DrupalKernel.php

Same filename in other branches
  1. 9 core/lib/Drupal/Core/DrupalKernel.php
  2. 8.9.x core/lib/Drupal/Core/DrupalKernel.php
  3. 10 core/lib/Drupal/Core/DrupalKernel.php

Namespace

Drupal\Core

File

core/lib/Drupal/Core/DrupalKernel.php

View source
<?php

namespace Drupal\Core;

use Composer\Autoload\ClassLoader;
use Drupal\Component\EventDispatcher\Event;
use Drupal\Component\FileCache\FileCacheFactory;
use Drupal\Component\Serialization\PhpSerialize;
use Drupal\Component\Utility\UrlHelper;
use Drupal\Core\Cache\DatabaseBackend;
use Drupal\Core\Config\BootstrapConfigStorageFactory;
use Drupal\Core\Config\NullStorage;
use Drupal\Core\DependencyInjection\ContainerBuilder;
use Drupal\Component\DependencyInjection\ReverseContainer;
use Drupal\Core\DependencyInjection\ServiceModifierInterface;
use Drupal\Core\DependencyInjection\ServiceProviderInterface;
use Drupal\Core\DependencyInjection\YamlFileLoader;
use Drupal\Core\Extension\Extension;
use Drupal\Core\Extension\ExtensionDiscovery;
use Drupal\Core\File\MimeType\MimeTypeGuesser;
use Drupal\Core\Http\TrustedHostsRequestFactory;
use Drupal\Core\Installer\InstallerKernel;
use Drupal\Core\Installer\InstallerRedirectTrait;
use Drupal\Core\Language\Language;
use Drupal\Core\Security\RequestSanitizer;
use Drupal\Core\Site\Settings;
use Drupal\Core\Test\TestDatabase;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\DependencyInjection\ParameterBag\ParameterBag;
use Symfony\Component\HttpFoundation\RedirectResponse;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\Session\Session;
use Symfony\Component\HttpFoundation\Session\Storage\MockArraySessionStorage;
use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;
use Symfony\Component\HttpKernel\TerminableInterface;

/**
 * The DrupalKernel class is the core of Drupal itself.
 *
 * This class is responsible for building the Dependency Injection Container and
 * also deals with the registration of service providers. It allows registered
 * service providers to add their services to the container. Core provides the
 * CoreServiceProvider, which, in addition to registering any core services that
 * cannot be registered in the core.services.yaml file, adds any compiler passes
 * needed by core, e.g. for processing tagged services. Each module can add its
 * own service provider, i.e. a class implementing
 * Drupal\Core\DependencyInjection\ServiceProvider, to register services to the
 * container, or modify existing services.
 */
class DrupalKernel implements DrupalKernelInterface, TerminableInterface {
    use InstallerRedirectTrait;
    
    /**
     * Holds the class used for dumping the container to a PHP array.
     *
     * In combination with swapping the container class this is useful to e.g.
     * dump to the human-readable PHP array format to debug the container
     * definition in an easier way.
     *
     * @var string
     */
    protected $phpArrayDumperClass = '\\Drupal\\Component\\DependencyInjection\\Dumper\\OptimizedPhpArrayDumper';
    
    /**
     * Holds the default bootstrap container definition.
     *
     * @var array
     */
    protected $defaultBootstrapContainerDefinition = [
        'parameters' => [],
        'services' => [
            'database' => [
                'class' => 'Drupal\\Core\\Database\\Connection',
                'factory' => 'Drupal\\Core\\Database\\Database::getConnection',
                'arguments' => [
                    'default',
                ],
            ],
            'request_stack' => [
                'class' => 'Symfony\\Component\\HttpFoundation\\RequestStack',
            ],
            'datetime.time' => [
                'class' => 'Drupal\\Component\\Datetime\\Time',
                'arguments' => [
                    '@request_stack',
                ],
            ],
            'cache.container' => [
                'class' => 'Drupal\\Core\\Cache\\DatabaseBackend',
                'arguments' => [
                    '@database',
                    '@cache_tags_provider.container',
                    'container',
                    '@serialization.phpserialize',
                    '@datetime.time',
                    DatabaseBackend::MAXIMUM_NONE,
                ],
            ],
            'cache_tags_provider.container' => [
                'class' => 'Drupal\\Core\\Cache\\DatabaseCacheTagsChecksum',
                'arguments' => [
                    '@database',
                ],
            ],
            'serialization.phpserialize' => [
                'class' => PhpSerialize::class,
            ],
        ],
    ];
    
    /**
     * Holds the class used for instantiating the bootstrap container.
     *
     * @var string
     */
    protected $bootstrapContainerClass = '\\Drupal\\Component\\DependencyInjection\\PhpArrayContainer';
    
    /**
     * Holds the bootstrap container.
     *
     * @var \Symfony\Component\DependencyInjection\ContainerInterface
     */
    protected $bootstrapContainer;
    
    /**
     * Holds the container instance.
     *
     * @var \Drupal\Component\DependencyInjection\ContainerInterface
     */
    protected $container;
    
    /**
     * The environment, e.g. 'testing', 'install'.
     *
     * @var string
     */
    protected $environment;
    
    /**
     * Whether the kernel has been booted.
     *
     * @var bool
     */
    protected $booted = FALSE;
    
    /**
     * Whether essential services have been set up properly by preHandle().
     *
     * @var bool
     */
    protected $prepared = FALSE;
    
    /**
     * Holds the list of enabled modules.
     *
     * @var array
     *   An associative array whose keys are module names and whose values are
     *   ignored.
     */
    protected $moduleList;
    
    /**
     * List of available modules and installation profiles.
     *
     * @var \Drupal\Core\Extension\Extension[]
     */
    protected $moduleData = [];
    
    /**
     * The class loader object.
     *
     * @var \Composer\Autoload\ClassLoader
     */
    protected $classLoader;
    
    /**
     * Config storage object used for reading enabled modules configuration.
     *
     * @var \Drupal\Core\Config\StorageInterface
     */
    protected $configStorage;
    
    /**
     * Whether the container can be dumped.
     *
     * @var bool
     */
    protected $allowDumping;
    
    /**
     * Whether the container needs to be rebuilt the next time it is initialized.
     *
     * @var bool
     */
    protected $containerNeedsRebuild = FALSE;
    
    /**
     * Whether the container needs to be dumped once booting is complete.
     *
     * @var bool
     */
    protected $containerNeedsDumping;
    
