1 files changed, 55 insertions, 20 deletions

diff --git a/lib/private/legacy/OC_Template.php b/lib/private/legacy/OC_Template.php
index 974f26fa381..545d5a73a63 100644
--- a/lib/private/legacy/OC_Template.php
+++ b/lib/private/legacy/OC_Template.php
@@ -21,6 +21,7 @@
  * @author Roeland Jago Douma <roeland@famdouma.nl>
  * @author Thomas Müller <thomas.mueller@tmit.eu>
  * @author Vincent Petry <vincent@nextcloud.com>
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
  *
  * @license AGPL-3.0
  *
@@ -38,7 +39,9 @@
  *
  */
 use OC\TemplateLayout;
+use OCP\AppFramework\Http\Events\BeforeTemplateRenderedEvent;
 use OCP\AppFramework\Http\TemplateResponse;
+use OCP\EventDispatcher\IEventDispatcher;
 
 require_once __DIR__.'/template/functions.php';
 
@@ -249,20 +252,44 @@ class OC_Template extends \OC\Template\Base {
 			// If the hint is the same as the message there is no need to display it twice.
 			$hint = '';
 		}
+		$errors = [['error' => $error_msg, 'hint' => $hint]];
 
 		http_response_code($statusCode);
 		try {
-			$content = new \OC_Template('', 'error', 'error', false);
-			$errors = [['error' => $error_msg, 'hint' => $hint]];
-			$content->assign('errors', $errors);
-			$content->printPage();
-		} catch (\Exception $e) {
+			// Try rendering themed html error page
+			$response = new TemplateResponse(
+				'',
+				'error',
+				['errors' => $errors],
+				TemplateResponse::RENDER_AS_ERROR,
+				$statusCode,
+			);
+			$event = new BeforeTemplateRenderedEvent(false, $response);
+			\OC::$server->get(IEventDispatcher::class)->dispatchTyped($event);
+			print($response->render());
+		} catch (\Throwable $e1) {
 			$logger = \OC::$server->getLogger();
-			$logger->error("$error_msg $hint", ['app' => 'core']);
-			$logger->logException($e, ['app' => 'core']);
+			$logger->logException($e1, [
+				'app' => 'core',
+				'message' => 'Rendering themed error page failed. Falling back to unthemed error page.'
+			]);
 
-			header('Content-Type: text/plain; charset=utf-8');
-			print("$error_msg $hint");
+			try {
+				// Try rendering unthemed html error page
+				$content = new \OC_Template('', 'error', 'error', false);
+				$content->assign('errors', $errors);
+				$content->printPage();
+			} catch (\Exception $e2) {
+				// If nothing else works, fall back to plain text error page
+				$logger->error("$error_msg $hint", ['app' => 'core']);
+				$logger->logException($e2, [
+					'app' => 'core',
+					'message' => 'Rendering unthemed error page failed. Falling back to plain text error page.'
+				]);
+
+				header('Content-Type: text/plain; charset=utf-8');
+				print("$error_msg $hint");
+			}
 		}
 		die();
 	}
@@ -275,8 +302,10 @@ class OC_Template extends \OC\Template\Base {
 	 * @suppress PhanAccessMethodInternal
 	 */
 	public static function printExceptionErrorPage($exception, $statusCode = 503) {
+		$debug = false;
 		http_response_code($statusCode);
 		try {
+			$debug = \OC::$server->getSystemConfig()->getValue('debug', false);
 			$request = \OC::$server->getRequest();
 			$content = new \OC_Template('', 'exception', 'error', false);
 			$content->assign('errorClass', get_class($exception));
@@ -285,7 +314,7 @@ class OC_Template extends \OC\Template\Base {
 			$content->assign('file', $exception->getFile());
 			$content->assign('line', $exception->getLine());
 			$content->assign('exception', $exception);
-			$content->assign('debugMode', \OC::$server->getSystemConfig()->getValue('debug', false));
+			$content->assign('debugMode', $debug);
 			$content->assign('remoteAddr', $request->getRemoteAddress());
 			$content->assign('requestID', $request->getId());
 			$content->printPage();
@@ -296,22 +325,28 @@ class OC_Template extends \OC\Template\Base {
 				$logger->logException($e, ['app' => 'core']);
 			} catch (Throwable $e) {
 				// no way to log it properly - but to avoid a white page of death we send some output
-				header('Content-Type: text/plain; charset=utf-8');
-				print("Internal Server Error\n\n");
-				print("The server encountered an internal error and was unable to complete your request.\n");
-				print("Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.\n");
-				print("More details can be found in the server log.\n");
+				self::printPlainErrorPage($e, $debug);
 
 				// and then throw it again to log it at least to the web server error log
 				throw $e;
 			}
 
-			header('Content-Type: text/plain; charset=utf-8');
-			print("Internal Server Error\n\n");
-			print("The server encountered an internal error and was unable to complete your request.\n");
-			print("Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.\n");
-			print("More details can be found in the server log.\n");
+			self::printPlainErrorPage($e, $debug);
 		}
 		die();
 	}
+
+	private static function printPlainErrorPage(\Throwable $exception, bool $debug = false) {
+		header('Content-Type: text/plain; charset=utf-8');
+		print("Internal Server Error\n\n");
+		print("The server encountered an internal error and was unable to complete your request.\n");
+		print("Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.\n");
+		print("More details can be found in the server log.\n");
+
+		if ($debug) {
+			print("\n");
+			print($exception->getMessage() . ' ' . $exception->getFile() . ' at ' . $exception->getLine() . "\n");
+			print($exception->getTraceAsString());
+		}
+	}
 }