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root / drupal7 / includes / module.inc @ d719f12f

1
<?php
2

    
3
/**
4
 * @file
5
 * API for loading and interacting with Drupal modules.
6
 */
7

    
8
/**
9
 * Loads all the modules that have been enabled in the system table.
10
 *
11
 * @param $bootstrap
12
 *   Whether to load only the reduced set of modules loaded in "bootstrap mode"
13
 *   for cached pages. See bootstrap.inc.
14
 *
15
 * @return
16
 *   If $bootstrap is NULL, return a boolean indicating whether all modules
17
 *   have been loaded.
18
 */
19
function module_load_all($bootstrap = FALSE) {
20
  static $has_run = FALSE;
21

    
22
  if (isset($bootstrap)) {
23
    foreach (module_list(TRUE, $bootstrap) as $module) {
24
      drupal_load('module', $module);
25
    }
26
    // $has_run will be TRUE if $bootstrap is FALSE.
27
    $has_run = !$bootstrap;
28
  }
29
  return $has_run;
30
}
31

    
32

    
33
/**
34
 * Returns a list of currently active modules.
35
 *
36
 * Usually, this returns a list of all enabled modules. When called early on in
37
 * the bootstrap, it will return a list of vital modules only (those needed to
38
 * generate cached pages).
39
 *
40
 * All parameters to this function are optional and should generally not be
41
 * changed from their defaults.
42
 *
43
 * @param $refresh
44
 *   (optional) Whether to force the module list to be regenerated (such as
45
 *   after the administrator has changed the system settings). Defaults to
46
 *   FALSE.
47
 * @param $bootstrap_refresh
48
 *   (optional) When $refresh is TRUE, setting $bootstrap_refresh to TRUE forces
49
 *   the module list to be regenerated using the reduced set of modules loaded
50
 *   in "bootstrap mode" for cached pages. Otherwise, setting $refresh to TRUE
51
 *   generates the complete list of enabled modules.
52
 * @param $sort
53
 *   (optional) By default, modules are ordered by weight and module name. Set
54
 *   this option to TRUE to return a module list ordered only by module name.
55
 * @param $fixed_list
56
 *   (optional) If an array of module names is provided, this will override the
57
 *   module list with the given set of modules. This will persist until the next
58
 *   call with $refresh set to TRUE or with a new $fixed_list passed in. This
59
 *   parameter is primarily intended for internal use (e.g., in install.php and
60
 *   update.php).
61
 *
62
 * @return
63
 *   An associative array whose keys and values are the names of the modules in
64
 *   the list.
65
 */
66
function module_list($refresh = FALSE, $bootstrap_refresh = FALSE, $sort = FALSE, $fixed_list = NULL) {
67
  static $list = array(), $sorted_list;
68

    
69
  if (empty($list) || $refresh || $fixed_list) {
70
    $list = array();
71
    $sorted_list = NULL;
72
    if ($fixed_list) {
73
      foreach ($fixed_list as $name => $module) {
74
        drupal_get_filename('module', $name, $module['filename']);
75
        $list[$name] = $name;
76
      }
77
    }
78
    else {
79
      if ($refresh) {
80
        // For the $refresh case, make sure that system_list() returns fresh
81
        // data.
82
        drupal_static_reset('system_list');
83
      }
84
      if ($bootstrap_refresh) {
85
        $list = system_list('bootstrap');
86
      }
87
      else {
88
        // Not using drupal_map_assoc() here as that requires common.inc.
89
        $list = array_keys(system_list('module_enabled'));
90
        $list = (!empty($list) ? array_combine($list, $list) : array());
91
      }
92
    }
93
  }
94
  if ($sort) {
95
    if (!isset($sorted_list)) {
96
      $sorted_list = $list;
97
      ksort($sorted_list);
98
    }
99
    return $sorted_list;
100
  }
101
  return $list;
102
}
103

    
104
/**
105
 * Builds a list of bootstrap modules and enabled modules and themes.
106
 *
107
 * @param $type
108
 *   The type of list to return:
109
 *   - module_enabled: All enabled modules.
110
 *   - bootstrap: All enabled modules required for bootstrap.
111
 *   - theme: All themes.
112
 *
113
 * @return
114
 *   An associative array of modules or themes, keyed by name. For $type
115
 *   'bootstrap', the array values equal the keys. For $type 'module_enabled'
116
 *   or 'theme', the array values are objects representing the respective
117
 *   database row, with the 'info' property already unserialized.
118
 *
119
 * @see module_list()
120
 * @see list_themes()
121
 */
122
function system_list($type) {
123
  $lists = &drupal_static(__FUNCTION__);
124

