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41 results

bootstrap.inc

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  • Dries's avatar
    - Patch #1222194 by Gábor Hojtsy, plach: rename global to ().
    Dries Buytaert authored
    a58940f1
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    bootstrap.inc 115.06 KiB
    <?php
    
    use Symfony\Component\ClassLoader\UniversalClassLoader;
    use Symfony\Component\ClassLoader\ApcUniversalClassLoader;
    
    /**
     * @file
     * Functions that need to be loaded on every Drupal request.
     */
    
    /**
     * The current system version.
     */
    const VERSION = '8.0-dev';
    
    /**
     * Core API compatibility.
     */
    const DRUPAL_CORE_COMPATIBILITY = '8.x';
    
    /**
     * Minimum supported version of PHP.
     */
    const DRUPAL_MINIMUM_PHP = '5.3.2';
    
    /**
     * Minimum recommended value of PHP memory_limit.
     */
    const DRUPAL_MINIMUM_PHP_MEMORY_LIMIT = '32M';
    
    /**
     * Indicates that the item should never be removed unless explicitly selected.
     *
     * The item may be removed using cache()->delete() with a cache ID.
     */
    const CACHE_PERMANENT = 0;
    
    /**
     * Indicates that the item should be removed at the next general cache wipe.
     */
    const CACHE_TEMPORARY = -1;
    
    /**
     * @defgroup logging_severity_levels Logging severity levels
     * @{
     * Logging severity levels as defined in RFC 3164.
     *
     * The WATCHDOG_* constant definitions correspond to the logging severity levels
     * defined in RFC 3164, section 4.1.1. PHP supplies predefined LOG_* constants
     * for use in the syslog() function, but their values on Windows builds do not
     * correspond to RFC 3164. The associated PHP bug report was closed with the
     * comment, "And it's also not a bug, as Windows just have less log levels,"
     * and "So the behavior you're seeing is perfectly normal."
     *
     * @see http://www.faqs.org/rfcs/rfc3164.html
     * @see http://bugs.php.net/bug.php?id=18090
     * @see http://php.net/manual/function.syslog.php
     * @see http://php.net/manual/network.constants.php
     * @see watchdog()
     * @see watchdog_severity_levels()
     */
    
    /**
     * Log message severity -- Emergency: system is unusable.
     */
    const WATCHDOG_EMERGENCY = 0;
    
    /**
     * Log message severity -- Alert: action must be taken immediately.
     */
    const WATCHDOG_ALERT = 1;
    
    /**
     * Log message severity -- Critical: critical conditions.
     */
    const WATCHDOG_CRITICAL = 2;
    
    /**
     * Log message severity -- Error: error conditions.
     */
    const WATCHDOG_ERROR = 3;
    
    /**
     * Log message severity -- Warning: warning conditions.
     */
    const WATCHDOG_WARNING = 4;
    
    /**
     * Log message severity -- Notice: normal but significant condition.
     */
    const WATCHDOG_NOTICE = 5;
    
    /**
     * Log message severity -- Informational: informational messages.
     */
    const WATCHDOG_INFO = 6;
    
    /**
     * Log message severity -- Debug: debug-level messages.
     */
    const WATCHDOG_DEBUG = 7;
    
    /**
     * @} End of "defgroup logging_severity_levels".
     */
    
    /**
     * First bootstrap phase: initialize configuration.
     */
    const DRUPAL_BOOTSTRAP_CONFIGURATION = 0;
    
    /**
     * Second bootstrap phase: try to serve a cached page.
     */
    const DRUPAL_BOOTSTRAP_PAGE_CACHE = 1;
    
    /**
     * Third bootstrap phase: initialize database layer.
     */
    const DRUPAL_BOOTSTRAP_DATABASE = 2;
    
    /**
     * Fourth bootstrap phase: initialize the variable system.
     */
    const DRUPAL_BOOTSTRAP_VARIABLES = 3;
    
    /**
     * Fifth bootstrap phase: initialize session handling.
     */
    const DRUPAL_BOOTSTRAP_SESSION = 4;
    
    /**
     * Sixth bootstrap phase: set up the page header.
     */
    const DRUPAL_BOOTSTRAP_PAGE_HEADER = 5;
    
    /**
     * Seventh bootstrap phase: find out language of the page.
     */
    const DRUPAL_BOOTSTRAP_LANGUAGE = 6;
    
    /**
     * Final bootstrap phase: Drupal is fully loaded; validate and fix input data.
     */
    const DRUPAL_BOOTSTRAP_FULL = 7;
    
    /**
     * Role ID for anonymous users; should match what's in the "role" table.
     */
    const DRUPAL_ANONYMOUS_RID = 1;
    
    /**
     * Role ID for authenticated users; should match what's in the "role" table.
     */
    const DRUPAL_AUTHENTICATED_RID = 2;
    
    /**
     * The number of bytes in a kilobyte.
     *
     * For more information, visit http://en.wikipedia.org/wiki/Kilobyte.
     */
    const DRUPAL_KILOBYTE = 1024;
    
    /**
     * System language (only applicable to UI).
     *
     * Refers to the language used in Drupal and module/theme source code.
     */
    const LANGUAGE_SYSTEM = 'system';
    
    /**
     * The language code used when no language is explicitly assigned.
     *
     * Defined by ISO639-2 for "Undetermined".
     */
    const LANGUAGE_NONE = 'und';
    
    /**
     * The type of language used to define the content language.
     */
    const LANGUAGE_TYPE_CONTENT = 'language_content';
    
    /**
     * The type of language used to select the user interface.
     */
    const LANGUAGE_TYPE_INTERFACE = 'language_interface';
    
    /**
     * The type of language used for URLs.
     */
    const LANGUAGE_TYPE_URL = 'language_url';
    
    /**
     * Language written left to right. Possible value of $language->direction.
     */
    const LANGUAGE_LTR = 0;
    
    /**
     * Language written right to left. Possible value of $language->direction.
     */
    const LANGUAGE_RTL = 1;
    
    /**
     * Time of the current request in seconds elapsed since the Unix Epoch.
     *
     * This differs from $_SERVER['REQUEST_TIME'], which is stored as a float
     * since PHP 5.4.0. Float timestamps confuse most PHP functions
     * (including date_create()).
     *
     * @see http://php.net/manual/reserved.variables.server.php
     * @see http://php.net/manual/function.time.php
     */
    define('REQUEST_TIME', (int) $_SERVER['REQUEST_TIME']);
    
    /**
     * Flag for drupal_set_title(); text is not sanitized, so run check_plain().
     */
    const CHECK_PLAIN = 0;
    
    /**
     * Flag for drupal_set_title(); text has already been sanitized.
     */
    const PASS_THROUGH = -1;
    
    /**
     * Signals that the registry lookup cache should be reset.
     */
    const REGISTRY_RESET_LOOKUP_CACHE = 1;
    
    /**
     * Signals that the registry lookup cache should be written to storage.
     */
    const REGISTRY_WRITE_LOOKUP_CACHE = 2;
    
    /**
     * Regular expression to match PHP function names.
     *
     * @see http://php.net/manual/en/language.functions.php
     */
    const DRUPAL_PHP_FUNCTION_PATTERN = '[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*';
    
    /**
     * Provides a caching wrapper to be used in place of large array structures.
     *
     * This class should be extended by systems that need to cache large amounts
     * of data and have it represented as an array to calling functions. These
     * arrays can become very large, so ArrayAccess is used to allow different
     * strategies to be used for caching internally (lazy loading, building caches
     * over time etc.). This can dramatically reduce the amount of data that needs
     * to be loaded from cache backends on each request, and memory usage from
     * static caches of that same data.
     *
     * Note that array_* functions do not work with ArrayAccess. Systems using
     * DrupalCacheArray should use this only internally. If providing API functions
     * that return the full array, this can be cached separately or returned
     * directly. However since DrupalCacheArray holds partial content by design, it
     * should be a normal PHP array or otherwise contain the full structure.
     *
     * Note also that due to limitations in PHP prior to 5.3.4, it is impossible to
     * write directly to the contents of nested arrays contained in this object.
     * Only writes to the top-level array elements are possible. So if you
     * previously had set $object['foo'] = array(1, 2, 'bar' => 'baz'), but later
     * want to change the value of 'bar' from 'baz' to 'foobar', you cannot do so
     * a targeted write like $object['foo']['bar'] = 'foobar'. Instead, you must
     * overwrite the entire top-level 'foo' array with the entire set of new
     * values: $object['foo'] = array(1, 2, 'bar' => 'foobar'). Due to this same
     * limitation, attempts to create references to any contained data, nested or
     * otherwise, will fail silently. So $var = &$object['foo'] will not throw an
     * error, and $var will be populated with the contents of $object['foo'], but
     * that data will be passed by value, not reference. For more information on
     * the PHP limitation, see the note in the official PHP documentation at·
     * http://php.net/manual/en/arrayaccess.offsetget.php on
     * ArrayAccess::offsetGet().
     *
     * By default, the class accounts for caches where calling functions might
     * request keys in the array that won't exist even after a cache rebuild. This
     * prevents situations where a cache rebuild would be triggered over and over
     * due to a 'missing' item. These cases are stored internally as a value of
     * NULL. This means that the offsetGet() and offsetExists() methods
     * must be overridden if caching an array where the top level values can
     * legitimately be NULL, and where $object->offsetExists() needs to correctly
     * return (equivalent to array_key_exists() vs. isset()). This should not
     * be necessary in the majority of cases.
     *
     * Classes extending this class must override at least the
     * resolveCacheMiss() method to have a working implementation.
     *
     * offsetSet() is not overridden by this class by default. In practice this
     * means that assigning an offset via arrayAccess will only apply while the
     * object is in scope and will not be written back to the persistent cache.
     * This follows a similar pattern to static vs. persistent caching in
     * procedural code. Extending classes may wish to alter this behaviour, for
     * example by overriding offsetSet() and adding an automatic call to persist().
     *
     * @see SchemaCache
     */
    abstract class DrupalCacheArray implements ArrayAccess {
    
      /**
       * A cid to pass to cache()->set() and cache()->get().
       */
      protected $cid;
    
      /**
       * A bin to pass to cache()->set() and cache()->get().
       */
      protected $bin;
    
      /**
       * An array of keys to add to the cache at the end of the request.
       */
      protected $keysToPersist = array();
    
      /**
       * Storage for the data itself.
       */
      protected $storage = array();
    
      /**
       * Constructs a DrupalCacheArray object.
       *
       * @param $cid
       *   The cid for the array being cached.
       * @param $bin
       *   The bin to cache the array.
       */
      public function __construct($cid, $bin) {
        $this->cid = $cid;
        $this->bin = $bin;
    
        if ($cached = cache($bin)->get($this->cid)) {
         $this->storage = $cached->data;
        }
      }
    
      /**
       * Implements ArrayAccess::offsetExists().
       */
      public function offsetExists($offset) {
        return $this->offsetGet($offset) !== NULL;
      }
    
      /**
       * Implements ArrayAccess::offsetGet().
       */
      public function offsetGet($offset) {
        if (isset($this->storage[$offset]) || array_key_exists($offset, $this->storage)) {
          return $this->storage[$offset];
        }
        else {
          return $this->resolveCacheMiss($offset);
        }
      }
    
      /**
       * Implements ArrayAccess::offsetSet().
       */
      public function offsetSet($offset, $value) {
        $this->storage[$offset] = $value;
      }
    
      /**
       * Implements ArrayAccess::offsetUnset().
       */
      public function offsetUnset($offset) {
        unset($this->storage[$offset]);
      }
    
      /**
       * Flags an offset value to be written to the persistent cache.
       *
       * If a value is assigned to a cache object with offsetSet(), by default it
       * will not be written to the persistent cache unless it is flagged with this
       * method. This allows items to be cached for the duration of a request,
       * without necessarily writing back to the persistent cache at the end.
       *
       * @param $offset
       *   The array offset that was request.
       * @param $persist
       *   Optional boolean to specify whether the offset should be persisted or
       *   not, defaults to TRUE. When called with $persist = FALSE the offset will
       *   be unflagged so that it will not written at the end of the request.
       */
      protected function persist($offset, $persist = TRUE) {
        $this->keysToPersist[$offset] = $persist;
      }
    
      /**
       * Resolves a cache miss.
       *
       * When an offset is not found in the object, this is treated as a cache
       * miss. This method allows classes implementing the interface to look up
       * the actual value and allow it to be cached.
       *
       * @param $offset
       *   The offset that was requested.
       *
       * @return
       *   The value of the offset, or NULL if no value was found.
       */
      abstract protected function resolveCacheMiss($offset);
    
      /**
       * Writes a value to the persistent cache immediately.
       *
       * @param $data
       *   The data to write to the persistent cache.
       * @param $lock
       *   Whether to acquire a lock before writing to cache.
       */
      protected function set($data, $lock = TRUE) {
        // Lock cache writes to help avoid stampedes.
        // To implement locking for cache misses, override __construct().
        $lock_name = $this->cid . ':' . $this->bin;
        if (!$lock || lock_acquire($lock_name)) {
          if ($cached = cache($this->bin)->get($this->cid)) {
            $data = $cached->data + $data;
          }
          cache($this->bin)->set($this->cid, $data);
          if ($lock) {
            lock_release($lock_name);
          }
        }
      }
    
