Set a maximum level of encoding nested arguments of exception traces

This will make sure that nested objects or arrays do not cause exceeding
the maximum nesting level of functions when parsing arguments of an
exception trace

Signed-off-by: Julius Härtl <jus@bitgrid.net>

lib/private/Log/ExceptionSerializer.php

@@ -228,14 +228,27 @@ class ExceptionSerializer {
 		}, $filteredTrace);
 	}
 
-	private function encodeArg($arg) {
+	private function encodeArg($arg, $nestingLevel = 5) {
 		if (is_object($arg)) {
+			if ($nestingLevel === 0) {
+				return [
+					'__class__' => get_class($arg),
+					'__properties__' => 'Encoding skipped as the maximum nesting level was reached',
+				];
+			}
+
 			$data = get_object_vars($arg);
 			$data['__class__'] = get_class($arg);
-			return array_map([$this, 'encodeArg'], $data);
+			return array_map(function ($arg) use ($nestingLevel) {
+				return $this->encodeArg($arg, $nestingLevel - 1);
+			}, $data);
 		}
 
 		if (is_array($arg)) {
+			if ($nestingLevel === 0) {
+				return ['Encoding skipped as the maximum nesting level was reached'];
+			}
+
 			// Only log the first 5 elements of an array unless we are on debug
 			if ((int)$this->systemConfig->getValue('loglevel', 2) !== 0) {
 				$elemCount = count($arg);
@@ -244,7 +257,9 @@ class ExceptionSerializer {
 					$arg[] = 'And ' . ($elemCount - 5) . ' more entries, set log level to debug to see all entries';
 				}
 			}
-			return array_map([$this, 'encodeArg'], $arg);
+			return array_map(function ($e) use ($nestingLevel) {
+				return $this->encodeArg($e, $nestingLevel - 1);
+			}, $arg);
 		}
 
 		return $arg;