PTHREAD_SIGMASK

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
NOTES
EXAMPLE
SEE ALSO
COLOPHON

NAME

pthread_sigmask − examine and change mask of blocked signals

SYNOPSIS

#include <signal.h>

int pthread_sigmask(int how, const sigset_t *set, sigset_t *oldset);

Compile and link with −pthread.

DESCRIPTION

The pthread_sigmask() function is just like sigprocmask(2), with the difference that its use in multithreaded programs is explicitly specified by POSIX.1-2001. Other differences are noted in this page.

For a description of the arguments and operation of this function, see sigprocmask(2).

RETURN VALUE

On success, pthread_sigmask() returns 0; on error, it returns an error number.

ERRORS

See sigprocmask(2).

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Image grohtml-75301.png

CONFORMING TO

POSIX.1-2001.

NOTES

A new thread inherits a copy of its creator’s signal mask.

EXAMPLE

The program below blocks some signals in the main thread, and then creates a dedicated thread to fetch those signals via sigwait(3). The following shell session demonstrates its use:

$ ./a.out &
[1] 5423
$ kill −QUIT %1
Signal handling thread got signal 3
$ kill −USR1 %1
Signal handling thread got signal 10
$ kill −TERM %1
[1]+ Terminated ./a.out

Program source
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>

/* Simple error handling functions */

#define handle_error_en(en, msg) \
do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)

static void *
sig_thread(void *arg)
{
sigset_t *set = arg;
int s, sig;

for (;;) {
s = sigwait(set, &sig);
if (s != 0)
handle_error_en(s, "sigwait");
printf("Signal handling thread got signal %d\n", sig);
}
}

int
main(int argc, char *argv[])
{
pthread_t thread;
sigset_t set;
int s;

/* Block SIGQUIT and SIGUSR1; other threads created by main()
will inherit a copy of the signal mask. */

sigemptyset(&set);
sigaddset(&set, SIGQUIT);
sigaddset(&set, SIGUSR1);
s = pthread_sigmask(SIG_BLOCK, &set, NULL);
if (s != 0)
handle_error_en(s, "pthread_sigmask");

s = pthread_create(&thread, NULL, &sig_thread, (void *) &set);
if (s != 0)
handle_error_en(s, "pthread_create");

/* Main thread carries on to create other threads and/or do
other work */

pause(); /* Dummy pause so we can test program */
}

SEE ALSO

sigaction(2), sigpending(2), sigprocmask(2), pthread_create(3), pthread_kill(3), sigsetops(3), pthreads(7), signal(7)

COLOPHON

This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.