Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\Core\EventSubscriber;
Chris@0: 
Chris@17: use Drupal\Component\Render\FormattableMarkup;
Chris@0: use Drupal\Core\Config\ConfigFactoryInterface;
Chris@0: use Drupal\Core\StringTranslation\StringTranslationTrait;
Chris@0: use Drupal\Core\Utility\Error;
Chris@0: use Symfony\Component\EventDispatcher\EventSubscriberInterface;
Chris@0: use Symfony\Component\HttpFoundation\Response;
Chris@0: use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
Chris@0: use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;
Chris@0: use Symfony\Component\HttpKernel\KernelEvents;
Chris@0: 
Chris@0: /**
Chris@0:  * Last-chance handler for exceptions: the final exception subscriber.
Chris@0:  *
Chris@0:  * This handler will catch any exceptions not caught elsewhere and report
Chris@0:  * them as an error page.
Chris@0:  *
Chris@0:  * Each format has its own way of handling exceptions:
Chris@0:  * - html: exception.default_html, exception.custom_page_html and
Chris@0:  *   exception.fast_404_html
Chris@0:  * - json: exception.default_json
Chris@0:  *
Chris@0:  * And when the serialization module is installed, all serialization formats are
Chris@0:  * handled by a single exception subscriber:: serialization.exception.default.
Chris@0:  *
Chris@0:  * This exception subscriber runs after all the above (it has a lower priority),
Chris@0:  * which makes it the last-chance exception handler. It always sends a plain
Chris@0:  * text response. If it's a displayable error and the error level is configured
Chris@0:  * to be verbose, then a helpful backtrace is also printed.
Chris@0:  */
Chris@0: class FinalExceptionSubscriber implements EventSubscriberInterface {
Chris@0:   use StringTranslationTrait;
Chris@0: 
Chris@0:   /**
Chris@0:    * @var string
Chris@0:    *
Chris@0:    * One of the error level constants defined in bootstrap.inc.
Chris@0:    */
Chris@0:   protected $errorLevel;
Chris@0: 
Chris@0:   /**
Chris@0:    * The config factory.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Config\ConfigFactoryInterface
Chris@0:    */
Chris@0:   protected $configFactory;
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a new FinalExceptionSubscriber.
Chris@0:    *
Chris@0:    * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
Chris@0:    *   The configuration factory.
Chris@0:    */
Chris@0:   public function __construct(ConfigFactoryInterface $config_factory) {
Chris@0:     $this->configFactory = $config_factory;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Gets the configured error level.
Chris@0:    *
Chris@0:    * @return string
Chris@0:    */
Chris@0:   protected function getErrorLevel() {
Chris@0:     if (!isset($this->errorLevel)) {
Chris@0:       $this->errorLevel = $this->configFactory->get('system.logging')->get('error_level');
Chris@0:     }
Chris@0:     return $this->errorLevel;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Handles exceptions for this subscriber.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
Chris@0:    *   The event to process.
Chris@0:    */
Chris@0:   public function onException(GetResponseForExceptionEvent $event) {
Chris@0:     $exception = $event->getException();
Chris@0:     $error = Error::decodeException($exception);
Chris@0: 
Chris@0:     // Display the message if the current error reporting level allows this type
Chris@0:     // of message to be displayed, and unconditionally in update.php.
Chris@0:     $message = '';
Chris@0:     if ($this->isErrorDisplayable($error)) {
Chris@0:       // If error type is 'User notice' then treat it as debug information
Chris@0:       // instead of an error message.
Chris@0:       // @see debug()
Chris@0:       if ($error['%type'] == 'User notice') {
Chris@0:         $error['%type'] = 'Debug';
Chris@0:       }
Chris@0: 
Chris@0:       $error = $this->simplifyFileInError($error);
Chris@0: 
Chris@0:       unset($error['backtrace']);
Chris@0: 
Chris@0:       if (!$this->isErrorLevelVerbose()) {
Chris@0:         // Without verbose logging, use a simple message.
