remove asprintf warnings

modules/cachectl/cachectl.c

@@ -192,9 +192,11 @@ static char* prune(void *env, struct kr_module *module, const char *args)
 	char *result = NULL;
 	ret = kr_cache_txn_commit(&txn);
 	if (ret != 0) {
-		asprintf(&result, "{ \"pruned\": %d, \"error\": \"%s\" }", pruned, knot_strerror(ret));
+		if (-1 == asprintf(&result, "{ \"pruned\": %d, \"error\": \"%s\" }", pruned, knot_strerror(ret)))
+			result = NULL;
 	} else {
-		asprintf(&result, "{ \"pruned\": %d }", pruned);
+		if (-1 == asprintf(&result, "{ \"pruned\": %d }", pruned))
+			result = NULL;
 	}
 
 	return result;

modules/hints/hints.c

@@ -329,7 +329,8 @@ static char* hint_set(void *env, struct kr_module *module, const char *args)
 	}
 
 	char *result = NULL;
-	asprintf(&result, "{ \"result\": %s", ret == 0 ? "true" : "false");
+	if (-1 == asprintf(&result, "{ \"result\": %s }", ret == 0 ? "true" : "false"))
+		result = NULL;
 	return result;
 }