    /**
     * List of discovered services.yml path names.
     *
     * This is a nested array whose top-level keys are 'app' and 'site', denoting
     * the origin of a service provider. Site-specific providers have to be
     * collected separately, because they need to be processed last, so as to be
     * able to override services from application service providers.
     *
     * @var array
     */
    protected $serviceYamls;
    
    /**
     * List of discovered service provider class names or objects.
     *
     * This is a nested array whose top-level keys are 'app' and 'site', denoting
     * the origin of a service provider. Site-specific providers have to be
     * collected separately, because they need to be processed last, so as to be
     * able to override services from application service providers.
     *
     * Allowing objects is for example used to allow
     * \Drupal\KernelTests\KernelTestBase to register itself as service provider.
     *
     * @var array
     */
    protected $serviceProviderClasses;
    
    /**
     * List of instantiated service provider classes.
     *
     * @var array
     *
     * @see \Drupal\Core\DrupalKernel::$serviceProviderClasses
     */
    protected $serviceProviders;
    
    /**
     * Whether the PHP environment has been initialized.
     *
     * This legacy phase can only be booted once because it sets session INI
     * settings. If a session has already been started, re-generating these
     * settings would break the session.
     *
     * @var bool
     */
    protected static $isEnvironmentInitialized = FALSE;
    
    /**
     * The site path directory.
     *
     * Site path is relative to the app root directory.
     * Usually defined as "sites/default".
     *
     * By default, Drupal uses sites/default.
     *
     * @var string
     */
    protected $sitePath;
    
    /**
     * The app root.
     *
     * @var string
     */
    protected $root;
    
    /**
     * Create a DrupalKernel object from a request.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request.
     * @param $class_loader
     *   The class loader. Normally Composer's ClassLoader, as included by the
     *   front controller, but may also be decorated.
     * @param string $environment
     *   String indicating the environment, e.g. 'prod' or 'dev'.
     * @param bool $allow_dumping
     *   (optional) FALSE to stop the container from being written to or read
     *   from disk. Defaults to TRUE.
     * @param string $app_root
     *   (optional) The path to the application root as a string. If not supplied,
     *   the application root will be computed.
     *
     * @return static
     *
     * @throws \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
     *   In case the host name in the request is not trusted.
     */
    public static function createFromRequest(Request $request, $class_loader, $environment, $allow_dumping = TRUE, $app_root = NULL) {
        $kernel = new static($environment, $class_loader, $allow_dumping, $app_root);
        static::bootEnvironment($app_root);
        $kernel->initializeSettings($request);
        return $kernel;
    }
    
    /**
     * Constructs a DrupalKernel object.
     *
     * @param string $environment
     *   String indicating the environment, e.g. 'prod' or 'dev'.
     * @param $class_loader
     *   The class loader. Normally \Composer\Autoload\ClassLoader, as included by
     *   the front controller, but may also be decorated.
     * @param bool $allow_dumping
     *   (optional) FALSE to stop the container from being written to or read
     *   from disk. Defaults to TRUE.
     * @param string $app_root
     *   (optional) The path to the application root as a string. If not supplied,
     *   the application root will be computed.
     */
    public function __construct($environment, $class_loader, $allow_dumping = TRUE, $app_root = NULL) {
        $this->environment = $environment;
        $this->classLoader = $class_loader;
        $this->allowDumping = $allow_dumping;
        if ($app_root === NULL) {
            $app_root = static::guessApplicationRoot();
        }
        $this->root = $app_root;
    }
    
    /**
     * Determine the application root directory based on this file's location.
     *
     * @return string
     *   The application root.
     */
    protected static function guessApplicationRoot() {
        // Determine the application root by:
        // - Removing the namespace directories from the path.
        // - Getting the path to the directory two levels up from the path
        //   determined in the previous step.
        return dirname(substr(__DIR__, 0, -strlen(__NAMESPACE__)), 2);
    }
    
    /**
     * Returns the appropriate site directory for a request.
     *
     * Once the kernel has been created DrupalKernelInterface::getSitePath() is
     * preferred since it gets the statically cached result of this method.
     *
     * Site directories contain all site specific code. This includes settings.php
     * for bootstrap level configuration, file configuration stores, public file
     * storage and site specific modules and themes.
     *
     * A file named sites.php must be present in the sites directory for
     * multisite. If it doesn't exist, then 'sites/default' will be used.
     *
     * Finds a matching site 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 'sites/default'. See
     * default.settings.php for examples on how the URL is converted to a
     * directory.
     *
     * The sites.php file in the sites directory 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 https://www.drupal.org:8080/my-site/test whose
     * configuration file is in sites/example.com, the array should be defined as:
     * @code
     * $sites = [
     *   '8080.www.drupal.org.my-site.test' => 'example.com',
     * ];
     * @endcode
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The current request.
     * @param bool $require_settings
     *   Only 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 string $app_root
     *   (optional) The path to the application root as a string. If not supplied,
     *   the application root will be computed.
     *
     * @return string
     *   The path of the matching directory.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
     *   In case the host name in the request is invalid.
     *
     * @see \Drupal\Core\DrupalKernelInterface::getSitePath()
     * @see \Drupal\Core\DrupalKernelInterface::setSitePath()
     * @see default.settings.php
     * @see example.sites.php
     */
    public static function findSitePath(Request $request, $require_settings = TRUE, $app_root = NULL) {
        if (static::validateHostname($request) === FALSE) {
            throw new BadRequestHttpException();
        }
        if ($app_root === NULL) {
            $app_root = static::guessApplicationRoot();
        }
        // Check for a test override.
        if ($test_prefix = drupal_valid_test_ua()) {
            $test_db = new TestDatabase($test_prefix);
            return $test_db->getTestSitePath();
        }
        // Determine whether multi-site functionality is enabled. If not, return
        // the default directory.
        if (!file_exists($app_root . '/sites/sites.php')) {
            return 'sites/default';
        }
        // Pre-populate host and script variables, then include sites.php which may
        // populate $sites with a site-directory mapping.
        $script_name = $request->server
            ->get('SCRIPT_NAME');
        if (!$script_name) {
            $script_name = $request->server
                ->get('SCRIPT_FILENAME');
        }
        $http_host = $request->getHttpHost();
        $sites = [];
        include $app_root . '/sites/sites.php';
        // Construct an identifier from pieces of the (port plus) host plus script
        // path (excluding the filename). Loop over all possibilities starting from
        // most specific, then dropping pieces from the start of the port/hostname
        // while keeping the full path, then gradually dropping pieces from the end
        // of the path... until we find a directory corresponding to the identifier.
        $path_parts = explode('/', $script_name);
        $host_parts = explode('.', implode('.', array_reverse(explode(':', rtrim($http_host, '.')))));
        for ($i = count($path_parts) - 1; $i > 0; $i--) {
            for ($j = count($host_parts); $j > 0; $j--) {
                // Assume the path has a leading slash, so the imploded path parts are
                // either a path identifier with leading dot, or an empty string.
                $site_id = implode('.', array_slice($host_parts, -$j)) . implode('.', array_slice($path_parts, 0, $i));
                // If the identifier is a key in $sites, check for a directory matching
                // the corresponding value. Otherwise, check for a directory matching
                // the identifier.
                if (isset($sites[$site_id]) && file_exists($app_root . '/sites/' . $sites[$site_id])) {
                    $site_id = $sites[$site_id];
                }
                if (file_exists($app_root . '/sites/' . $site_id . '/settings.php') || !$require_settings && file_exists($app_root . '/sites/' . $site_id)) {
                    return "sites/{$site_id}";
                }
            }
        }
        return 'sites/default';
    }
    
