zone: don't log serial 0 if no zone available

src/knot/zone/events/handlers.c

@@ -356,6 +356,7 @@ int event_load(conf_t *conf, zone_t *zone)
 	zone->zonefile_mtime = mtime;
 	zone_contents_t *old = zone_switch_contents(zone, contents);
 	zone->flags &= ~ZONE_EXPIRED;
+	bool old_contents = (old != NULL);
 	uint32_t old_serial = zone_contents_serial(old);
 	if (old != NULL) {
 		synchronize_rcu();
@@ -385,8 +386,12 @@ int event_load(conf_t *conf, zone_t *zone)
 	}
 
 	uint32_t current_serial = zone_contents_serial(zone->contents);
-	log_zone_info(zone->name, "loaded, serial %u -> %u",
-	              old_serial, current_serial);
+	if (old_contents) {
+		log_zone_info(zone->name, "loaded, serial %u -> %u",
+		              old_serial, current_serial);
+	} else {
+		log_zone_info(zone->name, "loaded, serial %u", current_serial);
+	}
 
 	return KNOT_EOK;
 
@@ -718,4 +723,3 @@ uint32_t bootstrap_next(uint32_t timer)
 	}
 	return timer;
 }
-

src/knot/zone/zonedb-load.c

@@ -79,8 +79,8 @@ static zone_status_t zone_file_status(conf_t *conf, const zone_t *old_zone,
 /*!
  * \brief Log message about loaded zone (name and status).
  *
- * \param zone       Zone structure.
- * \param status     Zone file status.
+ * \param zone    Zone structure.
+ * \param status  Zone file status.
  */
 static void log_zone_load_info(const zone_t *zone, zone_status_t status)
 {
@@ -97,14 +97,14 @@ static void log_zone_load_info(const zone_t *zone, zone_status_t status)
 	}
 	assert(action);
 
-	uint32_t serial = 0;
 	if (zone->contents && zone->contents->apex) {
 		const knot_rdataset_t *soa = node_rdataset(zone->contents->apex,
 		                                           KNOT_RRTYPE_SOA);
-		serial = knot_soa_serial(soa);
+		uint32_t serial = knot_soa_serial(soa);
+		log_zone_info(zone->name, "zone %s, serial %u", action, serial);
+	} else {
+		log_zone_info(zone->name, "zone %s", action);
 	}
-
-	log_zone_info(zone->name, "zone %s, serial %u", action, serial);
 }
 
 static zone_t *create_zone_from(const knot_dname_t *name, server_t *server)