Manpages - pthread_sigmask.3
Table of Contents
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.
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 specified 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 threading implementation. See *nptl*(7) for details.
EXAMPLES
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, &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_attr_setsigmask_np*(3), *pthread_create*(3), *pthread_kill*(3), *sigsetops*(3), *pthreads*(7), *signal*(7)
COLOPHON
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