      /**
       * Destructs the DrupalCacheArray object.
       */
      public function __destruct() {
        $data = array();
        foreach ($this->keysToPersist as $offset => $persist) {
          if ($persist) {
            $data[$offset] = $this->storage[$offset];
          }
        }
        if (!empty($data)) {
          $this->set($data);
        }
      }
    }
    
    /**
     * Starts the timer with the specified name.
     *
     * If you start and stop the same timer multiple times, the measured intervals
     * will be accumulated.
     *
     * @param $name
     *   The name of the timer.
     */
    function timer_start($name) {
      global $timers;
    
      $timers[$name]['start'] = microtime(TRUE);
      $timers[$name]['count'] = isset($timers[$name]['count']) ? ++$timers[$name]['count'] : 1;
    }
    
    /**
     * Reads 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;
    
      if (isset($timers[$name]['start'])) {
        $stop = microtime(TRUE);
        $diff = round(($stop - $timers[$name]['start']) * 1000, 2);
    
        if (isset($timers[$name]['time'])) {
          $diff += $timers[$name]['time'];
        }
        return $diff;
      }
      return $timers[$name]['time'];
    }
    
    /**
     * Stops the timer with the specified name.
     *
     * @param $name
     *   The name of the timer.
     *
     * @return
     *   A timer array. The array contains the number of times the timer has been
     *   started and stopped (count) and the accumulated timer value in ms (time).
     */
    function timer_stop($name) {
      global $timers;
    
      if (isset($timers[$name]['start'])) {
        $stop = microtime(TRUE);
        $diff = round(($stop - $timers[$name]['start']) * 1000, 2);
        if (isset($timers[$name]['time'])) {
          $timers[$name]['time'] += $diff;
        }
        else {
          $timers[$name]['time'] = $diff;
        }
        unset($timers[$name]['start']);
      }
    
      return $timers[$name];
    }
    
    /**
     * Finds the appropriate configuration directory.
     *
     * Finds a matching configuration directory by stripping the website's
     * hostname from left to right and pathname from right to left. The first
     * configuration file found will be used and the remaining ones will be ignored.
     * If no configuration file is found, return a default value '$confdir/default'.
     *
     * With a site located at http://www.example.com:8080/mysite/test/, the file,
     * settings.php, is searched for in the following directories:
     *
     * - $confdir/8080.www.example.com.mysite.test
     * - $confdir/www.example.com.mysite.test
     * - $confdir/example.com.mysite.test
     * - $confdir/com.mysite.test
     *
     * - $confdir/8080.www.example.com.mysite
     * - $confdir/www.example.com.mysite
     * - $confdir/example.com.mysite
     * - $confdir/com.mysite
     *
     * - $confdir/8080.www.example.com
     * - $confdir/www.example.com
     * - $confdir/example.com
     * - $confdir/com
     *
     * - $confdir/default
     *
     * If a file named sites.php is present in the $confdir, it will be loaded
     * prior to scanning for directories. It should define an associative array
     * named $sites, which maps domains to directories. It should be in the form
     * of:
     * @code
     * $sites = array(
     *   'The url to alias' => 'A directory within the sites directory'
     * );
     * @endcode
     * For example:
     * @code
     * $sites = array(
     *   'devexample.com' => 'example.com',
     *   'localhost.example' => 'example.com',
     * );
     * @endcode
     * 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
     * domain of the live server. Since Drupal stores file paths into the database
     * (files, system table, etc.) this will ensure the paths are correct while
     * accessed on development servers.
     *
     * @param bool $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 bool $reset
     *   Force a full search for matching directories even if one had been
     *   found previously. Defaults to FALSE.
     *
     * @return
     *   The path of the matching directory.
     */
    function conf_path($require_settings = TRUE, $reset = FALSE) {
      $conf = &drupal_static(__FUNCTION__, '');
    
      if ($conf && !$reset) {
        return $conf;
      }
    
      $script_name = $_SERVER['SCRIPT_NAME'];
      if (!$script_name) {
        $script_name = $_SERVER['SCRIPT_FILENAME'];
      }
      $http_host = $_SERVER['HTTP_HOST'];
      $conf = find_conf_path($http_host, $script_name, $require_settings);
      return $conf;
    }
    
    /**
     * Finds the appropriate configuration directory for a given host and path.
     *
     * @param $http_host
     *   The hostname and optional port number, e.g. "www.example.com" or
     *   "www.example.com:8080".
     * @param $script_name
     *   The part of the url following the hostname, including the leading slash.
     *
     * @return
     *   The path of the matching configuration directory.
     *
     * @see conf_path()
     */
    function find_conf_path($http_host, $script_name, $require_settings = TRUE) {
      $confdir = 'sites';
    
      $sites = array();
      if (file_exists(DRUPAL_ROOT . '/' . $confdir . '/sites.php')) {
        // This will overwrite $sites with the desired mappings.
        include(DRUPAL_ROOT . '/' . $confdir . '/sites.php');
      }
    
      $uri = explode('/', $script_name);
      $server = explode('.', implode('.', array_reverse(explode(':', rtrim($http_host, '.')))));
      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, $i));
          if (isset($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))) {
            $conf = "$confdir/$dir";
            return $conf;
          }
        }
      }
      $conf = "$confdir/default";
      return $conf;
    }
    
    /**
     * Sets 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()) {
      // Allow the provided URL to override any existing values in $_SERVER.
      if (isset($variables['url'])) {
        $url = parse_url($variables['url']);
        if (isset($url['host'])) {
          $_SERVER['HTTP_HOST'] = $url['host'];
        }
        if (isset($url['path'])) {
          $_SERVER['SCRIPT_NAME'] = $url['path'];
        }
        unset($variables['url']);
      }
      // Define default values for $_SERVER keys. These will be used if $_SERVER
      // does not already define them and no other values are passed in to this
      // function.
      $defaults = array(
        'HTTP_HOST' => 'localhost',
        'SCRIPT_NAME' => NULL,
        'REMOTE_ADDR' => '127.0.0.1',
        'REQUEST_METHOD' => 'GET',
        'SERVER_NAME' => NULL,
        'SERVER_SOFTWARE' => NULL,
        'HTTP_USER_AGENT' => NULL,
      );
      // Replace elements of the $_SERVER array, as appropriate.
      $_SERVER = $variables + $_SERVER + $defaults;
    }
    
    /**
     * Initializes the PHP environment.
     */
    function drupal_environment_initialize() {
      if (!isset($_SERVER['HTTP_REFERER'])) {
        $_SERVER['HTTP_REFERER'] = '';
      }
      if (!isset($_SERVER['SERVER_PROTOCOL']) || ($_SERVER['SERVER_PROTOCOL'] != 'HTTP/1.0' && $_SERVER['SERVER_PROTOCOL'] != 'HTTP/1.1')) {
        $_SERVER['SERVER_PROTOCOL'] = 'HTTP/1.0';
      }
    
      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'] = '';
      }
    
      // 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();
    
      // Enforce E_STRICT, but allow users to set levels not part of E_STRICT.
      error_reporting(E_STRICT | E_ALL | error_reporting());
    
      // 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.
    
      // Don't escape quotes when reading files from the database, disk, etc.
      ini_set('magic_quotes_runtime', '0');
      // Use session cookies, not transparent sessions that puts the session id in
      // the query string.
      ini_set('session.use_cookies', '1');
      ini_set('session.use_only_cookies', '1');
      ini_set('session.use_trans_sid', '0');
      // Don't send HTTP headers using PHP's session handler.
      ini_set('session.cache_limiter', 'none');
      // Use httponly session cookies.
      ini_set('session.cookie_httponly', '1');
    
      // Set sane locale settings, to ensure consistent string, dates, times and
      // numbers handling.
      setlocale(LC_ALL, 'C');
    }
    
    /**
     * Validates that a hostname (for example $_SERVER['HTTP_HOST']) is safe.
     *
     * @return
     *  TRUE if only containing valid characters, or FALSE otherwise.
     */
    function drupal_valid_http_host($host) {
      return preg_match('/^\[?(?:[a-zA-Z0-9-:\]_]+\.?)+$/', $host);
    }
    
    /**
     * Sets the base URL, cookie domain, and session name from configuration.
     */
    function drupal_settings_initialize() {
      global $base_url, $base_path, $base_root;
    
      // Export the following settings.php variables to the global namespace
      global $databases, $cookie_domain, $conf, $installed_profile, $update_free_access, $db_url, $db_prefix, $drupal_hash_salt, $is_https, $base_secure_url, $base_insecure_url;
      $conf = array();
    
      if (file_exists(DRUPAL_ROOT . '/' . conf_path() . '/settings.php')) {
        include_once DRUPAL_ROOT . '/' . conf_path() . '/settings.php';
      }
      $is_https = isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) == 'on';
    
      if (isset($base_url)) {
        // Parse fixed base URL from settings.php.
        $parts = parse_url($base_url);
        $http_protocol = $parts['scheme'];
        if (!isset($parts['path'])) {
          $parts['path'] = '';
        }
        $base_path = $parts['path'] . '/';
        // 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
        $http_protocol = $is_https ? 'https' : 'http';
        $base_root = $http_protocol . '://' . $_SERVER['HTTP_HOST'];
    
        $base_url = $base_root;
    
        // $_SERVER['SCRIPT_NAME'] can, in contrast to $_SERVER['PHP_SELF'], not
        // be modified by a visitor.
        if ($dir = rtrim(dirname($_SERVER['SCRIPT_NAME']), '\/')) {
          // Remove "core" directory if present, allowing install.php, update.php,
          // cron.php and others to auto-detect a base path.
          $core_position = strrpos($dir, '/core');
          if ($core_position !== FALSE && strlen($dir) - 5 == $core_position) {
            $base_path = substr($dir, 0, $core_position);
          }
          else {
            $base_path = $dir;
          }
          $base_url .= $base_path;
          $base_path .= '/';
        }
        else {
          $base_path = '/';
        }
      }
      $base_secure_url = str_replace('http://', 'https://', $base_url);
      $base_insecure_url = str_replace('https://', 'http://', $base_url);
    
      if ($cookie_domain) {
        // If the user specifies the cookie domain, also use it for session name.
        $session_name = $cookie_domain;
      }
      else {
        // Otherwise use $base_url as session name, without the protocol
        // to use the same session identifiers across http and https.
        list( , $session_name) = explode('://', $base_url, 2);
        // HTTP_HOST can be modified by a visitor, but we already sanitized it
        // in drupal_settings_initialize().
        if (!empty($_SERVER['HTTP_HOST'])) {
          $cookie_domain = $_SERVER['HTTP_HOST'];
          // 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);
          }
          $cookie_domain = explode(':', $cookie_domain);
          $cookie_domain = '.' . $cookie_domain[0];
        }
      }
      // 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', $cookie_domain);
      }
      // To prevent session cookies from being hijacked, a user can configure the
      // SSL version of their website to only transfer session cookies via SSL by
      // using PHP's session.cookie_secure setting. The browser will then use two
      // separate session cookies for the HTTPS and HTTP versions of the site. So we
      // must use different session identifiers for HTTPS and HTTP to prevent a
      // cookie collision.
      if ($is_https) {
        ini_set('session.cookie_secure', TRUE);
      }
      $prefix = ini_get('session.cookie_secure') ? 'SSESS' : 'SESS';
      session_name($prefix . substr(hash('sha256', $session_name), 0, 32));
    }
    
    /**
     * Returns and optionally sets the filename for a system resource.
     *
     * The filename, whether provided, cached, or retrieved from the database, is
     * only returned if the file exists.
     *
     * 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.
     *
     * @param $type
     *   The type of the item (i.e. theme, theme_engine, module, profile).
     * @param $name
     *   The name of the item for which the filename is requested.
     * @param $filename
     *   The filename of the item if it is to be set explicitly rather
     *   than by consulting the database.
     *
     * @return
     *   The filename of the requested item.
     */
    function drupal_get_filename($type, $name, $filename = NULL) {
      // The location of files will not change during the request, so do not use
      // drupal_static().
      static $files = array(), $dirs = array();
    