    
125
  // For bootstrap modules, attempt to fetch the list from cache if possible.
126
  // if not fetch only the required information to fire bootstrap hooks
127
  // in case we are going to serve the page from cache.
128
  if ($type == 'bootstrap') {
129
    if (isset($lists['bootstrap'])) {
130
      return $lists['bootstrap'];
131
    }
132
    if ($cached = cache_get('bootstrap_modules', 'cache_bootstrap')) {
133
      $bootstrap_list = $cached->data;
134
    }
135
    else {
136
      $bootstrap_list = db_query("SELECT name, filename FROM {system} WHERE status = 1 AND bootstrap = 1 AND type = 'module' ORDER BY weight ASC, name ASC")->fetchAllAssoc('name');
137
      cache_set('bootstrap_modules', $bootstrap_list, 'cache_bootstrap');
138
    }
139
    // To avoid a separate database lookup for the filepath, prime the
140
    // drupal_get_filename() static cache for bootstrap modules only.
141
    // The rest is stored separately to keep the bootstrap module cache small.
142
    foreach ($bootstrap_list as $module) {
143
      drupal_get_filename('module', $module->name, $module->filename);
144
    }
145
    // We only return the module names here since module_list() doesn't need
146
    // the filename itself.
147
    $lists['bootstrap'] = array_keys($bootstrap_list);
148
  }
149
  // Otherwise build the list for enabled modules and themes.
150
  elseif (!isset($lists['module_enabled'])) {
151
    if ($cached = cache_get('system_list', 'cache_bootstrap')) {
152
      $lists = $cached->data;
153
    }
154
    else {
155
      $lists = array(
156
        'module_enabled' => array(),
157
        'theme' => array(),
158
        'filepaths' => array(),
159
      );
160
      // The module name (rather than the filename) is used as the fallback
161
      // weighting in order to guarantee consistent behavior across different
162
      // Drupal installations, which might have modules installed in different
163
      // locations in the file system. The ordering here must also be
164
      // consistent with the one used in module_implements().
165
      $result = db_query("SELECT * FROM {system} WHERE type = 'theme' OR (type = 'module' AND status = 1) ORDER BY weight ASC, name ASC");
166
      foreach ($result as $record) {
167
        $record->info = unserialize($record->info);
168
        // Build a list of all enabled modules.
169
        if ($record->type == 'module') {
170
          $lists['module_enabled'][$record->name] = $record;
171
        }
172
        // Build a list of themes.
173
        if ($record->type == 'theme') {
174
          $lists['theme'][$record->name] = $record;
175
        }
176
        // Build a list of filenames so drupal_get_filename can use it.
177
        if ($record->status) {
178
          $lists['filepaths'][] = array('type' => $record->type, 'name' => $record->name, 'filepath' => $record->filename);
179
        }
180
      }
181
      foreach ($lists['theme'] as $key => $theme) {
182
        if (!empty($theme->info['base theme'])) {
183
          // Make a list of the theme's base themes.
184
          require_once DRUPAL_ROOT . '/includes/theme.inc';
185
          $lists['theme'][$key]->base_themes = drupal_find_base_themes($lists['theme'], $key);
186
          // Don't proceed if there was a problem with the root base theme.
187
          if (!current($lists['theme'][$key]->base_themes)) {
188
            continue;
189
          }
190
          // Determine the root base theme.
191
          $base_key = key($lists['theme'][$key]->base_themes);
192
          // Add to the list of sub-themes for each of the theme's base themes.
193
          foreach (array_keys($lists['theme'][$key]->base_themes) as $base_theme) {
194
            $lists['theme'][$base_theme]->sub_themes[$key] = $lists['theme'][$key]->info['name'];
195
          }
196
          // Add the base theme's theme engine info.
197
          $lists['theme'][$key]->info['engine'] = isset($lists['theme'][$base_key]->info['engine']) ? $lists['theme'][$base_key]->info['engine'] : 'theme';
198
        }
199
        else {
200
          // A plain theme is its own engine.
201
          $base_key = $key;
202
          if (!isset($lists['theme'][$key]->info['engine'])) {
203
            $lists['theme'][$key]->info['engine'] = 'theme';
204
          }
205
        }
206
        // Set the theme engine prefix.
207
        $lists['theme'][$key]->prefix = ($lists['theme'][$key]->info['engine'] == 'theme') ? $base_key : $lists['theme'][$key]->info['engine'];
208
      }
209
      cache_set('system_list', $lists, 'cache_bootstrap');
210
    }
211
    // To avoid a separate database lookup for the filepath, prime the
212
    // drupal_get_filename() static cache with all enabled modules and themes.
213
    foreach ($lists['filepaths'] as $item) {
214
      drupal_get_filename($item['type'], $item['name'], $item['filepath']);
215
    }
216
  }
217

    
218
  return $lists[$type];
219
}
220

    
221
/**
222
 * Resets all system_list() caches.
223
 */
224
function system_list_reset() {
225
  drupal_static_reset('system_list');
226
  drupal_static_reset('system_rebuild_module_data');
227
  drupal_static_reset('list_themes');
228
  cache_clear_all('bootstrap_modules', 'cache_bootstrap');
229
  cache_clear_all('system_list', 'cache_bootstrap');
230
}
231

    
232
/**
233
 * Determines which modules require and are required by each module.
234
 *
235
 * @param $files
236
 *   The array of filesystem objects used to rebuild the cache.
237
 *
238
 * @return
239
 *   The same array with the new keys for each module:
240
 *   - requires: An array with the keys being the modules that this module
241
 *     requires.
242
 *   - required_by: An array with the keys being the modules that will not work
243
 *     without this module.
244
 */
245
function _module_build_dependencies($files) {
246
  require_once DRUPAL_ROOT . '/includes/graph.inc';
247
  foreach ($files as $filename => $file) {
248
    $graph[$file->name]['edges'] = array();
249
    if (isset($file->info['dependencies']) && is_array($file->info['dependencies'])) {
250
      foreach ($file->info['dependencies'] as $dependency) {
251
        $dependency_data = drupal_parse_dependency($dependency);
252
        $graph[$file->name]['edges'][$dependency_data['name']] = $dependency_data;
253
      }
254
    }
255
  }
256
  drupal_depth_first_search($graph);
257
  foreach ($graph as $module => $data) {
258
    $files[$module]->required_by = isset($data['reverse_paths']) ? $data['reverse_paths'] : array();
259
    $files[$module]->requires = isset($data['paths']) ? $data['paths'] : array();
260
    $files[$module]->sort = $data['weight'];
261
  }
262
  return $files;
263
}
264

    
265
/**
266
 * Determines whether a given module exists.
267
 *
268
 * @param string $module
269
 *   The name of the module (without the .module extension).
270
 *
271
 * @return bool
272
 *   TRUE if the module is both installed and enabled, FALSE otherwise.
273
 */
274
function module_exists($module) {
275
  $list = module_list();
276
  return isset($list[$module]);
277
}
278

