Improve exception handling

If there is an exception in the template handling then a white page is shown.
This improves the handling of this and shows text only about the internal
error.

To test this just setup redis as cache and then disable the php-redis module.

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

index.php

@@ -47,7 +47,16 @@ try {
 	OC_Template::printExceptionErrorPage($ex);
 } catch (\OC\HintException $ex) {
 	OC_Response::setStatus(OC_Response::STATUS_SERVICE_UNAVAILABLE);
-	OC_Template::printErrorPage($ex->getMessage(), $ex->getHint());
+	try {
+		OC_Template::printErrorPage($ex->getMessage(), $ex->getHint());
+	} catch (Exception $ex2) {
+		\OC::$server->getLogger()->logException($ex, array('app' => 'index'));
+		\OC::$server->getLogger()->logException($ex2, array('app' => 'index'));
+
+		//show the user a detailed error page
+		OC_Response::setStatus(OC_Response::STATUS_INTERNAL_SERVER_ERROR);
+		OC_Template::printExceptionErrorPage($ex);
+	}
 } catch (\OC\User\LoginException $ex) {
 	OC_Response::setStatus(OC_Response::STATUS_FORBIDDEN);
 	OC_Template::printErrorPage($ex->getMessage(), $ex->getMessage());

lib/private/Log.php

@@ -331,6 +331,9 @@ class Log implements ILogger {
 			'Line' => $exception->getLine(),
 		);
 		$data['Trace'] = preg_replace('!(' . implode('|', $this->methodsWithSensitiveParameters) . ')\(.*\)!', '$1(*** sensitive parameters replaced ***)', $data['Trace']);
+		if ($exception instanceof HintException) {
+			$data['Hint'] = $exception->getHint();
+		}
 		$msg = isset($context['message']) ? $context['message'] : 'Exception';
 		$msg .= ': ' . json_encode($data);
 		$this->log($level, $msg, $context);