      // Profiles are a special case: they have a fixed location and naming.
      if ($type == 'profile') {
        $profile_filename = "profiles/$name/$name.profile";
        $files[$type][$name] = file_exists($profile_filename) ? $profile_filename : FALSE;
      }
      if (!isset($files[$type])) {
        $files[$type] = array();
      }
    
      if (!empty($filename) && file_exists($filename)) {
        $files[$type][$name] = $filename;
      }
      elseif (isset($files[$type][$name])) {
        // nothing
      }
      // Verify that we have an active database connection, before querying
      // the database. This is required because this function is called both
      // before we have a database connection (i.e. during installation) and
      // when a database connection fails.
      else {
        try {
          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(DRUPAL_ROOT . '/' . $file)) {
              $files[$type][$name] = $file;
            }
          }
        }
        catch (Exception $e) {
          // The database table may not exist because Drupal is not yet installed,
          // or the database might be down. We have a fallback for this case so we
          // hide the error completely.
        }
        // Fallback to searching the filesystem if the database could not find the
        // file or the file returned by the database is not found.
        if (!isset($files[$type][$name])) {
          // We have a consistent directory naming: modules, themes...
          $dir = $type . 's';
          if ($type == 'theme_engine') {
            $dir = 'themes/engines';
            $extension = 'engine';
          }
          elseif ($type == 'theme') {
            $extension = 'info';
          }
          else {
            $extension = $type;
          }
    
          if (!isset($dirs[$dir][$extension])) {
            $dirs[$dir][$extension] = TRUE;
            if (!function_exists('drupal_system_listing')) {
              require_once DRUPAL_ROOT . '/core/includes/common.inc';
            }
            // 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.
            $matches = drupal_system_listing("/^" . DRUPAL_PHP_FUNCTION_PATTERN . "\.$extension$/", $dir, 'name', 0);
            foreach ($matches as $matched_name => $file) {
              $files[$type][$matched_name] = $file->uri;
            }
          }
        }
      }
    
      if (isset($files[$type][$name])) {
        return $files[$type][$name];
      }
    }
    
    /**
     * Loads 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.
     */
    function variable_initialize($conf = array()) {
      // NOTE: caching the variables improves performance by 20% when serving
      // cached pages.
      if ($cached = cache('bootstrap')->get('variables')) {
        $variables = $cached->data;
      }
      else {
        // Cache miss. Avoid a stampede.
        $name = 'variable_init';
        if (!lock_acquire($name, 1)) {
          // Another request is building the variable cache.
          // Wait, then re-run this function.
          lock_wait($name);
          return variable_initialize($conf);
        }
        else {
          // Proceed with variable rebuild.
          $variables = array_map('unserialize', db_query('SELECT name, value FROM {variable}')->fetchAllKeyed());
          cache('bootstrap')->set('variables', $variables);
          lock_release($name);
        }
      }
    
      foreach ($conf as $name => $value) {
        $variables[$name] = $value;
      }
    
      return $variables;
    }
    
    /**
     * Returns a persistent variable.
     *
     * Case-sensitivity of the variable_* functions depends on the database
     * collation used. To avoid problems, always use lower case for persistent
     * variable names.
     *
     * @param $name
     *   The name of the variable to return.
     * @param $default
     *   The default value to use if this variable has never been set.
     *
     * @return
     *   The value of the variable.
     *
     * @see variable_del()
     * @see variable_set()
     */
    function variable_get($name, $default = NULL) {
      global $conf;
    
      return isset($conf[$name]) ? $conf[$name] : $default;
    }
    
    /**
     * Sets a persistent variable.
     *
     * Case-sensitivity of the variable_* functions depends on the database
     * collation used. To avoid problems, always use lower case for persistent
     * variable names.
     *
     * @param $name
     *   The name of the variable to set.
     * @param $value
     *   The value to set. This can be any PHP data type; these functions take care
     *   of serialization as necessary.
     *
     * @see variable_del()
     * @see variable_get()
     */
    function variable_set($name, $value) {
      global $conf;
    
      db_merge('variable')->key(array('name' => $name))->fields(array('value' => serialize($value)))->execute();
    
      cache('bootstrap')->delete('variables');
    
      $conf[$name] = $value;
    }
    
    /**
     * Unsets a persistent variable.
     *
     * Case-sensitivity of the variable_* functions depends on the database
     * collation used. To avoid problems, always use lower case for persistent
     * variable names.
     *
     * @param $name
     *   The name of the variable to undefine.
     *
     * @see variable_get()
     * @see variable_set()
     */
    function variable_del($name) {
      global $conf;
    
      db_delete('variable')
        ->condition('name', $name)
        ->execute();
      cache('bootstrap')->delete('variables');
    
      unset($conf[$name]);
    }
    
    /**
     * Retrieves the current page from the cache.
     *
     * 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.
     *
     * @param $check_only
     *   (optional) Set to TRUE to only return whether a previous call found a
     *   cache entry.
     *
     * @return
     *   The cache object, if the page was found in the cache, NULL otherwise.
     */
    function drupal_page_get_cache($check_only = FALSE) {
      global $base_root;
      static $cache_hit = FALSE;
    
      if ($check_only) {
        return $cache_hit;
      }
    
      if (drupal_page_is_cacheable()) {
        $cache = cache('page')->get($base_root . request_uri());
        if ($cache !== FALSE) {
          $cache_hit = TRUE;
        }
        return $cache;
      }
    }
    
    /**
     * Determines the cacheability of the current page.
     *
     * @param $allow_caching
     *   Set to FALSE if you want to prevent this page to get cached.
     *
     * @return
     *   TRUE if the current page can be cached, FALSE otherwise.
     */
    function drupal_page_is_cacheable($allow_caching = NULL) {
      $allow_caching_static = &drupal_static(__FUNCTION__, TRUE);
      if (isset($allow_caching)) {
        $allow_caching_static = $allow_caching;
      }
    
      return $allow_caching_static && ($_SERVER['REQUEST_METHOD'] == 'GET' || $_SERVER['REQUEST_METHOD'] == 'HEAD')
        && !drupal_is_cli();
    }
    
    /**
     * Invokes a bootstrap hook in all bootstrap modules that implement it.
     *
     * @param $hook
     *   The name of the bootstrap hook to invoke.
     *
     * @see bootstrap_hooks()
     */
    function bootstrap_invoke_all($hook) {
      // Bootstrap modules should have been loaded when this function is called, so
      // we don't need to tell module_list() to reset its internal list (and we
      // therefore leave the first parameter at its default value of FALSE). We
      // still pass in TRUE for the second parameter, though; in case this is the
      // first time during the bootstrap that module_list() is called, we want to
      // make sure that its internal cache is primed with the bootstrap modules
      // only.
      foreach (module_list(FALSE, TRUE) as $module) {
        drupal_load('module', $module);
        module_invoke($module, $hook);
      }
    }
    
    /**
     * Includes a file with the provided type and name.
     *
     * This prevents 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) {
      // Once a file is included this can't be reversed during a request so do not
      // use drupal_static() here.
      static $files = array();
    
      if (isset($files[$type][$name])) {
        return TRUE;
      }
    
      $filename = drupal_get_filename($type, $name);
    
      if ($filename) {
        include_once DRUPAL_ROOT . '/' . $filename;
        $files[$type][$name] = TRUE;
    
        return TRUE;
      }
    
      return FALSE;
    }
    
    /**
     * Sets 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 the special 'Status' header name.
     * @param $value
     *   The HTTP header value; if equal to FALSE, the specified header is unset.
     *   If $name is 'Status', this is expected to be a status code followed by a
     *   reason phrase, e.g. "404 Not Found".
     * @param $append
     *   Whether to append the value to an existing header or to replace it.
     */
    function drupal_add_http_header($name, $value, $append = FALSE) {
      // The headers as name/value pairs.
      $headers = &drupal_static('drupal_http_headers', array());
    
      $name_lower = strtolower($name);
      _drupal_set_preferred_header_name($name);
    
      if ($value === FALSE) {
        $headers[$name_lower] = FALSE;
      }
      elseif (isset($headers[$name_lower]) && $append) {
        // Multiple headers with identical names may be combined using comma (RFC
        // 2616, section 4.2).
        $headers[$name_lower] .= ',' . $value;
      }
      else {
        $headers[$name_lower] = $value;
      }
      drupal_send_headers(array($name => $headers[$name_lower]), TRUE);
    }
    
    /**
     * Gets the HTTP response headers for the current page.
     *
     * @param $name
     *   An HTTP header name. If omitted, all headers are returned as name/value
     *   pairs. If an array value is FALSE, the header has been unset.
     *
     * @return
     *   A string containing the header value, or FALSE if the header has been set,
     *   or NULL if the header has not been set.
     */
    function drupal_get_http_header($name = NULL) {
      $headers = &drupal_static('drupal_http_headers', array());
      if (isset($name)) {
        $name = strtolower($name);
        return isset($headers[$name]) ? $headers[$name] : NULL;
      }
      else {
        return $headers;
      }
    }
    
    /**
     * Sets the preferred name for the HTTP header.
     *
     * 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;
    }
    
    /**
     * Sends the HTTP response headers that were previously set, adding defaults.
     *
     * Headers are set in drupal_add_http_header(). Default headers are not set
     * if they have been replaced or unset using drupal_add_http_header().
     *
     * @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);
      $headers = drupal_get_http_header();
      if ($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);
        }
      }
    }
    
    /**
     * Sets HTTP headers in preparation for a page response.
     *
     * 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.
     *
     * @see drupal_page_set_cache()
     */
    function drupal_page_header() {
      $headers_sent = &drupal_static(__FUNCTION__, FALSE);
      if ($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);
    }
    
    /**
     * Sets HTTP headers in preparation for a cached page response.
     *
     * The headers allow as much as possible in proxies and browsers without any
     * particular knowledge about the pages. Modules can override these headers
     * using drupal_add_http_header().
     *
     * 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.
     */
    function drupal_serve_page_from_cache(stdClass $cache) {
      // 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.
      $hook_boot_headers = drupal_get_http_header();
    
      // Headers generated in this function, that may be replaced or unset using
      // drupal_add_http_headers(). Keys are mixed-case.
      $default_headers = array();
    
      foreach ($cache->data['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[$name_lower])) {
          drupal_add_http_header($name, $value);
          unset($cache->data['headers'][$name]);
        }
      }
    
      // If the client sent a session cookie, a cached copy will only be served
      // to that one particular client due to Vary: Cookie. Thus, do not set
      // max-age > 0, allowing the page to be cached by external proxies, when a
      // session cookie is present unless the Vary header has been replaced or
      // unset in hook_boot().
      $max_age = !isset($_COOKIE[session_name()]) || isset($hook_boot_headers['vary']) ? variable_get('page_cache_maximum_age', 0) : 0;
      $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);
    
      // 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;
      $if_none_match = isset($_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
          && $if_modified_since == $cache->created) {  // if-modified-since must match
        header($_SERVER['SERVER_PROTOCOL'] . ' 304 Not Modified');
        drupal_send_headers($default_headers);
        return;
      }
    
      // Send the remaining headers.
      foreach ($cache->data['headers'] as $name => $value) {
        drupal_add_http_header($name, $value);
      }
    
      $default_headers['Last-Modified'] = gmdate(DATE_RFC1123, $cache->created);
    
      // 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');
      }
    
      if ($page_compression) {
        header('Vary: Accept-Encoding', FALSE);
        // If page_compression is enabled, the cache contains gzipped data.
        if ($return_compressed) {
          // $cache->data['body'] is already gzip'ed, so make sure
          // zlib.output_compression does not compress it once more.
          ini_set('zlib.output_compression', '0');
          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.
          $cache->data['body'] = gzinflate(substr(substr($cache->data['body'], 10), 0, -8));
        }
      }
    
      // Print the page.
      print $cache->data['body'];
    }
    
    /**
     * Defines the critical hooks that force modules to always be loaded.
     */
    function bootstrap_hooks() {
      return array('boot', 'exit', 'watchdog', 'language_init');
    }
    
    /**
     * Unserializes and appends elements from a serialized string.
     *
     * @param $obj
     *   The object to which the elements are appended.
     * @param $field
     *   The attribute of $obj whose value should be unserialized.
     */
    function drupal_unpack($obj, $field = 'data') {
      if ($obj->$field && $data = unserialize($obj->$field)) {
        foreach ($data as $key => $value) {
          if (!empty($key) && !isset($obj->$key)) {
            $obj->$key = $value;
          }
        }
      }
      return $obj;
    }
    
    /**
     * Translates a string to the current language or to a given language.
     *
     * The t() function serves two purposes. First, at run-time it translates
     * user-visible text into the appropriate language. Second, various mechanisms
     * that figure out what text needs to be translated work off t() -- the text
     * inside t() calls is added to the database of strings to be translated.
     * These strings are expected to be in English, so the first argument should
     * always be in English. To enable a fully-translatable site, it is important
     * that all human-readable text that will be displayed on the site or sent to
     * a user is passed through the t() function, or a related function. See the
     * @link http://drupal.org/node/322729 Localization API @endlink pages for
     * more information, including recommendations on how to break up or not
     * break up strings for translation.
     *
     * You should never use t() to translate variables, such as calling
     * @code t($text); @endcode, unless the text that the variable holds has been
     * passed through t() elsewhere (e.g., $text is one of several translated
     * literal strings in an array). It is especially important never to call
     * @code t($user_text); @endcode, where $user_text is some text that a user
     * entered - doing that can lead to cross-site scripting and other security
     * problems. However, you can use variable substitution in your string, to put
     * variable text such as user names or link URLs into translated text. Variable
     * substitution looks like this:
     * @code
     * $text = t("@name's blog", array('@name' => user_format_name($account)));
     * @endcode
     * Basically, you can put variables like @name into your string, and t() will
     * substitute their sanitized values at translation time. (See the
     * Localization API pages referenced above and the documentation of
     * format_string() for details.) Translators can then rearrange the string as
     * necessary for the language (e.g., in Spanish, it might be "blog de @name").
     *
     * During the Drupal installation phase, some resources used by t() wil not be
     * available to code that needs localization. See st() and get_t() for
     * alternatives.
     *
     * @param $string
     *   A string containing the English string to translate.
     * @param $args
     *   An associative array of replacements to make after translation. Based
     *   on the first character of the key, the value is escaped and/or themed.
     *   See format_string() for details.
     * @param $options
     *   An associative array of additional options, with the following elements:
     *   - 'langcode' (defaults to the current language): The language code to
     *     translate to a language other than what is used to display the page.
     *   - 'context' (defaults to the empty context): The context the source string
     *     belongs to.
     *
     * @return
     *   The translated string.
     *
     * @see st()
     * @see get_t()
     * @see format_string()
     * @ingroup sanitization
     */
    function t($string, array $args = array(), array $options = array()) {
      global $language_interface;
      static $custom_strings;
    