    /**
     * {@inheritdoc}
     */
    public function setSitePath($path) {
        if ($this->booted && $path !== $this->sitePath) {
            throw new \LogicException('Site path cannot be changed after calling boot()');
        }
        $this->sitePath = $path;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSitePath() {
        return $this->sitePath;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getAppRoot() {
        return $this->root;
    }
    
    /**
     * {@inheritdoc}
     */
    public function boot() {
        if ($this->booted) {
            return $this;
        }
        // Ensure that findSitePath is set.
        if (!$this->sitePath) {
            throw new \Exception('Kernel does not have site path set before calling boot()');
        }
        // Initialize the FileCacheFactory component. We have to do it here instead
        // of in \Drupal\Component\FileCache\FileCacheFactory because we can not use
        // the Settings object in a component.
        $configuration = Settings::get('file_cache');
        // Provide a default configuration, if not set.
        if (!isset($configuration['default'])) {
            // @todo Use extension_loaded('apcu') for non-testbot
            //   https://www.drupal.org/node/2447753.
            if (function_exists('apcu_fetch')) {
                $configuration['default']['cache_backend_class'] = '\\Drupal\\Component\\FileCache\\ApcuFileCacheBackend';
            }
        }
        FileCacheFactory::setConfiguration($configuration);
        FileCacheFactory::setPrefix(Settings::getApcuPrefix('file_cache', $this->root));
        $this->bootstrapContainer = new $this->bootstrapContainerClass(Settings::get('bootstrap_container_definition', $this->defaultBootstrapContainerDefinition));
        // Initialize the container.
        $this->initializeContainer();
        // Add the APCu prefix to use to cache found/not-found classes.
        if (Settings::get('class_loader_auto_detect', TRUE) && method_exists($this->classLoader, 'setApcuPrefix')) {
            // Vary the APCu key by which modules are installed to allow
            // class_exists() checks to determine functionality.
            $id = 'class_loader:' . crc32(implode(':', array_keys($this->container
                ->getParameter('container.modules'))));
            $prefix = Settings::getApcuPrefix($id, $this->root);
            $this->classLoader
                ->setApcuPrefix($prefix);
        }
        $this->booted = TRUE;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function shutdown() {
        if (FALSE === $this->booted) {
            return;
        }
        $this->container
            ->get('stream_wrapper_manager')
            ->unregister();
        $this->booted = FALSE;
        $this->configStorage = NULL;
        $this->container = NULL;
        $this->moduleList = NULL;
        $this->moduleData = [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContainer() {
        return $this->container;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCachedContainerDefinition() {
        $cache = $this->bootstrapContainer
            ->get('cache.container')
            ->get($this->getContainerCacheKey());
        if ($cache) {
            return $cache->data;
        }
        return NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function loadLegacyIncludes() {
        require_once $this->root . '/core/includes/common.inc';
        require_once $this->root . '/core/includes/module.inc';
        require_once $this->root . '/core/includes/theme.inc';
        require_once $this->root . '/core/includes/form.inc';
        require_once $this->root . '/core/includes/errors.inc';
    }
    
    /**
     * {@inheritdoc}
     */
    public function preHandle(Request $request) {
        // Sanitize the request.
        $request = RequestSanitizer::sanitize($request, (array) Settings::get(RequestSanitizer::SANITIZE_INPUT_SAFE_KEYS, []), (bool) Settings::get(RequestSanitizer::SANITIZE_LOG, FALSE));
        // Ensure that there is a session on every request.
        if (!$request->hasSession()) {
            $this->initializeEphemeralSession($request);
        }
        $this->loadLegacyIncludes();
        // Load all enabled modules.
        $this->container
            ->get('module_handler')
            ->loadAll();
        // Register stream wrappers.
        $this->container
            ->get('stream_wrapper_manager')
            ->register();
        // Initialize legacy request globals.
        $this->initializeRequestGlobals($request);
        // Put the request on the stack.
        $this->container
            ->get('request_stack')
            ->push($request);
        // Set the allowed protocols.
        UrlHelper::setAllowedProtocols($this->container
            ->getParameter('filter_protocols'));
        // Override of Symfony's MIME type guesser singleton.
        MimeTypeGuesser::registerWithSymfonyGuesser($this->container);
        $this->prepared = TRUE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function discoverServiceProviders() {
        $this->serviceYamls = [
            'app' => [],
            'site' => [],
        ];
        $this->serviceProviderClasses = [
            'app' => [],
            'site' => [],
        ];
        $this->serviceYamls['app']['core'] = 'core/core.services.yml';
        $this->serviceProviderClasses['app']['core'] = 'Drupal\\Core\\CoreServiceProvider';
        // Retrieve enabled modules and register their namespaces.
        if (!isset($this->moduleList)) {
            $extensions = $this->getConfigStorage()
                ->read('core.extension');
            // If core.extension configuration does not exist and we're not in the
            // installer itself, then we need to put the kernel into a pre-installer
            // mode. The container should not be dumped because Drupal is yet to be
            // installed. The installer service provider is registered to ensure that
            // cache and other automatically created tables are not created if
            // database settings are available. None of this is required when the
            // installer is running because the installer has its own kernel and
            // manages the addition of its own service providers.
            // @see install_begin_request()
            if ($extensions === FALSE && !InstallerKernel::installationAttempted()) {
                $this->allowDumping = FALSE;
                $this->containerNeedsDumping = FALSE;
                $GLOBALS['conf']['container_service_providers']['InstallerServiceProvider'] = 'Drupal\\Core\\Installer\\InstallerServiceProvider';
            }
            $this->moduleList = $extensions['module'] ?? [];
        }
        $module_filenames = $this->getModuleFileNames();
        $this->classLoaderAddMultiplePsr4($this->getModuleNamespacesPsr4($module_filenames));
        // Load each module's serviceProvider class.
        foreach ($module_filenames as $module => $filename) {
            $camelized = ContainerBuilder::camelize($module);
            $name = "{$camelized}ServiceProvider";
            $class = "Drupal\\{$module}\\{$name}";
            if (class_exists($class)) {
                $this->serviceProviderClasses['app'][$module] = $class;
            }
            $filename = dirname($filename) . "/{$module}.services.yml";
            if (file_exists($filename)) {
                $this->serviceYamls['app'][$module] = $filename;
            }
        }
        // Add site-specific service providers.
        if (!empty($GLOBALS['conf']['container_service_providers'])) {
            foreach ($GLOBALS['conf']['container_service_providers'] as $class) {
                if (is_string($class) && class_exists($class) || is_object($class) && ($class instanceof ServiceProviderInterface || $class instanceof ServiceModifierInterface)) {
                    $this->serviceProviderClasses['site'][] = $class;
                }
            }
        }
        $this->addServiceFiles(Settings::get('container_yamls', []));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getServiceProviders($origin) {
        return $this->serviceProviders[$origin];
    }
    
