PTHREAD_SIGMASK(3) Linux Programmer's Manual PTHREAD_SIGMASK(3)NAMEpthread_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.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
pthread_sigmask():
_POSIX_C_SOURCE >= 199506L || _XOPEN_SOURCE >= 500
DESCRIPTION
The pthread_sigmask() function is just like sigprocmask(2), with the
difference that its use in multithreaded programs is explicitly speci‐
fied by POSIX.1. 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).
┌──────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────┼───────────────┼─────────┤
│pthread_sigmask() │ Thread safety │ MT-Safe │
└──────────────────┴───────────────┴─────────┘
CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
NOTES
A new thread inherits a copy of its creator's signal mask.
The glibc pthread_sigmask() function silently ignores attempts to block
the two real-time signals that are used internally by the NPTL thread‐
ing implementation. See nptl(7) for details.
EXAMPLE
The program below blocks some signals in the main thread, and then cre‐
ates 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 ALSOsigaction(2), sigpending(2), sigprocmask(2), pthread_create(3),
pthread_kill(3), sigsetops(3), pthreads(7), signal(7)COLOPHON
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latest version of this page, can be found at
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Linux 2017-09-15 PTHREAD_SIGMASK(3)