      // Merge in default.
      if (empty($options['langcode'])) {
        $options['langcode'] = isset($language_interface->langcode) ? $language_interface->langcode : LANGUAGE_SYSTEM;
      }
      if (empty($options['context'])) {
        $options['context'] = '';
      }
    
      // First, check for an array of customized strings. If present, use the array
      // *instead of* database lookups. This is a high performance way to provide a
      // handful of string replacements. See settings.php for examples.
      // Cache the $custom_strings variable to improve performance.
      if (!isset($custom_strings[$options['langcode']])) {
        $custom_strings[$options['langcode']] = variable_get('locale_custom_strings_' . $options['langcode'], array());
      }
      // Custom strings work for English too, even if locale module is disabled.
      if (isset($custom_strings[$options['langcode']][$options['context']][$string])) {
        $string = $custom_strings[$options['langcode']][$options['context']][$string];
      }
      // Translate with locale module if enabled.
      elseif ($options['langcode'] != LANGUAGE_SYSTEM && ($options['langcode'] != 'en' || variable_get('locale_translate_english', FALSE)) && function_exists('locale')) {
        $string = locale($string, $options['context'], $options['langcode']);
      }
      if (empty($args)) {
        return $string;
      }
      else {
        return format_string($string, $args);
      }
    }
    
    /**
     * Replaces placeholders with sanitized values in a string.
     *
     * @param $string
     *   A string containing placeholders.
     * @param $args
     *   An associative array of replacements to make. Occurrences in $string of
     *   any key in $args are replaced with the corresponding value, after
     *   sanitization. The sanitization function depends on the first character of
     *   the key:
     *   - !variable: Inserted as is. Use this for text that has already been
     *     sanitized.
     *   - @variable: Escaped to HTML using check_plain(). Use this for anything
     *     displayed on a page on the site.
     *   - %variable: Escaped as a placeholder for user-submitted content using
     *     drupal_placeholder(), which shows up as <em>emphasized</em> text.
     *
     * @see t()
     * @ingroup sanitization
     */
    function format_string($string, array $args = array()) {
      // Transform arguments before inserting them.
      foreach ($args as $key => $value) {
        switch ($key[0]) {
          case '@':
            // Escaped only.
            $args[$key] = check_plain($value);
            break;
    
          case '%':
          default:
            // Escaped and placeholder.
            $args[$key] = drupal_placeholder($value);
            break;
    
          case '!':
            // Pass-through.
        }
      }
      return strtr($string, $args);
    }
    
    /**
     * Encodes special characters in a plain-text string for display as HTML.
     *
     * Also validates strings as UTF-8 to prevent cross site scripting attacks on
     * Internet Explorer 6.
     *
     * @param $text
     *   The text to be checked or processed.
     *
     * @return
     *   An HTML safe version of $text, or an empty string if $text is not
     *   valid UTF-8.
     *
     * @see drupal_validate_utf8()
     * @ingroup sanitization
     */
    function check_plain($text) {
      return htmlspecialchars($text, ENT_QUOTES, 'UTF-8');
    }
    
    /**
     * Checks whether a string is valid UTF-8.
     *
     * All functions designed to filter input should use drupal_validate_utf8
     * to ensure they operate on valid UTF-8 strings to prevent bypass of the
     * filter.
     *
     * When text containing an invalid UTF-8 lead byte (0xC0 - 0xFF) is presented
     * as UTF-8 to Internet Explorer 6, the program may misinterpret subsequent
     * bytes. When these subsequent bytes are HTML control characters such as
     * quotes or angle brackets, parts of the text that were deemed safe by filters
     * end up in locations that are potentially unsafe; An onerror attribute that
     * is outside of a tag, and thus deemed safe by a filter, can be interpreted
     * by the browser as if it were inside the tag.
     *
     * The function does not return FALSE for strings containing character codes
     * above U+10FFFF, even though these are prohibited by RFC 3629.
     *
     * @param $text
     *   The text to check.
     *
     * @return
     *   TRUE if the text is valid UTF-8, FALSE if not.
     */
    function drupal_validate_utf8($text) {
      if (strlen($text) == 0) {
        return TRUE;
      }
      // With the PCRE_UTF8 modifier 'u', preg_match() fails silently on strings
      // containing invalid UTF-8 byte sequences. It does not reject character
      // codes above U+10FFFF (represented by 4 or more octets), though.
      return (preg_match('/^./us', $text) == 1);
    }
    
    /**
     * Returns the equivalent of Apache's $_SERVER['REQUEST_URI'] variable.
     *
     * Because $_SERVER['REQUEST_URI'] is only available on Apache, we generate an
     * equivalent using other environment variables.
     */
    function request_uri() {
      if (isset($_SERVER['REQUEST_URI'])) {
        $uri = $_SERVER['REQUEST_URI'];
      }
      else {
        if (isset($_SERVER['argv'])) {
          $uri = $_SERVER['SCRIPT_NAME'] . '?' . $_SERVER['argv'][0];
        }
        elseif (isset($_SERVER['QUERY_STRING'])) {
          $uri = $_SERVER['SCRIPT_NAME'] . '?' . $_SERVER['QUERY_STRING'];
        }
        else {
          $uri = $_SERVER['SCRIPT_NAME'];
        }
      }
      // Prevent multiple slashes to avoid cross site requests via the Form API.
      $uri = '/' . ltrim($uri, '/');
    
      return $uri;
    }
    
    /**
     * Logs an exception.
     *
     * This is a wrapper function for watchdog() which automatically decodes an
     * exception.
     *
     * @param $type
     *   The category to which this message belongs.
     * @param $exception
     *   The exception that is going to be logged.
     * @param $message
     *   The message to store in the log. If empty, a text that contains all useful
     *   information about the passed-in exception is used.
     * @param $variables
     *   Array of variables to replace in the message on display. Defaults to the
     *   return value of drupal_decode_exception().
     * @param $severity
     *   The severity of the message, as per RFC 3164.
     * @param $link
     *   A link to associate with the message.
     *
     * @see watchdog()
     * @see drupal_decode_exception()
     */
    function watchdog_exception($type, Exception $exception, $message = NULL, $variables = array(), $severity = WATCHDOG_ERROR, $link = NULL) {
    
       // Use a default value if $message is not set.
       if (empty($message)) {
         // The exception message is run through check_plain() by _drupal_decode_exception().
         $message = '%type: !message in %function (line %line of %file).';
       }
       // $variables must be an array so that we can add the exception information.
       if (!is_array($variables)) {
         $variables = array();
       }
    
       require_once DRUPAL_ROOT . '/core/includes/errors.inc';
       $variables += _drupal_decode_exception($exception);
       watchdog($type, $message, $variables, $severity, $link);
    }
    
    /**
     * Logs a system message.
     *
     * @param $type
     *   The category to which this message belongs. Can be any string, but the
     *   general practice is to use the name of the module calling watchdog().
     * @param $message
     *   The message to store in the log. Keep $message translatable
     *   by not concatenating dynamic values into it! Variables in the
     *   message should be added by using placeholder strings alongside
     *   the variables argument to declare the value of the placeholders.
     *   See t() for documentation on how $message and $variables interact.
     * @param $variables
     *   Array of variables to replace in the message on display or
     *   NULL if message is already translated or not possible to
     *   translate.
     * @param $severity
     *   The severity of the message, as per RFC 3164. Possible values are
     *   WATCHDOG_ERROR, WATCHDOG_WARNING, etc.
     * @param $link
     *   A link to associate with the message.
     *
     * @see watchdog_severity_levels()
     * @see hook_watchdog()
     */
    function watchdog($type, $message, $variables = array(), $severity = WATCHDOG_NOTICE, $link = NULL) {
      global $user, $base_root;
    
      static $in_error_state = FALSE;
    
      // It is possible that the error handling will itself trigger an error. In that case, we could
      // end up in an infinite loop. To avoid that, we implement a simple static semaphore.
      if (!$in_error_state && function_exists('module_implements')) {
        $in_error_state = TRUE;
    
        // Prepare the fields to be logged
        $log_entry = array(
          'type'        => $type,
          'message'     => $message,
          'variables'   => $variables,
          'severity'    => $severity,
          'link'        => $link,
          'user'        => $user,
          'request_uri' => $base_root . request_uri(),
          'referer'     => isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : '',
          'ip'          => ip_address(),
          'timestamp'   => REQUEST_TIME,
        );
    
        // Call the logging hooks to log/process the message
        foreach (module_implements('watchdog') as $module) {
          module_invoke($module, 'watchdog', $log_entry);
        }
    
        // It is critical that the semaphore is only cleared here, in the parent
        // watchdog() call (not outside the loop), to prevent recursive execution.
        $in_error_state = FALSE;
      }
    }
    
    /**
     * Sets a message which reflects the status of the performed operation.
     *
     * If the function is called with no arguments, this function returns all set
     * messages without clearing them.
     *
     * @param $message
     *   The message to be displayed to the user. For consistency with other
     *   messages, it should begin with a capital letter and end with a period.
     * @param $type
     *   The type of the message. One of the following values are possible:
     *   - 'status'
     *   - 'warning'
     *   - 'error'
     * @param $repeat
     *   If this is FALSE and the message is already set, then the message won't
     *   be repeated.
     */
    function drupal_set_message($message = NULL, $type = 'status', $repeat = TRUE) {
      if ($message) {
        if (!isset($_SESSION['messages'][$type])) {
          $_SESSION['messages'][$type] = array();
        }
    
        if ($repeat || !in_array($message, $_SESSION['messages'][$type])) {
          $_SESSION['messages'][$type][] = $message;
        }
    
        // Mark this page as being uncacheable.
        drupal_page_is_cacheable(FALSE);
      }
    
      // Messages not set when DB connection fails.
      return isset($_SESSION['messages']) ? $_SESSION['messages'] : NULL;
    }
    
    /**
     * Returns all messages that have been set.
     *
     * @param $type
     *   (optional) Only return messages of this type.
     * @param $clear_queue
     *   (optional) Set to FALSE if you do not want to clear the messages queue
     *
     * @return
     *   An associative array, the key is the message type, the value an array
     *   of messages. If the $type parameter is passed, you get only that type,
     *   or an empty array if there are no such messages. If $type is not passed,
     *   all message types are returned, or an empty array if none exist.
     */
    function drupal_get_messages($type = NULL, $clear_queue = TRUE) {
      if ($messages = drupal_set_message()) {
        if ($type) {
          if ($clear_queue) {
            unset($_SESSION['messages'][$type]);
          }
          if (isset($messages[$type])) {
            return array($type => $messages[$type]);
          }
        }
        else {
          if ($clear_queue) {
            unset($_SESSION['messages']);
          }
          return $messages;
        }
      }
      return array();
    }
    
    /**
     * Gets the title of the current page.
     *
     * The title is displayed on the page and in the title bar.
     *
     * @return
     *   The current page's title.
     */
    function drupal_get_title() {
      $title = drupal_set_title();
    
      // During a bootstrap, menu.inc is not included and thus we cannot provide a title.
      if (!isset($title) && function_exists('menu_get_active_title')) {
        $title = check_plain(menu_get_active_title());
      }
    
      return $title;
    }
    
    /**
     * Sets the title of the current page.
     *
     * The title is displayed on the page and in the title bar.
     *
     * @param $title
     *   Optional string value to assign to the page title; or if set to NULL
     *   (default), leaves the current title unchanged.
     * @param $output
     *   Optional flag - normally should be left as CHECK_PLAIN. Only set to
     *   PASS_THROUGH if you have already removed any possibly dangerous code
     *   from $title using a function like check_plain() or filter_xss(). With this
     *   flag the string will be passed through unchanged.
     *
     * @return
     *   The updated title of the current page.
     */
    function drupal_set_title($title = NULL, $output = CHECK_PLAIN) {
      $stored_title = &drupal_static(__FUNCTION__);
    
      if (isset($title)) {
        $stored_title = ($output == PASS_THROUGH) ? $title : check_plain($title);
      }
    
      return $stored_title;
    }
    
    /**
     * Checks to see if an IP address has been blocked.
     *
     * Blocked IP addresses are stored in the database by default. However for
     * performance reasons we allow an override in settings.php. This allows us
     * to avoid querying the database at this critical stage of the bootstrap if
     * an administrative interface for IP address blocking is not required.
     *
     * @param $ip
     *   IP address to check.
     *
     * @return bool
     *   TRUE if access is denied, FALSE if access is allowed.
     */
    function drupal_is_denied($ip) {
      // Because this function is called on every page request, we first check
      // for an array of IP addresses in settings.php before querying the
      // database.
      $blocked_ips = variable_get('blocked_ips');
      $denied = FALSE;
      if (isset($blocked_ips) && is_array($blocked_ips)) {
        $denied = in_array($ip, $blocked_ips);
      }
      // Only check if database.inc is loaded already. If
      // $conf['page_cache_without_database'] = TRUE; is set in settings.php,
      // then the database won't be loaded here so the IPs in the database
      // won't be denied. However the user asked explicitly not to use the
      // database and also in this case it's quite likely that the user relies
      // on higher performance solutions like a firewall.
      elseif (class_exists('Database', FALSE)) {
        $denied = (bool)db_query("SELECT 1 FROM {blocked_ips} WHERE ip = :ip", array(':ip' => $ip))->fetchField();
      }
      return $denied;
    }
    
