如何处理 Linux 套接字 revents POLLERR、POLLHUP 和 POLLNVAL? [英] How to handle the Linux socket revents POLLERR, POLLHUP and POLLNVAL?

问题描述

我想知道当 poll 设置这些位时应该做什么?关闭套接字，忽略它还是什么?

I'm wondering what should be done when poll set these bits? Close socket, ignore it or what?

推荐答案

A POLLHUP 表示套接字不再连接.在 TCP 中，这意味着 FIN 已被接收和发送.

A POLLHUP means the socket is no longer connected. In TCP, this means FIN has been received and sent.

A POLLERR 表示套接字出现异步错误.在 TCP 中，这通常意味着 RST 已被接收或发送.如果文件描述符不是套接字，POLLERR 可能意味着设备不支持轮询.

A POLLERR means the socket got an asynchronous error. In TCP, this typically means a RST has been received or sent. If the file descriptor is not a socket, POLLERR might mean the device does not support polling.

对于上述两种情况，socket 文件描述符仍然是打开的，并且还没有被关闭(但是 shutdown() 可能已经被调用了).文件描述符上的 close() 将释放仍代表套接字保留的资源.理论上，应该可以立即重用套接字(例如，通过另一个 connect() 调用).

For both of the conditions above, the socket file descriptor is still open, and has not yet been closed (but shutdown() may have already been called). A close() on the file descriptor will release resources that are still being reserved on behalf of the socket. In theory, it should be possible to reuse the socket immediately (e.g., with another connect() call).

A POLLNVAL 表示套接字文件描述符未打开.close() 会出错.

A POLLNVAL means the socket file descriptor is not open. It would be an error to close() it.

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