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41 results

NodeFormController.php

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    bootstrap.inc 91.24 KiB
    <?php
    
    use Drupal\Component\Utility\Crypt;
    use Drupal\Component\Utility\NestedArray;
    use Drupal\Component\Utility\Settings;
    use Drupal\Component\Utility\String;
    use Drupal\Component\Utility\Timer;
    use Drupal\Component\Utility\Unicode;
    use Drupal\Component\Utility\Url;
    use Drupal\Core\DrupalKernel;
    use Drupal\Core\Database\Database;
    use Drupal\Core\DependencyInjection\ContainerBuilder;
    use Drupal\Core\Utility\Title;
    use Drupal\Core\Utility\Error;
    use Symfony\Component\ClassLoader\ApcClassLoader;
    use Symfony\Component\DependencyInjection\ContainerInterface;
    use Symfony\Component\DependencyInjection\Container;
    use Symfony\Component\DependencyInjection\Reference;
    use Symfony\Component\DependencyInjection\Exception\RuntimeException as DependencyInjectionRuntimeException;
    use Symfony\Component\HttpFoundation\Request;
    use Symfony\Component\HttpFoundation\Response;
    use Drupal\Core\Language\Language;
    use Drupal\Core\Lock\DatabaseLockBackend;
    use Drupal\Core\Lock\LockBackendInterface;
    use Drupal\Core\Session\UserSession;
    
    /**
     * @file
     * Functions that need to be loaded on every Drupal request.
     */
    
    /**
     * Minimum supported version of PHP.
     */
    const DRUPAL_MINIMUM_PHP = '5.3.10';
    
    /**
     * Minimum recommended value of PHP memory_limit.
     */
    const DRUPAL_MINIMUM_PHP_MEMORY_LIMIT = '32M';
    
    /**
     * Error reporting level: display no errors.
     */
    const ERROR_REPORTING_HIDE = 'hide';
    
    /**
     * Error reporting level: display errors and warnings.
     */
    const ERROR_REPORTING_DISPLAY_SOME = 'some';
    
    /**
     * Error reporting level: display all messages.
     */
    const ERROR_REPORTING_DISPLAY_ALL = 'all';
    
    /**
     * Error reporting level: display all messages, plus backtrace information.
     */
    const ERROR_REPORTING_DISPLAY_VERBOSE = 'verbose';
    
    /**
     * @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 conditions.
     */
    const WATCHDOG_CRITICAL = 2;
    
    /**
     * Log message severity -- Error conditions.
     */
    const WATCHDOG_ERROR = 3;
    
    /**
     * Log message severity -- Warning conditions.
     */
    const WATCHDOG_WARNING = 4;
    
    /**
     * Log message severity -- Normal but significant conditions.
     */
    const WATCHDOG_NOTICE = 5;
    
    /**
     * Log message severity -- Informational messages.
     */
    const WATCHDOG_INFO = 6;
    
    /**
     * Log message severity -- 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, initalize a kernel.
     */
    const DRUPAL_BOOTSTRAP_KERNEL = 1;
    
    /**
     * Third bootstrap phase: try to serve a cached page.
     */
    const DRUPAL_BOOTSTRAP_PAGE_CACHE = 2;
    
    /**
     * Fourth bootstrap phase: load code for subsystems and modules.
     */
    const DRUPAL_BOOTSTRAP_CODE = 3;
    
    /**
     * Final bootstrap phase: initialize language, path, theme, and modules.
     */
    const DRUPAL_BOOTSTRAP_FULL = 4;
    
    /**
     * Role ID for anonymous users; should match what's in the "role" table.
     */
    const DRUPAL_ANONYMOUS_RID = 'anonymous';
    
    /**
     * Role ID for authenticated users; should match what's in the "role" table.
     */
    const DRUPAL_AUTHENTICATED_RID = 'authenticated';
    
    /**
     * The number of bytes in a kilobyte.
     *
     * For more information, visit http://en.wikipedia.org/wiki/Kilobyte.
     */
    const DRUPAL_KILOBYTE = 1024;
    
    /**
     * The maximum number of characters in a module or theme name.
     */
    const DRUPAL_EXTENSION_NAME_MAX_LENGTH = 50;
    
    /**
     * 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 has already been sanitized.
     *
     * @todo Move to the Title class.
     */
    const PASS_THROUGH = -1;
    
    /**
     * Regular expression to match PHP function names.
     *
     * @see http://php.net/manual/language.functions.php
     */
    const DRUPAL_PHP_FUNCTION_PATTERN = '[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*';
    
    /**
     * $config_directories key for active directory.
     *
     * @see config_get_config_directory()
     */
    const CONFIG_ACTIVE_DIRECTORY = 'active';
    
    /**
     * $config_directories key for staging directory.
     *
     * @see config_get_config_directory()
     */
    const CONFIG_STAGING_DIRECTORY = 'staging';
    
    /**
     * Defines the root directory of the Drupal installation.
     *
     * This strips two levels of directories off the current directory.
     */
    define('DRUPAL_ROOT', dirname(dirname(__DIR__)));
    
    /**
     * Returns the appropriate configuration directory.
     *
     * Returns the configuration path based on the site's hostname, port, and
     * pathname. Uses find_conf_path() to find the current configuration directory.
     * See default.settings.php for examples on how the URL is converted to a
     * directory.
     *
     * @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 $reset
     *   Force a full search for matching directories even if one had been
     *   found previously. Defaults to FALSE.
     *
     * @return
     *   The path of the matching directory.
     *
     * @see default.settings.php
     */
    function conf_path($require_settings = TRUE, $reset = FALSE) {
      static $conf_path;
    
      if (isset($conf_path) && !$reset) {
        return $conf_path;
      }
    
      // Check for a simpletest override.
      if ($test_prefix = drupal_valid_test_ua()) {
        $conf_path = 'sites/simpletest/' . substr($test_prefix, 10);
        return $conf_path;
      }
    
      // Otherwise, use the normal $conf_path.
      $script_name = $_SERVER['SCRIPT_NAME'];
      if (!$script_name) {
        $script_name = $_SERVER['SCRIPT_FILENAME'];
      }
      $http_host = $_SERVER['HTTP_HOST'];
      $conf_path = find_conf_path($http_host, $script_name, $require_settings);
      return $conf_path;
    }
    
    /**
     * Finds the appropriate configuration directory for a given host and path.
     *
     * Finds a matching configuration directory file by stripping the website's
     * hostname from left to right and pathname from right to left. By default,
     * the directory must contain a 'settings.php' file for it to match. If the
     * parameter $require_settings is set to FALSE, then a directory without a
     * 'settings.php' file will match as well. The first configuration
     * file found will be used and the remaining ones will be ignored. If no
     * configuration file is found, returns a default value '$confdir/default'. See
     * default.settings.php for examples on how the URL is converted to a directory.
     *
     * If a file named sites.php is present in the $confdir, it will be loaded
     * prior to scanning for directories. That file can define aliases in an
     * associative array named $sites. The array is written in the format
     * '<port>.<domain>.<path>' => 'directory'. As an example, to create a
     * directory alias for http://www.drupal.org:8080/mysite/test whose configuration
     * file is in sites/example.com, the array should be defined as:
     * @code
     * $sites = array(
     *   '8080.www.drupal.org.mysite.test' => 'example.com',
     * );
     * @endcode
     *
     * @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.
     * @param $require_settings
     *   Defaults to TRUE. If TRUE, then only match directories with a
     *   'settings.php' file. Otherwise match any directory.
     *
     * @return
     *   The path of the matching configuration directory.
     *
     * @see default.settings.php
     * @see example.sites.php
     * @see conf_path()
     */
    function find_conf_path($http_host, $script_name, $require_settings = TRUE) {
      // Determine whether multi-site functionality is enabled.
      if (!file_exists(DRUPAL_ROOT . '/sites/sites.php')) {
        return 'sites/default';
      }
    
