bootstrap.inc 87.7 KB
Newer Older
1
<?php
Dries's avatar
   
Dries committed
2
// $Id$
Dries's avatar
   
Dries committed
3

Dries's avatar
   
Dries committed
4
5
6
7
/**
 * @file
 * Functions that need to be loaded on every Drupal request.
 */
Dries's avatar
   
Dries committed
8

9
10
11
/**
 * The current system version.
 */
webchick's avatar
webchick committed
12
define('VERSION', '7.0-dev');
13
14
15
16
17
18
19
20
21
22
23
24
25
26

/**
 * Core API compatibility.
 */
define('DRUPAL_CORE_COMPATIBILITY', '7.x');

/**
 * Minimum supported version of PHP.
 */
define('DRUPAL_MINIMUM_PHP',    '5.2.0');

/**
 * Minimum recommended value of PHP memory_limit.
 */
27
define('DRUPAL_MINIMUM_PHP_MEMORY_LIMIT',    '40M');
28
29
30
31

/**
 * Minimum supported version of MySQL, if it is used.
 */
32
define('DRUPAL_MINIMUM_MYSQL',  '5.0.15');
33
34
35
36
37
38

/**
 * Minimum supported version of PostgreSQL, if it is used.
 */
define('DRUPAL_MINIMUM_PGSQL',  '8.3');

39
/**
40
41
42
 * Indicates that the item should never be removed unless explicitly selected.
 *
 * The item may be removed using cache_clear_all() with a cache ID.
43
 */
44
define('CACHE_PERMANENT', 0);
45
46
47
48

/**
 * Indicates that the item should be removed at the next general cache wipe.
 */
49
define('CACHE_TEMPORARY', -1);
Dries's avatar
   
Dries committed
50

51
52
53
/**
 * Indicates that page caching is disabled.
 */
54
define('CACHE_DISABLED', 0);
55
56
57
58

/**
 * Indicates that page caching is enabled, using "normal" mode.
 */
59
define('CACHE_NORMAL', 1);
60

61
/**
62
 * Log message severity -- Emergency: system is unusable.
63
 *
64
65
 * @see watchdog()
 * @see watchdog_severity_levels()
66
 */
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
define('WATCHDOG_EMERG', 0);

/**
 * Log message severity -- Alert: action must be taken immediately.
 *
 * @see watchdog()
 * @see watchdog_severity_levels()
 */
define('WATCHDOG_ALERT', 1);

/**
 * Log message severity -- Critical: critical conditions.
 *
 * @see watchdog()
 * @see watchdog_severity_levels()
 */
define('WATCHDOG_CRITICAL', 2);

/**
 * Log message severity -- Error: error conditions.
 *
 * @see watchdog()
 * @see watchdog_severity_levels()
 */
define('WATCHDOG_ERROR', 3);

/**
 * Log message severity -- Warning: warning conditions.
 *
 * @see watchdog()
 * @see watchdog_severity_levels()
 */
define('WATCHDOG_WARNING', 4);

/**
 * Log message severity -- Notice: normal but significant condition.
 *
 * @see watchdog()
 * @see watchdog_severity_levels()
 */
define('WATCHDOG_NOTICE', 5);

/**
 * Log message severity -- Informational: informational messages.
 *
 * @see watchdog()
 * @see watchdog_severity_levels()
 */
define('WATCHDOG_INFO', 6);

/**
 * Log message severity -- Debug: debug-level messages.
 *
 * @see watchdog()
 * @see watchdog_severity_levels()
 */
define('WATCHDOG_DEBUG', 7);
124

125
126
127
/**
 * First bootstrap phase: initialize configuration.
 */
128
define('DRUPAL_BOOTSTRAP_CONFIGURATION', 0);
129
130

/**
131
 * Second bootstrap phase: try to serve a cached page.
132
 */
133
define('DRUPAL_BOOTSTRAP_PAGE_CACHE', 1);
134
135
136
137

/**
 * Third bootstrap phase: initialize database layer.
 */
138
define('DRUPAL_BOOTSTRAP_DATABASE', 2);
139
140

/**
141
 * Fourth bootstrap phase: initialize the variable system.
142
 */
143
define('DRUPAL_BOOTSTRAP_VARIABLES', 3);
144
145

/**
146
 * Fifth bootstrap phase: initialize session handling.
147
 */
148
define('DRUPAL_BOOTSTRAP_SESSION', 4);
149
150

/**
151
 * Sixth bootstrap phase: set up the page header.
152
 */
153
define('DRUPAL_BOOTSTRAP_PAGE_HEADER', 5);
154
155

/**
156
 * Seventh bootstrap phase: find out language of the page.
157
 */
158
define('DRUPAL_BOOTSTRAP_LANGUAGE', 6);
159
160
161
162
163

/**
 * Final bootstrap phase: Drupal is fully loaded; validate and fix
 * input data.
 */
164
define('DRUPAL_BOOTSTRAP_FULL', 7);
165

166
167
168
/**
 * Role ID for anonymous users; should match what's in the "role" table.
 */
169
define('DRUPAL_ANONYMOUS_RID', 1);
170
171
172
173

/**
 * Role ID for authenticated users; should match what's in the "role" table.
 */
174
175
define('DRUPAL_AUTHENTICATED_RID', 2);

176
/**
177
 * The number of bytes in a kilobyte. For more information, visit
178
179
180
181
 * http://en.wikipedia.org/wiki/Kilobyte.
 */
define('DRUPAL_KILOBYTE', 1024);

182
183
184
/**
 * The language code used when no language is explicitly assigned.
 *
185
 * Defined by ISO639-2 for "Undetermined".
186
 */
187
define('LANGUAGE_NONE', 'und');
188

189
/**
190
 * The type of language used to define the content language.
191
 */
192
define('LANGUAGE_TYPE_CONTENT', 'language');
193
194

/**
195
 * The type of language used to select the user interface.
196
 */
197
define('LANGUAGE_TYPE_INTERFACE', 'language_interface');
198
199

