sigsuspend

sigsuspend用于在接收到某个信号之前,临时用mask替换进程的信号掩码,并暂停进程执行,直到收到信号为止。

#include <signal.h>

int sigsuspend(const sigset_t *mask);

The sigsuspend() function replaces the current signal mask of the calling thread with the set of signals pointed to by sigmask and then suspends the thread until delivery of a signal whose action is either to execute a signal-catching function or to terminate the process. This will not cause any other signals that may have been pending on the process to become pending on the thread.

If the action is to terminate the process then sigsuspend() will never return. If the action is to execute a signal-catching function, thensigsuspend() will return after the signal-catching function returns, with the signal mask restored to the set that existed prior to thesigsuspend() call.

It is not possible to block signals that cannot be ignored. This is enforced by the system without causing an error to be indicated.

也就是说,进程执行到sigsuspend时,sigsuspend并不会立刻返回,进程处于TASK_INTERRUPTIBLE状态并立刻放弃CPU,等待UNBLOCK(mask之外的)信号的唤醒。进程在接收到UNBLOCK(mask之外)信号后,调用处理函数,然后还原信号集,sigsuspend返回,进程恢复执行。

sigsuspend返回后将恢复调用之前的的信号掩码。信号处理函数完成后,进程将继续执行。该系统调用始终返回-1,并将errno设置为EINTR.

Since sigsuspend() suspends process execution indefinitely, there is no successful completion return value. If a return occurs, -1 is returned and errno is set to indicate the error.

The sigsuspend() function will fail if:

[EINTR]

A signal is caught by the calling process and control is returned from the signal-catching function.

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