      $sites = array();
      include DRUPAL_ROOT . '/sites/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 . '/sites/' . $sites[$dir])) {
            $dir = $sites[$dir];
          }
          if (file_exists(DRUPAL_ROOT . '/sites/' . $dir . '/settings.php') || (!$require_settings && file_exists(DRUPAL_ROOT . '/sites/' . $dir))) {
            return "sites/$dir";
          }
        }
      }
      return 'sites/default';
    }
    
    /**
     * Returns the path of a configuration directory.
     *
     * @param string $type
     *   (optional) The type of config directory to return. Drupal core provides
     *   'active' and 'staging'. Defaults to CONFIG_ACTIVE_DIRECTORY.
     *
     * @return string
     *   The configuration directory path.
     */
    function config_get_config_directory($type = CONFIG_ACTIVE_DIRECTORY) {
      global $config_directories;
    
      if (!empty($config_directories[$type])) {
        return $config_directories[$type];
      }
      throw new Exception(format_string('The configuration directory type %type does not exist.', array('%type' => $type)));
    }
    
    /**
     * 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::request()->getClientIP()
     * 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 $variables
     *   (optional) An associative array of variables within
     *   \Drupal::request()->server that should be replaced. If the special element
     *   'url' is provided in this array, it will be used to populate some of the
     *   server defaults; it should be set to the URL of the current page request,
     *   excluding any GET request but including the script name
     *   (e.g., http://www.example.com/mysite/index.php).
     *
     * @see conf_path()
     * @see request_uri()
     * @see \Symfony\Component\HttpFoundation\Request::getClientIP()
     */
    function drupal_override_server_variables($variables = array()) {
      $request = \Drupal::request();
      $server_vars = $request->server->all();
      // 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_vars['HTTP_HOST'] = $url['host'];
        }
        if (isset($url['path'])) {
          $server_vars['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.
      $request->server->replace($variables + $server_vars + $defaults);
    
      // @todo remove once conf_path() no longer uses $_SERVER.
      $_SERVER = $request->server->all();
    }
    
    /**
     * 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'] = '';
      }
    
      // @todo Refactor with the Symfony Request object.
      _current_path(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.
    
      // Deny execution with enabled "magic quotes" (both GPC and runtime).
      if (get_magic_quotes_gpc() || get_magic_quotes_runtime()) {
        header($_SERVER['SERVER_PROTOCOL'] . ' 500 Internal Server Error');
        print "PHP's 'magic_quotes_gpc' and 'magic_quotes_runtime' settings are not supported and must be disabled.";
        exit;
      }
    
      // 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.
      // Send an empty string to disable the cache limiter.
      ini_set('session.cache_limiter', '');
      // 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() {
      // Export these settings.php variables to the global namespace.
      global $base_url, $databases, $cookie_domain, $drupal_hash_salt, $config_directories, $config;
      $settings = array();
      $config = array();
    
      // Make conf_path() available as local variable in settings.php.
      $conf_path = conf_path();
      if (is_readable(DRUPAL_ROOT . '/' . $conf_path . '/settings.php')) {
        require DRUPAL_ROOT . '/' . $conf_path . '/settings.php';
      }
      // Initialize Settings.
      new Settings($settings);
    }
    
    /**
     * Initializes global request variables.
     *
     * @todo D8: Eliminate this entirely in favor of Request object.
     */
    function _drupal_request_initialize() {
      // Provided by settings.php.
      // @see drupal_settings_initialize()
      global $base_url, $cookie_domain;
      // Set and derived from $base_url by this function.
      global $base_path, $base_root, $script_path;
      global $base_secure_url, $base_insecure_url;
    
      $is_https = isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) == 'on';
    
      if (isset($base_url)) {
        // Parse fixed base URL from settings.php.
        $parts = parse_url($base_url);
        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;
    
        // For a request URI of '/index.php/foo', $_SERVER['SCRIPT_NAME'] is
        // '/index.php', whereas $_SERVER['PHP_SELF'] is '/index.php/foo'.
        if ($dir = rtrim(dirname($_SERVER['SCRIPT_NAME']), '\/')) {
          // Remove "core" directory if present, allowing install.php, update.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);
    
      // Determine the path of the script relative to the base path, and add a
      // trailing slash. This is needed for creating URLs to Drupal pages.
      if (!isset($script_path)) {
        $script_path = '';
        // We don't expect scripts outside of the base path, but sanity check
        // anyway.
        if (strpos($_SERVER['SCRIPT_NAME'], $base_path) === 0) {
          $script_path = substr($_SERVER['SCRIPT_NAME'], strlen($base_path)) . '/';
          // If the request URI does not contain the script name, then clean URLs
          // are in effect and the script path can be similarly dropped from URL
          // generation. For servers that don't provide $_SERVER['REQUEST_URI'], we
          // do not know the actual URI requested by the client, and request_uri()
          // returns a URI with the script name, resulting in non-clean URLs unless
          // there's other code that intervenes.
          if (strpos(request_uri(TRUE) . '/', $base_path . $script_path) !== 0) {
            $script_path = '';
          }
          // @todo Temporary BC for install.php, update.php, and other scripts.
          //   - http://drupal.org/node/1547184
          //   - http://drupal.org/node/1546082
          if ($script_path !== 'index.php/') {
            $script_path = '';
          }
        }
      }
    
      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 located
     * in any of these three places:
     *
     * core/modules/foo/foo.module
     * 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 (theme, theme_engine, module, profile).
     * @param $name
     *   The name of the item for which the filename is requested.
     * @param $filename
     *   The filename of the item if it is to be set explicitly rather
     *   than by consulting the database.
     *
     * @return
     *   The filename of the requested item or NULL if the item is not found.
     */
    function drupal_get_filename($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 converted into modules in system_rebuild_module_data().
      // @todo Remove false-exposure of profiles as modules.
      $original_type = $type;
      if ($type == 'profile') {
        $type = 'module';
      }
      if (!isset($files[$type])) {
        $files[$type] = array();
      }
    
