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This article will explain in detail what is the use of the sigsuspend function for you. The editor thinks it is very practical, so I share it with you for reference. I hope you can get something after reading this article.

The function of the sigsuspend function: if you want to sleep while waiting for the signal to occur, it is appropriate to use the sigsuspend function.

Example of sigsuspend function

Header file: # include

An error example of protecting the critical section code: (sigprocmask () and pause () implementation)

# include

# include

# include

Implementation of voidhandler (intsig) / / signal processing function

{

Printf ("SIGINTsig")

}

Intmain ()

{

Sigset_tnew,old

Structsigactionact

Act.sa_handler=handler;// signal processing function handler

Sigemptyset & act.sa_mask)

Act.sa_flags=0

Sigaction (SIGINT,&act,0); / / prepare to capture SIGINT signal

Sigemptyset & new)

Sigaddset & new,SIGINT)

Sigprocmask (SIG_BLOCK,&new,&old); / / blocks the SIGINT signal while saving the current signal set

Printf ("Blocked")

Sigprocmask (SIG_SETMASK,&old,NULL); / / unblocking

Pause ()

Return0

}

The problem with the above example is: it was expected that after pause (), the SIGINT signal could end the program; however, if there is a SIGINT signal between "unblocking" and "pause", the program will hang all the time because of pause.

Solving the problem of sigsuspend function

If a signal is sent to the process when it is blocked, the transmission of the signal is delayed until it is unblocked. To the application, the signal seems to occur between unblocking the SIGINT and the pause. If this happens, or if the signal does occur between the unblocking time and the pause, then a problem arises. Because we may never see the signal again, in this sense, the signal that occurs in this time window (between unblocking and pause) is lost, thus blocking the pause forever.

To correct this problem, you need to restore the signal mask word in an atomic operation and then hibernate the process. This functionality is provided by the sigsuspend function.

# include

Intsigsuspend (constsigset_t*sigmask)

Return value:-1 and set errno to EINTR

Set the signal mask of the process to the value pointed to by sigmask. The process is suspended before a signal is caught or a signal that terminates the process occurs. If a signal is caught and returned from the signal handler, the sigsuspend returns and the signal mask for the process is set to the value before calling sigsuspend.

Note that this function did not successfully return a value. If it returns to the caller, it always returns-1 and sets errno to EINTR (representing an interrupted system call).

This is the end of this article on "what is the use of sigsuspend function". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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