/**
200
 * The type of language used for URLs.
201
 */
202
define('LANGUAGE_TYPE_URL', 'language_url');
203

204
205
206
207
208
209
210
211
212
213
/**
 * Language written left to right. Possible value of $language->direction.
 */
define('LANGUAGE_LTR', 0);

/**
 * Language written right to left. Possible value of $language->direction.
 */
define('LANGUAGE_RTL', 1);

214
215
216
/**
 * For convenience, define a short form of the request time global.
 */
217
define('REQUEST_TIME', $_SERVER['REQUEST_TIME']);
218

219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
/**
 * @name Title text filtering flags
 * @{
 * Flags for use in drupal_set_title().
 */

/**
 * Flag for drupal_set_title(); text is not sanitized, so run check_plain().
 */
define('CHECK_PLAIN', 0);

/**
 * Flag for drupal_set_title(); text has already been sanitized.
 */
define('PASS_THROUGH', -1);

235
/**
236
 * Signals that the registry lookup cache should be reset.
237
238
239
240
 */
define('REGISTRY_RESET_LOOKUP_CACHE', 1);

/**
241
 * Signals that the registry lookup cache should be written to storage.
242
243
244
 */
define('REGISTRY_WRITE_LOOKUP_CACHE', 2);

245
246
247
248
249
/**
 * @} End of "Title text filtering flags".
 */


Dries's avatar
   
Dries committed
250
/**
251
252
 * Start the timer with the specified name. If you start and stop the same
 * timer multiple times, the measured intervals will be accumulated.
Dries's avatar
   
Dries committed
253
254
255
256
257
258
259
 *
 * @param name
 *   The name of the timer.
 */
function timer_start($name) {
  global $timers;

260
  $timers[$name]['start'] = microtime(TRUE);
261
  $timers[$name]['count'] = isset($timers[$name]['count']) ? ++$timers[$name]['count'] : 1;
Dries's avatar
   
Dries committed
262
263
264
265
266
267
268
269
270
271
272
273
274
}

/**
 * Read the current timer value without stopping the timer.
 *
 * @param name
 *   The name of the timer.
 * @return
 *   The current timer value in ms.
 */
function timer_read($name) {
  global $timers;

275
  if (isset($timers[$name]['start'])) {
276
    $stop = microtime(TRUE);
277
    $diff = round(($stop - $timers[$name]['start']) * 1000, 2);
Dries's avatar
   
Dries committed
278

279
280
281
282
    if (isset($timers[$name]['time'])) {
      $diff += $timers[$name]['time'];
    }
    return $diff;
283
  }
284
  return $timers[$name]['time'];
Dries's avatar
   
Dries committed
285
286
287
288
289
290
291
292
}

/**
 * Stop the timer with the specified name.
 *
 * @param name
 *   The name of the timer.
 * @return
293
294
 *   A timer array. The array contains the number of times the timer has been
 *   started and stopped (count) and the accumulated timer value in ms (time).
Dries's avatar
   
Dries committed
295
296
297
298
 */
function timer_stop($name) {
  global $timers;

299
300
301
302
303
304
  if (isset($timers[$name]['time'])) {
    $timers[$name]['time'] += timer_read($name);
  }
  else {
    $timers[$name]['time'] = timer_read($name);
  }
Dries's avatar
   
Dries committed
305
306
307
308
  unset($timers[$name]['start']);

  return $timers[$name];
}
309

Dries's avatar
   
Dries committed
310
/**
311
 * Find the appropriate configuration directory.
Dries's avatar
   
Dries committed
312
 *
313
314
 * Try finding a matching configuration directory by stripping the website's
 * hostname from left to right and pathname from right to left. The first
315
 * configuration file found will be used; the remaining will ignored. If no
316
 * configuration file is found, return a default value '$confdir/default'.
Dries's avatar
Dries committed
317
 *
318
 * Example for a fictitious site installed at
319
320
 * http://www.drupal.org:8080/mysite/test/ the 'settings.php' is searched in
 * the following directories:
Dries's avatar
   
Dries committed
321
 *
322
323
324
325
 *  1. $confdir/8080.www.drupal.org.mysite.test
 *  2. $confdir/www.drupal.org.mysite.test
 *  3. $confdir/drupal.org.mysite.test
 *  4. $confdir/org.mysite.test
Dries's avatar
   
Dries committed
326
 *
327
328
329
330
 *  5. $confdir/8080.www.drupal.org.mysite
 *  6. $confdir/www.drupal.org.mysite
 *  7. $confdir/drupal.org.mysite
 *  8. $confdir/org.mysite
Dries's avatar
   
Dries committed
331
 *
332
333
334
335
 *  9. $confdir/8080.www.drupal.org
 * 10. $confdir/www.drupal.org
 * 11. $confdir/drupal.org
 * 12. $confdir/org
Dries's avatar
   
Dries committed
336
 *
337
 * 13. $confdir/default
338
 *
339
 * If a file named sites.php is present in the $confdir, it will be loaded
340
341
 * prior to scanning for directories. It should define an associative array
 * named $sites, which maps domains to directories. It should be in the form
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
 * of:
 *
 * $sites = array(
 *   'The url to alias' => 'A directory within the sites directory'
 * );
 *
 * For example:
 *
 * $sites = array(
 *   'devexample.com' => 'example.com',
 *   'localhost/example' => 'example.com',
 * );
 *
 * The above array will cause Drupal to look for a directory named
 * "example.com" in the sites directory whenever a request comes from
 * "example.com", "devexample.com", or "localhost/example". That is useful
 * on development servers, where the domain name may not be the same as the
359
 * domain of the live server. Since Drupal stores file paths into the database
360
361
362
 * (files, system table, etc.) this will ensure the paths are correct while
 * accessed on development servers.
 *
363
364
365
366
367
368
369
370
371
372
 * @param $require_settings
 *   Only configuration directories with an existing settings.php file
 *   will be recognized. Defaults to TRUE. During initial installation,
 *   this is set to FALSE so that Drupal can detect a matching directory,
 *   then create a new settings.php file in it.
 * @param reset
 *   Force a full search for matching directories even if one had been
 *   found previously.
 * @return
 *   The path of the matching directory.
Dries's avatar
   
