backup/converter/convertlib.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  * Provides base converter classes
  20  *
  21  * @package    core
  22  * @subpackage backup-convert
  23  * @copyright  2011 Mark Nielsen <mark@moodlerooms.com>
  24  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25  */
  26
  27 defined('MOODLE_INTERNAL') || die();
  28
  29 require_once($CFG->dirroot . '/backup/util/includes/convert_includes.php');
  30
  31 /**
  32  * Base converter class
  33  *
  34  * All Moodle backup converters are supposed to extend this base class.
  35  *
  36  * @throws convert_exception
  37  */
  38 abstract class base_converter implements loggable {
  39
  40     /** @var string unique identifier of this converter instance */
  41     protected $id;
  42
  43     /** @var string the name of the directory containing the unpacked backup being converted */
  44     protected $tempdir;
  45
  46     /** @var string the name of the directory where the backup is converted to */
  47     protected $workdir;
  48
  49     /** @var null|base_logger logger to use during the conversion */
  50     protected $logger = null;
  51
  52     /**
  53      * Constructor
  54      *
  55      * @param string $tempdir the relative path to the directory containing the unpacked backup to convert
  56      * @param null|base_logger logger to use during the conversion
  57      */
  58     public function __construct($tempdir, $logger = null) {
  59
  60         $this->tempdir  = $tempdir;
  61         $this->id       = convert_helper::generate_id($tempdir);
  62         $this->workdir  = $tempdir . '_' . $this->get_name() . '_' . $this->id;
  63         $this->set_logger($logger);
  64         $this->log('instantiating '.$this->get_name().' converter '.$this->get_id(), backup::LOG_DEBUG);
  65         $this->log('conversion source directory', backup::LOG_DEBUG, $this->tempdir);
  66         $this->log('conversion target directory', backup::LOG_DEBUG, $this->workdir);
  67         $this->init();
  68     }
  69
  70     /**
  71      * Sets the logger to use during the conversion
  72      *
  73      * @param null|base_logger $logger
  74      */
  75     public function set_logger($logger) {
  76         if (is_null($logger) or ($logger instanceof base_logger)) {
  77             $this->logger = $logger;
  78         }
  79     }
  80
  81     /**
  82      * If the logger was set for the converter, log the message
  83      *
  84      * If the $display is enabled, the spaces in the $message text are removed
  85      * and the text is used as a string identifier in the core_backup language file.
  86      *
  87      * @see backup_helper::log()
  88      * @param string $message message text
  89      * @param int $level message level {@example backup::LOG_WARNING}
  90      * @param null|mixed $a additional information
  91      * @param null|int $depth the message depth
  92      * @param bool $display whether the message should be sent to the output, too
  93      */
  94     public function log($message, $level, $a = null, $depth = null, $display = false) {
  95         if ($this->logger instanceof base_logger) {
  96             backup_helper::log($message, $level, $a, $depth, $display, $this->logger);
  97         }
  98     }
  99
 100     /**
 101      * Get instance identifier
 102      *
 103      * @return string the unique identifier of this converter instance
 104      */
 105     public function get_id() {
 106         return $this->id;
 107     }
 108
 109     /**
 110      * Get converter name
 111      *
 112      * @return string the system name of the converter
 113      */
 114     public function get_name() {
 115         return array_shift(explode('_', get_class($this)));
 116     }
 117
 118     /**
 119      * Converts the backup directory
 120      */
 121     public function convert() {
 122
 123         try {
 124             $this->log('creating the target directory', backup::LOG_DEBUG);
 125             $this->create_workdir();
 126
 127             $this->log('executing the conversion', backup::LOG_DEBUG);
 128             $this->execute();
 129
 130             $this->log('replacing the source directory with the converted version', backup::LOG_DEBUG);
 131             $this->replace_tempdir();
 132         } catch (Exception $e) {
 133         }
 134
 135         // clean-up stuff if needed
 136         $this->destroy();
 137
 138         // eventually re-throw the execution exception
 139         if (isset($e) and ($e instanceof Exception)) {
 140             throw $e;
 141         }
 142     }
 143
 144     /**
 145      * @return string the full path to the working directory
 146      */
 147     public function get_workdir_path() {
 148         global $CFG;
 149
 150         return "$CFG->tempdir/backup/$this->workdir";
 151     }
 152
 153     /**
 154      * @return string the full path to the directory with the source backup
 155      */
 156     public function get_tempdir_path() {
 157         global $CFG;
 158
 159         return "$CFG->tempdir/backup/$this->tempdir";
 160     }
 161
 162     /// public static methods //////////////////////////////////////////////////
 163
 164     /**
 165      * Makes sure that this converter is available at this site
 166      *
 167      * This is intended for eventual PHP extensions check, environment check etc.