    /**
     * Handles denied users.
     *
     * @param $ip
     *   IP address to check. Prints a message and exits if access is denied.
     */
    function drupal_block_denied($ip) {
      // Deny access to blocked IP addresses - t() is not yet available.
      if (drupal_is_denied($ip)) {
        header($_SERVER['SERVER_PROTOCOL'] . ' 403 Forbidden');
        print 'Sorry, ' . check_plain(ip_address()) . ' has been banned.';
        exit();
      }
    }
    
    /**
     * Returns a string of highly randomized bytes (over the full 8-bit range).
     *
     * This function is better than simply calling mt_rand() or any other built-in
     * PHP function because it can return a long string of bytes (compared to < 4
     * bytes normally from mt_rand()) and uses the best available pseudo-random
     * source.
     *
     * @param $count
     *   The number of characters (bytes) to return in the string.
     */
    function drupal_random_bytes($count)  {
      // $random_state does not use drupal_static as it stores random bytes.
      static $random_state, $bytes, $php_compatible;
      // Initialize on the first call. The contents of $_SERVER includes a mix of
      // user-specific and system information that varies a little with each page.
      if (!isset($random_state)) {
        $random_state = print_r($_SERVER, TRUE);
        if (function_exists('getmypid')) {
          // Further initialize with the somewhat random PHP process ID.
          $random_state .= getmypid();
        }
        $bytes = '';
      }
      if (strlen($bytes) < $count) {
        // PHP versions prior 5.3.4 experienced openssl_random_pseudo_bytes()
        // locking on Windows and rendered it unusable.
        if (!isset($php_compatible)) {
          $php_compatible = version_compare(PHP_VERSION, '5.3.4', '>=');
        }
        // /dev/urandom is available on many *nix systems and is considered the
        // best commonly available pseudo-random source.
        if ($fh = @fopen('/dev/urandom', 'rb')) {
          // PHP only performs buffered reads, so in reality it will always read
          // at least 4096 bytes. Thus, it costs nothing extra to read and store
          // that much so as to speed any additional invocations.
          $bytes .= fread($fh, max(4096, $count));
          fclose($fh);
        }
        // openssl_random_pseudo_bytes() will find entropy in a system-dependent
        // way.
        elseif ($php_compatible && function_exists('openssl_random_pseudo_bytes')) {
          $bytes .= openssl_random_pseudo_bytes($count - strlen($bytes));
        }
        // If /dev/urandom is not available or returns no bytes, this loop will
        // generate a good set of pseudo-random bytes on any system.
        // Note that it may be important that our $random_state is passed
        // through hash() prior to being rolled into $output, that the two hash()
        // invocations are different, and that the extra input into the first one -
        // the microtime() - is prepended rather than appended. This is to avoid
        // directly leaking $random_state via the $output stream, which could
        // allow for trivial prediction of further "random" numbers.
        while (strlen($bytes) < $count) {
          $random_state = hash('sha256', microtime() . mt_rand() . $random_state);
          $bytes .= hash('sha256', mt_rand() . $random_state, TRUE);
        }
      }
      $output = substr($bytes, 0, $count);
      $bytes = substr($bytes, $count);
      return $output;
    }
    
    /**
     * Calculates a base-64 encoded, URL-safe sha-256 hmac.
     *
     * @param $data
     *   String to be validated with the hmac.
     * @param $key
     *   A secret string key.
     *
     * @return
     *   A base-64 encoded sha-256 hmac, with + replaced with -, / with _ and
     *   any = padding characters removed.
     */
    function drupal_hmac_base64($data, $key) {
      $hmac = base64_encode(hash_hmac('sha256', $data, $key, TRUE));
      // Modify the hmac so it's safe to use in URLs.
      return strtr($hmac, array('+' => '-', '/' => '_', '=' => ''));
    }
    
    /**
     * Calculates a base-64 encoded, URL-safe sha-256 hash.
     *
     * @param $data
     *   String to be hashed.
     *
     * @return
     *   A base-64 encoded sha-256 hash, with + replaced with -, / with _ and
     *   any = padding characters removed.
     */
    function drupal_hash_base64($data) {
      $hash = base64_encode(hash('sha256', $data, TRUE));
      // Modify the hash so it's safe to use in URLs.
      return strtr($hash, array('+' => '-', '/' => '_', '=' => ''));
    }
    
    /**
     * Merges multiple arrays, recursively, and returns the merged array.
     *
     * This function is similar to PHP's array_merge_recursive() function, but it
     * handles non-array values differently. When merging values that are not both
     * arrays, the latter value replaces the former rather than merging with it.
     *
     * Example:
     * @code
     * $link_options_1 = array('fragment' => 'x', 'attributes' => array('title' => t('X'), 'class' => array('a', 'b')));
     * $link_options_2 = array('fragment' => 'y', 'attributes' => array('title' => t('Y'), 'class' => array('c', 'd')));
     *
     * // This results in array('fragment' => array('x', 'y'), 'attributes' => array('title' => array(t('X'), t('Y')), 'class' => array('a', 'b', 'c', 'd'))).
     * $incorrect = array_merge_recursive($link_options_1, $link_options_2);
     *
     * // This results in array('fragment' => 'y', 'attributes' => array('title' => t('Y'), 'class' => array('a', 'b', 'c', 'd'))).
     * $correct = drupal_array_merge_deep($link_options_1, $link_options_2);
     * @endcode
     *
     * @param ...
     *   Arrays to merge.
     *
     * @return
     *   The merged array.
     *
     * @see drupal_array_merge_deep_array()
     */
    function drupal_array_merge_deep() {
      return drupal_array_merge_deep_array(func_get_args());
    }
    
    /**
     * Merges multiple arrays, recursively, and returns the merged array.
     *
     * This function is equivalent to drupal_array_merge_deep(), except the
     * input arrays are passed as a single array parameter rather than a variable
     * parameter list.
     *
     * The following are equivalent:
     * - drupal_array_merge_deep($a, $b);
     * - drupal_array_merge_deep_array(array($a, $b));
     *
     * The following are also equivalent:
     * - call_user_func_array('drupal_array_merge_deep', $arrays_to_merge);
     * - drupal_array_merge_deep_array($arrays_to_merge);
     *
     * @see drupal_array_merge_deep()
     */
    function drupal_array_merge_deep_array($arrays) {
      $result = array();
    
      foreach ($arrays as $array) {
        foreach ($array as $key => $value) {
          // Renumber integer keys as array_merge_recursive() does. Note that PHP
          // automatically converts array keys that are integer strings (e.g., '1')
          // to integers.
          if (is_integer($key)) {
            $result[] = $value;
          }
          // Recurse when both values are arrays.
          elseif (isset($result[$key]) && is_array($result[$key]) && is_array($value)) {
            $result[$key] = drupal_array_merge_deep_array(array($result[$key], $value));
          }
          // Otherwise, use the latter value, overriding any previous value.
          else {
            $result[$key] = $value;
          }
        }
      }
    
      return $result;
    }
    
    /**
     * Generates a default anonymous $user object.
     *
     * @return Object - the user object.
     */
    function drupal_anonymous_user() {
      $user = new stdClass();
      $user->uid = 0;
      $user->hostname = ip_address();
      $user->roles = array();
      $user->roles[DRUPAL_ANONYMOUS_RID] = 'anonymous user';
      $user->cache = 0;
      return $user;
    }
    
    /**
     * Ensures Drupal is bootstrapped to the specified phase.
     *
     * The bootstrap phase is an integer constant identifying a phase of Drupal
     * to load. Each phase adds to the previous one, so invoking a later phase
     * automatically runs the earlier phases as well. To access the Drupal
     * database from a script without loading anything else, include bootstrap.inc
     * and call drupal_bootstrap(DRUPAL_BOOTSTRAP_DATABASE).
     *
     * @param $phase
     *   A constant. Allowed values are the DRUPAL_BOOTSTRAP_* constants.
     * @param $new_phase
     *   A boolean, set to FALSE if calling drupal_bootstrap from inside a
     *   function called from drupal_bootstrap (recursion).
     *
     * @return
     *   The most recently completed phase.
     */
    function drupal_bootstrap($phase = NULL, $new_phase = TRUE) {
      // Not drupal_static(), because does not depend on any run-time information.
      static $phases = array(
        DRUPAL_BOOTSTRAP_CONFIGURATION,
        DRUPAL_BOOTSTRAP_PAGE_CACHE,
        DRUPAL_BOOTSTRAP_DATABASE,
        DRUPAL_BOOTSTRAP_VARIABLES,
        DRUPAL_BOOTSTRAP_SESSION,
        DRUPAL_BOOTSTRAP_PAGE_HEADER,
        DRUPAL_BOOTSTRAP_LANGUAGE,
        DRUPAL_BOOTSTRAP_FULL,
      );
      // Not drupal_static(), because the only legitimate API to control this is to
      // call drupal_bootstrap() with a new phase parameter.
      static $final_phase;
      // Not drupal_static(), because it's impossible to roll back to an earlier
      // bootstrap state.
      static $stored_phase = -1;
    
      // When not recursing, store the phase name so it's not forgotten while
      // recursing.
      if ($new_phase) {
        $final_phase = $phase;
      }
      if (isset($phase)) {
        // Call a phase if it has not been called before and is below the requested
        // phase.
        while ($phases && $phase > $stored_phase && $final_phase > $stored_phase) {
          $current_phase = array_shift($phases);
    
          // This function is re-entrant. Only update the completed phase when the
          // current call actually resulted in a progress in the bootstrap process.
          if ($current_phase > $stored_phase) {
            $stored_phase = $current_phase;
          }
    
          switch ($current_phase) {
            case DRUPAL_BOOTSTRAP_CONFIGURATION:
              _drupal_bootstrap_configuration();
              break;
    
            case DRUPAL_BOOTSTRAP_PAGE_CACHE:
              _drupal_bootstrap_page_cache();
              break;
    
            case DRUPAL_BOOTSTRAP_DATABASE:
              _drupal_bootstrap_database();
              break;
    
            case DRUPAL_BOOTSTRAP_VARIABLES:
              _drupal_bootstrap_variables();
              break;
    
            case DRUPAL_BOOTSTRAP_SESSION:
              require_once DRUPAL_ROOT . '/' . variable_get('session_inc', 'core/includes/session.inc');
              drupal_session_initialize();
              break;
    
            case DRUPAL_BOOTSTRAP_PAGE_HEADER:
              _drupal_bootstrap_page_header();
              break;
    
            case DRUPAL_BOOTSTRAP_LANGUAGE:
              drupal_language_initialize();
              break;
    
            case DRUPAL_BOOTSTRAP_FULL:
              require_once DRUPAL_ROOT . '/core/includes/common.inc';
              _drupal_bootstrap_full();
              break;
          }
        }
      }
      return $stored_phase;
    }
    
    /**
     * Returns the time zone of the current user.
     */
    function drupal_get_user_timezone() {
      global $user;
      if (variable_get('configurable_timezones', 1) && $user->uid && $user->timezone) {
        return $user->timezone;
      }
      else {
        // Ignore PHP strict notice if time zone has not yet been set in the php.ini
        // configuration.
        return variable_get('date_default_timezone', @date_default_timezone_get());
      }
    }
    
    /**
     * Provides custom PHP error handling.
     *
     * @param $error_level
     *   The level of the error raised.
     * @param $message
     *   The error message.
     * @param $filename
     *   The filename that the error was raised in.
     * @param $line
     *   The line number the error was raised at.
     * @param $context
     *   An array that points to the active symbol table at the point the error
     *   occurred.
     */
    function _drupal_error_handler($error_level, $message, $filename, $line, $context) {
      require_once DRUPAL_ROOT . '/core/includes/errors.inc';
      _drupal_error_handler_real($error_level, $message, $filename, $line, $context);
    }
    