Dries committed
373
 */
374
function conf_path($require_settings = TRUE, $reset = FALSE) {
375
  $conf = &drupal_static(__FUNCTION__, '');
Dries's avatar
   
Dries committed
376

377
  if ($conf && !$reset) {
Dries's avatar
Dries committed
378
379
    return $conf;
  }
Dries's avatar
   
Dries committed
380

Dries's avatar
   
Dries committed
381
  $confdir = 'sites';
382
383
384
385
386
387
388

  $sites = array();
  if (file_exists(DRUPAL_ROOT . '/' . $confdir . '/sites.php')) {
    // This will overwrite $sites with the desired mappings.
    include(DRUPAL_ROOT . '/' . $confdir . '/sites.php');
  }

389
  $uri = explode('/', $_SERVER['SCRIPT_NAME'] ? $_SERVER['SCRIPT_NAME'] : $_SERVER['SCRIPT_FILENAME']);
390
  $server = explode('.', implode('.', array_reverse(explode(':', rtrim($_SERVER['HTTP_HOST'], '.')))));
Dries's avatar
Dries committed
391
392
393
  for ($i = count($uri) - 1; $i > 0; $i--) {
    for ($j = count($server); $j > 0; $j--) {
      $dir = implode('.', array_slice($server, -$j)) . implode('.', array_slice($uri, 0, $i));
394
395
396
397
      if (isset($sites[$dir]) && file_exists(DRUPAL_ROOT . '/' . $confdir . '/' . $sites[$dir])) {
        $dir = $sites[$dir];
      }
      if (file_exists(DRUPAL_ROOT . '/' . $confdir . '/' . $dir . '/settings.php') || (!$require_settings && file_exists(DRUPAL_ROOT . '/' . $confdir . '/' . $dir))) {
Dries's avatar
Dries committed
398
399
400
        $conf = "$confdir/$dir";
        return $conf;
      }
Dries's avatar
   
Dries committed
401
402
    }
  }
Dries's avatar
Dries committed
403
404
  $conf = "$confdir/default";
  return $conf;
Dries's avatar
   
Dries committed
405
406
}

407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
/**
 * Set appropriate server variables needed for command line scripts to work.
 *
 * This function can be called by command line scripts before bootstrapping
 * Drupal, to ensure that the page loads with the desired server parameters.
 * This is because many parts of Drupal assume that they are running in a web
 * browser and therefore use information from the global PHP $_SERVER variable
 * that does not get set when Drupal is run from the command line.
 *
 * In many cases, the default way in which this function populates the $_SERVER
 * variable is sufficient, and it can therefore be called without passing in
 * any input. However, command line scripts running on a multisite installation
 * (or on any installation that has settings.php stored somewhere other than
 * the sites/default folder) need to pass in the URL of the site to allow
 * Drupal to detect the correct location of the settings.php file. Passing in
 * the 'url' parameter is also required for functions like request_uri() to
 * return the expected values.
 *
 * Most other parameters do not need to be passed in, but may be necessary in
 * some cases; for example, if Drupal's ip_address() function needs to return
 * anything but the standard localhost value ('127.0.0.1'), the command line
 * script should pass in the desired value via the 'REMOTE_ADDR' key.
 *
 * @param $variables
 *   (optional) An associative array of variables within $_SERVER that should
 *   be replaced. If the special element 'url' is provided in this array, it
 *   will be used to populate some of the server defaults; it should be set to
 *   the URL of the current page request, excluding any $_GET request but
 *   including the script name (e.g., http://www.example.com/mysite/index.php).
 *
 * @see conf_path()
 * @see request_uri()
 * @see ip_address()
 */
function drupal_override_server_variables($variables = array()) {
  // Set defaults based on the provided URL.
  if (isset($variables['url'])) {
    $url = parse_url($variables['url']);
    unset($variables['url']);
  }
  else {
    $url = array();
  }
  $url += array(
    'path' => '',
    'host' => 'localhost',
  );
  $defaults = array(
    'HTTP_HOST' => $url['host'],
    'SCRIPT_NAME' => $url['path'],
    'REMOTE_ADDR' => '127.0.0.1',
    'REQUEST_METHOD' => 'GET',
    'SERVER_NAME' => NULL,
460
    'SERVER_SOFTWARE' => NULL,
461
462
463
464
465
466
    'HTTP_USER_AGENT' => NULL,
  );
  // Replace elements of the $_SERVER array, as appropriate.
  $_SERVER = $variables + $_SERVER + $defaults;
}

467
/**
468
 * Initialize PHP environment.
469
 */
470
function drupal_environment_initialize() {
471
472
  if (!isset($_SERVER['HTTP_REFERER'])) {
    $_SERVER['HTTP_REFERER'] = '';
473
  }
474
475
476
  if (!isset($_SERVER['SERVER_PROTOCOL']) || ($_SERVER['SERVER_PROTOCOL'] != 'HTTP/1.0' && $_SERVER['SERVER_PROTOCOL'] != 'HTTP/1.1')) {
    $_SERVER['SERVER_PROTOCOL'] = 'HTTP/1.0';
  }
477

478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
  if (isset($_SERVER['HTTP_HOST'])) {
    // As HTTP_HOST is user input, ensure it only contains characters allowed
    // in hostnames. See RFC 952 (and RFC 2181).
    // $_SERVER['HTTP_HOST'] is lowercased here per specifications.
    $_SERVER['HTTP_HOST'] = strtolower($_SERVER['HTTP_HOST']);
    if (!drupal_valid_http_host($_SERVER['HTTP_HOST'])) {
      // HTTP_HOST is invalid, e.g. if containing slashes it may be an attack.
      header($_SERVER['SERVER_PROTOCOL'] . ' 400 Bad Request');
      exit;
    }
  }
  else {
    // Some pre-HTTP/1.1 clients will not send a Host header. Ensure the key is
    // defined for E_ALL compliance.
    $_SERVER['HTTP_HOST'] = '';
493
494
  }

