mirror of https://github.com/mkerrisk/man-pages
176 lines
4.4 KiB
Groff
176 lines
4.4 KiB
Groff
.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH PTHREAD_SIGMASK 3 2015-08-08 "Linux" "Linux Programmer's Manual"
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.SH NAME
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pthread_sigmask \- examine and change mask of blocked signals
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.SH SYNOPSIS
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.nf
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.B #include <signal.h>
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.PP
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.BI "int pthread_sigmask(int " how ", const sigset_t *" set \
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", sigset_t *" oldset );
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.fi
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.PP
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Compile and link with \fI\-pthread\fP.
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.PP
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.PP
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.ad l
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.BR pthread_sigmask ():
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.RS 4
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_POSIX_C_SOURCE\ >=\ 199506L || _XOPEN_SOURCE\ >=\ 500
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.RE
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.ad b
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.SH DESCRIPTION
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The
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.BR pthread_sigmask ()
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function is just like
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.BR sigprocmask (2),
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with the difference that its use in multithreaded programs
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is explicitly specified by POSIX.1.
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Other differences are noted in this page.
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.PP
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For a description of the arguments and operation of this function, see
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.BR sigprocmask (2).
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.SH RETURN VALUE
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On success,
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.BR pthread_sigmask ()
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returns 0;
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on error, it returns an error number.
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.SH ERRORS
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See
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.BR sigprocmask (2).
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lb lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR pthread_sigmask ()
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T} Thread safety MT-Safe
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.TE
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.SH CONFORMING TO
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POSIX.1-2001, POSIX.1-2008.
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.SH NOTES
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A new thread inherits a copy of its creator's signal mask.
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.PP
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The glibc
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.BR pthread_sigmask ()
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function silently ignores attempts to block the two real-time signals that
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are used internally by the NPTL threading implementation.
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See
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.BR nptl (7)
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for details.
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.SH EXAMPLE
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The program below blocks some signals in the main thread,
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and then creates a dedicated thread to fetch those signals via
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.BR sigwait (3).
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The following shell session demonstrates its use:
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.PP
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.in +4n
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.EX
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.RB "$" " ./a.out &"
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[1] 5423
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.RB "$" " kill \-QUIT %1"
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Signal handling thread got signal 3
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.RB "$" " kill \-USR1 %1"
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Signal handling thread got signal 10
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.RB "$" " kill \-TERM %1"
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[1]+ Terminated ./a.out
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.EE
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.in
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.SS Program source
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\&
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.EX
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <signal.h>
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#include <errno.h>
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/* Simple error handling functions */
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#define handle_error_en(en, msg) \\
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do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
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static void *
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sig_thread(void *arg)
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{
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sigset_t *set = arg;
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int s, sig;
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for (;;) {
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s = sigwait(set, &sig);
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if (s != 0)
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handle_error_en(s, "sigwait");
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printf("Signal handling thread got signal %d\\n", sig);
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}
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}
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int
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main(int argc, char *argv[])
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{
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pthread_t thread;
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sigset_t set;
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int s;
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/* Block SIGQUIT and SIGUSR1; other threads created by main()
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will inherit a copy of the signal mask. */
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sigemptyset(&set);
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sigaddset(&set, SIGQUIT);
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sigaddset(&set, SIGUSR1);
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s = pthread_sigmask(SIG_BLOCK, &set, NULL);
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if (s != 0)
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handle_error_en(s, "pthread_sigmask");
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s = pthread_create(&thread, NULL, &sig_thread, (void *) &set);
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if (s != 0)
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handle_error_en(s, "pthread_create");
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/* Main thread carries on to create other threads and/or do
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other work */
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pause(); /* Dummy pause so we can test program */
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}
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.EE
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.SH SEE ALSO
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.BR sigaction (2),
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.BR sigpending (2),
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.BR sigprocmask (2),
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.BR pthread_create (3),
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.BR pthread_kill (3),
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.BR sigsetops (3),
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.BR pthreads (7),
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.BR signal (7)
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