 168      * All checks that do not depend on actual backup data should be done here.
 169      *
 170      * @return boolean true if this converter should be considered as available
 171      */
 172     public static function is_available() {
 173         return true;
 174     }
 175
 176     /**
 177      * Detects the format of the backup directory
 178      *
 179      * Moodle 2.x format is being detected by the core itself. The converters are
 180      * therefore supposed to detect the source format. Eventually, if the target
 181      * format os not {@link backup::FORMAT_MOODLE} then they should be able to
 182      * detect both source and target formats.
 183      *
 184      * @param string $tempdir the name of the backup directory
 185      * @return null|string null if not recognized, backup::FORMAT_xxx otherwise
 186      */
 187     public static function detect_format($tempdir) {
 188         return null;
 189     }
 190
 191     /**
 192      * Returns the basic information about the converter
 193      *
 194      * The returned array must contain the following keys:
 195      * 'from' - the supported source format, eg. backup::FORMAT_MOODLE1
 196      * 'to'   - the supported target format, eg. backup::FORMAT_MOODLE
 197      * 'cost' - the cost of the conversion, non-negative non-zero integer
 198      */
 199     public static function description() {
 200
 201         return array(
 202             'from'  => null,
 203             'to'    => null,
 204             'cost'  => null,
 205         );
 206     }
 207
 208     /// end of public API //////////////////////////////////////////////////////
 209
 210     /**
 211      * Initialize the instance if needed, called by the constructor
 212      */
 213     protected function init() {
 214     }
 215
 216     /**
 217      * Converts the contents of the tempdir into the target format in the workdir
 218      */
 219     protected abstract function execute();
 220
 221     /**
 222      * Prepares a new empty working directory
 223      */
 224     protected function create_workdir() {
 225
 226         fulldelete($this->get_workdir_path());
 227         if (!check_dir_exists($this->get_workdir_path())) {
 228             throw new convert_exception('failed_create_workdir');
 229         }
 230     }
 231
 232     /**
 233      * Replaces the source backup directory with the converted version
 234      *
 235      * If $CFG->keeptempdirectoriesonbackup is defined, the original source
 236      * source backup directory is kept for debugging purposes.
 237      */
 238     protected function replace_tempdir() {
 239         global $CFG;
 240
 241         if (empty($CFG->keeptempdirectoriesonbackup)) {
 242             fulldelete($this->get_tempdir_path());
 243         } else {
 244             if (!rename($this->get_tempdir_path(), $this->get_tempdir_path()  . '_' . $this->get_name() . '_' . $this->id . '_source')) {
 245                 throw new convert_exception('failed_rename_source_tempdir');
 246             }
 247         }
 248
 249         if (!rename($this->get_workdir_path(), $this->get_tempdir_path())) {
 250             throw new convert_exception('failed_move_converted_into_place');
 251         }
 252     }
 253
 254     /**
 255      * Cleans up stuff after the execution
 256      *
 257      * Note that we do not know if the execution was successful or not.
 258      * An exception might have been thrown.
 259      */
 260     protected function destroy() {
 261         global $CFG;
 262
 263         if (empty($CFG->keeptempdirectoriesonbackup)) {
 264             fulldelete($this->get_workdir_path());
 265         }
 266     }
 267 }
 268
 269 /**
 270  * General convert-related exception
 271  *
 272  * @author David Mudrak <david@moodle.com>
 273  */
 274 class convert_exception extends moodle_exception {
 275
 276     /**
 277      * Constructor
 278      *
 279      * @param string $errorcode key for the corresponding error string
 280      * @param object $a extra words and phrases that might be required in the error string
 281      * @param string $debuginfo optional debugging information
 282      */
 283     public function __construct($errorcode, $a = null, $debuginfo = null) {
 284         parent::__construct($errorcode, '', '', $a, $debuginfo);
 285     }
 286 }