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.
NAMEsigsuspend — 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 sig‐
suspend() 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(), sigaction(), sigaddset(),
sigdelset(), sigemptyset(), sigfillset()
The Base Definitions volume of POSIX.1‐2008, <signal.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 SIGSUSPEND(3P)