      if (!empty($filename)) {
        $files[$type][$name] = $filename;
      }
      elseif (isset($files[$type][$name])) {
        // nothing
      }
      else {
        // Verify that we have an keyvalue service before using it. This is required
        // because this function is called during installation.
        // @todo Inject database connection into KeyValueStore\DatabaseStorage.
        if (\Drupal::hasService('keyvalue') && function_exists('db_query')) {
          if ($type == 'module') {
            if (empty($files[$type])) {
              $files[$type] = \Drupal::moduleHandler()->getModuleList();
            }
            if (isset($files[$type][$name])) {
              return $files[$type][$name];
            }
          }
          try {
            $file_list = \Drupal::state()->get('system.' . $type . '.files');
            if ($file_list && isset($file_list[$name]) && file_exists(DRUPAL_ROOT . '/' . $file_list[$name])) {
              $files[$type][$name] = $file_list[$name];
            }
          }
          catch (Exception $e) {
            // The keyvalue service raised an exception because the backend might
            // be down. We have a fallback for this case so we hide the error
            // completely.
          }
        }
        // Fallback to searching the filesystem if the database could not find the
        // file or the file returned by the database is not found.
        if (!isset($files[$type][$name])) {
          // We have consistent directory naming: modules, themes...
          $dir = $type . 's';
          if ($type == 'theme_engine') {
            $dir = 'themes/engines';
            $extension = 'engine';
          }
          elseif ($type == 'theme') {
            $extension = 'info.yml';
          }
          // Profiles are converted into modules in system_rebuild_module_data().
          // @todo Remove false-exposure of profiles as modules.
          elseif ($original_type == 'profile') {
            $dir = 'profiles';
            $extension = 'profile';
          }
          else {
            $extension = $type;
          }
    
          if (!isset($dirs[$dir][$extension])) {
            $dirs[$dir][$extension] = TRUE;
            if (!function_exists('drupal_system_listing')) {
              require_once __DIR__ . '/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$/", $dir);
            foreach ($matches as $matched_name => $file) {
              $files[$type][$matched_name] = $file->uri;
            }
          }
        }
      }
    
      if (isset($files[$type][$name])) {
        return $files[$type][$name];
      }
    }
    
    /**
     * Returns a setting.
     *
     * Settings can be set in settings.php in the $settings array and requested
     * by this function. Settings should be used over configuration for read-only,
     * possibly low bootstrap configuration that is environment specific.
     *
     * @return \Drupal\Component\Utility\Settings
     *   The settings object.
     */
    function settings() {
      return Settings::getSingleton();
    }
    
    /**
     * Gets the page cache cid for this request.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request for this page.
     *
     * @return string
     *   The cid for this request.
     */
    function drupal_page_cache_get_cid(Request $request) {
      $cid_parts = array(
        $request->getUri(),
        \Drupal::service('content_negotiation')->getContentType($request),
      );
      return sha1(implode(':', $cid_parts));
    }
    
    /**
     * 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 \Symfony\Component\HttpFoundation\Request $request
     *   The request for this page.
     *
     * @return
     *   The cache object, if the page was found in the cache, NULL otherwise.
     */
    function drupal_page_get_cache(Request $request) {
      if (drupal_page_is_cacheable()) {
        return \Drupal::cache('page')->get(drupal_page_cache_get_cid($request));
      }
    }
    
    /**
     * 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();
    }
    
    /**
     * 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 $append
     *   Whether to append the value to an existing header or to replace it.
     *
     * @deprecated Header handling is being shifted to a Symfony response object.
     */
    function drupal_add_http_header($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;
      }
    }
    
    /**
     * Gets the HTTP response headers for the current page.
     *
     * @param $name
     *   An HTTP header name. If omitted, all headers are returned as name/value
     *   pairs. If an array value is FALSE, the header has been unset.
     *
     * @return
     *   A string containing the header value, or FALSE if the header has been set,
     *   or NULL if the header has not been set.
     *
     * @deprecated Header handling is being shifted to a Symfony response object.
     */
    function drupal_get_http_header($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 2616, section 4.2).
     *
     * @deprecated Header handling is being shifted to a Symfony response object.
     */
    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 array $default_headers
     *   (optional) An array of headers as name/value pairs.
     * @param bool $only_default
     *   (optional) If TRUE and headers have already been sent, send only the
     *   specified headers.
     *
     * @deprecated Header handling is being shifted to a Symfony response object.
     */
    function drupal_send_headers($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 !== FALSE) {
          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()
     *
     * @deprecated Header handling is being shifted to a Symfony response object.
     */
    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, Response $response, Request $request) {
      $config = \Drupal::config('system.performance');
    
      // First half: we must determine if we should be returning a 304.
    
      // Negotiate whether to use compression.
      $page_compression = !empty($cache->data['page_compressed']) && extension_loaded('zlib');
      $return_compressed = $page_compression && $request->server->has('HTTP_ACCEPT_ENCODING') && strpos($request->server->get('HTTP_ACCEPT_ENCODING'), 'gzip') !== FALSE;
    
      // Get headers. Keys are lower-case.
      $boot_headers = drupal_get_http_header();
    
      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).
        $name_lower = strtolower($name);
        if (in_array($name_lower, array('content-location', 'expires', 'cache-control', 'vary')) && !isset($boot_headers[$name_lower])) {
          $response->headers->set($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.
      $max_age = !$request->cookies->has(session_name()) || isset($boot_headers['vary']) ? $config->get('cache.page.max_age') : 0;
      $response->headers->set('Cache-Control', 'public, max-age=' . $max_age);
    
      // Entity tag should change if the output changes.
      $response->setEtag($cache->created);
    
      // See if the client has provided the required HTTP headers.
      $if_modified_since = $request->server->has('HTTP_IF_MODIFIED_SINCE') ? strtotime($request->server->get('HTTP_IF_MODIFIED_SINCE')) : FALSE;
      $if_none_match = $request->server->has('HTTP_IF_NONE_MATCH') ? stripslashes($request->server->get('HTTP_IF_NONE_MATCH')) : FALSE;
    
      if ($if_modified_since && $if_none_match
          && $if_none_match == $response->headers->get('etag') // etag must match
          && $if_modified_since == $cache->created) {  // if-modified-since must match
        $response->setStatusCode(304);
        return;
      }
    
      // Second half: we're not returning a 304, so put in other headers.
    
      // Send the remaining headers.
      foreach ($cache->data['headers'] as $name => $value) {
        $response->headers->set($name, $value);
        drupal_add_http_header($name, $value);
      }
    
      $response->setLastModified(\DateTime::createFromFormat('U', $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).
      if (!$response->getExpires()) {
        $response->setExpires(\DateTime::createFromFormat('j-M-Y H:i:s T', '19-Nov-1978 05:00:00 GMT'));
      }
    
      // 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 (!isset($boot_headers['vary']) && !settings()->get('omit_vary_cookie')) {
        $response->setVary('Cookie', FALSE);
      }
    
      if ($page_compression) {
        $response->setVary('accept-encoding', FALSE);
        // If page_compression is enabled, the cache contains gzipped data.
        if ($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');
          $response->headers->set('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));
        }
      }
    
      $response->setContent($cache->data['body']);
    }
    
    /**
     * 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.
     *
     * @section sec_translating_vars Translating Variables
     * 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 about how to define variables in your string.)
     * Translators can then rearrange the string as necessary for the language
     * (e.g., in Spanish, it might be "blog de @name").
     *
     * @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 $options
     *   An associative array of additional options, with the following elements:
     *   - 'langcode' (defaults to the current language): The language code to
     *     translate to a language other than what is used to display the page.
     *   - 'context' (defaults to the empty context): The context the source string
     *     belongs to.
     *
     * @return
     *   The translated string.
     *
     * @see format_string()
     * @ingroup sanitization
     */
    function t($string, array $args = array(), array $options = array()) {
      return \Drupal::translation()->translate($string, $args, $options);
    }
    
