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
signals 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 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()
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 calling 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.
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
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