    
279
/**
280
 * Loads a module's installation hooks.
281
 *
282
 * @param $module
283
 *   The name of the module (without the .module extension).
284
 *
285
 * @return
286
 *   The name of the module's install file, if successful; FALSE otherwise.
287
 */
288
function module_load_install($module) {
289
  // Make sure the installation API is available
290
  include_once DRUPAL_ROOT . '/includes/install.inc';
291

    
292
  return module_load_include('install', $module);
293
}
294

    
295
/**
296
 * Loads a module include file.
297
 *
298
 * Examples:
299
 * @code
300
 *   // Load node.admin.inc from the node module.
301
 *   module_load_include('inc', 'node', 'node.admin');
302
 *   // Load content_types.inc from the node module.
303
 *   module_load_include('inc', 'node', 'content_types');
304
 * @endcode
305
 *
306
 * Do not use this function to load an install file, use module_load_install()
307
 * instead. Do not use this function in a global context since it requires
308
 * Drupal to be fully bootstrapped, use require_once DRUPAL_ROOT . '/path/file'
309
 * instead.
310
 *
311
 * @param $type
312
 *   The include file's type (file extension).
313
 * @param $module
314
 *   The module to which the include file belongs.
315
 * @param $name
316
 *   (optional) The base file name (without the $type extension). If omitted,
317
 *   $module is used; i.e., resulting in "$module.$type" by default.
318
 *
319
 * @return
320
 *   The name of the included file, if successful; FALSE otherwise.
321
 */
322
function module_load_include($type, $module, $name = NULL) {
323
  if (!isset($name)) {
324
    $name = $module;
325
  }
326

    
327
  if (function_exists('drupal_get_path')) {
328
    $file = DRUPAL_ROOT . '/' . drupal_get_path('module', $module) . "/$name.$type";
329
    if (is_file($file)) {
330
      require_once $file;
331
      return $file;
332
    }
333
  }
334
  return FALSE;
335
}
336

    
337
/**
338
 * Loads an include file for each module enabled in the {system} table.
339
 */
340
function module_load_all_includes($type, $name = NULL) {
341
  $modules = module_list();
342
  foreach ($modules as $module) {
343
    module_load_include($type, $module, $name);
344
  }
345
}
346

    
347
/**
348
 * Enables or installs a given list of modules.
349
 *
350
 * Definitions:
351
 * - "Enabling" is the process of activating a module for use by Drupal.
352
 * - "Disabling" is the process of deactivating a module.
353
 * - "Installing" is the process of enabling it for the first time or after it
354
 *   has been uninstalled.
355
 * - "Uninstalling" is the process of removing all traces of a module.
356
 *
357
 * Order of events:
358
 * - Gather and add module dependencies to $module_list (if applicable).
359
 * - For each module that is being enabled:
360
 *   - Install module schema and update system registries and caches.
361
 *   - If the module is being enabled for the first time or had been
362
 *     uninstalled, invoke hook_install() and add it to the list of installed
363
 *     modules.
364
 *   - Invoke hook_enable().
365
 * - Invoke hook_modules_installed().
366
 * - Invoke hook_modules_enabled().
367
 *
368
 * @param $module_list
369
 *   An array of module names.
370
 * @param $enable_dependencies
371
 *   If TRUE, dependencies will automatically be added and enabled in the
372
 *   correct order. This incurs a significant performance cost, so use FALSE
373
 *   if you know $module_list is already complete and in the correct order.
374
 *
375
 * @return
376
 *   FALSE if one or more dependencies are missing, TRUE otherwise.
377
 *
378
 * @see hook_install()
379
 * @see hook_enable()
380
 * @see hook_modules_installed()
381
 * @see hook_modules_enabled()
382
 */
383
function module_enable($module_list, $enable_dependencies = TRUE) {
384
  if ($enable_dependencies) {
385
    // Get all module data so we can find dependencies and sort.
386
    $module_data = system_rebuild_module_data();
387
    // Create an associative array with weights as values.
388
    $module_list = array_flip(array_values($module_list));
389

    
390
    while (list($module) = each($module_list)) {
391
      if (!isset($module_data[$module])) {
392
        // This module is not found in the filesystem, abort.
393
        return FALSE;
394
      }
395
      if ($module_data[$module]->status) {
396
        // Skip already enabled modules.
397
        unset($module_list[$module]);
398
        continue;
399
      }
400
      $module_list[$module] = $module_data[$module]->sort;
401

    
402
      // Add dependencies to the list, with a placeholder weight.
403
      // The new modules will be processed as the while loop continues.
404
      foreach (array_keys($module_data[$module]->requires) as $dependency) {
405
        if (!isset($module_list[$dependency])) {
406
          $module_list[$dependency] = 0;
407
        }
408
      }
409
    }
410

    
411
    if (!$module_list) {
412
      // Nothing to do. All modules already enabled.
413
      return TRUE;
414
    }
415

    
416
    // Sort the module list by pre-calculated weights.
417
    arsort($module_list);
418
    $module_list = array_keys($module_list);
419
  }
420

    
421
  // Required for module installation checks.
422
  include_once DRUPAL_ROOT . '/includes/install.inc';
423

    
424
  $modules_installed = array();
425
  $modules_enabled = array();
426
  foreach ($module_list as $module) {
427
    // Only process modules that are not already enabled.
428
    $existing = db_query("SELECT status FROM {system} WHERE type = :type AND name = :name", array(
429
      ':type' => 'module',
430
      ':name' => $module))
431
      ->fetchObject();
432
    if ($existing->status == 0) {
433
      // Load the module's code.
434
      drupal_load('module', $module);
435
      module_load_install($module);
436

