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sigsuspend.2 (2010 09)

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sigsuspend(2) sigsuspend(2)
NAME
sigsuspend - wait for a signal
SYNOPSIS
#include <signal.h>
int sigsuspend(const sigset_t *sigmask);
DESCRIPTION
The sigsuspend() function replaces the current signal mask of the calling thread with the set of sig-
nals pointed to by sigmask and then suspends the thread until delivery of a signal whose action is
either to execute a signal-catching function or to terminate the process. This will not cause any other sig-
nals that may have been pending on the process to become pending on the thread.
If the action is to terminate the process then
sigsuspend() will never return. If the action is to execute
a signal-catching function, then
sigsuspend() will 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 is returned and errno is set to indicate the error.
ERRORS
The
sigsuspend() function will fail if:
[EINTR] A signal is caught by the calling process and control is returned from the signal-
catching function.
[EFAULT] sigmask points to an invalid address. The reliable detection of this error is
implementation-dependent.
APPLICATION USAGE
Threads Considerations
Since blocked signal masks are maintained at the thread level,
sigsuspend() modifies only the cal-
ling thread’s blocked signal mask. sigsuspend() suspends only the calling thread until it receives a
signal.
If other threads in the process do not block the signal, the signal may be delivered to another thread in
the process and the thread in
sigsuspend() may continue waiting. For this reason, the use of
sigwait (2) is recommended instead of sigsuspend() for multi-threaded applications.
For more information regarding signals and threads, refer to signal (5).
LWP (Lightweight Processes) Considerations
sigsuspend() modifies only the calling LWP’s signal mask and suspends only the calling LWP until
receipt of a signal.
AUTHOR
sigsuspend() was derived from the IEEE POSIX 1003.1-1988 Standard.
SEE ALSO
pause(2), sigaction(2), sigpending(2), sigprocmask(2), sigsetops(3C), sigwait(2), signal(5).
CHANGE HISTORY
First released in Issue 3.
Entry included for alignment with the POSIX.1-1988 standard.
STANDARDS CONFORMANCE
sigsuspend(): AES, SVID3, XPG3, XPG4, FIPS 151-2, POSIX.1
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

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