www.LinuxHowtos.org
PTHREAD_SIGMASK
Section: Linux Programmer's Manual (3)Updated: 2017-09-15
Index Return to Main Contents
NAME
pthread_sigmask - examine and change mask of blocked signalsSYNOPSIS
#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.
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 4.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.