Linux repositories inspector
Linux
2019-03-06
Aliases: pthread_kill(3), sigwait(3)

manpages-dev

Manual pages about using GNU/Linux for development

man-pages

Linux kernel and C library user-space interface documentation

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

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
Interface Attribute Value
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 */ }

COLOPHON

This page is part of release 5.00 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/.
⇧ Top