Merge pull request #603 from alltilla/metrics-labels-get-crash-fix-2

filterx/metrics_labels: fix crash when getting non-existent label

Author: MrAnno

lib/filterx/object-metrics-labels.c

@@ -85,10 +85,7 @@ _get_subscript(FilterXDict *s, FilterXObject *key)
   if (!filterx_object_extract_string_ref(key, &key_str, NULL))
     return NULL;
 
-  if (!self->labels->len)
-    return NULL;
-
-  for (guint i = self->labels->len - 1; i >= 0; i--)
+  for (gssize i = (gssize)(self->labels->len) - 1; i >= 0; i--)
     {
       StatsClusterLabel *label = &g_array_index(self->labels, StatsClusterLabel, i);
       if (strcmp(label->name, key_str) == 0)

tests/light/functional_tests/filterx/test_filterx_funcs.py

@@ -503,3 +503,23 @@ def test_unset_empties_replacement_list(config, syslog_ng):
 
     assert file_final.get_stats()["processed"] == 1
     assert file_final.read_log() == r"""["do","do","do","do",{"a":{"s":{"d":"do"}}},[["do"]]]"""
+
+
+def test_metrics_labels_get(config, syslog_ng):
+    (file_final,) = create_config(
+        config, r"""
+            $MSG = {};
+
+            labels = metrics_labels();
+            $MSG.empty_labels_does_not_exist = labels["empty-labels-does-not-exist"] ?? "fallback";
+
+            labels["foo"] = "bar";
+            $MSG.does_not_exist = labels["does-not-exist"] ?? "fallback";
+
+            $MSG.exists = labels["foo"] ?? "fallback";
+    """,
+    )
+    syslog_ng.start(config)
+
+    assert file_final.get_stats()["processed"] == 1
+    assert file_final.read_log() == r"""{"empty_labels_does_not_exist":"fallback","does_not_exist":"fallback","exists":"bar"}"""