    /**
     * {@inheritdoc}
     */
    public function terminate(Request $request, Response $response) : void {
        if ($this->booted && $this->getHttpKernel() instanceof TerminableInterface) {
            // Only run terminate() when essential services have been set up properly
            // by preHandle() before.
            if ($this->prepared === TRUE) {
                $this->getHttpKernel()
                    ->terminate($request, $response);
            }
            // For destructable services, always call the destruct method if they were
            // initialized during the request. Destruction is not necessary if the
            // service was not used.
            foreach ($this->container
                ->getParameter('kernel.destructable_services') as $id) {
                if ($this->container
                    ->initialized($id)) {
                    $service = $this->container
                        ->get($id);
                    $service->destruct();
                }
            }
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function handle(Request $request, $type = self::MAIN_REQUEST, $catch = TRUE) : Response {
        // Ensure sane PHP environment variables.
        static::bootEnvironment();
        try {
            if (!$this->booted) {
                $this->initializeSettings($request);
                $this->boot();
            }
            $response = $this->getHttpKernel()
                ->handle($request, $type, $catch);
        } catch (\Exception $e) {
            if ($catch === FALSE) {
                throw $e;
            }
            $response = $this->handleException($e, $request, $type);
        }
        // Adapt response headers to the current request.
        $response->prepare($request);
        return $response;
    }
    
    /**
     * Converts an exception into a response.
     *
     * @param \Exception $e
     *   An exception
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   A Request instance
     * @param int $type
     *   The type of the request (one of HttpKernelInterface::MAIN_REQUEST or
     *   HttpKernelInterface::SUB_REQUEST)
     *
     * @return \Symfony\Component\HttpFoundation\Response
     *   A Response instance
     *
     * @throws \Exception
     *   If the passed in exception cannot be turned into a response.
     */
    protected function handleException(\Exception $e, $request, $type) {
        if ($this->shouldRedirectToInstaller($e, $this->container ? $this->container
            ->get('database') : NULL)) {
            return new RedirectResponse($request->getBasePath() . '/core/install.php', 302, [
                'Cache-Control' => 'no-cache',
            ]);
        }
        if ($e instanceof HttpExceptionInterface) {
            $response = new Response($e->getMessage(), $e->getStatusCode());
            $response->headers
                ->add($e->getHeaders());
            return $response;
        }
        throw $e;
    }
    
    /**
     * Returns module data on the filesystem.
     *
     * @param $module
     *   The name of the module.
     *
     * @return \Drupal\Core\Extension\Extension|bool
     *   Returns an Extension object if the module is found, FALSE otherwise.
     */
    protected function moduleData($module) {
        if (!$this->moduleData) {
            // First, find profiles.
            $listing = new ExtensionDiscovery($this->root);
            $listing->setProfileDirectories([]);
            $all_profiles = $listing->scan('profile');
            $profiles = array_intersect_key($all_profiles, $this->moduleList);
            $profile_directories = array_map(function (Extension $profile) {
                return $profile->getPath();
            }, $profiles);
            $listing->setProfileDirectories($profile_directories);
            // Now find modules.
            $this->moduleData = $profiles + $listing->scan('module');
        }
        return $this->moduleData[$module] ?? FALSE;
    }
    
    /**
     * Implements Drupal\Core\DrupalKernelInterface::updateModules().
     *
     * @todo Remove obsolete $module_list parameter. Only $module_filenames is
     *   needed.
     */
    public function updateModules(array $module_list, array $module_filenames = []) {
        $pre_existing_module_namespaces = [];
        if ($this->booted && is_array($this->moduleList)) {
            $pre_existing_module_namespaces = $this->getModuleNamespacesPsr4($this->getModuleFileNames());
        }
        $this->moduleList = $module_list;
        foreach ($module_filenames as $name => $extension) {
            $this->moduleData[$name] = $extension;
        }
        // If we haven't yet booted, we don't need to do anything: the new module
        // list will take effect when boot() is called. However we set a
        // flag that the container needs a rebuild, so that a potentially cached
        // container is not used. If we have already booted, then rebuild the
        // container in order to refresh the serviceProvider list and container.
        $this->containerNeedsRebuild = TRUE;
        if ($this->booted) {
            // We need to register any new namespaces to a new class loader because
            // the current class loader might have stored a negative result for a
            // class that is now available.
            // @see \Composer\Autoload\ClassLoader::findFile()
            $new_namespaces = array_diff_key($this->getModuleNamespacesPsr4($this->getModuleFileNames()), $pre_existing_module_namespaces);
            if (!empty($new_namespaces)) {
                $additional_class_loader = new ClassLoader();
                $this->classLoaderAddMultiplePsr4($new_namespaces, $additional_class_loader);
                $additional_class_loader->register();
            }
            $this->initializeContainer();
        }
    }
    
    /**
     * Returns the container cache key based on the environment.
     *
     * The 'environment' consists of:
     * - The kernel environment string.
     * - The Drupal version constant.
     * - The deployment identifier from settings.php. This allows custom
     *   deployments to force a container rebuild.
     * - The operating system running PHP. This allows compiler passes to optimize
     *   services for different operating systems.
     * - The paths to any additional container YAMLs from settings.php.
     *
     * @return string
     *   The cache key used for the service container.
     */
    protected function getContainerCacheKey() {
        $parts = [
            'service_container',
            $this->environment,
            \Drupal::VERSION,
            Settings::get('deployment_identifier'),
            PHP_OS,
            serialize(Settings::get('container_yamls')),
        ];
        return implode(':', $parts);
    }
    
