All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice(s), this list of conditions and the following disclaimer as
the first lines of this file unmodified other than the possible
addition of one or more copyright notices.
2. Redistributions in binary form must reproduce the above copyright
notice(s), this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
$FreeBSD: releng/9.3/lib/libc/sys/sigwait.2 241224 2012-10-05 14:20:53Z jilles $
.Dd September 27, 2012 .Dt SIGWAIT 2 .Os .Sh NAME .Nm sigwait .Nd select a set of signals .Sh LIBRARY .Lb libc .Sh SYNOPSIS n signal.h .Ft int .Fn sigwait "const sigset_t * restrict set" "int * restrict sig" .Sh DESCRIPTION The .Fn sigwait system call selects a set of signals, specified by .Fa set . If none of the selected signals are pending, .Fn sigwait waits until one or more of the selected signals has been generated. Then .Fn sigwait atomically clears one of the selected signals from the set of pending signals for the process and sets the location pointed to by .Fa sig to the signal number that was cleared.
p The signals specified by .Fa set should be blocked at the time of the call to .Fn sigwait .
p If more than one thread is using .Fn sigwait to wait for the same signal, no more than one of these threads will return from .Fn sigwait with the signal number. If more than a single thread is blocked in .Fn sigwait for a signal when that signal is generated for the process, it is unspecified which of the waiting threads returns from .Fn sigwait . If the signal is generated for a specific thread, as by .Fn pthread_kill , only that thread will return.
p Should any of the multiple pending signals in the range .Dv SIGRTMIN to .Dv 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. .Sh IMPLEMENTATION NOTES The .Fn sigwait function is implemented as a wrapper around the .Fn __sys_sigwait system call, which retries the call on .Er EINTR error. .Sh RETURN VALUES If successful, .Fn sigwait returns 0 and sets the location pointed to by .Fa sig to the cleared signal number. Otherwise, an error number is returned. .Sh ERRORS The .Fn sigwait system call will fail if: l -tag -width Er t Bq Er EINVAL The .Fa set argument specifies one or more invalid signal numbers. .El .Sh SEE ALSO .Xr sigaction 2 , .Xr sigpending 2 , .Xr sigqueue 2 , .Xr sigsuspend 2 , .Xr sigtimedwait 2 , .Xr sigwaitinfo 2 , .Xr pause 3 , .Xr pthread_sigmask 3 .Sh STANDARDS The .Fn sigwait function conforms to .St -p1003.1-96 .