495
496
497
498
499
500
501
  // When clean URLs are enabled, emulate ?q=foo/bar using REQUEST_URI. It is
  // not possible to append the query string using mod_rewrite without the B
  // flag (this was added in Apache 2.2.8), because mod_rewrite unescapes the
  // path before passing it on to PHP. This is a problem when the path contains
  // e.g. "&" or "%" that have special meanings in URLs and must be encoded.
  $_GET['q'] = request_path();

502
503
  // Enforce E_ALL, but allow users to set levels not part of E_ALL.
  error_reporting(E_ALL | error_reporting());
504

505
506
507
  // Override PHP settings required for Drupal to work properly.
  // sites/default/default.settings.php contains more runtime settings.
  // The .htaccess file contains settings that cannot be changed at runtime.
508

509
  // Prevent PHP from generating HTML error messages.
510
  ini_set('html_errors', 0);
511
  // Don't escape quotes when reading files from the database, disk, etc.
512
  ini_set('magic_quotes_runtime', '0');
513
514
  // Use session cookies, not transparent sessions that puts the session id in
  // the query string.
515
  ini_set('session.use_cookies', '1');
516
  ini_set('session.use_only_cookies', '1');
517
  ini_set('session.use_trans_sid', '0');
518
519
  // Don't send HTTP headers using PHP's session handler.
  ini_set('session.cache_limiter', 'none');
520
521
  // Use httponly session cookies.
  ini_set('session.cookie_httponly', '1');
522
523
}

524
/**
525
 * Validate that a hostname (for example $_SERVER['HTTP_HOST']) is safe.
526
527
528
529
 *
 * @return
 *  TRUE if only containing valid characters, or FALSE otherwise.
 */
530
531
function drupal_valid_http_host($host) {
  return preg_match('/^\[?(?:[a-zA-Z0-9-:\]_]+\.?)+$/', $host);
532
533
}

534
/**
535
536
 * Loads the configuration and sets the base URL, cookie domain, and
 * session name correctly.
537
 */
538
function drupal_settings_initialize() {
539
540
  global $base_url, $base_path, $base_root;

Dries's avatar
Dries committed
541
  // Export the following settings.php variables to the global namespace
542
  global $databases, $db_prefix, $cookie_domain, $conf, $installed_profile, $update_free_access, $db_url, $drupal_hash_salt, $is_https, $base_secure_url, $base_insecure_url;
Dries's avatar
Dries committed
543
544
  $conf = array();

545
546
  if (file_exists(DRUPAL_ROOT . '/' . conf_path() . '/settings.php')) {
    include_once DRUPAL_ROOT . '/' . conf_path() . '/settings.php';
547
  }
548
549
550
551

  if (isset($base_url)) {
    // Parse fixed base URL from settings.php.
    $parts = parse_url($base_url);
552
    $http_protocol = $parts['scheme'];
553
554
555
    if (!isset($parts['path'])) {
      $parts['path'] = '';
    }
556
    $base_path = $parts['path'] . '/';
557
558
559
560
561
    // Build $base_root (everything until first slash after "scheme://").
    $base_root = substr($base_url, 0, strlen($base_url) - strlen($parts['path']));
  }
  else {
    // Create base URL
562
563
    $http_protocol = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == 'on') ? 'https' : 'http';
    $base_root = $http_protocol . '://' . $_SERVER['HTTP_HOST'];
564

565
    $base_url = $base_root;
566
567
568

    // $_SERVER['SCRIPT_NAME'] can, in contrast to $_SERVER['PHP_SELF'], not
    // be modified by a visitor.
569
570
    if ($dir = rtrim(dirname($_SERVER['SCRIPT_NAME']), '\/')) {
      $base_path = $dir;
571
572
573
574
575
576
577
      $base_url .= $base_path;
      $base_path .= '/';
    }
    else {
      $base_path = '/';
    }
  }
578
579
580
  $is_https = $http_protocol == 'https';
  $base_secure_url = str_replace('http://', 'https://', $base_url);
  $base_insecure_url = str_replace('https://', 'http://', $base_url);
581
582
583
584
585
586

  if ($cookie_domain) {
    // If the user specifies the cookie domain, also use it for session name.
    $session_name = $cookie_domain;
  }
  else {
587
588
589
    // Otherwise use $base_url as session name, without the protocol
    // to use the same session identifiers across http and https.
    list( , $session_name) = explode('://', $base_url, 2);
590
591
    // HTTP_HOST can be modified by a visitor, but we already sanitized it
    // in drupal_settings_initialize().
592
    if (!empty($_SERVER['HTTP_HOST'])) {
593
      $cookie_domain = $_SERVER['HTTP_HOST'];
594
595
596
597
598
599
600
    }
  }
  // Strip leading periods, www., and port numbers from cookie domain.
  $cookie_domain = ltrim($cookie_domain, '.');
  if (strpos($cookie_domain, 'www.') === 0) {
    $cookie_domain = substr($cookie_domain, 4);
  }
601
  $cookie_domain = explode(':', $cookie_domain);
602
  $cookie_domain = '.' . $cookie_domain[0];
603
604
605
606
607
  // Per RFC 2109, cookie domains must contain at least one dot other than the
  // first. For hosts such as 'localhost' or IP Addresses we don't set a cookie domain.
  if (count(explode('.', $cookie_domain)) > 2 && !is_numeric(str_replace('.', '', $cookie_domain))) {
    ini_set('session.cookie_domain', $cookie_domain);
  }
608
609
610
611
612
613
614
615
616
617
618
  // To prevent session cookies from being hijacked, a user can configure the
  // SSL version of their website to only transfer session cookies via SSL by
  // using PHP's session.cookie_secure setting. The browser will then use two
  // separate session cookies for the HTTPS and HTTP versions of the site. So we
  // must use different session identifiers for HTTPS and HTTP to prevent a
  // cookie collision.
  if ($is_https) {
    ini_set('session.cookie_secure', TRUE);
  }
  $prefix = ini_get('session.cookie_secure') ? 'SSESS' : 'SESS';
  session_name($prefix . md5($session_name));
619
620
}