    /**
     * Returns the kernel parameters.
     *
     * @return array An array of kernel parameters
     */
    protected function getKernelParameters() {
        return [
            'kernel.environment' => $this->environment,
        ];
    }
    
    /**
     * Initializes the service container.
     *
     * @return \Symfony\Component\DependencyInjection\ContainerInterface
     */
    protected function initializeContainer() {
        $this->containerNeedsDumping = FALSE;
        $session_started = FALSE;
        $all_messages = [];
        if (isset($this->container)) {
            // Save the id of the currently logged in user.
            if ($this->container
                ->initialized('current_user')) {
                $current_user_id = $this->container
                    ->get('current_user')
                    ->id();
            }
            // After rebuilding the container some objects will have stale services.
            // Record a map of objects to service IDs prior to rebuilding the
            // container in order to ensure
            // \Drupal\Core\DependencyInjection\DependencySerializationTrait works as
            // expected.
            $this->container
                ->get(ReverseContainer::class)
                ->recordContainer();
            // If there is a session, close and save it.
            if ($this->container
                ->initialized('session')) {
                $session = $this->container
                    ->get('session');
                if ($session->isStarted()) {
                    $session_started = TRUE;
                    $session->save();
                }
                unset($session);
            }
            $all_messages = $this->container
                ->get('messenger')
                ->all();
        }
        // If the module list hasn't already been set in updateModules and we are
        // not forcing a rebuild, then try and load the container from the cache.
        if (empty($this->moduleList) && !$this->containerNeedsRebuild) {
            $container_definition = $this->getCachedContainerDefinition();
        }
        // If there is no cached container definition, build a new container from
        // scratch.
        if (!isset($container_definition)) {
            $container = $this->compileContainer();
            // Only dump the container if dumping is allowed. This is useful for
            // KernelTestBase, which never wants to use the real container, but always
            // the container builder.
            if ($this->allowDumping) {
                $dumper = new $this->phpArrayDumperClass($container);
                $container_definition = $dumper->getArray();
            }
        }
        // The container was rebuilt successfully.
        $this->containerNeedsRebuild = FALSE;
        // Only create a new class if we have a container definition.
        if (isset($container_definition)) {
            // Drupal provides two dynamic parameters to access specific paths that
            // are determined from the request.
            $container_definition['parameters']['app.root'] = $this->getAppRoot();
            $container_definition['parameters']['site.path'] = $this->getSitePath();
            $class = Settings::get('container_base_class', '\\Drupal\\Core\\DependencyInjection\\Container');
            $container = new $class($container_definition);
        }
        $this->attachSynthetic($container);
        $this->container = $container;
        if ($session_started) {
            $this->container
                ->get('session')
                ->start();
        }
        // The request stack is preserved across container rebuilds. Re-inject the
        // new session into the main request if one was present before.
        if ($request_stack = $this->container
            ->get('request_stack', ContainerInterface::NULL_ON_INVALID_REFERENCE)) {
            if ($request = $request_stack->getMainRequest()) {
                $subrequest = TRUE;
                $request->setSession($this->container
                    ->get('session'));
            }
        }
        if (!empty($current_user_id)) {
            $this->container
                ->get('current_user')
                ->setInitialAccountId($current_user_id);
        }
        // Re-add messages.
        foreach ($all_messages as $type => $messages) {
            foreach ($messages as $message) {
                $this->container
                    ->get('messenger')
                    ->addMessage($message, $type);
            }
        }
        \Drupal::setContainer($this->container);
        // Allow other parts of the codebase to react on container initialization in
        // subrequest.
        if (!empty($subrequest)) {
            $this->container
                ->get('event_dispatcher')
                ->dispatch(new Event(), self::CONTAINER_INITIALIZE_SUBREQUEST_FINISHED);
        }
        // If needs dumping flag was set, dump the container.
        if ($this->containerNeedsDumping && !$this->cacheDrupalContainer($container_definition)) {
            $this->container
                ->get('logger.factory')
                ->get('DrupalKernel')
                ->error('Container cannot be saved to cache.');
        }
        return $this->container;
    }
    
    /**
     * Setup a consistent PHP environment.
     *
     * This method sets PHP environment options we want to be sure are set
     * correctly for security or just saneness.
     *
     * @param string $app_root
     *   (optional) The path to the application root as a string. If not supplied,
     *   the application root will be computed.
     */
    public static function bootEnvironment($app_root = NULL) {
        if (static::$isEnvironmentInitialized) {
            return;
        }
        // Determine the application root if it's not supplied.
        if ($app_root === NULL) {
            $app_root = static::guessApplicationRoot();
        }
        error_reporting(E_ALL);
        // Override PHP settings required for Drupal to work properly.
        // sites/default/default.settings.php contains more runtime settings.
        // The .htaccess file contains settings that cannot be changed at runtime.
        if (PHP_SAPI !== 'cli') {
            // Use session cookies, not transparent sessions that puts the session id
            // in the query string.
            ini_set('session.use_cookies', '1');
            if (\PHP_VERSION_ID < 80400) {
                ini_set('session.use_only_cookies', '1');
                ini_set('session.use_trans_sid', '0');
            }
            // Don't send HTTP headers using PHP's session handler.
            // Send an empty string to disable the cache limiter.
            ini_set('session.cache_limiter', '');
            // Use httponly session cookies.
            ini_set('session.cookie_httponly', '1');
        }
        // Set sane locale settings, to ensure consistent string, dates, times and
        // numbers handling.
        setlocale(LC_ALL, 'C.UTF-8', 'C');
        // Set appropriate configuration for multi-byte strings.
        mb_internal_encoding('utf-8');
        mb_language('uni');
        // Indicate that code is operating in a test child site.
        if (!defined('DRUPAL_TEST_IN_CHILD_SITE')) {
            if ($test_prefix = drupal_valid_test_ua()) {
                $test_db = new TestDatabase($test_prefix);
                // 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
                // the 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', $app_root . '/' . $test_db->getTestSitePath() . '/error.log');
                // Ensure that a rewritten settings.php is used if OPcache is on.
                ini_set('opcache.validate_timestamps', 'on');
                ini_set('opcache.revalidate_freq', 0);
            }
            else {
                // Ensure that no other code defines this.
                define('DRUPAL_TEST_IN_CHILD_SITE', FALSE);
            }
        }
        // Set the Drupal custom error handler.
        set_error_handler('_drupal_error_handler');
        set_exception_handler('_drupal_exception_handler');
        static::$isEnvironmentInitialized = TRUE;
    }
    
