添加socket的监听到fltk的循环

void sock_cb(int fd, void *user_data)
{
    int size;
    char buf[MAX_BUF_SIZE];
        struct lgsm_handle *handle=(struct lgsm_handle*)user_data;

    size = read(fd, buf, MAX_BUF_SIZE);
    if (size > 0) {
        handle_packet_greedy(handle, buf, size, NULL);
        return;
    } else if (size == 0) { /* EOF */
        return;
    } else {
        g_warning("cs_dispatch:%s %s",
                  "read error from libgsmd:",
                  g_strerror(errno));
        return;
    }
}
fltk::add_fd(fd, READ, sock_cb, handle);//一有数据发到该socket,就会执行sock_cb