static int signal_name_owner_changed(sd_bus_message *message, void *userdata, sd_bus_error *error) {
        const char *name, *old_owner, *new_owner;
        Unit *u = userdata;
        int r;

        assert(message);
        assert(u);

        r = sd_bus_message_read(message, "sss", &name, &old_owner, &new_owner);
        if (r < 0) {
                bus_log_parse_error(r);
                return 0;
        }

        old_owner = empty_to_null(old_owner);
        new_owner = empty_to_null(new_owner);

        if (UNIT_VTABLE(u)->bus_name_owner_change)
                UNIT_VTABLE(u)->bus_name_owner_change(u, name, old_owner, new_owner);

        return 0;
}
Unknown