    
437
      // Update the database and module list to reflect the new module. This
438
      // needs to be done first so that the module's hook implementations,
439
      // hook_schema() in particular, can be called while it is being
440
      // installed.
441
      db_update('system')
442
        ->fields(array('status' => 1))
443
        ->condition('type', 'module')
444
        ->condition('name', $module)
445
        ->execute();
446
      // Refresh the module list to include it.
447
      system_list_reset();
448
      module_list(TRUE);
449
      module_implements('', FALSE, TRUE);
450
      _system_update_bootstrap_status();
451
      // Update the registry to include it.
452
      registry_update();
453
      // Refresh the schema to include it.
454
      drupal_get_schema(NULL, TRUE);
455
      // Update the theme registry to include it.
456
      drupal_theme_rebuild();
457
      // Clear entity cache.
458
      entity_info_cache_clear();
459

    
460
      // Now install the module if necessary.
461
      if (drupal_get_installed_schema_version($module, TRUE) == SCHEMA_UNINSTALLED) {
462
        drupal_install_schema($module);
463

    
464
        // Set the schema version to the number of the last update provided
465
        // by the module.
466
        $versions = drupal_get_schema_versions($module);
467
        $version = $versions ? max($versions) : SCHEMA_INSTALLED;
468

    
469
        // If the module has no current updates, but has some that were
470
        // previously removed, set the version to the value of
471
        // hook_update_last_removed().
472
        if ($last_removed = module_invoke($module, 'update_last_removed')) {
473
          $version = max($version, $last_removed);
474
        }
475
        drupal_set_installed_schema_version($module, $version);
476
        // Allow the module to perform install tasks.
477
        module_invoke($module, 'install');
478
        // Record the fact that it was installed.
479
        $modules_installed[] = $module;
480
        watchdog('system', '%module module installed.', array('%module' => $module), WATCHDOG_INFO);
481
      }
482

    
483
      // Enable the module.
484
      module_invoke($module, 'enable');
485

    
486
      // Record the fact that it was enabled.
487
      $modules_enabled[] = $module;
488
      watchdog('system', '%module module enabled.', array('%module' => $module), WATCHDOG_INFO);
489
    }
490
  }
491

    
492
  // If any modules were newly installed, invoke hook_modules_installed().
493
  if (!empty($modules_installed)) {
494
    module_invoke_all('modules_installed', $modules_installed);
495
  }
496

    
497
  // If any modules were newly enabled, invoke hook_modules_enabled().
498
  if (!empty($modules_enabled)) {
499
    module_invoke_all('modules_enabled', $modules_enabled);
500
  }
501

    
502
  return TRUE;
503
}
504

    
505
/**
506
 * Disables a given set of modules.
507
 *
508
 * @param $module_list
509
 *   An array of module names.
510
 * @param $disable_dependents
511
 *   If TRUE, dependent modules will automatically be added and disabled in the
512
 *   correct order. This incurs a significant performance cost, so use FALSE
513
 *   if you know $module_list is already complete and in the correct order.
514
 */
515
function module_disable($module_list, $disable_dependents = TRUE) {
516
  if ($disable_dependents) {
517
    // Get all module data so we can find dependents and sort.
518
    $module_data = system_rebuild_module_data();
519
    // Create an associative array with weights as values.
520
    $module_list = array_flip(array_values($module_list));
521

    
522
    $profile = drupal_get_profile();
523
    while (list($module) = each($module_list)) {
524
      if (!isset($module_data[$module]) || !$module_data[$module]->status) {
525
        // This module doesn't exist or is already disabled, skip it.
526
        unset($module_list[$module]);
527
        continue;
528
      }
529
      $module_list[$module] = $module_data[$module]->sort;
530

    
531
      // Add dependent modules to the list, with a placeholder weight.
532
      // The new modules will be processed as the while loop continues.
533
      foreach ($module_data[$module]->required_by as $dependent => $dependent_data) {
534
        if (!isset($module_list[$dependent]) && $dependent != $profile) {
535
          $module_list[$dependent] = 0;
536
        }
537
      }
538
    }
539

    
540
    // Sort the module list by pre-calculated weights.
541
    asort($module_list);
542
    $module_list = array_keys($module_list);
543
  }
544

    
545
  $invoke_modules = array();
546

    
547
  foreach ($module_list as $module) {
548
    if (module_exists($module)) {
549
      // Check if node_access table needs rebuilding.
550
      if (!node_access_needs_rebuild() && module_hook($module, 'node_grants')) {
551
        node_access_needs_rebuild(TRUE);
552
      }
553

    
554
      module_load_install($module);
555
      module_invoke($module, 'disable');
556
      db_update('system')
557
        ->fields(array('status' => 0))
558
        ->condition('type', 'module')
559
        ->condition('name', $module)
560
        ->execute();
561
      $invoke_modules[] = $module;
562
      watchdog('system', '%module module disabled.', array('%module' => $module), WATCHDOG_INFO);
563
    }
564
  }
565

    
566
  if (!empty($invoke_modules)) {
567
    // Refresh the module list to exclude the disabled modules.
568
    system_list_reset();
569
    module_list(TRUE);
570
    module_implements('', FALSE, TRUE);
571
    entity_info_cache_clear();
572
    // Invoke hook_modules_disabled before disabling modules,
573
    // so we can still call module hooks to get information.
574
    module_invoke_all('modules_disabled', $invoke_modules);
575
    // Update the registry to remove the newly-disabled module.
576
    registry_update();
577
    _system_update_bootstrap_status();
578
    // Update the theme registry to remove the newly-disabled module.
579
    drupal_theme_rebuild();
580
  }
581

