5 at_recvfrom函数中的while循环的跳出条件可能有些问题

发布于 2022-04-14 17:47:33 浏览：1189 订阅该版

情景：客户端这边通过at_socket建立连接后（该socket为阻塞式），然后调用at_recvfrom等待接受数据，程序在```rt_sem_take(sock->recv_notice, timeout)```进行调度，此时服务器这边直接断开连接，这时候会调用```at_closed_notice_cb()```，后续进行调度回到at_recvfrom中时，由于没有接受到数据，不满足跳出循环的逻辑，便会一直卡死在这。
```
at_recvfrom()部分代码

while (1)
    {
        /* wait the receive semaphore */
        if (rt_sem_take(sock->recv_notice, timeout) < 0)
        {
            LOG_E("AT socket (%d) receive timeout (%d)!", socket, timeout);
            errno = EAGAIN;
            result = -1;
            goto __exit;
        }
        else
        {
            /* get receive buffer to receiver ring buffer */
            rt_mutex_take(sock->recv_lock, RT_WAITING_FOREVER);
            recv_len = at_recvpkt_get(&(sock->recvpkt_list), (char *) mem, len);
            rt_mutex_release(sock->recv_lock);
            if (recv_len > 0) /* 是否在此处添加对于socket状态的判断？（sock->state == AT_SOCKET_CLOSED） */
            {
                break;
            }

}
    }
```

```
static void at_closed_notice_cb(struct at_socket *sock, at_socket_evt_t event, const char *buff, size_t bfsz)
{
    RT_ASSERT(event == AT_SOCKET_EVT_CLOSED);

/* check the socket object status */
    if (sock->magic != AT_SOCKET_MAGIC)
    {
        return;
    }

at_do_event_changes(sock, AT_EVENT_RECV, RT_TRUE);
    at_do_event_changes(sock, AT_EVENT_ERROR, RT_TRUE);

sock->state = AT_SOCKET_CLOSED;
    rt_sem_release(sock->recv_notice);
}
```