Dries's avatar
Dries committed
621
622
/**
 * Returns and optionally sets the filename for a system item (module,
623
 * theme, etc.). The filename, whether provided, cached, or retrieved
Dries's avatar
Dries committed
624
625
 * from the database, is only returned if the file exists.
 *
Dries's avatar
Dries committed
626
627
628
629
630
631
632
633
634
635
636
637
 * This function plays a key role in allowing Drupal's resources (modules
 * and themes) to be located in different places depending on a site's
 * configuration. For example, a module 'foo' may legally be be located
 * in any of these three places:
 *
 * modules/foo/foo.module
 * sites/all/modules/foo/foo.module
 * sites/example.com/modules/foo/foo.module
 *
 * Calling drupal_get_filename('module', 'foo') will give you one of
 * the above, depending on where the module is located.
 *
Dries's avatar
Dries committed
638
 * @param $type
639
 *   The type of the item (i.e. theme, theme_engine, module, profile).
Dries's avatar
Dries committed
640
641
642
643
644
645
646
647
648
 * @param $name
 *   The name of the item for which the filename is requested.
 * @param $filename
 *   The filename of the item if it is to be set explicitly rather
 *   than by consulting the database.
 *
 * @return
 *   The filename of the requested item.
 */
Dries's avatar
Dries committed
649
function drupal_get_filename($type, $name, $filename = NULL) {
650
651
652
  // The location of files will not change during the request, so do not use
  // drupal_static().
  static $files = array();
Dries's avatar
Dries committed
653

654
  if (!isset($files[$type])) {
Dries's avatar
Dries committed
655
656
657
    $files[$type] = array();
  }

658
  if (!empty($filename) && file_exists($filename)) {
Dries's avatar
Dries committed
659
660
    $files[$type][$name] = $filename;
  }
661
  elseif (isset($files[$type][$name])) {
Dries's avatar
Dries committed
662
663
    // nothing
  }
Dries's avatar
Dries committed
664
  // Verify that we have an active database connection, before querying
665
  // the database. This is required because this function is called both
Dries's avatar
Dries committed
666
667
  // before we have a database connection (i.e. during installation) and
  // when a database connection fails.
Dries's avatar
Dries committed
668
  else {
669
    try {
670
671
672
673
674
      if (function_exists('db_query')) {
        $file = db_query("SELECT filename FROM {system} WHERE name = :name AND type = :type", array(':name' => $name, ':type' => $type))->fetchField();
        if (file_exists($file)) {
          $files[$type][$name] = $file;
        }
675
676
      }
    }
677
    catch (Exception $e) {
678
679
680
681
682
683
684
685
686
687
688
      // The database table may not exist because Drupal is not yet installed,
      // or the database might be down. We have a fallback for this case so we
      // hide the error completely.
    }
    // Fallback to searching the filesystem if the database could not find the
    // file or the file returned by the database is not found.
    if (!isset($files[$type][$name])) {
      // We have a consistent directory naming: modules, themes...
      $dir = $type . 's';
      if ($type == 'theme_engine') {
        $dir = 'themes/engines';
689
        $extension = 'engine';
690
691
      }
      elseif ($type == 'theme') {
692
        $extension = 'info';
693
694
      }
      else {
695
        $extension = $type;
696
697
      }

698
699
700
      if (!function_exists('drupal_system_listing')) {
        require_once DRUPAL_ROOT . '/includes/common.inc';
      }
701
702
703
704
705
706
707
      // Scan the appropriate directories for all files with the requested
      // extension, not just the file we are currently looking for. This
      // prevents unnecessary scans from being repeated when this function is
      // called more than once in the same page request.
      $matches = drupal_system_listing("/\.$extension$/", $dir, 'name', 0);
      foreach ($matches as $matched_name => $file) {
        $files[$type][$matched_name] = $file->uri;
Dries's avatar
Dries committed
708
709
710
711
      }
    }
  }

712
713
714
  if (isset($files[$type][$name])) {
    return $files[$type][$name];
  }
Dries's avatar
Dries committed
715
716
}

Dries's avatar
   
Dries committed
717
718
719
720
721
722
723
/**
 * Load the persistent variable table.
 *
 * The variable table is composed of values that have been saved in the table
 * with variable_set() as well as those explicitly specified in the configuration
 * file.
 */
724
function variable_initialize($conf = array()) {
725
  // NOTE: caching the variables improves performance by 20% when serving cached pages.
726
  if ($cached = cache_get('variables', 'cache_bootstrap')) {
727
    $variables = $cached->data;
Dries's avatar
   
Dries committed
728
729
  }
  else {
730
    $variables = array_map('unserialize', db_query('SELECT name, value FROM {variable}')->fetchAllKeyed());
731
    cache_set('variables', $variables, 'cache_bootstrap');
Dries's avatar
   
Dries committed
732
733
734
735
  }

  foreach ($conf as $name => $value) {
    $variables[$name] = $value;
Dries's avatar
   
Dries committed
736
737
  }

Dries's avatar
   
Dries committed
738
  return $variables;
Dries's avatar
   
Dries committed
739
740
}

Dries's avatar
   
Dries committed
741
742
743
744
745
746
747
748
749
/**
 * Return a persistent variable.
 *
 * @param $name
 *   The name of the variable to return.
 * @param $default
 *   The default value to use if this variable has never been set.
 * @return
 *   The value of the variable.
750
751
 *
 * @see variable_del(), variable_set()
Dries's avatar
   
Dries committed
752
 */
753
function variable_get($name, $default = NULL) {
Dries's avatar
   
Dries committed
754
755
756
757
758
  global $conf;

  return isset($conf[$name]) ? $conf[$name] : $default;
}

Dries's avatar
   
Dries committed
759
760
761
762
763
764
765
766
/**
 * Set a persistent variable.
 *
 * @param $name
 *   The name of the variable to set.
 * @param $value
 *   The value to set. This can be any PHP data type; these functions take care
 *   of serialization as necessary.
767
768
 *
 * @see variable_del(), variable_get()
Dries's avatar
   
