table of contents
pthread_sigmask(3) | Library Functions Manual | pthread_sigmask(3) |
NAME¶
pthread_sigmask - examine and change mask of blocked signals
LIBRARY¶
POSIX threads library (libpthread, -lpthread)
SYNOPSIS¶
#include <signal.h>
int pthread_sigmask(int how, const sigset_t *set, sigset_t *oldset);
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 |
STANDARDS¶
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 <errno.h> #include <pthread.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <unistd.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(void) {
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)
2022-12-15 | Linux man-pages 6.03 |