Chris@0: 
Chris@17:         // We use \Drupal\Component\Render\FormattableMarkup directly here,
Chris@17:         // rather than use t() since we are in the middle of error handling, and
Chris@17:         // we don't want t() to cause further errors.
Chris@17:         $message = new FormattableMarkup('%type: @message in %function (line %line of %file).', $error);
Chris@0:       }
Chris@0:       else {
Chris@0:         // With verbose logging, we will also include a backtrace.
Chris@0: 
Chris@0:         $backtrace_exception = $exception;
Chris@0:         while ($backtrace_exception->getPrevious()) {
Chris@0:           $backtrace_exception = $backtrace_exception->getPrevious();
Chris@0:         }
Chris@0:         $backtrace = $backtrace_exception->getTrace();
Chris@0:         // First trace is the error itself, already contained in the message.
Chris@0:         // While the second trace is the error source and also contained in the
Chris@0:         // message, the message doesn't contain argument values, so we output it
Chris@0:         // once more in the backtrace.
Chris@0:         array_shift($backtrace);
Chris@0: 
Chris@0:         // Generate a backtrace containing only scalar argument values.
Chris@0:         $error['@backtrace'] = Error::formatBacktrace($backtrace);
Chris@17:         $message = new FormattableMarkup('%type: @message in %function (line %line of %file). <pre class="backtrace">@backtrace</pre>', $error);
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     $content = $this->t('The website encountered an unexpected error. Please try again later.');
Chris@0:     $content .= $message ? '</br></br>' . $message : '';
Chris@0:     $response = new Response($content, 500, ['Content-Type' => 'text/plain']);
Chris@0: 
Chris@0:     if ($exception instanceof HttpExceptionInterface) {
Chris@0:       $response->setStatusCode($exception->getStatusCode());
Chris@0:       $response->headers->add($exception->getHeaders());
Chris@0:     }
Chris@0:     else {
Chris@0:       $response->setStatusCode(Response::HTTP_INTERNAL_SERVER_ERROR, '500 Service unavailable (with message)');
Chris@0:     }
Chris@0: 
Chris@0:     $event->setResponse($response);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public static function getSubscribedEvents() {
Chris@0:     // Run as the final (very late) KernelEvents::EXCEPTION subscriber.
Chris@0:     $events[KernelEvents::EXCEPTION][] = ['onException', -256];
Chris@0:     return $events;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Checks whether the error level is verbose or not.
Chris@0:    *
Chris@0:    * @return bool
Chris@0:    */
Chris@0:   protected function isErrorLevelVerbose() {
Chris@0:     return $this->getErrorLevel() === ERROR_REPORTING_DISPLAY_VERBOSE;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Wrapper for error_displayable().
Chris@0:    *
Chris@0:    * @param $error
Chris@0:    *   Optional error to examine for ERROR_REPORTING_DISPLAY_SOME.
Chris@0:    *
Chris@0:    * @return bool
Chris@0:    *
Chris@0:    * @see \error_displayable
Chris@0:    */
Chris@0:   protected function isErrorDisplayable($error) {
Chris@0:     return error_displayable($error);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Attempts to reduce error verbosity in the error message's file path.
Chris@0:    *
Chris@0:    * Attempts to reduce verbosity by removing DRUPAL_ROOT from the file path in
Chris@0:    * the message. This does not happen for (false) security.
Chris@0:    *
Chris@0:    * @param $error
Chris@0:    *   Optional error to examine for ERROR_REPORTING_DISPLAY_SOME.
Chris@0:    *
Chris@0:    * @return
Chris@0:    *   The updated $error.
Chris@0:    */
Chris@0:   protected function simplifyFileInError($error) {
Chris@0:     // Attempt to reduce verbosity by removing DRUPAL_ROOT from the file path
Chris@0:     // in the message. This does not happen for (false) security.
Chris@0:     $root_length = strlen(DRUPAL_ROOT);
Chris@0:     if (substr($error['%file'], 0, $root_length) == DRUPAL_ROOT) {
Chris@0:       $error['%file'] = substr($error['%file'], $root_length + 1);
Chris@0:     }
Chris@0:     return $error;
Chris@0:   }
Chris@0: 
Chris@0: }