    
582
  // If there remains no more node_access module, rebuilding will be
583
  // straightforward, we can do it right now.
584
  if (node_access_needs_rebuild() && count(module_implements('node_grants')) == 0) {
585
    node_access_rebuild();
586
  }
587
}
588

    
589
/**
590
 * @defgroup hooks Hooks
591
 * @{
592
 * Allow modules to interact with the Drupal core.
593
 *
594
 * Drupal's module system is based on the concept of "hooks". A hook is a PHP
595
 * function that is named foo_bar(), where "foo" is the name of the module
596
 * (whose filename is thus foo.module) and "bar" is the name of the hook. Each
597
 * hook has a defined set of parameters and a specified result type.
598
 *
599
 * To extend Drupal, a module need simply implement a hook. When Drupal wishes
600
 * to allow intervention from modules, it determines which modules implement a
601
 * hook and calls that hook in all enabled modules that implement it.
602
 *
603
 * The available hooks to implement are explained here in the Hooks section of
604
 * the developer documentation. The string "hook" is used as a placeholder for
605
 * the module name in the hook definitions. For example, if the module file is
606
 * called example.module, then hook_help() as implemented by that module would
607
 * be defined as example_help().
608
 *
609
 * The example functions included are not part of the Drupal core, they are
610
 * just models that you can modify. Only the hooks implemented within modules
611
 * are executed when running Drupal.
612
 *
613
 * @see themeable
614
 * @see callbacks
615
 */
616

    
617
 /**
618
  * @defgroup callbacks Callbacks
619
  * @{
620
  * Callback function signatures.
621
  *
622
  * Drupal's API sometimes uses callback functions to allow you to define how
623
  * some type of processing happens. A callback is a function with a defined
624
  * signature, which you define in a module. Then you pass the function name as
625
  * a parameter to a Drupal API function or return it as part of a hook
626
  * implementation return value, and your function is called at an appropriate
627
  * time. For instance, when setting up batch processing you might need to
628
  * provide a callback function for each processing step and/or a callback for
629
  * when processing is finished; you would do that by defining these functions
630
  * and passing their names into the batch setup function.
631
  *
632
  * Callback function signatures, like hook definitions, are described by
633
  * creating and documenting dummy functions in a *.api.php file; normally, the
634
  * dummy callback function's name should start with "callback_", and you should
635
  * document the parameters and return value and provide a sample function body.
636
  * Then your API documentation can refer to this callback function in its
637
  * documentation. A user of your API can usually name their callback function
638
  * anything they want, although a standard name would be to replace "callback_"
639
  * with the module name.
640
  *
641
  * @see hooks
642
  * @see themeable
643
  *
644
  * @}
645
  */
646

    
647
/**
648
 * Determines whether a module implements a hook.
649
 *
650
 * @param $module
651
 *   The name of the module (without the .module extension).
652
 * @param $hook
653
 *   The name of the hook (e.g. "help" or "menu").
654
 *
655
 * @return
656
 *   TRUE if the module is both installed and enabled, and the hook is
657
 *   implemented in that module.
658
 */
659
function module_hook($module, $hook) {
660
  $function = $module . '_' . $hook;
661
  if (function_exists($function)) {
662
    return TRUE;
663
  }
664
  // If the hook implementation does not exist, check whether it may live in an
665
  // optional include file registered via hook_hook_info().
666
  $hook_info = module_hook_info();
667
  if (isset($hook_info[$hook]['group'])) {
668
    module_load_include('inc', $module, $module . '.' . $hook_info[$hook]['group']);
669
    if (function_exists($function)) {
670
      return TRUE;
671
    }
672
  }
673
  return FALSE;
674
}
675

    
676
/**
677
 * Determines which modules are implementing a hook.
678
 *
679
 * Lazy-loaded include files specified with "group" via hook_hook_info() or
680
 * hook_module_implements_alter() will be automatically included by this
681
 * function when necessary.
682
 *
683
 * @param string $hook
684
 *   The name of the hook (e.g. "help" or "menu").
685
 * @param bool $sort
686
 *   By default, modules are ordered by weight and filename, settings this option
687
 *   to TRUE, module list will be ordered by module name.
688
 * @param bool $reset
689
 *   For internal use only: Whether to force the stored list of hook
690
 *   implementations to be regenerated (such as after enabling a new module,
691
 *   before processing hook_enable).
692
 *
693
 * @return
694
 *   An array with the names of the modules which are implementing this hook.
695
 *
696
 * @see module_implements_write_cache()
697
 */
698
function module_implements($hook, $sort = FALSE, $reset = FALSE) {
699
  // Use the advanced drupal_static() pattern, since this is called very often.
700
  static $drupal_static_fast;
701
  if (!isset($drupal_static_fast)) {
702
    $drupal_static_fast['implementations'] = &drupal_static(__FUNCTION__);
703
    $drupal_static_fast['verified'] = &drupal_static(__FUNCTION__ . ':verified');
704
  }
705
  $implementations = &$drupal_static_fast['implementations'];
706
  $verified = &$drupal_static_fast['verified'];
707

    
708
  // We maintain a persistent cache of hook implementations in addition to the
709
  // static cache to avoid looping through every module and every hook on each
710
  // request. Benchmarks show that the benefit of this caching outweighs the
711
  // additional database hit even when using the default database caching
712
  // backend and only a small number of modules are enabled. The cost of the
713
  // cache_get() is more or less constant and reduced further when non-database
714
  // caching backends are used, so there will be more significant gains when a
715
  // large number of modules are installed or hooks invoked, since this can
716
  // quickly lead to module_hook() being called several thousand times
717
  // per request.
718
  if ($reset) {
719
    $implementations = array();
720
    $verified = array();
721
    cache_set('module_implements', array(), 'cache_bootstrap');
722
    drupal_static_reset('module_hook_info');
723
    drupal_static_reset('drupal_alter');
724
    cache_clear_all('hook_info', 'cache_bootstrap');
725
    return;
726
  }
727