    /**
     * Provides custom PHP exception handling.
     *
     * Uncaught exceptions are those not enclosed in a try/catch block. They are
     * always fatal: the execution of the script will stop as soon as the exception
     * handler exits.
     *
     * @param $exception
     *   The exception object that was thrown.
     */
    function _drupal_exception_handler($exception) {
      require_once DRUPAL_ROOT . '/core/includes/errors.inc';
    
      try {
        // Log the message to the watchdog and return an error page to the user.
        _drupal_log_error(_drupal_decode_exception($exception), TRUE);
      }
      catch (Exception $exception2) {
        // Another uncaught exception was thrown while handling the first one.
        // If we are displaying errors, then do so with no possibility of a further uncaught exception being thrown.
        if (error_displayable()) {
          print '<h1>Additional uncaught exception thrown while handling exception.</h1>';
          print '<h2>Original</h2><p>' . _drupal_render_exception_safe($exception) . '</p>';
          print '<h2>Additional</h2><p>' . _drupal_render_exception_safe($exception2) . '</p><hr />';
        }
      }
    }
    
    /**
     * Sets up the script environment and loads settings.php.
     */
    function _drupal_bootstrap_configuration() {
      // Set the Drupal custom error handler.
      set_error_handler('_drupal_error_handler');
      set_exception_handler('_drupal_exception_handler');
    
      drupal_environment_initialize();
      // Start a page timer:
      timer_start('page');
      // Initialize the configuration, including variables from settings.php.
      drupal_settings_initialize();
    
      // Include and activate the class loader.
      $loader = drupal_classloader();
    
      // Register explicit vendor namespaces.
      $loader->registerNamespaces(array(
        // All Symfony-borrowed code lives in /core/vendor/Symfony.
        'Symfony' => DRUPAL_ROOT . '/core/vendor',
      ));
      // Register the Drupal namespace for classes in core as a fallback.
      // This allows to register additional namespaces within the Drupal namespace
      // (e.g., for modules) and avoids an additional file_exists() on the Drupal
      // core namespace, since the class loader can already determine the best
      // namespace match based on a string comparison. It further allows modules to
      // register/overload namespaces in Drupal core.
      $loader->registerNamespaceFallbacks(array(
        // All Drupal-namespaced code in core lives in /core/lib/Drupal.
        'Drupal' => DRUPAL_ROOT . '/core/lib',
      ));
    }
    
    /**
     * Attempts to serve a page from the cache.
     */
    function _drupal_bootstrap_page_cache() {
      global $user;
    
      // Allow specifying special cache handlers in settings.php, like
      // using memcached or files for storing cache information.
      require_once DRUPAL_ROOT . '/core/includes/cache.inc';
      foreach (variable_get('cache_backends', array()) as $include) {
        require_once DRUPAL_ROOT . '/' . $include;
      }
      // Check for a cache mode force from settings.php.
      if (variable_get('page_cache_without_database')) {
        $cache_enabled = TRUE;
      }
      else {
        drupal_bootstrap(DRUPAL_BOOTSTRAP_VARIABLES, FALSE);
        $cache_enabled = variable_get('cache');
      }
      drupal_block_denied(ip_address());
      // If there is no session cookie and cache is enabled (or forced), try
      // to serve a cached page.
      if (!isset($_COOKIE[session_name()]) && $cache_enabled) {
        // Make sure there is a user object because its timestamp will be
        // checked, hook_boot might check for anonymous user etc.
        $user = drupal_anonymous_user();
        // Get the page from the cache.
        $cache = drupal_page_get_cache();
        // If there is a cached page, display it.
        if (is_object($cache)) {
          header('X-Drupal-Cache: HIT');
          // Restore the metadata cached with the page.
          $_GET['q'] = $cache->data['path'];
          drupal_set_title($cache->data['title'], PASS_THROUGH);
          date_default_timezone_set(drupal_get_user_timezone());
          // If the skipping of the bootstrap hooks is not enforced, call
          // hook_boot.
          if (variable_get('page_cache_invoke_hooks', TRUE)) {
            bootstrap_invoke_all('boot');
          }
          drupal_serve_page_from_cache($cache);
          // If the skipping of the bootstrap hooks is not enforced, call
          // hook_exit.
          if (variable_get('page_cache_invoke_hooks', TRUE)) {
            bootstrap_invoke_all('exit');
          }
          // We are done.
          exit;
        }
        else {
          header('X-Drupal-Cache: MISS');
        }
      }
    }
    
    /**
     * Initializes the database system and registers autoload functions.
     */
    function _drupal_bootstrap_database() {
      // Redirect the user to the installation script if Drupal has not been
      // installed yet (i.e., if no $databases array has been defined in the
      // settings.php file) and we are not already installing.
      if (empty($GLOBALS['databases']) && !drupal_installation_attempted()) {
        include_once DRUPAL_ROOT . '/core/includes/install.inc';
        install_goto('core/install.php');
      }
    
      // The user agent header is used to pass a database prefix in the request when
      // running tests. However, for security reasons, it is imperative that we
      // validate we ourselves made the request.
      if ($test_prefix = drupal_valid_test_ua()) {
        // Set the test run id for use in other parts of Drupal.
        $test_info = &$GLOBALS['drupal_test_info'];
        $test_info['test_run_id'] = $test_prefix;
        $test_info['in_child_site'] = TRUE;
    
        foreach ($GLOBALS['databases']['default'] as &$value) {
          // Extract the current default database prefix.
          if (!isset($value['prefix'])) {
            $current_prefix = '';
          }
          elseif (is_array($value['prefix'])) {
            $current_prefix = $value['prefix']['default'];
          }
          else {
            $current_prefix = $value['prefix'];
          }
    
          // Remove the current database prefix and replace it by our own.
          $value['prefix'] = array(
            'default' => $current_prefix . $test_prefix,
          );
        }
      }
    
      // Initialize the database system. Note that the connection
      // won't be initialized until it is actually requested.
      require_once DRUPAL_ROOT . '/core/includes/database/database.inc';
    
      // Register autoload functions so that we can access classes and interfaces.
      // The database autoload routine comes first so that we can load the database
      // system without hitting the database. That is especially important during
      // the install or upgrade process.
      spl_autoload_register('drupal_autoload_class');
      spl_autoload_register('drupal_autoload_interface');
    }
    
    /**
     * Loads system variables and all enabled bootstrap modules.
     */
    function _drupal_bootstrap_variables() {
      global $conf;
    
      // Initialize the lock system.
      require_once DRUPAL_ROOT . '/' . variable_get('lock_inc', 'core/includes/lock.inc');
      lock_initialize();
    
      // Load variables from the database, but do not overwrite variables set in settings.php.
      $conf = variable_initialize(isset($conf) ? $conf : array());
      // Load bootstrap modules.
      require_once DRUPAL_ROOT . '/core/includes/module.inc';
      module_load_all(TRUE);
    }
    
    /**
     * Invokes hook_boot(), initializes locking system, and sends HTTP headers.
     */
    function _drupal_bootstrap_page_header() {
      bootstrap_invoke_all('boot');
    
      if (!drupal_is_cli()) {
        ob_start();
        drupal_page_header();
      }
    }
    
    /**
     * Returns the current bootstrap phase for this Drupal process.
     *
     * The current phase is the one most recently completed by drupal_bootstrap().
     *
     * @see drupal_bootstrap()
     */
    function drupal_get_bootstrap_phase() {
      return drupal_bootstrap();
    }
    
    /**
     * Returns the test prefix if this is an internal request from SimpleTest.
     *
     * @return
     *   Either the simpletest prefix (the string "simpletest" followed by any
     *   number of digits) or FALSE if the user agent does not contain a valid
     *   HMAC and timestamp.
     */
    function drupal_valid_test_ua() {
      global $drupal_hash_salt;
      // No reason to reset this.
      static $test_prefix;
    
      if (isset($test_prefix)) {
        return $test_prefix;
      }
    
      if (isset($_SERVER['HTTP_USER_AGENT']) && preg_match("/^(simpletest\d+);(.+);(.+);(.+)$/", $_SERVER['HTTP_USER_AGENT'], $matches)) {
        list(, $prefix, $time, $salt, $hmac) = $matches;
        $check_string =  $prefix . ';' . $time . ';' . $salt;
        // We use the salt from settings.php to make the HMAC key, since
        // the database is not yet initialized and we can't access any Drupal variables.
        // The file properties add more entropy not easily accessible to others.
        $key = $drupal_hash_salt . filectime(__FILE__) . fileinode(__FILE__);
        $time_diff = REQUEST_TIME - $time;
        // Since we are making a local request a 5 second time window is allowed,
        // and the HMAC must match.
        if ($time_diff >= 0 && $time_diff <= 5 && $hmac == drupal_hmac_base64($check_string, $key)) {
          $test_prefix = $prefix;
          return $test_prefix;
        }
      }
    
      $test_prefix = FALSE;
      return $test_prefix;
    }
    
    /**
     * Generates a user agent string with a HMAC and timestamp for simpletest.
     */
    function drupal_generate_test_ua($prefix) {
      global $drupal_hash_salt;
      static $key;
    
      if (!isset($key)) {
        // We use the salt from settings.php to make the HMAC key, since
        // the database is not yet initialized and we can't access any Drupal variables.
        // The file properties add more entropy not easily accessible to others.
        $key = $drupal_hash_salt . filectime(__FILE__) . fileinode(__FILE__);
      }
      // Generate a moderately secure HMAC based on the database credentials.
      $salt = uniqid('', TRUE);
      $check_string = $prefix . ';' . time() . ';' . $salt;
      return $check_string . ';' . drupal_hmac_base64($check_string, $key);
    }
    
    /**
     * Enables use of the theme system without requiring database access.
     *
     * Loads and initializes the theme system for site installs, updates and when
     * the site is in maintenance mode. This also applies when the database fails.
     *
     * @see _drupal_maintenance_theme()
     */
    function drupal_maintenance_theme() {
      require_once DRUPAL_ROOT . '/core/includes/theme.maintenance.inc';
      _drupal_maintenance_theme();
    }
    
    /**
     * Returns a simple 404 Not Found page.
     *
     * If fast 404 pages are enabled, and this is a matching page then print a
     * simple 404 page and exit.
     *
     * This function is called from drupal_deliver_html_page() at the time when a
     * a normal 404 page is generated, but it can also optionally be called directly
     * from settings.php to prevent a Drupal bootstrap on these pages. See
     * documentation in settings.php for the benefits and drawbacks of using this.
     *
     * Paths to dynamically-generated content, such as image styles, should also be
     * accounted for in this function.
     */
    function drupal_fast_404() {
      $exclude_paths = variable_get('404_fast_paths_exclude', FALSE);
      if ($exclude_paths && !preg_match($exclude_paths, $_GET['q'])) {
        $fast_paths = variable_get('404_fast_paths', FALSE);
        if ($fast_paths && preg_match($fast_paths, $_GET['q'])) {
          drupal_add_http_header('Status', '404 Not Found');
          $fast_404_html = variable_get('404_fast_html', '<html xmlns="http://www.w3.org/1999/xhtml"><head><title>404 Not Found</title></head><body><h1>Not Found</h1><p>The requested URL "@path" was not found on this server.</p></body></html>');
          // Replace @path in the variable with the page path.
          print strtr($fast_404_html, array('@path' => check_plain(request_uri())));
          exit;
        }
      }
    }
    
    /**
     * Returns TRUE if a Drupal installation is currently being attempted.
     */
    function drupal_installation_attempted() {
      return defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'install';
    }
    
    /**
     * Returns the name of the proper localization function.
     *
     * get_t() exists to support localization for code that might run during
     * the installation phase, when some elements of the system might not have
     * loaded.
     *
     * This would include implementations of hook_install(), which could run
     * during the Drupal installation phase, and might also be run during
     * non-installation time, such as while installing the module from the the
     * module administration page.
     *
     * Example usage:
     * @code
     *   $t = get_t();
     *   $translated = $t('translate this');
     * @endcode
     *
     * Use t() if your code will never run during the Drupal installation phase.
     * Use st() if your code will only run during installation and never any other
     * time. Use get_t() if your code could run in either circumstance.
     *
     * @see t()
     * @see st()
     * @ingroup sanitization
     */
    function get_t() {
      static $t;
      // This is not converted to drupal_static because there is no point in
      // resetting this as it can not change in the course of a request.
      if (!isset($t)) {
        $t = drupal_installation_attempted() ? 'st' : 't';
      }
      return $t;
    }
    
    /**
     * Initializes all the defined language types.
     */
    function drupal_language_initialize() {
      $types = language_types_get_all();
    
      // Ensure the language is correctly returned, even without multilanguage
      // support. Also make sure we have a $language fallback, in case a language
      // negotiation callback needs to do a full bootstrap.
      // Useful for eg. XML/HTML 'lang' attributes.
      $default = language_default();
      foreach ($types as $type) {
        $GLOBALS[$type] = $default;
      }
      if (language_multilingual()) {
        include_once DRUPAL_ROOT . '/core/includes/language.inc';
        foreach ($types as $type) {
          $GLOBALS[$type] = language_types_initialize($type);
        }
        // Allow modules to react on language system initialization in multilingual
        // environments.
        bootstrap_invoke_all('language_init');
      }
    }
    
    /**
     * Returns an array of the available language types.
     */
    function language_types_get_all() {
      return array_keys(variable_get('language_types', language_types_get_default()));
    }
    /**
     * Returns a list of the built-in language types.
     *
     * @return
     *   An array of key-values pairs where the key is the language type name and
     *   the value is its configurability (TRUE/FALSE).
     */
    function language_types_get_default() {
      return array(
        LANGUAGE_TYPE_INTERFACE => TRUE,
        LANGUAGE_TYPE_CONTENT => FALSE,
        LANGUAGE_TYPE_URL => FALSE,
      );
    }
    
