在现代POSIX系统(即Linux)下，可以使用sigprocmask()函数。

#include <signal.h>

void block_signal(int signal_to_block /* i.e. SIGPIPE */ )
{
    sigset_t set;
    sigset_t old_state;

    // get the current state
    //
    sigprocmask(SIG_BLOCK, NULL, &old_state);

    // add signal_to_block to that existing state
    //
    set = old_state;
    sigaddset(&set, signal_to_block);

    // block that signal also
    //
    sigprocmask(SIG_BLOCK, &set, NULL);

    // ... deal with old_state if required ...
}

如果您想稍后恢复以前的状态，请确保将old_state保存在安全的地方。如果你多次调用这个函数，你需要使用一个堆栈，或者只保存第一个或最后一个old_state…或者有一个函数可以移除特定的阻塞信号。

更多信息请阅读手册页。

或者我应该用处理程序捕获SIGPIPE并忽略它?

我相信这是对的。您想知道另一端什么时候关闭了它们的描述符，这就是SIGPIPE告诉您的。

Sam

您通常希望忽略SIGPIPE并直接在代码中处理错误。这是因为C语言中的信号处理程序对它们能做的事情有很多限制。

最可移植的方法是将SIGPIPE处理程序设置为SIG_IGN。这将防止任何套接字或管道写入导致SIGPIPE信号。

要忽略SIGPIPE信号，请使用以下代码:

signal(SIGPIPE, SIG_IGN);

如果使用send()调用，另一个选项是使用MSG_NOSIGNAL选项，该选项将在每个调用的基础上关闭SIGPIPE行为。注意，并非所有操作系统都支持MSG_NOSIGNAL标志。

最后，您可能还想考虑SO_SIGNOPIPE套接字标志，该标志可以在某些操作系统上使用setsockopt()设置。这将防止SIGPIPE仅仅因为写入它所设置的套接字而引起。

在这篇文章中，我描述了SO_NOSIGPIPE和MSG_NOSIGNAL都不可用的Solaris情况下可能的解决方案。

Instead, we have to temporarily suppress SIGPIPE in the current thread that executes library code. Here's how to do this: to suppress SIGPIPE we first check if it is pending. If it does, this means that it is blocked in this thread, and we have to do nothing. If the library generates additional SIGPIPE, it will be merged with the pending one, and that's a no-op. If SIGPIPE is not pending then we block it in this thread, and also check whether it was already blocked. Then we are free to execute our writes. When we are to restore SIGPIPE to its original state, we do the following: if SIGPIPE was pending originally, we do nothing. Otherwise we check if it is pending now. If it does (which means that out actions have generated one or more SIGPIPEs), then we wait for it in this thread, thus clearing its pending status (to do this we use sigtimedwait() with zero timeout; this is to avoid blocking in a scenario where malicious user sent SIGPIPE manually to a whole process: in this case we will see it pending, but other thread may handle it before we had a change to wait for it). After clearing pending status we unblock SIGPIPE in this thread, but only if it wasn't blocked originally.

示例代码位于https://github.com/kroki/XProbes/blob/1447f3d93b6dbf273919af15e59f35cca58fcc23/src/libxprobes.c#L156

You cannot prevent the process on the far end of a pipe from exiting, and if it exits before you've finished writing, you will get a SIGPIPE signal. If you SIG_IGN the signal, then your write will return with an error - and you need to note and react to that error. Just catching and ignoring the signal in a handler is not a good idea -- you must note that the pipe is now defunct and modify the program's behaviour so it does not write to the pipe again (because the signal will be generated again, and ignored again, and you'll try again, and the whole process could go on for a long time and waste a lot of CPU power).

Linux手册说:

EPIPE面向连接的本端已经关闭 套接字。在这种情况下，进程还将接收一个SIGPIPE 除非设置了MSG_NOSIGNAL。

但是对于Ubuntu 12.04来说，这是不对的。我为这种情况编写了一个测试，我总是收到没有SIGPIPE的EPIPE。如果我试图第二次写入同一个损坏的套接字，就会生成SIGPIPE。所以你不需要忽略SIGPIPE，如果这个信号发生了，这意味着你的程序中有逻辑错误。