    /**
     * Formats a string for HTML display by replacing variable placeholders.
     *
     * @see \Drupal\Component\Utility\String::format()
     * @see t()
     * @ingroup sanitization
     */
    function format_string($string, array $args = array()) {
      return String::format($string, $args);
    }
    
    /**
     * Encodes special characters in a plain-text string for display as HTML.
     *
     * @see \Drupal\Component\Utility\String::checkPlain()
     * @see drupal_validate_utf8()
     * @ingroup sanitization
     *
     * @deprecated as of Drupal 8.0. Use
     *   Drupal\Component\Utility\String::checkPlain() directly instead.
     */
    function check_plain($text) {
      return String::checkPlain($text);
    }
    
    /**
     * 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 $text
     *   The text to check.
     *
     * @return
     *   TRUE if the text is valid UTF-8, FALSE if not.
     *
     * @see \Drupal\Component\Utility\Unicode::validateUtf8()
     */
    function drupal_validate_utf8($text) {
      return Unicode::validateUtf8($text);
    }
    
    /**
     * Returns the equivalent of Apache's $_SERVER['REQUEST_URI'] variable.
     *
     * Because $_SERVER['REQUEST_URI'] is only available on Apache, we generate an
     * equivalent using other environment variables.
     *
     * @todo The above comment is incorrect: http://drupal.org/node/1547294.
     */
    function request_uri($omit_query_string = FALSE) {
      if (isset($_SERVER['REQUEST_URI'])) {
        $uri = $_SERVER['REQUEST_URI'];
      }
      else {
        if (isset($_SERVER['argv'][0])) {
          $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 $omit_query_string ? strtok($uri, '?') : $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 or
     *   NULL if message is already translated or not possible to
     *   translate.
     * @param $severity
     *   The severity of the message, as per RFC 3164.
     * @param $link
     *   A link to associate with the message.
     *
     * @see watchdog()
     * @see \Drupal\Core\Utility\Error::decodeException()
     */
    function watchdog_exception($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
         // \Drupal\Component\Utility\String::checkPlain() by
         // \Drupal\Core\Utility\Error:decodeException().
         $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();
       }
    
       $variables += Error::decodeException($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 array() if
     *   message is already translated or not possible to translate.
     * @param $severity
     *   The severity of the message; one of the following values as defined in
     *   @link http://www.faqs.org/rfcs/rfc3164.html RFC 3164: @endlink
     *   - WATCHDOG_EMERGENCY: Emergency, system is unusable.
     *   - WATCHDOG_ALERT: Alert, action must be taken immediately.
     *   - WATCHDOG_CRITICAL: Critical conditions.
     *   - WATCHDOG_ERROR: Error conditions.
     *   - WATCHDOG_WARNING: Warning conditions.
     *   - WATCHDOG_NOTICE: (default) Normal but significant conditions.
     *   - WATCHDOG_INFO: Informational messages.
     *   - WATCHDOG_DEBUG: Debug-level messages.
     * @param $link
     *   A link to associate with the message.
     *
     * @see watchdog_severity_levels()
     * @see hook_watchdog()
     */
    function watchdog($type, $message, array $variables = NULL, $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;
    
        // The user object may not exist in all conditions, so 0 is substituted if needed.
        $user_uid = isset($user) ? $user->id() : 0;
    
        // Prepare the fields to be logged
        $log_entry = array(
          'type'        => $type,
          'message'     => $message,
          'variables'   => $variables,
          'severity'    => $severity,
          'link'        => $link,
          'user'        => $user,
          'uid'         => $user_uid,
          'request_uri' => '',
          'referer'     => '',
          'ip'          => '',
          // Request time isn't accurate for long processes, use time() instead.
          'timestamp'   => time(),
        );
    
        try {
          $request = \Drupal::request();
          $log_entry['request_uri'] = $request->getUri();
          $log_entry['referer'] = $request->headers->get('Referer', '');
          $log_entry['ip'] = $request->getClientIP();
        }
        catch (DependencyInjectionRuntimeException $e) {
          // We are not in a request context.
        }
    
        // Call the logging hooks to log/process the message
        foreach (\Drupal::moduleHandler()->getImplementations('watchdog') as $module) {
          $function = $module . '_watchdog';
          $function($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 to display to the user.
     *
     * Messages are stored in a session variable and displayed in the page template
     * via the $messages theme variable.
     *
     * Example usage:
     * @code
     * drupal_set_message(t('An error occurred and processing did not complete.'), 'error');
     * @endcode
     *
     * @param string $message
     *   (optional) The translated 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 string $type
     *   (optional) The message's type. Defaults to 'status'. These values are
     *   supported:
     *   - 'status'
     *   - 'warning'
     *   - 'error'
     * @param bool $repeat
     *   (optional) If this is FALSE and the message is already set, then the
     *   message won't be repeated. Defaults to FALSE.
     *
     * @return array|null
     *   A multidimensional array with keys corresponding to the set message types.
     *   The indexed array values of each contain the set messages for that type.
     *   Or, if there are no messages set, the function returns NULL.
     *
     * @see drupal_get_messages()
     * @see theme_status_messages()
     */
    function drupal_set_message($message = NULL, $type = 'status', $repeat = FALSE) {
      if ($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 with drupal_set_message().
     *
     * @param string $type
     *   (optional) Limit the messages returned by type. Defaults to NULL, meaning
     *   all types. These values are supported:
     *   - NULL
     *   - 'status'
     *   - 'warning'
     *   - 'error'
     * @param bool $clear_queue
     *   (optional) If this is TRUE, the queue will be cleared of messages of the
     *   type specified in the $type parameter. Otherwise the queue will be left
     *   intact. Defaults to TRUE.
     *
     * @return array
     *   A multidimensional array with keys corresponding to the set message types.
     *   The indexed array values of each contain the set messages for that type.
     *   The messages returned are limited to the type specified in the $type
     *   parameter. If there are no messages of the specified type, an empty array
     *   is returned.
     *
     * @see drupal_set_message()
     * @see theme_status_messages()
     */
    function drupal_get_messages($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() {
      return drupal_set_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 Title::CHECK_PLAIN. Only set to
     *   PASS_THROUGH if you have already removed any possibly dangerous code
     *   from $title using a function like
     *   \Drupal\Component\Utility\String::checkPlain() or filter_xss(). With this
     *   flag the string will be passed through unchanged.
     *
     * @return
     *   The updated title of the current page.
     */
    function drupal_set_title($title = NULL, $output = Title::CHECK_PLAIN) {
      $stored_title = &drupal_static(__FUNCTION__);
    
      if (isset($title)) {
        $stored_title = ($output == PASS_THROUGH) ? $title : String::checkPlain($title);
      }
    
      return $stored_title;
    }
    
    /**
     * Generates a default anonymous $user object.
     *
     * @return \Drupal\Core\Session\AccountInterface
     *   The user session object.
     */
    function drupal_anonymous_user() {
      try {
        $request = \Drupal::request();
        $hostname = $request->getClientIP();
      }
      catch (DependencyInjectionRuntimeException $e) {
        // We are not in a request context.
        $hostname = '';
      }
    