    /**
     * Locate site path and initialize settings singleton.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The current request.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
     *   In case the host name in the request is not trusted.
     */
    protected function initializeSettings(Request $request) {
        $site_path = static::findSitePath($request);
        $this->setSitePath($site_path);
        Settings::initialize($this->root, $site_path, $this->classLoader);
        // Initialize our list of trusted HTTP Host headers to protect against
        // header attacks.
        $host_patterns = Settings::get('trusted_host_patterns', []);
        if (PHP_SAPI !== 'cli' && !empty($host_patterns)) {
            if (static::setupTrustedHosts($request, $host_patterns) === FALSE) {
                throw new BadRequestHttpException('The provided host name is not valid for this server.');
            }
        }
    }
    
    /**
     * Bootstraps the legacy global request variables.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The current request.
     *
     * @todo D8: Eliminate this entirely in favor of Request object.
     */
    protected function initializeRequestGlobals(Request $request) {
        global $base_url;
        // Set and derived from $base_url by this function.
        global $base_path, $base_root;
        global $base_secure_url, $base_insecure_url;
        // Create base URL.
        $base_root = $request->getSchemeAndHttpHost();
        $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($request->server
            ->get('SCRIPT_NAME')), '\\/')) {
            // Remove "core" directory if present, allowing install.php,
            // authorize.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);
    }
    
    /**
     * Returns service instances to persist from an old container to a new one.
     */
    protected function getServicesToPersist(ContainerInterface $container) {
        $persist = [];
        foreach ($container->getParameter('persist_ids') as $id) {
            // It's pointless to persist services not yet initialized.
            if ($container->initialized($id)) {
                $persist[$id] = $container->get($id);
            }
        }
        return $persist;
    }
    
    /**
     * Moves persistent service instances into a new container.
     */
    protected function persistServices(ContainerInterface $container, array $persist) {
        foreach ($persist as $id => $object) {
            // Do not override services already set() on the new container, for
            // example 'service_container'.
            if (!$container->initialized($id)) {
                $container->set($id, $object);
            }
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function rebuildContainer() {
        // Empty module properties and for them to be reloaded from scratch.
        $this->moduleList = NULL;
        $this->moduleData = [];
        $this->containerNeedsRebuild = TRUE;
        $container = $this->initializeContainer();
        // ThemeManager::render() fails without this. Normally ::preHandle() has
        // a ->loadAll() call.
        $container->get('module_handler')
            ->loadAll();
        return $container;
    }
    
    /**
     * {@inheritdoc}
     */
    public function resetContainer() : ContainerInterface {
        $session_started = FALSE;
        $subrequest = FALSE;
        $reload_module_handler = FALSE;
        // Save the id of the currently logged in user.
        if ($this->container
            ->initialized('current_user')) {
            $current_user_id = $this->container
                ->get('current_user')
                ->id();
        }
        if ($this->container
            ->initialized('module_handler') && $this->container
            ->get('module_handler')
            ->isLoaded()) {
            $reload_module_handler = TRUE;
        }
        // After rebuilding the container some objects will have stale services.
        // Record a map of objects to service IDs prior to rebuilding the
        // container in order to ensure
        // \Drupal\Core\DependencyInjection\DependencySerializationTrait works as
        // expected.
        $this->container
            ->get(ReverseContainer::class)
            ->recordContainer();
        // If there is a session, close and save it.
        if ($this->container
            ->initialized('session')) {
            $session = $this->container
                ->get('session');
            if ($session->isStarted()) {
                $session_started = TRUE;
                $session->save();
            }
            unset($session);
        }
        $all_messages = $this->container
            ->get('messenger')
            ->all();
        $persist = $this->getServicesToPersist($this->container);
        $this->container
            ->reset();
        $this->persistServices($this->container, $persist);
        $this->container
            ->set('kernel', $this);
        // Set the class loader which was registered as a synthetic service.
        $this->container
            ->set('class_loader', $this->classLoader);
        if ($reload_module_handler) {
            $this->container
                ->get('module_handler')
                ->reload();
        }
        if ($session_started) {
            $this->container
                ->get('session')
                ->start();
        }
        // The request stack is preserved across container rebuilds. Re-inject the
        // new session into the main request if one was present before.
        if ($request_stack = $this->container
            ->get('request_stack', ContainerInterface::NULL_ON_INVALID_REFERENCE)) {
            if ($request = $request_stack->getMainRequest()) {
                $subrequest = TRUE;
                $request->setSession($this->container
                    ->get('session'));
            }
        }
        if (!empty($current_user_id)) {
            $this->container
                ->get('current_user')
                ->setInitialAccountId($current_user_id);
        }
        // Re-add messages.
        foreach ($all_messages as $type => $messages) {
            foreach ($messages as $message) {
                $this->container
                    ->get('messenger')
                    ->addMessage($message, $type);
            }
        }
        // Allow other parts of the codebase to react on container reset in
        // subrequest.
        if (!empty($subrequest)) {
            $this->container
                ->get('event_dispatcher')
                ->dispatch(new Event(), self::CONTAINER_INITIALIZE_SUBREQUEST_FINISHED);
        }
        return $this->container;
    }
    
    /**
     * {@inheritdoc}
     */
    public function invalidateContainer() {
        // An invalidated container needs a rebuild.
        $this->containerNeedsRebuild = TRUE;
        // If we have not yet booted, settings or bootstrap services might not yet
        // be available. In that case the container will not be loaded from cache
        // due to the above setting when the Kernel is booted.
        if (!$this->booted) {
            return;
        }
        // Also remove the container definition from the cache backend.
        $this->bootstrapContainer
            ->get('cache.container')
            ->deleteAll();
    }
    
    /**
     * Attach synthetic values on to kernel.
     *
     * @param \Symfony\Component\DependencyInjection\ContainerInterface $container
     *   Container object
     *
     * @return \Symfony\Component\DependencyInjection\ContainerInterface
     */
    protected function attachSynthetic(ContainerInterface $container) {
        $persist = [];
        if (isset($this->container)) {
            $persist = $this->getServicesToPersist($this->container);
        }
        $this->persistServices($container, $persist);
        // All namespaces must be registered before we attempt to use any service
        // from the container.
        $this->classLoaderAddMultiplePsr4($container->getParameter('container.namespaces'));
        $container->set('kernel', $this);
        // Set the class loader which was registered as a synthetic service.
        $container->set('class_loader', $this->classLoader);
        return $container;
    }
    
