+int sd_bus_message_new_method_errorf(
+ sd_bus *bus,
+ sd_bus_message *call,
+ sd_bus_message **m,
+ const char *name,
+ const char *format,
+ ...) {
+
+ _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+ sd_bus_message *t;
+ va_list ap;
+ int r;
+
+ if (!name)
+ return -EINVAL;
+ if (!m)
+ return -EINVAL;
+
+ r = message_new_reply(bus, call, SD_BUS_MESSAGE_TYPE_METHOD_ERROR, &t);
+ if (r < 0)
+ return r;
+
+ r = message_append_field_string(t, SD_BUS_MESSAGE_HEADER_ERROR_NAME, SD_BUS_TYPE_STRING, name, &t->error.name);
+ if (r < 0)
+ goto fail;
+
+ if (format) {
+ _cleanup_free_ char *message = NULL;
+
+ va_start(ap, format);
+ r = vasprintf(&message, format, ap);
+ va_end(ap);
+
+ if (r < 0) {
+ r = -ENOMEM;
+ goto fail;
+ }
+
+ r = message_append_basic(t, SD_BUS_TYPE_STRING, message, (const void**) &t->error.message);
+ if (r < 0)
+ goto fail;
+ }
+
+ *m = t;
+ return 0;
+
+fail:
+ message_free(t);
+ return r;
+}
+