      $values = array(
        'uid' => 0,
        'hostname' => $hostname,
        'roles' => array(DRUPAL_ANONYMOUS_RID),
      );
      return new UserSession($values);
    }
    
    /**
     * Ensures Drupal is bootstrapped to the specified phase.
     *
     * In order to bootstrap Drupal from another PHP script, you can use this code:
     * @code
     *   require_once '/path/to/drupal/core/vendor/autoload.php';
     *   require_once '/path/to/drupal/core/includes/bootstrap.inc';
     *   drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);
     * @endcode
     *
     * @param $phase
     *   A constant telling which phase to bootstrap to. When you bootstrap to a
     *   particular phase, all earlier phases are run automatically. Possible
     *   values:
     *   - DRUPAL_BOOTSTRAP_CONFIGURATION: Initializes configuration.
     *   - DRUPAL_BOOTSTRAP_KERNEL: Initalizes a kernel.
     *   - DRUPAL_BOOTSTRAP_PAGE_CACHE: Tries to serve a cached page.
     *   - DRUPAL_BOOTSTRAP_CODE: Loads code for subsystems and modules.
     *   - DRUPAL_BOOTSTRAP_FULL: Fully loads Drupal. Validates and fixes input
     *     data.
     *
     * @return
     *   The most recently completed phase.
     */
    function drupal_bootstrap($phase = NULL) {
      // Not drupal_static(), because does not depend on any run-time information.
      static $phases = array(
        DRUPAL_BOOTSTRAP_CONFIGURATION,
        DRUPAL_BOOTSTRAP_KERNEL,
        DRUPAL_BOOTSTRAP_PAGE_CACHE,
        DRUPAL_BOOTSTRAP_CODE,
        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 = -1;
      // Not drupal_static(), because it's impossible to roll back to an earlier
      // bootstrap state.
      static $stored_phase = -1;
    
      // Store the phase name so it's not forgotten during recursion. Additionally,
      // ensure that $final_phase is never rolled back to an earlier bootstrap
      // state.
      if ($phase > $final_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_KERNEL:
              _drupal_bootstrap_kernel();
              break;
    
            case DRUPAL_BOOTSTRAP_PAGE_CACHE:
              _drupal_bootstrap_page_cache();
              break;
    
            case DRUPAL_BOOTSTRAP_CODE:
              require_once __DIR__ . '/common.inc';
              _drupal_bootstrap_code();
              break;
    
            case DRUPAL_BOOTSTRAP_FULL:
              _drupal_bootstrap_full();
              break;
          }
        }
      }
      return $stored_phase;
    }
    
    /**
     * Handles an entire PHP request.
     *
     * This function may be called by PHP scripts (e.g., Drupal's index.php) that
     * want Drupal to take over the entire PHP processing of the request. The only
     * expectation is that PHP's superglobals are initialized as desired (PHP does
     * this automatically, but some scripts might want to alter them) and that the
     * DRUPAL_ROOT constant is defined and set to the absolute server directory of
     * Drupal's codebase.
     *
     * Scripts and applications that want to invoke multiple Drupal requests within
     * a single PHP request, or Drupal request handling within some larger workflow,
     * should not call this function, but instead instantiate and use
     * \Drupal\Core\DrupalKernel as needed.
     *
     * @param boolean $test_only
     *   Whether to restrict handling to only requests invoked by SimpleTest.
     *
     * @see index.php
     */
    function drupal_handle_request($test_only = FALSE) {
      // Initialize the environment, load settings.php, and activate a PSR-0 class
      // autoloader with required namespaces registered.
      drupal_bootstrap(DRUPAL_BOOTSTRAP_CONFIGURATION);
    
      // Exit if we should be in a test environment but aren't.
      if ($test_only && !drupal_valid_test_ua()) {
        header($_SERVER['SERVER_PROTOCOL'] . ' 403 Forbidden');
        exit;
      }
    
      $kernel = new DrupalKernel('prod', drupal_classloader(), !$test_only);
    
      // @todo Remove this once everything in the bootstrap has been
      //   converted to services in the DIC.
      $kernel->boot();
    
      // Create a request object from the HttpFoundation.
      $request = Request::createFromGlobals();
      \Drupal::getContainer()->set('request', $request);
    
      drupal_bootstrap(DRUPAL_BOOTSTRAP_CODE);
    
      $response = $kernel->handle($request)->prepare($request)->send();
    
      $kernel->terminate($request, $response);
    }
    
    /**
     * Returns the time zone of the current user.
     */
    function drupal_get_user_timezone() {
      global $user;
      $config = \Drupal::config('system.date');
    
      if ($user && $config->get('timezone.user.configurable') && $user->isAuthenticated() && $user->getTimezone()) {
        return $user->getTimezone();
      }
      else {
        // Ignore PHP strict notice if time zone has not yet been set in the php.ini
        // configuration.
        $config_data_default_timezone = $config->get('timezone.default');
        return !empty($config_data_default_timezone) ? $config_data_default_timezone : @date_default_timezone_get();
      }
    }
    
    /**
     * Gets a salt useful for hardening against SQL injection.
     *
     * @return
     *   A salt based on information in settings.php, not in the database.
     */
    function drupal_get_hash_salt() {
      global $drupal_hash_salt, $databases;
      // If the $drupal_hash_salt variable is empty, a hash of the serialized
      // database credentials is used as a fallback salt.
      return empty($drupal_hash_salt) ? hash('sha256', serialize($databases)) : $drupal_hash_salt;
    }
    
    /**
     * 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, $context) {
      require_once __DIR__ . '/errors.inc';
      _drupal_error_handler_real($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 __DIR__ . '/errors.inc';
    
      try {
        // Log the message to the watchdog and return an error page to the user.
        _drupal_log_error(Error::decodeException($exception), TRUE);
      }
      catch (Exception $exception2) {
        // Another uncaught exception was thrown while handling the first one.
        // If we are displaying errors, then do so with no possibility of a further uncaught exception being thrown.
        if (error_displayable()) {
          print '<h1>Additional uncaught exception thrown while handling exception.</h1>';
          print '<h2>Original</h2><p>' . Error::renderExceptionSafe($exception) . '</p>';
          print '<h2>Additional</h2><p>' . Error::renderExceptionSafe($exception2) . '</p><hr />';
        }
      }
    }
    
    /**
     * Sets up the script environment and loads settings.php.
     */
    function _drupal_bootstrap_configuration() {
      drupal_environment_initialize();
    
      // Indicate that code is operating in a test child site.
      if ($test_prefix = drupal_valid_test_ua()) {
        // Only code that interfaces directly with tests should rely on this
        // constant; e.g., the error/exception handler conditionally adds further
        // error information into HTTP response headers that are consumed by
        // Simpletest's internal browser.
        define('DRUPAL_TEST_IN_CHILD_SITE', TRUE);
    
