SIGWAIT(2) BSD System Calls Manual SIGWAIT(2)NAMEsigwait — select a set of signals
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <signal.h>
int
sigwait(const sigset_t * restrict set, int * restrict sig);
DESCRIPTION
The sigwait() system call selects a set of signals, specified by set. If
none of the selected signals are pending, sigwait() waits until one or
more of the selected signals has been generated. Then sigwait() atomi‐
cally clears one of the selected signals from the set of pending signals
for the process and sets the location pointed to by sig to the signal
number that was cleared.
The signals specified by set should be blocked at the time of the call to
sigwait().
If more than one thread is using sigwait() to wait for the same signal,
no more than one of these threads will return from sigwait() with the
signal number. If more than a single thread is blocked in sigwait() for
a signal when that signal is generated for the process, it is unspecified
which of the waiting threads returns from sigwait(). If the signal is
generated for a specific thread, as by pthread_kill(), only that thread
will return.
Should any of the multiple pending signals in the range SIGRTMIN to
SIGRTMAX be selected, it will be the lowest numbered one. The selection
order between realtime and non-realtime signals, or between multiple
pending non-realtime signals, is unspecified.
RETURN VALUES
If successful, sigwait() returns 0 and sets the location pointed to by
sig to the cleared signal number. Otherwise, an error number is
returned.
ERRORS
The sigwait() system call will fail if:
[EINVAL] The set argument specifies one or more invalid signal
numbers.
[EFAULT] Any arguments point outside the allocated address
space or there is a memory protection fault.
SEE ALSOsigaction(2), sigpending(2), sigqueue(2), sigsuspend(2), sigtimedwait(2),
sigwaitinfo(2), pause(3), pthread_sigmask(3)STANDARDS
The sigwait() function conforms to ISO/IEC 9945-1:1996 (“POSIX.1”).
BSD November 11, 2005 BSD
