如何prevent SIGPIPEs（或妥善处理） [英] How to prevent SIGPIPEs (or handle them properly)

问题描述

我必须能够接受对TCP或本地UNIX套接字连接一个小型服务器程序，读取一个简单的命令，并根据命令，发送一个答复。问题是，客户端可能在答案没有兴趣有时候，早退出，所以写到插座会导致一个SIGPIPE，让我的服务器崩溃。什么是prevent这里崩溃的最佳做法？有没有一种方法来检查，如果该行的另一边是还在读书？ （选择（）似乎并不在这里工作，因为它总是说，插座是可写的）。或者我应该只是赶上了处理程序SIGPIPE和忽略它？

I have a small server program that accepts connections on a TCP or local UNIX socket, reads a simple command and, depending on the command, sends a reply. The problem is that the client may have no interest in the answer sometimes and exits early, so writing to that socket will cause a SIGPIPE and make my server crash. What's the best practice to prevent the crash here? Is there a way to check if the other side of the line is still reading? (select() doesn't seem to work here as it always says the socket is writable). Or should I just catch the SIGPIPE with a handler and ignore it?

推荐答案

您一般要忽略 SIGPIPE 并在code直接处理错误。这是因为在C信号处理对他们能做什么的限制。

You generally want to ignore the SIGPIPE and handle the error directly in your code. This is because signal handlers in C have many restrictions on what they can do.

最轻便的方式来做到这一点是设置 SIGPIPE 处理程序 SIG_IGN 。这将prevent从引起 SIGPIPE 信号的任何插座或管道写。

The most portable way to do this is to set the SIGPIPE handler to SIG_IGN. This will prevent any socket or pipe write from causing a SIGPIPE signal.

要忽略 SIGPIPE 信号，请使用以下code：

To ignore the SIGPIPE signal, use the following code:

signal(SIGPIPE, SIG_IGN);

如果您使用的发送（）通话，另一种选择是使用 MSG_NOSIGNAL 选项，将打开 SIGPIPE 关闭行为在每次呼叫的基础。请注意，并非所有的操作系​​统都支持 MSG_NOSIGNAL 标记。

If you're using the send() call, another option is to use the MSG_NOSIGNAL option, which will turn the SIGPIPE behavior off on a per call basis. Note that not all operating systems support the MSG_NOSIGNAL flag.

最后，您可能还需要考虑 SO_SIGNOPIPE 插座标志，可以用设置的setsockopt（）上某些操作系统。这将prevent SIGPIPE 由被写入造成的只是它被设置在插座上。

Lastly, you may also want to consider the SO_SIGNOPIPE socket flag that can be set with setsockopt() on some operating systems. This will prevent SIGPIPE from being caused by writes just to the sockets it is set on.

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