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| .TH PTHREAD_SIGMASK 3 2015-08-08 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| pthread_sigmask \- examine and change mask of blocked signals |
| .SH SYNOPSIS |
| .nf |
| .B #include <signal.h> |
| |
| .BI "int pthread_sigmask(int " how ", const sigset_t *" set \ |
| ", sigset_t *" oldset ); |
| .fi |
| .sp |
| Compile and link with \fI\-pthread\fP. |
| .sp |
| .in -4n |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .in |
| .sp |
| .ad l |
| .BR pthread_sigmask (): |
| .RS 4 |
| _POSIX_C_SOURCE\ >=\ 199506L || _XOPEN_SOURCE\ >=\ 500 |
| .RE |
| .ad b |
| .SH DESCRIPTION |
| The |
| .BR pthread_sigmask () |
| function is just like |
| .BR 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 |
| .BR sigprocmask (2). |
| .SH RETURN VALUE |
| On success, |
| .BR pthread_sigmask () |
| returns 0; |
| on error, it returns an error number. |
| .SH ERRORS |
| See |
| .BR sigprocmask (2). |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .TS |
| allbox; |
| lb lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR pthread_sigmask () |
| T} Thread safety MT-Safe |
| .TE |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008. |
| .SH NOTES |
| A new thread inherits a copy of its creator's signal mask. |
| |
| The glibc |
| .BR pthread_sigmask () |
| function silently ignores attempts to block the two real-time signals that |
| are used internally by the NPTL threading implementation. |
| See |
| .BR nptl (7) |
| for details. |
| .SH EXAMPLE |
| The program below blocks some signals in the main thread, |
| and then creates a dedicated thread to fetch those signals via |
| .BR sigwait (3). |
| The following shell session demonstrates its use: |
| |
| .in +4n |
| .nf |
| .RB "$" " ./a.out &" |
| [1] 5423 |
| .RB "$" " kill \-QUIT %1" |
| Signal handling thread got signal 3 |
| .RB "$" " kill \-USR1 %1" |
| Signal handling thread got signal 10 |
| .RB "$" " kill \-TERM %1" |
| [1]+ Terminated ./a.out |
| .fi |
| .in |
| .SS Program source |
| \& |
| .nf |
| #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 */ |
| } |
| .fi |
| .SH SEE ALSO |
| .BR sigaction (2), |
| .BR sigpending (2), |
| .BR sigprocmask (2), |
| .BR pthread_create (3), |
| .BR pthread_kill (3), |
| .BR sigsetops (3), |
| .BR pthreads (7), |
| .BR signal (7) |