    /**
     * Compiles a new service container.
     *
     * @return \Drupal\Core\DependencyInjection\ContainerBuilder The compiled service container
     */
    protected function compileContainer() {
        // We are forcing a container build so it is reasonable to assume that the
        // calling method knows something about the system has changed requiring the
        // container to be dumped to the filesystem.
        if ($this->allowDumping) {
            $this->containerNeedsDumping = TRUE;
        }
        $this->initializeServiceProviders();
        $container = $this->getContainerBuilder();
        $container->set('kernel', $this);
        $container->setParameter('container.modules', $this->getModulesParameter());
        $container->setParameter('install_profile', $this->getInstallProfile());
        // Get a list of namespaces and put it onto the container.
        $namespaces = $this->getModuleNamespacesPsr4($this->getModuleFileNames());
        // Add all components in \Drupal\Core and \Drupal\Component that have one of
        // the following directories:
        // - Element
        // - Entity
        // - Plugin
        foreach ([
            'Core',
            'Component',
        ] as $parent_directory) {
            $path = 'core/lib/Drupal/' . $parent_directory;
            $parent_namespace = 'Drupal\\' . $parent_directory;
            foreach (new \DirectoryIterator($this->root . '/' . $path) as $component) {
                
                /** @var \DirectoryIterator $component */
                $pathname = $component->getPathname();
                if (!$component->isDot() && $component->isDir() && (is_dir($pathname . '/Plugin') || is_dir($pathname . '/Entity') || is_dir($pathname . '/Element'))) {
                    $namespaces[$parent_namespace . '\\' . $component->getFilename()] = $path . '/' . $component->getFilename();
                }
            }
        }
        $container->setParameter('container.namespaces', $namespaces);
        // Store the default language values on the container. This is so that the
        // default language can be configured using the configuration factory. This
        // avoids the circular dependencies that would created by
        // \Drupal\language\LanguageServiceProvider::alter() and allows the default
        // language to not be English in the installer.
        $default_language_values = Language::$defaultValues;
        if ($system = $this->getConfigStorage()
            ->read('system.site')) {
            if ($default_language_values['id'] != $system['langcode']) {
                $default_language_values = [
                    'id' => $system['langcode'],
                ];
            }
        }
        $container->setParameter('language.default_values', $default_language_values);
        // Register synthetic services.
        $container->register('class_loader')
            ->setSynthetic(TRUE);
        $container->register('kernel', 'Symfony\\Component\\HttpKernel\\KernelInterface')
            ->setSynthetic(TRUE);
        $container->register('service_container', 'Symfony\\Component\\DependencyInjection\\ContainerInterface')
            ->setSynthetic(TRUE);
        // Register aliases of synthetic services for autowiring.
        $container->setAlias(DrupalKernelInterface::class, 'kernel');
        $container->setAlias(ContainerInterface::class, 'service_container');
        // Register application services.
        $yaml_loader = new YamlFileLoader($container);
        foreach ($this->serviceYamls['app'] as $filename) {
            $yaml_loader->load($filename);
        }
        foreach ($this->serviceProviders['app'] as $provider) {
            if ($provider instanceof ServiceProviderInterface) {
                $provider->register($container);
            }
        }
        // Register site-specific service overrides.
        foreach ($this->serviceYamls['site'] as $filename) {
            $yaml_loader->load($filename);
        }
        foreach ($this->serviceProviders['site'] as $provider) {
            if ($provider instanceof ServiceProviderInterface) {
                $provider->register($container);
            }
        }
        // Identify all services whose instances should be persisted when rebuilding
        // the container during the lifetime of the kernel (e.g., during a kernel
        // reboot). Include synthetic services, because by definition, they cannot
        // be automatically re-instantiated. Also include services tagged to
        // persist.
        $persist_ids = [];
        foreach ($container->getDefinitions() as $id => $definition) {
            // It does not make sense to persist the container itself, exclude it.
            if ($id !== 'service_container' && ($definition->isSynthetic() || $definition->getTag('persist'))) {
                $persist_ids[] = $id;
            }
        }
        $container->setParameter('persist_ids', $persist_ids);
        $container->setParameter('app.root', $this->getAppRoot());
        $container->setParameter('site.path', $this->getSitePath());
        $container->compile();
        return $container;
    }
    
    /**
     * Registers all service providers to the kernel.
     *
     * @throws \LogicException
     */
    protected function initializeServiceProviders() {
        $this->discoverServiceProviders();
        $this->serviceProviders = [
            'app' => [],
            'site' => [],
        ];
        foreach ($this->serviceProviderClasses as $origin => $classes) {
            foreach ($classes as $name => $class) {
                if (!is_object($class)) {
                    $this->serviceProviders[$origin][$name] = new $class();
                }
                else {
                    $this->serviceProviders[$origin][$name] = $class;
                }
            }
        }
    }
    
    /**
     * Gets a new ContainerBuilder instance used to build the service container.
     *
     * @return \Drupal\Core\DependencyInjection\ContainerBuilder
     */
    protected function getContainerBuilder() {
        return new ContainerBuilder(new ParameterBag($this->getKernelParameters()));
    }
    
    /**
     * Stores the container definition in a cache.
     *
     * @param array $container_definition
     *   The container definition to cache.
     *
     * @return bool
     *   TRUE if the container was successfully cached.
     */
    protected function cacheDrupalContainer(array $container_definition) {
        $saved = TRUE;
        try {
            $this->bootstrapContainer
                ->get('cache.container')
                ->set($this->getContainerCacheKey(), $container_definition);
        } catch (\Exception) {
            // There is no way to get from the Cache API if the cache set was
            // successful or not, hence an Exception is caught and the caller informed
            // about the error condition.
            $saved = FALSE;
        }
        return $saved;
    }
    
    /**
     * Gets a http kernel from the container.
     *
     * @return \Symfony\Component\HttpKernel\HttpKernelInterface
     */
    protected function getHttpKernel() {
        return $this->container
            ->get('http_kernel');
    }
    
    /**
     * Returns the active configuration storage to use during building the container.
     *
     * @return \Drupal\Core\Config\StorageInterface
     */
    protected function getConfigStorage() {
        if (!isset($this->configStorage)) {
            // The active configuration storage may not exist yet; e.g., in the early
            // installer so if an exception is thrown use a NullStorage.
            try {
                $this->configStorage = BootstrapConfigStorageFactory::get($this->classLoader);
            } catch (\Exception) {
                $this->configStorage = new NullStorage();
            }
        }
        return $this->configStorage;
    }
    