    /**
     * Returns TRUE if there is more than one language enabled.
     */
    function language_multilingual() {
      // The "language_count" variable stores the number of enabled languages to
      // avoid unnecessarily querying the database when building the list of
      // enabled languages on monolingual sites.
      return variable_get('language_count', 1) > 1;
    }
    
    /**
     * Returns a list of configured languages.
     *
     * @param $only_enabled
     *   (optional) Whether to return only enabled languages.
     *
     * @return
     *   An associative array of languages, keyed by the language code, ordered by
     *   weight ascending and name ascending.
     */
    function language_list($only_enabled = FALSE) {
      $languages = &drupal_static(__FUNCTION__);
      // Initialize master language list.
      if (!isset($languages)) {
        // Initialize local language list caches.
        $languages = array('all' => array(), 'enabled' => array());
    
        // Fill in master language list based on current configuration.
        $default = language_default();
        if (language_multilingual() || module_exists('language')) {
          // Use language module configuration if available.
          $languages['all'] = db_query('SELECT * FROM {language} ORDER BY weight ASC, name ASC')->fetchAllAssoc('langcode');
        }
        else {
          // No language module, so use the default language only.
          $languages['all'][$default->langcode] = $default;
        }
    
        // Initialize default property so callers have an easy reference and can
        // save the same object without data loss. Also fill in the filtered list
        // of enabled languages only.
        foreach ($languages['all'] as $langcode => $language) {
          $languages['all'][$langcode]->default = ($langcode == $default->langcode);
          if ($language->enabled) {
            $languages['enabled'][$langcode] = $languages['all'][$langcode];
          }
        }
      }
    
      return $only_enabled ? $languages['enabled'] : $languages['all'];
    }
    
    /**
     * Loads a language object from the database.
     *
     * @param $langcode
     *   The language code.
     *
     * @return
     *   A fully-populated language object or FALSE.
     */
    function language_load($langcode) {
      $languages = language_list();
      return isset($languages[$langcode]) ? $languages[$langcode] : FALSE;
    }
    
    /**
     * Produced the printed name for a language for display.
     *
     * @param $langcode
     *   The language code.
     *
     * @return
     *   The printed name of the language.
     */
    function language_name($langcode) {
      if ($langcode == LANGUAGE_NONE) {
        return t('None');
      }
    
      if ($language = language_load($langcode)) {
        return $language->name;
      }
    
      return t('Unknown (@langcode)', array('@langcode' => $langcode));
    }
    
    /**
     * Returns the default language used on the site.
     *
     * @return
     *   A language object.
     */
    function language_default() {
      $default = variable_get('language_default', (object) array(
        'langcode' => 'en',
        'name' => 'English',
        'direction' => 0,
        'enabled' => 1,
        'weight' => 0,
      ));
      $default->default = TRUE;
      return $default;
    }
    
    /**
     * Returns the requested URL path of the page being viewed.
     *
     * Examples:
     * - http://example.com/node/306 returns "node/306".
     * - http://example.com/drupalfolder/node/306 returns "node/306" while
     *   base_path() returns "/drupalfolder/".
     * - http://example.com/path/alias (which is a path alias for node/306) returns
     *   "path/alias" as opposed to the internal path.
     * - http://example.com/index.php returns an empty string (meaning: front page).
     * - http://example.com/index.php?page=1 returns an empty string.
     *
     * @return
     *   The requested Drupal URL path.
     *
     * @see current_path()
     */
    function request_path() {
      static $path;
    
      if (isset($path)) {
        return $path;
      }
    
      if (isset($_GET['q'])) {
        // This is a request with a ?q=foo/bar query string. $_GET['q'] is
        // overwritten in drupal_path_initialize(), but request_path() is called
        // very early in the bootstrap process, so the original value is saved in
        // $path and returned in later calls.
        $path = $_GET['q'];
      }
      elseif (isset($_SERVER['REQUEST_URI'])) {
        // This request is either a clean URL, or 'index.php', or nonsense.
        // Extract the path from REQUEST_URI.
        $request_path = strtok($_SERVER['REQUEST_URI'], '?');
        $base_path_len = strlen(rtrim(dirname($_SERVER['SCRIPT_NAME']), '\/'));
        // Unescape and strip $base_path prefix, leaving q without a leading slash.
        $path = substr(urldecode($request_path), $base_path_len + 1);
        // If the path equals the script filename, either because 'index.php' was
        // explicitly provided in the URL, or because the server added it to
        // $_SERVER['REQUEST_URI'] even when it wasn't provided in the URL (some
        // versions of Microsoft IIS do this), the front page should be served.
        if ($path == basename($_SERVER['PHP_SELF'])) {
          $path = '';
        }
      }
      else {
        // This is the front page.
        $path = '';
      }
    
      // Under certain conditions Apache's RewriteRule directive prepends the value
      // assigned to $_GET['q'] with a slash. Moreover we can always have a trailing
      // slash in place, hence we need to normalize $_GET['q'].
      $path = trim($path, '/');
    
      return $path;
    }
    
    /**
     * Returns a component of the current Drupal path.
     *
     * When viewing a page at the path "admin/structure/types", for example, arg(0)
     * returns "admin", arg(1) returns "structure", and arg(2) returns "types".
     *
     * Avoid use of this function where possible, as resulting code is hard to
     * read. In menu callback functions, attempt to use named arguments. See the
     * explanation in menu.inc for how to construct callbacks that take arguments.
     * When attempting to use this function to load an element from the current
     * path, e.g. loading the node on a node page, use menu_get_object() instead.
     *
     * @param $index
     *   The index of the component, where each component is separated by a '/'
     *   (forward-slash), and where the first component has an index of 0 (zero).
     * @param $path
     *   A path to break into components. Defaults to the path of the current page.
     *
     * @return
     *   The component specified by $index, or NULL if the specified component was
     *   not found. If called without arguments, it returns an array containing all
     *   the components of the current path.
     */
    function arg($index = NULL, $path = NULL) {
      // Even though $arguments doesn't need to be resettable for any functional
      // reasons (the result of explode() does not depend on any run-time
      // information), it should be resettable anyway in case a module needs to
      // free up the memory used by it.
      // Use the advanced drupal_static() pattern, since this is called very often.
      static $drupal_static_fast;
      if (!isset($drupal_static_fast)) {
        $drupal_static_fast['arguments'] = &drupal_static(__FUNCTION__);
      }
      $arguments = &$drupal_static_fast['arguments'];
    
      if (!isset($path)) {
        $path = $_GET['q'];
      }
      if (!isset($arguments[$path])) {
        $arguments[$path] = explode('/', $path);
      }
      if (!isset($index)) {
        return $arguments[$path];
      }
      if (isset($arguments[$path][$index])) {
        return $arguments[$path][$index];
      }
    }
    
    /**
     * Returns the IP address of the client machine.
     *
     * If Drupal is behind a reverse proxy, we use the X-Forwarded-For header
     * instead of $_SERVER['REMOTE_ADDR'], which would be the IP address of
     * the proxy server, and not the client's. The actual header name can be
     * configured by the reverse_proxy_header variable.
     *
     * @return
     *   IP address of client machine, adjusted for reverse proxy and/or cluster
     *   environments.
     */
    function ip_address() {
      $ip_address = &drupal_static(__FUNCTION__);
    
      if (!isset($ip_address)) {
        $ip_address = $_SERVER['REMOTE_ADDR'];
    
        if (variable_get('reverse_proxy', 0)) {
          $reverse_proxy_header = variable_get('reverse_proxy_header', 'HTTP_X_FORWARDED_FOR');
          if (!empty($_SERVER[$reverse_proxy_header])) {
            // If an array of known reverse proxy IPs is provided, then trust
            // the XFF header if request really comes from one of them.
            $reverse_proxy_addresses = variable_get('reverse_proxy_addresses', array());
    
            // Turn XFF header into an array.
            $forwarded = explode(',', $_SERVER[$reverse_proxy_header]);
    
            // Trim the forwarded IPs; they may have been delimited by commas and spaces.
            $forwarded = array_map('trim', $forwarded);
    
            // Tack direct client IP onto end of forwarded array.
            $forwarded[] = $ip_address;
    
            // Eliminate all trusted IPs.
            $untrusted = array_diff($forwarded, $reverse_proxy_addresses);
    
            // The right-most IP is the most specific we can trust.
            $ip_address = array_pop($untrusted);
          }
        }
      }
    
      return $ip_address;
    }
    
    /**
     * @ingroup schemaapi
     * @{
     */
    
    /**
     * Gets the schema definition of a table, or the whole database schema.
     *
     * The returned schema will include any modifications made by any
     * module that implements hook_schema_alter().
     *
     * @param $table
     *   The name of the table. If not given, the schema of all tables is returned.
     * @param $rebuild
     *   If true, the schema will be rebuilt instead of retrieved from the cache.
     */
    function drupal_get_schema($table = NULL, $rebuild = FALSE) {
      static $schema;
    
      if ($rebuild || !isset($table)) {
        $schema = drupal_get_complete_schema($rebuild);
      }
      elseif (!isset($schema)) {
        $schema = new SchemaCache();
      }
    
      if (!isset($table)) {
        return $schema;
      }
      if (isset($schema[$table])) {
        return $schema[$table];
      }
      else {
        return FALSE;
      }
    }
    
    /**
     * Extends DrupalCacheArray to allow for dynamic building of the schema cache.
     */
    class SchemaCache extends DrupalCacheArray {
    
      /**
       * Constructs a SchemaCache object.
       */
      public function __construct() {
        // Cache by request method.
        parent::__construct('schema:runtime:' . ($_SERVER['REQUEST_METHOD'] == 'GET'), 'cache');
      }
    
      /**
       * Overrides DrupalCacheArray::resolveCacheMiss().
       */
      protected function resolveCacheMiss($offset) {
        $complete_schema = drupal_get_complete_schema();
        $value = isset($complete_schema[$offset]) ? $complete_schema[$offset] :  NULL;
        $this->storage[$offset] = $value;
        $this->persist($offset);
        return $value;
      }
    }
    
    /**
     * Gets the whole database schema.
     *
     * The returned schema will include any modifications made by any
     * module that implements hook_schema_alter().
     *
     * @param $rebuild
     *   If true, the schema will be rebuilt instead of retrieved from the cache.
     */
    function drupal_get_complete_schema($rebuild = FALSE) {
      static $schema = array();
    
      if (empty($schema) || $rebuild) {
        // Try to load the schema from cache.
        if (!$rebuild && $cached = cache()->get('schema')) {
          $schema = $cached->data;
        }
        // Otherwise, rebuild the schema cache.
        else {
          $schema = array();
          // Load the .install files to get hook_schema.
          // On some databases this function may be called before bootstrap has
          // been completed, so we force the functions we need to load just in case.
          if (function_exists('module_load_all_includes')) {
            // This function can be called very early in the bootstrap process, so
            // we force the module_list() cache to be refreshed to ensure that it
            // contains the complete list of modules before we go on to call
            // module_load_all_includes().
            module_list(TRUE);
            module_load_all_includes('install');
          }
    
          require_once DRUPAL_ROOT . '/core/includes/common.inc';
          // Invoke hook_schema for all modules.
          foreach (module_implements('schema') as $module) {
            // Cast the result of hook_schema() to an array, as a NULL return value
            // would cause array_merge() to set the $schema variable to NULL as well.
            // That would break modules which use $schema further down the line.
            $current = (array) module_invoke($module, 'schema');
            // Set 'module' and 'name' keys for each table, and remove descriptions,
            // as they needlessly slow down cache()->get() for every single request.
            _drupal_schema_initialize($current, $module);
            $schema = array_merge($schema, $current);
          }
    
          drupal_alter('schema', $schema);
          // If the schema is empty, avoid saving it: some database engines require
          // the schema to perform queries, and this could lead to infinite loops.
          if (!empty($schema) && (drupal_get_bootstrap_phase() == DRUPAL_BOOTSTRAP_FULL)) {
            cache()->set('schema', $schema);
          }
          if ($rebuild) {
            cache()->deletePrefix('schema:');
          }
        }
      }
    
      return $schema;
    }
    
    /**
     * @} End of "ingroup schemaapi".
     */
    
    
    /**
     * @ingroup registry
     * @{
     */
    
    /**
     * Initializes and returns the class loader.
     *
     * The class loader is responsible for lazy-loading all PSR-0 compatible
     * classes, interfaces, and traits (PHP 5.4 and later). Its only dependencies
     * are DRUPAL_ROOT and variable_get(). Otherwise it may be called as early as
     * possible.
     *
     * @return Symfony\Component\ClassLoader\UniversalClassLoader
     *   A UniversalClassLoader class instance (or extension thereof).
     */
    function drupal_classloader() {
      // Include the Symfony ClassLoader for loading PSR-0-compatible classes.
      require_once DRUPAL_ROOT . '/core/vendor/Symfony/Component/ClassLoader/UniversalClassLoader.php';
    