        // Log fatal errors to the test site directory.
        ini_set('log_errors', 1);
        ini_set('error_log', DRUPAL_ROOT . '/sites/simpletest/' . substr($test_prefix, 10) . '/error.log');
      }
      else {
        // Ensure that no other code defines this.
        define('DRUPAL_TEST_IN_CHILD_SITE', FALSE);
      }
    
      // Initialize the configuration, including variables from settings.php.
      drupal_settings_initialize();
      _drupal_request_initialize();
    
      // Activate the class loader.
      drupal_classloader();
    
      // Start a page timer:
      Timer::start('page');
    
      // Detect string handling method.
      Unicode::check();
    
      // Load the procedural configuration system helper functions.
      require_once __DIR__ . '/config.inc';
    
      // Set the Drupal custom error handler. (requires \Drupal::config())
      set_error_handler('_drupal_error_handler');
      set_exception_handler('_drupal_exception_handler');
    
      // 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() && !drupal_is_cli()) {
        include_once __DIR__ . '/install.inc';
        install_goto('core/install.php');
      }
    }
    
    /**
     * Initialize the kernel / service container.
     */
    function _drupal_bootstrap_kernel() {
      // Normally, index.php puts a container in the Drupal class by creating a
      // kernel. If there is no container yet, create one.
      if (!\Drupal::getContainer()) {
        $kernel = new DrupalKernel('prod', drupal_classloader());
        $kernel->boot();
        $request = Request::createFromGlobals();
        \Drupal::getContainer()->set('request', $request);
      }
    }
    
    /**
     * Attempts to serve a page from the cache.
     */
    function _drupal_bootstrap_page_cache() {
      global $user;
    
      require_once __DIR__ . '/cache.inc';
      require_once __DIR__ . '/database.inc';
      // Check for a cache mode force from settings.php.
      if (settings()->get('page_cache_without_database')) {
        $cache_enabled = TRUE;
      }
      else {
        $config = \Drupal::config('system.performance');
        $cache_enabled = $config->get('cache.page.use_internal');
      }
    
      $request = Request::createFromGlobals();
      // If there is no session cookie and cache is enabled (or forced), try
      // to serve a cached page.
      if (!$request->cookies->has(session_name()) && $cache_enabled) {
        // Make sure there is a user object because its timestamp will be checked.
        $user = drupal_anonymous_user();
        // Get the page from the cache.
        $cache = drupal_page_get_cache($request);
        // If there is a cached page, display it.
        if (is_object($cache)) {
          $response = new Response();
          $response->headers->set('X-Drupal-Cache', 'HIT');
          // Restore the metadata cached with the page.
          _current_path($cache->data['path']);
          drupal_set_title($cache->data['title'], PASS_THROUGH);
          date_default_timezone_set(drupal_get_user_timezone());
    
          drupal_serve_page_from_cache($cache, $response, $request);
    
          // We are done.
          $response->prepare($request);
          $response->send();
          exit;
        }
        else {
          drupal_add_http_header('X-Drupal-Cache', 'MISS');
        }
      }
    }
    
    /**
     * 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 list of enabled modules.
     *
     * @deprecated as of Drupal 8.0. Use
     *   \Drupal::moduleHandler()->getModuleList().
     *
     * @see \Drupal\Core\Extension\ModuleHandler::getModuleList()
     */
    function module_list() {
      $modules = array_keys(\Drupal::moduleHandler()->getModuleList());
      return array_combine($modules, $modules);
    }
    
    /**
     * Determines which modules are implementing a hook.
     *
     * @deprecated as of Drupal 8.0. Use
     *   \Drupal::moduleHandler()->getImplementations($hook).
     *
     * @see \Drupal\Core\Extension\ModuleHandler::getImplementations()
     */
    function module_implements($hook) {
      return \Drupal::moduleHandler()->getImplementations($hook);
    }
    
    /**
     * Invokes a hook in a particular module.
     *
     * All arguments are passed by value. Use \Drupal::moduleHandler()->alter() if
     * you need to pass arguments by reference.
     *
     * @deprecated in Drupal 8.x-dev, will be removed before Drupal 8.0. Use
     *   \Drupal::moduleHandler()->invoke($module, $hook, $args = array()).
     *
     * @see \Drupal\Core\Extension\ModuleHandler::alter()
     * @see \Drupal\Core\Extension\ModuleHandler::invoke()
     */
    function module_invoke($module, $hook) {
      $args = func_get_args();
      // Remove $module and $hook from the arguments.
      unset($args[0], $args[1]);
      return \Drupal::moduleHandler()->invoke($module, $hook, $args);
    }
    
    /**
     * Invokes a hook in all enabled modules that implement it.
     *
     * All arguments are passed by value. Use drupal_alter() if you need to pass
     * arguments by reference.
     *
     * @deprecated as of Drupal 8.0. Use
     *   \Drupal::moduleHandler()->invokeAll($hook).
     *
     * @see drupal_alter()
     * @see \Drupal\Core\Extension\ModuleHandler::invokeAll()
     */
    function module_invoke_all($hook) {
      $args = func_get_args();
      // Remove $hook from the arguments.
      unset($args[0]);
      return \Drupal::moduleHandler()->invokeAll($hook, $args);
    }
    
    /**
     * Passes alterable variables to specific hook_TYPE_alter() implementations.
     *
     * @deprecated as of Drupal 8.0. Use
     *   \Drupal::moduleHandler()->alter($hook).
     *
     * @see \Drupal\Core\Extension\ModuleHandler::alter()
     */
    function drupal_alter($type, &$data, &$context1 = NULL, &$context2 = NULL) {
      return \Drupal::moduleHandler()->alter($type, $data, $context1, $context2);
    }
    
    /**
     * Determines whether a given module exists.
     *
     * @deprecated as of Drupal 8.0. Use
     *   \Drupal::moduleHandler()->moduleExists($module).
     *
     * @see \Drupal\Core\Extension\ModuleHandler::moduleExists()
     */
    function module_exists($module) {
      return \Drupal::moduleHandler()->moduleExists($module);
    }
    
    /**
     * Determines whether a module implements a hook.
     *
     * @deprecated as of Drupal 8.0. Use
     *   \Drupal::moduleHandler()->implementsHook($module, $hook).
     *
     * @see \Drupal\Core\Extension\ModuleHandler::implementsHook()
     */
    function module_hook($module, $hook) {
      return \Drupal::moduleHandler()->implementsHook($module, $hook);
    }
    
    /**
     * Returns the test prefix if this is an internal request from SimpleTest.
     *
     * @param string $new_prefix
     *   Internal use only. A new prefix to be stored.
     *
     * @return string|FALSE
     *   Either the simpletest prefix (the string "simpletest" followed by any
     *   number of digits) or FALSE if the user agent does not contain a valid
     *   HMAC and timestamp.
     */
    function drupal_valid_test_ua($new_prefix = NULL) {
      static $test_prefix;
    
      if (isset($new_prefix)) {
        $test_prefix = $new_prefix;
      }
      if (isset($test_prefix)) {
        return $test_prefix;
      }
      // Unless the below User-Agent and HMAC validation succeeds, we are not in
      // a test environment.
      $test_prefix = FALSE;
    