    /**
     * Returns an array of Extension class parameters for all enabled modules.
     *
     * @return array
     */
    protected function getModulesParameter() {
        $extensions = [];
        foreach ($this->moduleList as $name => $weight) {
            if ($data = $this->moduleData($name)) {
                $extensions[$name] = [
                    'type' => $data->getType(),
                    'pathname' => $data->getPathname(),
                    'filename' => $data->getExtensionFilename(),
                ];
            }
        }
        return $extensions;
    }
    
    /**
     * Gets the file name for each enabled module.
     *
     * @return array
     *   Array where each key is a module name, and each value is a path to the
     *   respective *.info.yml file.
     */
    protected function getModuleFileNames() {
        $filenames = [];
        foreach ($this->moduleList as $module => $weight) {
            if ($data = $this->moduleData($module)) {
                $filenames[$module] = $data->getPathname();
            }
        }
        return $filenames;
    }
    
    /**
     * Gets the PSR-4 base directories for module namespaces.
     *
     * @param string[] $module_file_names
     *   Array where each key is a module name, and each value is a path to the
     *   respective *.info.yml file.
     *
     * @return string[]
     *   Array where each key is a module namespace like 'Drupal\system', and each
     *   value is the PSR-4 base directory associated with the module namespace.
     */
    protected function getModuleNamespacesPsr4($module_file_names) {
        $namespaces = [];
        foreach ($module_file_names as $module => $filename) {
            $namespaces["Drupal\\{$module}"] = dirname($filename) . '/src';
        }
        return $namespaces;
    }
    
    /**
     * Registers a list of namespaces with PSR-4 directories for class loading.
     *
     * @param array $namespaces
     *   Array where each key is a namespace like 'Drupal\system', and each value
     *   is either a PSR-4 base directory, or an array of PSR-4 base directories
     *   associated with this namespace.
     * @param object $class_loader
     *   The class loader. Normally \Composer\Autoload\ClassLoader, as included by
     *   the front controller, but may also be decorated.
     */
    protected function classLoaderAddMultiplePsr4(array $namespaces = [], $class_loader = NULL) {
        if ($class_loader === NULL) {
            $class_loader = $this->classLoader;
        }
        foreach ($namespaces as $prefix => $paths) {
            if (is_array($paths)) {
                foreach ($paths as $key => $value) {
                    $paths[$key] = $this->root . '/' . $value;
                }
            }
            elseif (is_string($paths)) {
                $paths = $this->root . '/' . $paths;
            }
            $class_loader->addPsr4($prefix . '\\', $paths);
        }
    }
    
    /**
     * Validates a hostname length.
     *
     * @param string $host
     *   A hostname.
     *
     * @return bool
     *   TRUE if the length is appropriate, or FALSE otherwise.
     */
    protected static function validateHostnameLength($host) {
        // Limit the length of the host name to 1000 bytes to prevent DoS attacks
        // with long host names.
        return strlen($host) <= 1000 && substr_count($host, '.') <= 100 && substr_count($host, ':') <= 100;
    }
    
    /**
     * Validates the hostname supplied from the HTTP request.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request object
     *
     * @return bool
     *   TRUE if the hostname is valid, or FALSE otherwise.
     */
    public static function validateHostname(Request $request) {
        // $request->getHost() can throw an UnexpectedValueException if it
        // detects a bad hostname, but it does not validate the length.
        try {
            $http_host = $request->getHost();
        } catch (\UnexpectedValueException) {
            return FALSE;
        }
        if (static::validateHostnameLength($http_host) === FALSE) {
            return FALSE;
        }
        return TRUE;
    }
    
    /**
     * Sets up the lists of trusted HTTP Host headers.
     *
     * Since the HTTP Host header can be set by the user making the request, it
     * is possible to create an attack vectors against a site by overriding this.
     * Symfony provides a mechanism for creating a list of trusted Host values.
     *
     * Host patterns (as regular expressions) can be configured through
     * settings.php for multisite installations, sites using ServerAlias without
     * canonical redirection, or configurations where the site responds to default
     * requests. For example,
     *
     * @code
     * $settings['trusted_host_patterns'] = [
     *   '^example\.com$',
     *   '^*.example\.com$',
     * ];
     * @endcode
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request object.
     * @param array $host_patterns
     *   The array of trusted host patterns.
     *
     * @return bool
     *   TRUE if the Host header is trusted, FALSE otherwise.
     *
     * @see https://www.drupal.org/docs/installing-drupal/trusted-host-settings
     * @see \Drupal\Core\Http\TrustedHostsRequestFactory
     */
    protected static function setupTrustedHosts(Request $request, $host_patterns) {
        Request::setTrustedHosts($host_patterns);
        // Get the host, which will validate the current request.
        try {
            $host = $request->getHost();
            // Fake requests created through Request::create() without passing in the
            // server variables from the main request have a default host of
            // 'localhost'. If 'localhost' does not match any of the trusted host
            // patterns these fake requests would fail the host verification. Instead,
            // TrustedHostsRequestFactory makes sure to pass in the server variables
            // from the main request.
            $request_factory = new TrustedHostsRequestFactory($host);
            Request::setFactory([
                $request_factory,
                'createRequest',
            ](...));
        } catch (\UnexpectedValueException) {
            return FALSE;
        }
        return TRUE;
    }
    
    /**
     * Add service files.
     *
     * @param string[] $service_yamls
     *   A list of service files.
     */
    protected function addServiceFiles(array $service_yamls) {
        $this->serviceYamls['site'] = array_filter($service_yamls, 'file_exists');
    }
    
    /**
     * Gets the active install profile.
     *
     * @return string|false|null
     *   The name of the active install profile or distribution, FALSE if there is
     *   no install profile or NULL if Drupal is being installed.
     */
    protected function getInstallProfile() {
        $config = $this->getConfigStorage()
            ->read('core.extension');
        if (is_array($config) && !array_key_exists('profile', $config)) {
            return FALSE;
        }
        return $config['profile'] ?? NULL;
    }
    
    /**
     * Initializes a session backed by in-memory store and puts it on the request.
     *
     * A simple in-memory store is sufficient for command line tools and tests.
     * Web requests will be processed by the session middleware where the mock
     * session is replaced by a session object backed with persistent storage and
     * a real session handler.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request.
     *
     * @see \Drupal\Core\StackMiddleware\Session::handle()
     */
    protected function initializeEphemeralSession(Request $request) : void {
        $session = new Session(new MockArraySessionStorage());
        $session->start();
        $request->setSession($session);
    }

}

Classes

Title Deprecated Summary
DrupalKernel The DrupalKernel class is the core of Drupal itself.

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