    
728
  // Fetch implementations from cache.
729
  // This happens on the first call to module_implements(*, *, FALSE) during a
730
  // request, but also when $implementations have been reset, e.g. after
731
  // module_enable().
732
  if (empty($implementations)) {
733
    $implementations = cache_get('module_implements', 'cache_bootstrap');
734
    if ($implementations === FALSE) {
735
      $implementations = array();
736
    }
737
    else {
738
      $implementations = $implementations->data;
739
    }
740
    // Forget all previously "verified" hooks, in case that $implementations
741
    // were cleared via drupal_static_reset('module_implements') instead of
742
    // module_implements(*, *, TRUE).
743
    $verified = array();
744
  }
745

    
746
  if (!isset($implementations[$hook])) {
747
    // The hook is not cached, so ensure that whether or not it has
748
    // implementations, that the cache is updated at the end of the request.
749
    $implementations['#write_cache'] = TRUE;
750
    // Discover implementations for this hook.
751
    $hook_info = module_hook_info();
752
    $implementations[$hook] = array();
753
    $list = module_list(FALSE, FALSE, $sort);
754
    foreach ($list as $module) {
755
      $include_file = isset($hook_info[$hook]['group']) && module_load_include('inc', $module, $module . '.' . $hook_info[$hook]['group']);
756
      // Since module_hook() may needlessly try to load the include file again,
757
      // function_exists() is used directly here.
758
      if (function_exists($module . '_' . $hook)) {
759
        $implementations[$hook][$module] = $include_file ? $hook_info[$hook]['group'] : FALSE;
760
      }
761
    }
762
    // Allow modules to change the weight of specific implementations, but avoid
763
    // an infinite loop.
764
    if ($hook != 'module_implements_alter') {
765
      // Remember the implementations before hook_module_implements_alter().
766
      $implementations_before = $implementations[$hook];
767
      drupal_alter('module_implements', $implementations[$hook], $hook);
768
      // Verify implementations that were added or modified.
769
      foreach (array_diff_assoc($implementations[$hook], $implementations_before) as $module => $group) {
770
        // If drupal_alter('module_implements') changed or added a $group, the
771
        // respective file needs to be included.
772
        if ($group) {
773
          module_load_include('inc', $module, "$module.$group");
774
        }
775
        // If a new implementation was added, verify that the function exists.
776
        if (!function_exists($module . '_' . $hook)) {
777
          unset($implementations[$hook][$module]);
778
        }
779
      }
780
    }
781
    // Implementations for this hook are now "verified".
782
    $verified[$hook] = TRUE;
783
  }
784
  elseif (!isset($verified[$hook])) {
785
    // Implementations for this hook were in the cache, but they are not
786
    // "verified" yet.
787
    foreach ($implementations[$hook] as $module => $group) {
788
      // If this hook implementation is stored in a lazy-loaded file, so include
789
      // that file first.
790
      if ($group) {
791
        module_load_include('inc', $module, "$module.$group");
792
      }
793
      // It is possible that a module removed a hook implementation without the
794
      // implementations cache being rebuilt yet, so we check whether the
795
      // function exists on each request to avoid undefined function errors.
796
      // Since module_hook() may needlessly try to load the include file again,
797
      // function_exists() is used directly here.
798
      if (!function_exists($module . '_' . $hook)) {
799
        // Clear out the stale implementation from the cache and force a cache
800
        // refresh to forget about no longer existing hook implementations.
801
        unset($implementations[$hook][$module]);
802
        $implementations['#write_cache'] = TRUE;
803
      }
804
    }
805
    $verified[$hook] = TRUE;
806
  }
807

    
808
  return array_keys($implementations[$hook]);
809
}
810

    
811
/**
812
 * Retrieves a list of hooks that are declared through hook_hook_info().
813
 *
814
 * @return
815
 *   An associative array whose keys are hook names and whose values are an
816
 *   associative array containing a group name. The structure of the array
817
 *   is the same as the return value of hook_hook_info().
818
 *
819
 * @see hook_hook_info()
820
 */
821
function module_hook_info() {
822
  // This function is indirectly invoked from bootstrap_invoke_all(), in which
823
  // case common.inc, subsystems, and modules are not loaded yet, so it does not
824
  // make sense to support hook groups resp. lazy-loaded include files prior to
825
  // full bootstrap.
826
  if (drupal_bootstrap(NULL, FALSE) != DRUPAL_BOOTSTRAP_FULL) {
827
    return array();
828
  }
829
  $hook_info = &drupal_static(__FUNCTION__);
830

    
831
  if (!isset($hook_info)) {
832
    $hook_info = array();
833
    $cache = cache_get('hook_info', 'cache_bootstrap');
834
    if ($cache === FALSE) {
835
      // Rebuild the cache and save it.
836
      // We can't use module_invoke_all() here or it would cause an infinite
837
      // loop.
838
      foreach (module_list() as $module) {
839
        $function = $module . '_hook_info';
840
        if (function_exists($function)) {
841
          $result = $function();
842
          if (isset($result) && is_array($result)) {
843
            $hook_info = array_merge_recursive($hook_info, $result);
844
          }
845
        }
846
      }
847
      // We can't use drupal_alter() for the same reason as above.
848
      foreach (module_list() as $module) {
849
        $function = $module . '_hook_info_alter';
850
        if (function_exists($function)) {
851
          $function($hook_info);
852
        }
853
      }
854
      cache_set('hook_info', $hook_info, 'cache_bootstrap');
855
    }
856
    else {
857
      $hook_info = $cache->data;
858
    }
859
  }
860