      // Perform a basic check on the User-Agent HTTP request header first. Any
      // inbound request that uses the simpletest UA header needs to be validated.
      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;
        // Read the hash salt prepared by drupal_generate_test_ua().
        // This function is called before settings.php is read and Drupal's error
        // handlers are set up. While Drupal's error handling may be properly
        // configured on production sites, the server's PHP error_reporting may not.
        // Ensure that no information leaks on production sites.
        $key_file = DRUPAL_ROOT . '/sites/simpletest/' . substr($prefix, 10) . '/.htkey';
        if (!is_readable($key_file)) {
          header($_SERVER['SERVER_PROTOCOL'] . ' 403 Forbidden');
          exit;
        }
        $private_key = file_get_contents($key_file);
        // The file properties add more entropy not easily accessible to others.
        $key = $private_key . filectime(__FILE__) . fileinode(__FILE__);
        $time_diff = REQUEST_TIME - $time;
        $test_hmac = Crypt::hmacBase64($check_string, $key);
        // Since we are making a local request a 5 second time window is allowed,
        // and the HMAC must match.
        if ($time_diff >= 0 && $time_diff <= 5 && $hmac === $test_hmac) {
          $test_prefix = $prefix;
        }
      }
      return $test_prefix;
    }
    
    /**
     * Generates a user agent string with a HMAC and timestamp for simpletest.
     */
    function drupal_generate_test_ua($prefix) {
      static $key, $last_prefix;
    
      if (!isset($key) || $last_prefix != $prefix) {
        $last_prefix = $prefix;
        $key_file = DRUPAL_ROOT . '/sites/simpletest/' . substr($prefix, 10) . '/.htkey';
        // When issuing an outbound HTTP client request from within an inbound test
        // request, then the outbound request has to use the same User-Agent header
        // as the inbound request. A newly generated private key for the same test
        // prefix would invalidate all subsequent inbound requests.
        // @see \Drupal\Core\Http\Plugin\SimpletestHttpRequestSubscriber
        if (DRUPAL_TEST_IN_CHILD_SITE && $parent_prefix = drupal_valid_test_ua()) {
          if ($parent_prefix != $prefix) {
            throw new \RuntimeException("Malformed User-Agent: Expected '$parent_prefix' but got '$prefix'.");
          }
          // If the file is not readable, a PHP warning is expected in this case.
          $private_key = file_get_contents($key_file);
        }
        else {
          // Generate and save a new hash salt for a test run.
          // Consumed by drupal_valid_test_ua() before settings.php is loaded.
          $private_key = Crypt::randomStringHashed(55);
          file_put_contents($key_file, $private_key);
        }
        // The file properties add more entropy not easily accessible to others.
        $key = $private_key . filectime(__FILE__) . fileinode(__FILE__);
      }
      // Generate a moderately secure HMAC based on the database credentials.
      $salt = uniqid('', TRUE);
      $check_string = $prefix . ';' . time() . ';' . $salt;
      return $check_string . ';' . Crypt::hmacBase64($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 __DIR__ . '/theme.maintenance.inc';
      _drupal_maintenance_theme();
    }
    
    /**
     * Returns TRUE if a Drupal installation is currently being attempted.
     */
    function drupal_installation_attempted() {
      // This cannot rely on the MAINTENANCE_MODE constant, since that would prevent
      // tests from using the non-interactive installer, in which case Drupal
      // only happens to be installed within the same request, but subsequently
      // executed code does not involve the installer at all.
      // @see install_drupal()
      return isset($GLOBALS['install_state']) && empty($GLOBALS['install_state']['installation_finished']);
    }
    
    /**
     * Initializes all the defined language types and sets the default langcode.
     */
    function drupal_language_initialize() {
      $language_manager = \Drupal::languageManager();
      $language_manager->init();
      \Drupal::translation()->setDefaultLangcode($language_manager->getCurrentLanguage()->id);
    }
    
    /**
     * Returns the language object for a given language type.
     *
     * @see \Drupal\Core\Language\LanguageManager
     *
     * @param string $type
     *   The type of language object needed, e.g. Language::TYPE_INTERFACE.
     *
     * @deprecated as of Drupal 8.0. Use
     *   \Drupal::languageManager()->getCurrentLanguage().
     */
    function language($type) {
      return \Drupal::languageManager()->getCurrentLanguage($type);
    }
    
    /**
     * Returns a list of languages set up on the site.
     *
     * @param $flags
     *   (optional) Specifies the state of the languages that have to be returned.
     *   It can be: Language::STATE_CONFIGURABLE, Language::STATE_LOCKED,
     *   Language::STATE_ALL.
     *
     * @return array
     *   An associative array of languages, keyed by the language code, ordered by
     *   weight ascending and name ascending.
     *
     * @deprecated as of Drupal 8.0. Use
     *   \Drupal::languageManager()->getLanguages() instead.
     */
    function language_list($flags = Language::STATE_CONFIGURABLE) {
      return \Drupal::languageManager()->getLanguages($flags);
    }
    
    /**
     * Loads a language object from the database.
     *
     * @param string $langcode
     *   The language code.
     *
     * @return \Drupal\core\Language\Language|null
     *   A fully-populated language object or NULL.
     *
     * @see \Drupal\Core\Language\LanguageManager::getLanguage()
     *
     * @deprecated as of Drupal 8.0. Use \Drupal::languageManager()->getLanguage()
     *   instead.
     */
    function language_load($langcode) {
      return \Drupal::languageManager()->getLanguage($langcode);
    }
    
    /**
     * Returns the default language used on the site.
     *
     * @return \Drupal\Core\Language\Language
     *   A language object.
     *
     * @deprecated as of Drupal 8.0. Use
     *   \Drupal::languageManager()->getDefaultLanguage() instead.
     */
    function language_default() {
      return \Drupal::languageManager()->getDefaultLanguage();
    }
    
    /**
     * 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;
      }
    
      // Get the part of the URI between the base path of the Drupal installation
      // and the query string, and unescape it.
      $request_path = request_uri(TRUE);
      $base_path_len = strlen(rtrim(dirname($_SERVER['SCRIPT_NAME']), '\/'));
      $path = substr(urldecode($request_path), $base_path_len + 1);
    
      // Depending on server configuration, the URI might or might not include the
      // script name. For example, the front page might be accessed as
      // http://example.com or as http://example.com/index.php, and the "user"
      // page might be accessed as http://example.com/user or as
      // http://example.com/index.php/user. Strip the script name from $path.
      $script = basename($_SERVER['SCRIPT_NAME']);
      if ($path == $script) {
        $path = '';
      }
      elseif (strpos($path, $script . '/') === 0) {
        $path = substr($path, strlen($script) + 1);
      }
    
      // Extra slashes can appear in URLs or under some conditions, added by Apache,
      // so normalize.
      $path = trim($path, '/');
    
      return $path;
    }
    
    /**
     * @todo This is a temporary function pending refactoring Drupal to use
     *   Symfony's Request object exclusively.
     */
    function _current_path($path = NULL) {
      static $current_path = '';
      if (isset($path)) {
        $current_path = $path;
      }
      return $current_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)) {
        // @todo The public function current_path() is not available during early
        //   bootstrap.
        $path = _current_path();
      }
      if (!isset($arguments[$path])) {
        $arguments[$path] = explode('/', $path);
      }
      if (!isset($index)) {
        return $arguments[$path];
      }
      if (isset($arguments[$path][$index])) {
        return $arguments[$path][$index];
      }
    }
    