Dries committed
769
 */
Dries's avatar
   
Dries committed
770
771
772
function variable_set($name, $value) {
  global $conf;

773
  db_merge('variable')->key(array('name' => $name))->fields(array('value' => serialize($value)))->execute();
Dries's avatar
   
Dries committed
774

775
  cache_clear_all('variables', 'cache_bootstrap');
Dries's avatar
   
Dries committed
776
777
778
779

  $conf[$name] = $value;
}

Dries's avatar
   
Dries committed
780
781
782
783
784
/**
 * Unset a persistent variable.
 *
 * @param $name
 *   The name of the variable to undefine.
785
786
 *
 * @see variable_get(), variable_set()
Dries's avatar
   
Dries committed
787
 */
Dries's avatar
   
Dries committed
788
function variable_del($name) {
Dries's avatar
Dries committed
789
790
  global $conf;

791
792
793
  db_delete('variable')
    ->condition('name', $name)
    ->execute();
794
  cache_clear_all('variables', 'cache_bootstrap');
Dries's avatar
   
Dries committed
795

Dries's avatar
Dries committed
796
  unset($conf[$name]);
Dries's avatar
   
Dries committed
797
798
}

Dries's avatar
   
Dries committed
799
800
801
/**
 * Retrieve the current page from the cache.
 *
802
803
804
805
806
 * Note: we do not serve cached pages to authenticated users, or to anonymous
 * users when $_SESSION is non-empty. $_SESSION may contain status messages
 * from a form submission, the contents of a shopping cart, or other user-
 * specific content that should not be cached and displayed to other users.
 *
807
808
809
810
 * @param $check_only
 *   (optional) Set to TRUE to only return whether a previous call found a
 *   cache entry.
 *
811
 * @return
812
 *   The cache object, if the page was found in the cache, NULL otherwise.
Dries's avatar
   
Dries committed
813
 */
814
function drupal_page_get_cache($check_only = FALSE) {
815
  global $base_root;
816
817
818
819
820
  static $cache_hit = FALSE;

  if ($check_only) {
    return $cache_hit;
  }
Dries's avatar
   
Dries committed
821

822
  if (drupal_page_is_cacheable()) {
823
824
825
826
827
    $cache = cache_get($base_root . request_uri(), 'cache_page');
    if ($cache !== FALSE) {
      $cache_hit = TRUE;
    }
    return $cache;
828
  }
829
830
831
832
833
834
}

/**
 * Determine the cacheability of the current page.
 *
 * @param $allow_caching
835
836
 *   Set to FALSE if you want to prevent this page to get cached.
 *
837
 * @return
838
 *   TRUE if the current page can be cached, FALSE otherwise.
839
840
841
842
843
 */
function drupal_page_is_cacheable($allow_caching = NULL) {
  $allow_caching_static = &drupal_static(__FUNCTION__, TRUE);
  if (isset($allow_caching)) {
    $allow_caching_static = $allow_caching;
Dries's avatar
   
Dries committed
844
  }
845
846

  return $allow_caching_static && ($_SERVER['REQUEST_METHOD'] == 'GET' || $_SERVER['REQUEST_METHOD'] == 'HEAD')
847
    && !drupal_is_cli();
Dries's avatar
   
Dries committed
848
849
}

850
851
852
853
854
855
856
/**
 * Call all init or exit hooks without including all modules.
 *
 * @param $hook
 *   The name of the bootstrap hook we wish to invoke.
 */
function bootstrap_invoke_all($hook) {
857
858
859
  // _drupal_bootstrap_page_cache() already loaded the bootstrap modules, so we
  // don't need to tell module_list() to reset its bootstrap list.
  foreach (module_list(FALSE, TRUE) as $module) {
860
861
862
863
864
    drupal_load('module', $module);
    module_invoke($module, $hook);
  }
}

Dries's avatar
Dries committed
865
/**
866
 * Includes a file with the provided type and name. This prevents
Dries's avatar
Dries committed
867
868
869
870
871
872
873
874
875
876
877
 * including a theme, engine, module, etc., more than once.
 *
 * @param $type
 *   The type of item to load (i.e. theme, theme_engine, module).
 * @param $name
 *   The name of the item to load.
 *
 * @return
 *   TRUE if the item is loaded or has already been loaded.
 */
function drupal_load($type, $name) {
878
879
880
  // Once a file is included this can't be reversed during a request so do not
  // use drupal_static() here.
  static $files = array();
Dries's avatar
Dries committed
881

882
  if (isset($files[$type][$name])) {
Dries's avatar
Dries committed
883
884
885
886
887
888
    return TRUE;
  }

  $filename = drupal_get_filename($type, $name);

  if ($filename) {
889
    include_once DRUPAL_ROOT . '/' . $filename;
Dries's avatar
Dries committed
890
891
892
893
894
895
896
897
    $files[$type][$name] = TRUE;

    return TRUE;
  }

  return FALSE;
}

898
899
900
901
902
903
904
905
906
907
908
909
910
911
/**
 * Set an HTTP response header for the current page.
 *
 * Note: When sending a Content-Type header, always include a 'charset' type,
 * too. This is necessary to avoid security bugs (e.g. UTF-7 XSS).
 *
 * @param $name
 *   The HTTP header name, or a status code followed by a reason phrase, e.g.
 *   "404 Not Found".
 * @param $value
 *   The HTTP header value; if omitted, the specified header is unset.
 * @param $append
 *   Whether to append the value to an existing header or to replace it.
 */
912
function drupal_add_http_header($name = NULL, $value = NULL, $append = FALSE) {
913
914
915
916
917
918
919
920
921
922
  // The headers as name/value pairs.
  $headers = &drupal_static(__FUNCTION__, array());

  if (!isset($name)) {
    return $headers;
  }

  // Save status codes using the special key ":status".
  if (preg_match('/^\d{3} /', $name)) {
    $value = $name;
923
    $name = $name_lower = ':status';
924
925
  }
  else {
926
    $name_lower = strtolower($name);
927
  }
928
  _drupal_set_preferred_header_name($name);
929
930

  if (!isset($value)) {
931
    $headers[$name_lower] = FALSE;
932
  }
933
  elseif (isset($headers[$name_lower]) && $append) {
934
935
    // Multiple headers with identical names may be combined using comma (RFC
    // 2616, section 4.2).
936
    $headers[$name_lower] .= ',' . $value;
937
938
  }
  else {
939
    $headers[$name_lower] = $value;
940
  }
941
  drupal_send_headers(array($name => $headers[$name_lower]), TRUE);
942
943
944
945
946
947
948
949
950
951
952
953
}

