloaderror') {
 783                 return self::RESULT_DOWNLOADERROR;
 784             } else {
 785                 throw new lang_installer_exception($installer->get_error(), $langcode);
 786             }
 787
 788         } else if ($status == COMPONENT_UPTODATE) {
 789             return self::RESULT_UPTODATE;
 790
 791         } else if ($status == COMPONENT_INSTALLED) {
 792             return self::RESULT_INSTALLED;
 793
 794         } else {
 795             throw new lang_installer_exception('unexpected_installer_result', $status);
 796         }
 797     }
 798 }
 799
 800
 801 /**
 802  * Exception thrown by {@link lang_installer}
 803  *
 804  * @copyright 2011 David Mudrak <david@moodle.com>
 805  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 806  */
 807 class lang_installer_exception extends moodle_exception {
 808
 809     public function __construct($errorcode, $debuginfo = null) {
 810         parent::__construct($errorcode, 'error', '', null, $debuginfo);
 811     }
 812 }