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pthread_sigmask(3) Library Functions Manual pthread_sigmask(3)
pthread_sigmask - examine and change mask of blocked signals
POSIX threads library (libpthread, -lpthread)
#include <signal.h> int pthread_sigmask(int how, const sigset_t *set, sigset_t *oldset); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): pthread_sigmask(): _POSIX_C_SOURCE >= 199506L || _XOPEN_SOURCE >= 500
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).
On success, pthread_sigmask() returns 0; on error, it returns an error number.
See sigprocmask(2).
For an explanation of the terms used in this section, see attributes(7). ┌─────────────────────────────────────┬───────────────┬─────────┐ │ Interface │ Attribute │ Value │ ├─────────────────────────────────────┼───────────────┼─────────┤ │ pthread_sigmask() │ Thread safety │ MT-Safe │ └─────────────────────────────────────┴───────────────┴─────────┘
POSIX.1-2008.
POSIX.1-2001.
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.
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 */ }
sigaction(2), sigpending(2), sigprocmask(2), pthread_attr_setsigmask_np(3), pthread_create(3), pthread_kill(3), sigsetops(3), pthreads(7), signal(7)
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Linux man-pages 6.9.1 2024-06-15 pthread_sigmask(3)
Pages that refer to this page: sigprocmask(2), pthread_attr_setsigmask_np(3), pthread_create(3), pthread_kill(3), pthread_sigqueue(3), sd_event_add_child(3), sd_event_add_signal(3), sigset(3), sigwait(3), nptl(7), pthreads(7), signal(7), signal-safety(7)