c ++如何使用select查看套接字是否已关闭 [英] c++ how to use select to see if a socket has closed

问题描述

谁能给我提供一个如何使用 select() 来查看客户端是否关闭了套接字连接的示例?

Can someone provide me an example of how to use select() to see if a client has closed the connection on a socket?

仅供参考.我用的是 linux.

FYI. I'm using linux.

谢谢！

推荐答案

下面的代码片段首先检查套接字是否被标记为可读(关闭时是这样)，然后检查是否真的有任何东西可以读取.

The below snippet first checks if the socket is marked readable (which it is when closed) and then if there's actually anything to be read.

#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/ioctl.h>

bool isclosed(int sock) {
  fd_set rfd;
  FD_ZERO(&rfd);
  FD_SET(sock, &rfd);
  timeval tv = { 0 };
  select(sock+1, &rfd, 0, 0, &tv);
  if (!FD_ISSET(sock, &rfd))
    return false;
  int n = 0;
  ioctl(sock, FIONREAD, &n);
  return n == 0;
}

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