sigsuspend(3p) — Linux manual page

SIGSUSPEND(3P)          POSIX Programmer's Manual         SIGSUSPEND(3P)

PROLOG

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME

       sigsuspend — wait for a signal

SYNOPSIS

       #include <signal.h>

       int sigsuspend(const sigset_t *sigmask);

DESCRIPTION

       The sigsuspend() function shall replace the current signal mask
       of the calling thread with the set of signals pointed to by
       sigmask and then suspend the thread until delivery of a signal
       whose action is either to execute a signal-catching function or
       to terminate the process. This shall not cause any other signals
       that may have been pending on the process to become pending on
       the thread.

       If the action is to terminate the process then sigsuspend() shall
       never return. If the action is to execute a signal-catching
       function, then sigsuspend() shall return after the signal-
       catching function returns, with the signal mask restored to the
       set that existed prior to the sigsuspend() call.

       It is not possible to block signals that cannot be ignored. This
       is enforced by the system without causing an error to be
       indicated.

RETURN VALUE

       Since sigsuspend() suspends thread execution indefinitely, there
       is no successful completion return value. If a return occurs, -1
       shall be returned and errno set to indicate the error.

ERRORS

       The sigsuspend() function shall fail if:

       EINTR  A signal is caught by the calling process and control is
              returned from the signal-catching function.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Normally, at the beginning of a critical code section, a
       specified set of signals is blocked using the sigprocmask()
       function. When the thread has completed the critical section and
       needs to wait for the previously blocked signal(s), it pauses by
       calling sigsuspend() with the mask that was returned by the
       sigprocmask() call.

RATIONALE

       Code which wants to avoid the ambiguity of the signal mask for
       thread cancellation handlers can install an additional
       cancellation handler which resets the signal mask to the expected
       value.

           void cleanup(void *arg)
           {
               sigset_t *ss = (sigset_t *) arg;
               pthread_sigmask(SIG_SETMASK, ss, NULL);
           }

           int call_sigsuspend(const sigset_t *mask)
           {
               sigset_t oldmask;
               int result;
               pthread_sigmask(SIG_SETMASK, NULL, &oldmask);
               pthread_cleanup_push(cleanup, &oldmask);
               result = sigsuspend(sigmask);
               pthread_cleanup_pop(0);
               return result;
           }

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section 2.4, Signal Concepts, pause(3p), sigaction(3p),
       sigaddset(3p), sigdelset(3p), sigemptyset(3p), sigfillset(3p)

       The Base Definitions volume of POSIX.1‐2017, signal.h(0p)

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                    SIGSUSPEND(3P)

Pages that refer to this page: signal.h(0p), pause(3p), pthread_sigmask(3p), sigaction(3p), sigaddset(3p), sigdelset(3p), sigemptyset(3p), sigfillset(3p), sighold(3p), sigismember(3p), siglongjmp(3p), signal(3p), sigsetjmp(3p), sigtimedwait(3p), sigwait(3p)

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