    
861
  return $hook_info;
862
}
863

    
864
/**
865
 * Writes the hook implementation cache.
866
 *
867
 * @see module_implements()
868
 */
869
function module_implements_write_cache() {
870
  // The list of implementations includes vital modules only before full
871
  // bootstrap, so do not write cache if we are not fully bootstrapped yet.
872
  if (drupal_get_bootstrap_phase() != DRUPAL_BOOTSTRAP_FULL) {
873
    return;
874
  }
875
  $implementations = &drupal_static('module_implements');
876
  if (isset($implementations['#write_cache'])) {
877
    unset($implementations['#write_cache']);
878
    cache_set('module_implements', $implementations, 'cache_bootstrap');
879
  }
880
}
881

    
882
/**
883
 * Invokes a hook in a particular module.
884
 *
885
 * All arguments are passed by value. Use drupal_alter() if you need to pass
886
 * arguments by reference.
887
 *
888
 * @param $module
889
 *   The name of the module (without the .module extension).
890
 * @param $hook
891
 *   The name of the hook to invoke.
892
 * @param ...
893
 *   Arguments to pass to the hook implementation.
894
 *
895
 * @return
896
 *   The return value of the hook implementation.
897
 *
898
 * @see drupal_alter()
899
 */
900
function module_invoke($module, $hook) {
901
  $args = func_get_args();
902
  // Remove $module and $hook from the arguments.
903
  unset($args[0], $args[1]);
904
  if (module_hook($module, $hook)) {
905
    return call_user_func_array($module . '_' . $hook, $args);
906
  }
907
}
908

    
909
/**
910
 * Invokes a hook in all enabled modules that implement it.
911
 *
912
 * All arguments are passed by value. Use drupal_alter() if you need to pass
913
 * arguments by reference.
914
 *
915
 * @param $hook
916
 *   The name of the hook to invoke.
917
 * @param ...
918
 *   Arguments to pass to the hook.
919
 *
920
 * @return
921
 *   An array of return values of the hook implementations. If modules return
922
 *   arrays from their implementations, those are merged into one array.
923
 *
924
 * @see drupal_alter()
925
 */
926
function module_invoke_all($hook) {
927
  $args = func_get_args();
928
  // Remove $hook from the arguments.
929
  unset($args[0]);
930
  $return = array();
931
  foreach (module_implements($hook) as $module) {
932
    $function = $module . '_' . $hook;
933
    if (function_exists($function)) {
934
      $result = call_user_func_array($function, $args);
935
      if (isset($result) && is_array($result)) {
936
        $return = array_merge_recursive($return, $result);
937
      }
938
      elseif (isset($result)) {
939
        $return[] = $result;
940
      }
941
    }
942
  }
943

    
944
  return $return;
945
}
946

    
947
/**
948
 * @} End of "defgroup hooks".
949
 */
950

    
951
/**
952
 * Returns an array of modules required by core.
953
 */
954
function drupal_required_modules() {
955
  $files = drupal_system_listing('/^' . DRUPAL_PHP_FUNCTION_PATTERN . '\.info$/', 'modules', 'name', 0);
956
  $required = array();
957

    
958
  // An installation profile is required and one must always be loaded.
959
  $required[] = drupal_get_profile();
960

    
961
  foreach ($files as $name => $file) {
962
    $info = drupal_parse_info_file($file->uri);
963
    if (!empty($info) && !empty($info['required']) && $info['required']) {
964
      $required[] = $name;
965
    }
966
  }
967

    
968
  return $required;
969
}
970

    
971
/**
972
 * Passes alterable variables to specific hook_TYPE_alter() implementations.
973
 *
974
 * This dispatch function hands off the passed-in variables to type-specific
975
 * hook_TYPE_alter() implementations in modules. It ensures a consistent
976
 * interface for all altering operations.
977
 *
978
 * A maximum of 2 alterable arguments is supported (a third is supported for
979
 * legacy reasons, but should not be used in new code). In case more arguments
980
 * need to be passed and alterable, modules provide additional variables
981
 * assigned by reference in the last $context argument:
982
 * @code
983
 *   $context = array(
984
 *     'alterable' => &$alterable,
985
 *     'unalterable' => $unalterable,
986
 *     'foo' => 'bar',
987
 *   );
988
 *   drupal_alter('mymodule_data', $alterable1, $alterable2, $context);
989
 * @endcode
990
 *
991
 * Note that objects are always passed by reference in PHP5. If it is absolutely
992
 * required that no implementation alters a passed object in $context, then an
993
 * object needs to be cloned:
994
 * @code
995
 *   $context = array(
996
 *     'unalterable_object' => clone $object,
997
 *   );
998
 *   drupal_alter('mymodule_data', $data, $context);
999
 * @endcode
1000
 *
1001
 * @param $type
1002
 *   A string describing the type of the alterable $data. 'form', 'links',
1003
 *   'node_content', and so on are several examples. Alternatively can be an
1004
 *   array, in which case hook_TYPE_alter() is invoked for each value in the
1005
 *   array, ordered first by module, and then for each module, in the order of
1006
 *   values in $type. For example, when Form API is using drupal_alter() to
1007
 *   execute both hook_form_alter() and hook_form_FORM_ID_alter()
1008
 *   implementations, it passes array('form', 'form_' . $form_id) for $type.
1009
 * @param $data
1010
 *   The variable that will be passed to hook_TYPE_alter() implementations to be
1011
 *   altered. The type of this variable depends on the value of the $type
1012
 *   argument. For example, when altering a 'form', $data will be a structured
1013
 *   array. When altering a 'profile', $data will be an object.
1014
 * @param $context1
1015
 *   (optional) An additional variable that is passed by reference.
1016
 * @param $context2
1017
 *   (optional) An additional variable that is passed by reference. If more
1018
 *   context needs to be provided to implementations, then this should be an
1019
 *   associative array as described above.
1020
 * @param $context3
1021
 *   (optional) An additional variable that is passed by reference. This
1022
 *   parameter is deprecated and will not exist in Drupal 8; consequently, it
1023
 *   should not be used for new Drupal 7 code either. It is here only for
1024
 *   backwards compatibility with older code that passed additional arguments
1025
 *   to drupal_alter().
1026
 */
1027
function drupal_alter($type, &$data, &$context1 = NULL, &$context2 = NULL, &$context3 = NULL) {
1028
  // Use the advanced drupal_static() pattern, since this is called very often.
1029
  static $drupal_static_fast;
1030
  if (!isset($drupal_static_fast)) {
1031
    $drupal_static_fast['functions'] = &drupal_static(__FUNCTION__);
1032
  }
1033
  $functions = &$drupal_static_fast['functions'];
1034