/**
 * Get the HTTP response headers for the current page.
 *
 * @param $name
 *   An HTTP header name. If omitted, all headers are returned as name/value
 *   pairs. If an array value is FALSE, the header has been unset.
 * @return
 *   A string containing the header value, or FALSE if the header has been set,
 *   or NULL if the header has not been set.
 */
954
955
function drupal_get_http_header($name = NULL) {
  $headers = drupal_add_http_header();
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
  if (isset($name)) {
    $name = strtolower($name);
    return isset($headers[$name]) ? $headers[$name] : NULL;
  }
  else {
    return $headers;
  }
}

/**
 * Header names are case-insensitive, but for maximum compatibility they should
 * follow "common form" (see RFC 2617, section 4.2).
 */
function _drupal_set_preferred_header_name($name = NULL) {
  static $header_names = array();

  if (!isset($name)) {
    return $header_names;
  }
  $header_names[strtolower($name)] = $name;
}

/**
979
 * Send the HTTP response headers previously set using drupal_add_http_header().
980
 * Add default headers, unless they have been replaced or unset using
981
 * drupal_add_http_header().
982
983
984
985
986
987
988
989
 *
 * @param $default_headers
 *   An array of headers as name/value pairs.
 * @param $single
 *   If TRUE and headers have already be sent, send only the specified header.
 */
function drupal_send_headers($default_headers = array(), $only_default = FALSE) {
  $headers_sent = &drupal_static(__FUNCTION__, FALSE);
990
  $headers = drupal_get_http_header();
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
  if ($only_default && $headers_sent) {
    $headers = array();
  }
  $headers_sent = TRUE;

  $header_names = _drupal_set_preferred_header_name();
  foreach ($default_headers as $name => $value) {
    $name_lower = strtolower($name);
    if (!isset($headers[$name_lower])) {
      $headers[$name_lower] = $value;
      $header_names[$name_lower] = $name;
    }
  }
  foreach ($headers as $name_lower => $value) {
    if ($name_lower == ':status') {
      header($_SERVER['SERVER_PROTOCOL'] . ' ' . $value);
    }
    // Skip headers that have been unset.
    elseif ($value) {
      header($header_names[$name_lower] . ': ' . $value);
    }
  }
}

Dries's avatar
   
Dries committed
1015
1016
/**
 * Set HTTP headers in preparation for a page response.
1017
 *
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
 * Authenticated users are always given a 'no-cache' header, and will fetch a
 * fresh page on every request. This prevents authenticated users from seeing
 * locally cached pages.
 *
 * Also give each page a unique ETag. This will force clients to include both
 * an If-Modified-Since header and an If-None-Match header when doing
 * conditional requests for the page (required by RFC 2616, section 13.3.4),
 * making the validation more robust. This is a workaround for a bug in Mozilla
 * Firefox that is triggered when Drupal's caching is enabled and the user
 * accesses Drupal via an HTTP proxy (see
 * https://bugzilla.mozilla.org/show_bug.cgi?id=269303): When an authenticated
 * user requests a page, and then logs out and requests the same page again,
 * Firefox may send a conditional request based on the page that was cached
 * locally when the user was logged in. If this page did not have an ETag
 * header, the request only contains an If-Modified-Since header. The date will
 * be recent, because with authenticated users the Last-Modified header always
 * refers to the time of the request. If the user accesses Drupal via a proxy
 * server, and the proxy already has a cached copy of the anonymous page with an
 * older Last-Modified date, the proxy may respond with 304 Not Modified, making
 * the client think that the anonymous and authenticated pageviews are
 * identical.
1039
 *
1040
 * @see drupal_page_set_cache()
Dries's avatar
   
Dries committed
1041
 */
Dries's avatar
   
Dries committed
1042
function drupal_page_header() {
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
  $headers_sent = &drupal_static(__FUNCTION__, FALSE);
  if ($headers_sent) {
    return TRUE;
  }
  $headers_sent = TRUE;

  $default_headers = array(
    'Expires' => 'Sun, 19 Nov 1978 05:00:00 GMT',
    'Last-Modified' => gmdate(DATE_RFC1123, REQUEST_TIME),
    'Cache-Control' => 'no-cache, must-revalidate, post-check=0, pre-check=0',
    'ETag' => '"' . REQUEST_TIME . '"',
  );
  drupal_send_headers($default_headers);
1056
}
Dries's avatar
   
Dries committed
1057

1058
1059
1060
/**
 * Set HTTP headers in preparation for a cached page response.
 *
1061
1062
 * The headers allow as much as possible in proxies and browsers without any
 * particular knowledge about the pages. Modules can override these headers
1063
 * using drupal_add_http_header().
1064
 *
1065
1066
1067
1068
 * If the request is conditional (using If-Modified-Since and If-None-Match),
 * and the conditions match those currently in the cache, a 304 Not Modified
 * response is sent.
 */
1069
function drupal_serve_page_from_cache(stdClass $cache) {
1070
1071
1072
1073
1074
  // Negotiate whether to use compression.
  $page_compression = variable_get('page_compression', TRUE) && extension_loaded('zlib');
  $return_compressed = $page_compression && isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE;

  // Get headers set in hook_boot(). Keys are lower-case.
1075
  $hook_boot_headers = drupal_get_http_header();
1076
1077

