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); |
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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).
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
pthread_sigmask() |
Thread safety | MT-Safe |
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 4.07 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/.
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