    
1035
  // Most of the time, $type is passed as a string, so for performance,
1036
  // normalize it to that. When passed as an array, usually the first item in
1037
  // the array is a generic type, and additional items in the array are more
1038
  // specific variants of it, as in the case of array('form', 'form_FORM_ID').
1039
  if (is_array($type)) {
1040
    $cid = implode(',', $type);
1041
    $extra_types = $type;
1042
    $type = array_shift($extra_types);
1043
    // Allow if statements in this function to use the faster isset() rather
1044
    // than !empty() both when $type is passed as a string, or as an array with
1045
    // one item.
1046
    if (empty($extra_types)) {
1047
      unset($extra_types);
1048
    }
1049
  }
1050
  else {
1051
    $cid = $type;
1052
  }
1053

    
1054
  // Some alter hooks are invoked many times per page request, so statically
1055
  // cache the list of functions to call, and on subsequent calls, iterate
1056
  // through them quickly.
1057
  if (!isset($functions[$cid])) {
1058
    $functions[$cid] = array();
1059
    $hook = $type . '_alter';
1060
    $modules = module_implements($hook);
1061
    if (!isset($extra_types)) {
1062
      // For the more common case of a single hook, we do not need to call
1063
      // function_exists(), since module_implements() returns only modules with
1064
      // implementations.
1065
      foreach ($modules as $module) {
1066
        $functions[$cid][] = $module . '_' . $hook;
1067
      }
1068
    }
1069
    else {
1070
      // For multiple hooks, we need $modules to contain every module that
1071
      // implements at least one of them.
1072
      $extra_modules = array();
1073
      foreach ($extra_types as $extra_type) {
1074
        $extra_modules = array_merge($extra_modules, module_implements($extra_type . '_alter'));
1075
      }
1076
      // If any modules implement one of the extra hooks that do not implement
1077
      // the primary hook, we need to add them to the $modules array in their
1078
      // appropriate order. module_implements() can only return ordered
1079
      // implementations of a single hook. To get the ordered implementations
1080
      // of multiple hooks, we mimic the module_implements() logic of first
1081
      // ordering by module_list(), and then calling
1082
      // drupal_alter('module_implements').
1083
      if (array_diff($extra_modules, $modules)) {
1084
        // Merge the arrays and order by module_list().
1085
        $modules = array_intersect(module_list(), array_merge($modules, $extra_modules));
1086
        // Since module_implements() already took care of loading the necessary
1087
        // include files, we can safely pass FALSE for the array values.
1088
        $implementations = array_fill_keys($modules, FALSE);
1089
        // Let modules adjust the order solely based on the primary hook. This
1090
        // ensures the same module order regardless of whether this if block
1091
        // runs. Calling drupal_alter() recursively in this way does not result
1092
        // in an infinite loop, because this call is for a single $type, so we
1093
        // won't end up in this code block again.
1094
        drupal_alter('module_implements', $implementations, $hook);
1095
        $modules = array_keys($implementations);
1096
      }
1097
      foreach ($modules as $module) {
1098
        // Since $modules is a merged array, for any given module, we do not
1099
        // know whether it has any particular implementation, so we need a
1100
        // function_exists().
1101
        $function = $module . '_' . $hook;
1102
        if (function_exists($function)) {
1103
          $functions[$cid][] = $function;
1104
        }
1105
        foreach ($extra_types as $extra_type) {
1106
          $function = $module . '_' . $extra_type . '_alter';
1107
          if (function_exists($function)) {
1108
            $functions[$cid][] = $function;
1109
          }
1110
        }
1111
      }
1112
    }
1113
    // Allow the theme to alter variables after the theme system has been
1114
    // initialized.
1115
    global $theme, $base_theme_info;
1116
    if (isset($theme)) {
1117
      $theme_keys = array();
1118
      foreach ($base_theme_info as $base) {
1119
        $theme_keys[] = $base->name;
1120
      }
1121
      $theme_keys[] = $theme;
1122
      foreach ($theme_keys as $theme_key) {
1123
        $function = $theme_key . '_' . $hook;
1124
        if (function_exists($function)) {
1125
          $functions[$cid][] = $function;
1126
        }
1127
        if (isset($extra_types)) {
1128
          foreach ($extra_types as $extra_type) {
1129
            $function = $theme_key . '_' . $extra_type . '_alter';
1130
            if (function_exists($function)) {
1131
              $functions[$cid][] = $function;
1132
            }
1133
          }
1134
        }
1135
      }
1136
    }
1137
  }
1138

    
1139
  foreach ($functions[$cid] as $function) {
1140
    $function($data, $context1, $context2, $context3);
1141
  }
1142
}