Some expected Sabre exceptions are now logged with DEBUG level

lib/private/connector/sabre/exceptionloggerplugin.php

@@ -11,6 +11,17 @@
 
 class OC_Connector_Sabre_ExceptionLoggerPlugin extends Sabre_DAV_ServerPlugin
 {
+	private $nonFatalExceptions = array(
+		'Sabre_DAV_Exception_NotAuthenticated' => true,
+		// the sync client uses this to find out whether files exist,
+		// so it is not always an error, log it as debug
+		'Sabre_DAV_Exception_NotFound' => true,
+		// this one mostly happens when the same file is uploaded at
+		// exactly the same time from two clients, only one client
+		// wins, the second one gets "Precondition failed"
+		'Sabre_DAV_Exception_PreconditionFailed' => true,
+	);
+
 	private $appName;
 
 	/**
@@ -43,8 +54,10 @@ class OC_Connector_Sabre_ExceptionLoggerPlugin extends Sabre_DAV_ServerPlugin
 	 */
 	public function logException($e) {
 		$exceptionClass = get_class($e);
-		if ($exceptionClass !== 'Sabre_DAV_Exception_NotAuthenticated') {
-			\OCP\Util::logException($this->appName, $e);
+		$level = \OCP\Util::FATAL;
+		if (isset($this->nonFatalExceptions[$exceptionClass])) {
+			$level = \OCP\Util::DEBUG;
 		}
+		\OCP\Util::logException($this->appName, $e, $level);
 	}
 }

lib/public/util.php

@@ -86,21 +86,22 @@ class Util {
 	 * if DEBUG mode is enabled
 	 * @param string $app app name
 	 * @param \Exception $ex exception to log
+	 * @param string $level log level, defaults to \OCP\Util::FATAL
 	 */
-	public static function logException( $app, \Exception $ex ) {
+	public static function logException( $app, \Exception $ex, $level = \OCP\Util::FATAL ) {
 		$class = get_class($ex);
 		$message = $class . ': ' . $ex->getMessage();
 		if ($ex->getCode()) {
 			$message .= ' [' . $ex->getCode() . ']';
 		}
-		\OCP\Util::writeLog($app, $message, \OCP\Util::FATAL);
+		\OCP\Util::writeLog($app, $message, $level);
 		if (defined('DEBUG') and DEBUG) {
 			// also log stack trace
 			$stack = explode("\n", $ex->getTraceAsString());
 			// first element is empty
 			array_shift($stack);
 			foreach ($stack as $s) {
-				\OCP\Util::writeLog($app, 'Exception: ' . $s, \OCP\Util::FATAL);
+				\OCP\Util::writeLog($app, 'Exception: ' . $s, $level);
 			}
 
 			// include cause
@@ -110,7 +111,7 @@ class Util {
 				if ($ex->getCode()) {
 					$message .= '[' . $ex->getCode() . '] ';
 				}
-				\OCP\Util::writeLog($app, 'Exception: ' . $message, \OCP\Util::FATAL);
+				\OCP\Util::writeLog($app, 'Exception: ' . $message, $level);
 			}
 		}
 	}