  // Headers generated in this function, that may be replaced or unset using
1078
  // drupal_add_http_headers(). Keys are mixed-case.
1079
1080
1081
1082
1083
1084
1085
1086
  $default_headers = array();

  foreach ($cache->headers as $name => $value) {
    // In the case of a 304 response, certain headers must be sent, and the
    // remaining may not (see RFC 2616, section 10.3.5). Do not override
    // headers set in hook_boot().
    $name_lower = strtolower($name);
    if (in_array($name_lower, array('content-location', 'expires', 'cache-control', 'vary')) && !isset($hook_boot_headers[$name_lower])) {
1087
      drupal_add_http_header($name, $value);
1088
1089
1090
1091
1092
1093
      unset($cache->headers[$name]);
    }
  }

  // If a cache is served from a HTTP proxy without hitting the web server,
  // the boot and exit hooks cannot be fired, so only allow caching in
1094
1095
  // proxies if boot hooks are disabled. If the client send a session cookie,
  // do not bother caching the page in a public proxy, because the cached copy
1096
1097
  // will only be served to that particular user due to Vary: Cookie, unless
  // the Vary header has been replaced or unset in hook_boot() (see below).
1098
  $max_age = !variable_get('page_cache_invoke_hooks', TRUE) && (!isset($_COOKIE[session_name()]) || isset($hook_boot_headers['vary'])) ? variable_get('cache_lifetime', 0) : 0;
1099
1100
1101
1102
1103
  $default_headers['Cache-Control'] = 'public, max-age=' . $max_age;

  // Entity tag should change if the output changes.
  $etag = '"' . $cache->created . '-' . intval($return_compressed) . '"';
  header('Etag: ' . $etag);
1104

1105
1106
  // See if the client has provided the required HTTP headers.
  $if_modified_since = isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) ? strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) : FALSE;
1107
1108
1109
1110
  $if_none_match = isset($_SERVER['HTTP_IF_NONE_MATCH']) ? stripslashes($_SERVER['HTTP_IF_NONE_MATCH']) : FALSE;

  if ($if_modified_since && $if_none_match
      && $if_none_match == $etag // etag must match
1111
      && $if_modified_since == $cache->created) {  // if-modified-since must match
1112
    header($_SERVER['SERVER_PROTOCOL'] . ' 304 Not Modified');
1113
    drupal_send_headers($default_headers);
1114
    return;
1115
  }
1116

1117
1118
  // Send the remaining headers.
  foreach ($cache->headers as $name => $value) {
1119
    drupal_add_http_header($name, $value);
1120
  }
1121

1122
  $default_headers['Last-Modified'] = gmdate(DATE_RFC1123, $cache->created);
1123

1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
  // HTTP/1.0 proxies does not support the Vary header, so prevent any caching
  // by sending an Expires date in the past. HTTP/1.1 clients ignores the
  // Expires header if a Cache-Control: max-age= directive is specified (see RFC
  // 2616, section 14.9.3).
  $default_headers['Expires'] = 'Sun, 19 Nov 1978 05:00:00 GMT';

  drupal_send_headers($default_headers);

  // Allow HTTP proxies to cache pages for anonymous users without a session
  // cookie. The Vary header is used to indicates the set of request-header
  // fields that fully determines whether a cache is permitted to use the
  // response to reply to a subsequent request for a given URL without
  // revalidation. If a Vary header has been set in hook_boot(), it is assumed
  // that the module knows how to cache the page.
  if (!isset($hook_boot_headers['vary']) && !variable_get('omit_vary_cookie')) {
    header('Vary: Cookie');
Dries's avatar
   
Dries committed
1140
  }
1141

1142
1143
1144
1145
  if ($page_compression) {
    header('Vary: Accept-Encoding', FALSE);
    // If page_compression is enabled, the cache contains gzipped data.
    if ($return_compressed) {
1146
1147
1148
      // $cache->data is already gzip'ed, so make sure zlib.output_compression
      // does not compress it once more.
      ini_set('zlib.output_compression', '0');
1149
1150
1151
1152
1153
1154
1155
      header('Content-Encoding: gzip');
    }
    else {
      // The client does not support compression, so unzip the data in the
      // cache. Strip the gzip header and run uncompress.
      $cache->data = gzinflate(substr(substr($cache->data, 10), 0, -8));
    }
1156
1157
1158
  }

  print $cache->data;
Dries's avatar
   
Dries committed
1159
1160
}

1161
1162
1163
1164
1165
1166
1167
/**
 * Define the critical hooks that force modules to always be loaded.
 */
function bootstrap_hooks() {
  return array('boot', 'exit', 'watchdog');
}

Dries's avatar
   
Dries committed
1168
1169
1170
1171
1172
1173
1174
1175
/**
 * Unserializes and appends elements from a serialized string.
 *
 * @param $obj
 *   The object to which the elements are appended.
 * @param $field
 *   The attribute of $obj whose value should be unserialized.
 */
Dries's avatar
   
Dries committed
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
function drupal_unpack($obj, $field = 'data') {
  if ($obj->$field && $data = unserialize($obj->$field)) {
    foreach ($data as $key => $value) {
      if (!isset($obj->$key)) {
        $obj->$key = $value;
      }
    }
  }
  return $obj;
}

1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
/**
 * Translate strings to the page language or a given language.
 *
 * Human-readable text that will be displayed somewhere within a page should
 * be run through the t() function.
 *
 * Examples:
 * @code
 *   if (!$info || !$info['extension']) {
 *     form_set_error('picture_upload', t('The uploaded file was not an image.'));
 *   }
 *
 *   $form['submit'] = array(
 *     '#type' => 'submit',
 *     '#value' => t('Log in'),
 *   );
 * @endcode
 *
 * Any text within t() can be extracted by translators and changed into
 * the equivalent text in their native language.
 *
 * Special variables called "placeholders" are used to signal dynamic
 * information in a string which should not be translated. Placeholders
 * can also be used for text that may change from time to time (such as
 *