stats: openmetrics - Include submetric name only when present

Otherwise we SIGSEGV.

diff --git a/src/stats/stats-service-openmetrics.c b/src/stats/stats-service-openmetrics.c
index a380b0bc73d328aa631bfd216830a7e282ba0148..6b312eb4ae321ca823fd806bb490f42662e867e9 100644 (file)
--- a/src/stats/stats-service-openmetrics.c
+++ b/src/stats/stats-service-openmetrics.c
@@ -290,9 +290,13 @@ static void
 openmetrics_export_submetric(struct openmetrics_request *req, string_t *out,
                             const struct metric *metric, int64_t timestamp)
 {
-       str_append_c(req->labels, '"');
-       json_append_escaped(req->labels, metric->sub_name);
-       str_append_c(req->labels, '"');
+       /* This metric may be a submetric and therefore have a label
+          associated with it. */
+       if (metric->sub_name != NULL) {
+               str_append_c(req->labels, '"');
+               json_append_escaped(req->labels, metric->sub_name);
+               str_append_c(req->labels, '"');
+       }
 
        if (req->metric_type == OPENMETRICS_METRIC_TYPE_HISTOGRAM) {
                if (metric->group_by == NULL ||