      // By default, use the UniversalClassLoader which is best for development,
      // as it does not break when code is moved on the file system. However, as it
      // is slow, allow to use the APC class loader in production.
      static $loader;
    
      if (!isset($loader)) {
        // @todo Use a cleaner way than variable_get() to switch autoloaders.
        switch (variable_get('autoloader_mode', 'default')) {
          case 'apc':
            if (function_exists('apc_store')) {
              require_once DRUPAL_ROOT . '/core/vendor/Symfony/Component/ClassLoader/ApcUniversalClassLoader.php';
              $loader = new ApcUniversalClassLoader('drupal.' . $GLOBALS['drupal_hash_salt']);
              break;
            }
          // Fall through to the default loader if APC was not loaded, so that the
          // site does not fail completely.
          case 'dev':
          case 'default':
          default:
            $loader = new UniversalClassLoader();
            break;
        }
        $loader->register();
      }
      return $loader;
    }
    
    /**
     * Confirms that an interface is available.
     *
     * This function is rarely called directly. Instead, it is registered as an
     * spl_autoload()  handler, and PHP calls it for us when necessary.
     *
     * @param $interface
     *   The name of the interface to check or load.
     *
     * @return
     *   TRUE if the interface is currently available, FALSE otherwise.
     */
    function drupal_autoload_interface($interface) {
      return _registry_check_code('interface', $interface);
    }
    
    /**
     * Confirms that a class is available.
     *
     * This function is rarely called directly. Instead, it is registered as an
     * spl_autoload()  handler, and PHP calls it for us when necessary.
     *
     * @param $class
     *   The name of the class to check or load.
     *
     * @return
     *   TRUE if the class is currently available, FALSE otherwise.
     */
    function drupal_autoload_class($class) {
      return _registry_check_code('class', $class);
    }
    
    /**
     * Checks for a resource in the registry.
     *
     * @param $type
     *   The type of resource we are looking up, or one of the constants
     *   REGISTRY_RESET_LOOKUP_CACHE or REGISTRY_WRITE_LOOKUP_CACHE, which
     *   signal that we should reset or write the cache, respectively.
     * @param $name
     *   The name of the resource, or NULL if either of the REGISTRY_* constants
     *   is passed in.
     *
     * @return
     *   TRUE if the resource was found, FALSE if not.
     *   NULL if either of the REGISTRY_* constants is passed in as $type.
     */
    function _registry_check_code($type, $name = NULL) {
      static $lookup_cache, $cache_update_needed;
    
      if ($type == 'class' && class_exists($name) || $type == 'interface' && interface_exists($name)) {
        return TRUE;
      }
    
      if (!isset($lookup_cache)) {
        $lookup_cache = array();
        if ($cache = cache('bootstrap')->get('lookup_cache')) {
          $lookup_cache = $cache->data;
        }
      }
    
      // When we rebuild the registry, we need to reset this cache so
      // we don't keep lookups for resources that changed during the rebuild.
      if ($type == REGISTRY_RESET_LOOKUP_CACHE) {
        $cache_update_needed = TRUE;
        $lookup_cache = NULL;
        return;
      }
    
      // Called from drupal_page_footer, we write to permanent storage if there
      // changes to the lookup cache for this request.
      if ($type == REGISTRY_WRITE_LOOKUP_CACHE) {
        if ($cache_update_needed) {
          cache('bootstrap')->set('lookup_cache', $lookup_cache);
        }
        return;
      }
    
      // $type is either 'interface' or 'class', so we only need the first letter to
      // keep the cache key unique.
      $cache_key = $type[0] . $name;
      if (isset($lookup_cache[$cache_key])) {
        if ($lookup_cache[$cache_key]) {
          require_once DRUPAL_ROOT . '/' . $lookup_cache[$cache_key];
        }
        return (bool) $lookup_cache[$cache_key];
      }
    
      // This function may get called when the default database is not active, but
      // there is no reason we'd ever want to not use the default database for
      // this query.
      $file = Database::getConnection('default', 'default')->query("SELECT filename FROM {registry} WHERE name = :name AND type = :type", array(
          ':name' => $name,
          ':type' => $type,
        ))
        ->fetchField();
    
      // Flag that we've run a lookup query and need to update the cache.
      $cache_update_needed = TRUE;
    
      // Misses are valuable information worth caching, so cache even if
      // $file is FALSE.
      $lookup_cache[$cache_key] = $file;
    
      if ($file) {
        require_once DRUPAL_ROOT . '/' . $file;
        return TRUE;
      }
      else {
        return FALSE;
      }
    }
    
    /**
     * Rescans all enabled modules and rebuilds the registry.
     *
     * Rescans all code in modules or includes directories, storing the location of
     * each interface or class in the database.
     */
    function registry_rebuild() {
      system_rebuild_module_data();
      registry_update();
    }
    
    /**
     * Updates the registry based on the latest files listed in the database.
     *
     * This function should be used when system_rebuild_module_data() does not need
     * to be called, because it is already known that the list of files in the
     * {system} table matches those in the file system.
     *
     * @see registry_rebuild()
     */
    function registry_update() {
      require_once DRUPAL_ROOT . '/core/includes/registry.inc';
      _registry_update();
    }
    
    /**
     * @} End of "ingroup registry".
     */
    
    /**
     * Provides central static variable storage.
     *
     * All functions requiring a static variable to persist or cache data within
     * a single page request are encouraged to use this function unless it is
     * absolutely certain that the static variable will not need to be reset during
     * the page request. By centralizing static variable storage through this
     * function, other functions can rely on a consistent API for resetting any
     * other function's static variables.
     *
     * Example:
     * @code
     * function example_list($field = 'default') {
     *   $examples = &drupal_static(__FUNCTION__);
     *   if (!isset($examples)) {
     *     // If this function is being called for the first time after a reset,
     *     // query the database and execute any other code needed to retrieve
     *     // information.
     *     ...
     *   }
     *   if (!isset($examples[$field])) {
     *     // If this function is being called for the first time for a particular
     *     // index field, then execute code needed to index the information already
     *     // available in $examples by the desired field.
     *     ...
     *   }
     *   // Subsequent invocations of this function for a particular index field
     *   // skip the above two code blocks and quickly return the already indexed
     *   // information.
     *   return $examples[$field];
     * }
     * function examples_admin_overview() {
     *   // When building the content for the overview page, make sure to get
     *   // completely fresh information.
     *   drupal_static_reset('example_list');
     *   ...
     * }
     * @endcode
     *
     * In a few cases, a function can have certainty that there is no legitimate
     * use-case for resetting that function's static variable. This is rare,
     * because when writing a function, it's hard to forecast all the situations in
     * which it will be used. A guideline is that if a function's static variable
     * does not depend on any information outside of the function that might change
     * during a single page request, then it's ok to use the "static" keyword
     * instead of the drupal_static() function.
     *
     * Example:
     * @code
     * function actions_do(...) {
     *   // $stack tracks the number of recursive calls.
     *   static $stack;
     *   $stack++;
     *   if ($stack > variable_get('actions_max_stack', 35)) {
     *     ...
     *     return;
     *   }
     *   ...
     *   $stack--;
     * }
     * @endcode
     *
     * In a few cases, a function needs a resettable static variable, but the
     * function is called many times (100+) during a single page request, so
     * every microsecond of execution time that can be removed from the function
     * counts. These functions can use a more cumbersome, but faster variant of
     * calling drupal_static(). It works by storing the reference returned by
     * drupal_static() in the calling function's own static variable, thereby
     * removing the need to call drupal_static() for each iteration of the function.
     * Conceptually, it replaces:
     * @code
     * $foo = &drupal_static(__FUNCTION__);
     * @endcode
     * with:
     * @code
     * // Unfortunately, this does not work.
     * static $foo = &drupal_static(__FUNCTION__);
     * @endcode
     * However, the above line of code does not work, because PHP only allows static
     * variables to be initializied by literal values, and does not allow static
     * variables to be assigned to references.
     * - http://php.net/manual/en/language.variables.scope.php#language.variables.scope.static
     * - http://php.net/manual/en/language.variables.scope.php#language.variables.scope.references
     * The example below shows the syntax needed to work around both limitations.
     * For benchmarks and more information, see http://drupal.org/node/619666.
     *
     * Example:
     * @code
     * function user_access($string, $account = NULL) {
     *   // Use the advanced drupal_static() pattern, since this is called very often.
     *   static $drupal_static_fast;
     *   if (!isset($drupal_static_fast)) {
     *     $drupal_static_fast['perm'] = &drupal_static(__FUNCTION__);
     *   }
     *   $perm = &$drupal_static_fast['perm'];
     *   ...
     * }
     * @endcode
     *
     * @param $name
     *   Globally unique name for the variable. For a function with only one static,
     *   variable, the function name (e.g. via the PHP magic __FUNCTION__ constant)
     *   is recommended. For a function with multiple static variables add a
     *   distinguishing suffix to the function name for each one.
     * @param $default_value
     *   Optional default value.
     * @param $reset
     *   TRUE to reset a specific named variable, or all variables if $name is NULL.
     *   Resetting every variable should only be used, for example, for running
     *   unit tests with a clean environment. Should be used only though via
     *   function drupal_static_reset() and the return value should not be used in
     *   this case.
     *
     * @return
     *   Returns a variable by reference.
     *
     * @see drupal_static_reset()
     */
    function &drupal_static($name, $default_value = NULL, $reset = FALSE) {
      static $data = array(), $default = array();
      // First check if dealing with a previously defined static variable.
      if (isset($data[$name]) || array_key_exists($name, $data)) {
        // Non-NULL $name and both $data[$name] and $default[$name] statics exist.
        if ($reset) {
          // Reset pre-existing static variable to its default value.
          $data[$name] = $default[$name];
        }
        return $data[$name];
      }
      // Neither $data[$name] nor $default[$name] static variables exist.
      if (isset($name)) {
        if ($reset) {
          // Reset was called before a default is set and yet a variable must be
          // returned.
          return $data;
        }
        // First call with new non-NULL $name. Initialize a new static variable.
        $default[$name] = $data[$name] = $default_value;
        return $data[$name];
      }
      // Reset all: ($name == NULL). This needs to be done one at a time so that
      // references returned by earlier invocations of drupal_static() also get
      // reset.
      foreach ($default as $name => $value) {
        $data[$name] = $value;
      }
      // As the function returns a reference, the return should always be a
      // variable.
      return $data;
    }
    
    /**
     * Resets one or all centrally stored static variable(s).
     *
     * @param $name
     *   Name of the static variable to reset. Omit to reset all variables.
     */
    function drupal_static_reset($name = NULL) {
      drupal_static($name, NULL, TRUE);
    }
    
    /**
     * Detects whether the current script is running in a command-line environment.
     */
    function drupal_is_cli() {
      return (!isset($_SERVER['SERVER_SOFTWARE']) && (php_sapi_name() == 'cli' || (is_numeric($_SERVER['argc']) && $_SERVER['argc'] > 0)));
    }
    
    /**
     * Formats text for emphasized display in a placeholder inside a sentence.
     *
     * Used automatically by format_string().
     *
     * @param $text
     *   The text to format (plain-text).
     *
     * @return
     *   The formatted text (html).
     */
    function drupal_placeholder($text) {
      return '<em class="placeholder">' . check_plain($text) . '</em>';
    }
    
    /**
     * Registers a function for execution on shutdown.
     *
     * Wrapper for register_shutdown_function() that catches thrown exceptions to
     * avoid "Exception thrown without a stack frame in Unknown".
     *
     * @param $callback
     *   The shutdown function to register.
     * @param ...
     *   Additional arguments to pass to the shutdown function.
     *
     * @return
     *   Array of shutdown functions to be executed.
     *
     * @see register_shutdown_function()
     * @ingroup php_wrappers
     */
    function &drupal_register_shutdown_function($callback = NULL) {
      // We cannot use drupal_static() here because the static cache is reset during
      // batch processing, which breaks batch handling.
      static $callbacks = array();
    
      if (isset($callback)) {
        // Only register the internal shutdown function once.
        if (empty($callbacks)) {
          register_shutdown_function('_drupal_shutdown_function');
        }
        $args = func_get_args();
        array_shift($args);
        // Save callback and arguments
        $callbacks[] = array('callback' => $callback, 'arguments' => $args);
      }
      return $callbacks;
    }
    
    /**
     * Executes registered shutdown functions.
     */
    function _drupal_shutdown_function() {
      $callbacks = &drupal_register_shutdown_function();
    
      // Set the CWD to DRUPAL_ROOT as it is not guaranteed to be the same as it
      // was in the normal context of execution.
      chdir(DRUPAL_ROOT);
    
      try {
        while (list($key, $callback) = each($callbacks)) {
          call_user_func_array($callback['callback'], $callback['arguments']);
        }
      }
      catch (Exception $exception) {
        // If we are displaying errors, then do so with no possibility of a further uncaught exception being thrown.
       require_once DRUPAL_ROOT . '/core/includes/errors.inc';
       if (error_displayable()) {
          print '<h1>Uncaught exception thrown in shutdown function.</h1>';
          print '<p>' . _drupal_render_exception_safe($exception) . '</p><hr />';
        }
      }
    }