    /**
     * 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). It's only dependency
     * is DRUPAL_ROOT. Otherwise it may be called as early as possible.
     *
     * @param $class_loader
     *   The name of class loader to use. This can be used to change the class
     *   loader class when calling drupal_classloader() from settings.php. It is
     *   ignored otherwise.
     *
     * @return \Composer\Autoload\ClassLoader
     *   A ClassLoader class instance (or extension thereof).
     */
    function drupal_classloader($class_loader = NULL) {
      // By default, use the ClassLoader 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)) {
    
        // Retrieve the Composer ClassLoader for loading classes.
        $loader = include __DIR__ . '/../vendor/autoload.php';
    
        // Register the class loader.
        // When configured to use APC, the ApcClassLoader is registered instead.
        // Note that ApcClassLoader decorates ClassLoader and only provides the
        // findFile() method, but none of the others. The actual registry is still
        // in ClassLoader.
        if (!isset($class_loader)) {
          $class_loader = settings()->get('class_loader', 'default');
        }
        if ($class_loader === 'apc') {
          require_once __DIR__ . '/../vendor/symfony/class-loader/Symfony/Component/ClassLoader/ApcClassLoader.php';
          $apc_loader = new ApcClassLoader('drupal.' . drupal_get_hash_salt(), $loader);
          $loader->unregister();
          $apc_loader->register();
        }
      }
      return $loader;
    }
    
    /**
     * Registers an additional namespace.
     *
     * @param string $name
     *   The namespace component to register; e.g., 'node'.
     * @param string $path
     *   The relative path to the Drupal component in the filesystem.
     */
    function drupal_classloader_register($name, $path) {
      $loader = drupal_classloader();
      $loader->add('Drupal\\' . $name, DRUPAL_ROOT . '/' . $path . '/lib');
    }
    
    /**
     * 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 drupal_session_started($set = NULL) {
     *   static $session_started = FALSE;
     *   if (isset($set)) {
     *     $session_started = $set;
     *   }
     *   return $session_started && session_id();
     * }
     * @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 $foo = &drupal_static(__FUNCTION__);
     * @endcode
     * However, the above line of code does not work, because PHP only allows static
     * variables to be initializied by literal values, and does not allow static
     * variables to be assigned to references.
     * - http://php.net/manual/language.variables.scope.php#language.variables.scope.static
     * - http://php.net/manual/language.variables.scope.php#language.variables.scope.references
     * The example below shows the syntax needed to work around both limitations.
     * For benchmarks and more information, see http://drupal.org/node/619666.
     *
     * Example:
     * @code
     * function user_access($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.
     *
     * @see \Drupal\Component\Utility\String::placeholder()
     */
    function drupal_placeholder($text) {
      return String::placeholder($text);
    }
    
    /**
     * 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();
        // Remove $callback from the arguments.
        unset($args[0]);
        // 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 $exception) {
        // If using PHP-FPM then fastcgi_finish_request() will have been fired
        // preventing further output to the browser.
        if (!function_exists('fastcgi_finish_request')) {
          // If we are displaying errors, then do so with no possibility of a
          // further uncaught exception being thrown.
          require_once __DIR__ . '/errors.inc';
          if (error_displayable()) {
            print '<h1>Uncaught exception thrown in shutdown function.</h1>';
            print '<p>' . Error::renderExceptionSafe($exception) . '</p><hr />';
          }
        }
        error_log($exception);
      }
    }
    
    /**
     * Compares the memory required for an operation to the available memory.
     *
     * @param $required
     *   The memory required for the operation, expressed as a number of bytes with
     *   optional SI or IEC binary unit prefix (e.g. 2, 3K, 5MB, 10G, 6GiB, 8bytes,
     *   9mbytes).
     * @param $memory_limit
     *   (optional) The memory limit for the operation, expressed as a number of
     *   bytes with optional SI or IEC binary unit prefix (e.g. 2, 3K, 5MB, 10G,
     *   6GiB, 8bytes, 9mbytes). If no value is passed, the current PHP
     *   memory_limit will be used. Defaults to NULL.
     *
     * @return
     *   TRUE if there is sufficient memory to allow the operation, or FALSE
     *   otherwise.
     */
    function drupal_check_memory_limit($required, $memory_limit = NULL) {
      if (!isset($memory_limit)) {
        $memory_limit = ini_get('memory_limit');
      }
    
      // There is sufficient memory if:
      // - No memory limit is set.
      // - The memory limit is set to unlimited (-1).
      // - The memory limit is greater than or equal to the memory required for
      //   the operation.
      return ((!$memory_limit) || ($memory_limit == -1) || (parse_size($memory_limit) >= parse_size($required)));
    }
    
    /**
     * @defgroup lock Locking mechanisms
     * @{
     * Functions to coordinate long-running operations across requests.
     *
     * In most environments, multiple Drupal page requests (a.k.a. threads or
     * processes) will execute in parallel. This leads to potential conflicts or
     * race conditions when two requests execute the same code at the same time. A
     * common example of this is a rebuild like menu_router_rebuild() where we
     * invoke many hook implementations to get and process data from all active
     * modules, and then delete the current data in the database to insert the new
     * afterwards.
     *
     * This is a cooperative, advisory lock system. Any long-running operation
     * that could potentially be attempted in parallel by multiple requests should
     * try to acquire a lock before proceeding. By obtaining a lock, one request
     * notifies any other requests that a specific operation is in progress which
     * must not be executed in parallel.
     *
     * To use this API, pick a unique name for the lock. A sensible choice is the
     * name of the function performing the operation. A very simple example use of
     * this API:
     * @code
     * function mymodule_long_operation() {
     *   if (lock()->acquire('mymodule_long_operation')) {
     *     // Do the long operation here.
     *     // ...
     *     lock()->release('mymodule_long_operation');
     *   }
     * }
     * @endcode
     *
     * If a function acquires a lock it should always release it when the
     * operation is complete by calling lock()->release(), as in the example.
     *
     * A function that has acquired a lock may attempt to renew a lock (extend the
     * duration of the lock) by calling lock()->acquire() again during the operation.
     * Failure to renew a lock is indicative that another request has acquired
     * the lock, and that the current operation may need to be aborted.
     *
     * If a function fails to acquire a lock it may either immediately return, or
     * it may call lock()->wait() if the rest of the current page request requires
     * that the operation in question be complete. After lock()->wait() returns,
     * the function may again attempt to acquire the lock, or may simply allow the
     * page request to proceed on the assumption that a parallel request completed
     * the operation.
     *
     * lock()->acquire() and lock()->wait() will automatically break (delete) a lock
     * whose duration has exceeded the timeout specified when it was acquired.
     */
    
    /**
     * Get locking layer instance.
     *
     * @deprecated Use \Drupal::lock() instead, or even better have the lock service
     *   injected into your object.
     *
     * @return \Drupal\Core\Lock\LockBackendInterface
     */
    function lock() {
      return \Drupal::lock();
    }
    
    /**
     * @} End of "defgroup lock".
     */