4.3BSD-Reno/src/lib/libc/sys/sigsuspend.2

.\" Copyright (c) 1983 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms are permitted provided
.\" that: (1) source distributions retain this entire copyright notice and
.\" comment, and (2) distributions including binaries display the following
.\" acknowledgement:  ``This product includes software developed by the
.\" University of California, Berkeley and its contributors'' in the
.\" documentation or other materials provided with the distribution and in
.\" all advertising materials mentioning features or use of this software.
.\" Neither the name of the University nor the names of its contributors may
.\" be used to endorse or promote products derived from this software without
.\" specific prior written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.\"	@(#)sigsuspend.2	6.1 (Berkeley) 7/1/90
.\"
.TH SIGSUSPEND 2 "July 1, 1990"
.UC 7
.SH NAME
sigsuspend \- atomically release blocked signals and wait for interrupt
.SH SYNOPSIS
.B #include <signal.h>
.ft B
sigsuspend(sigmask)
.br
sigset_t *sigmask;
.ft R
.SH DESCRIPTION
.I Sigsuspend
temporarily changes the blocked signal mask to the set to which
.I sigmask
points,
and then waits for a signal to arrive;
on return the previous set of masked signals is restored.
The signal mask set
is usually empty to indicate that all
signals are to be unblocked for the duration of the call.
The
.I sigsuspend
function
always terminates by being interrupted, returning \-1 with
.I errno
set to EINTR.
.PP
In normal usage, a signal is blocked using
.IR sigprocmask (2),
to begin a critical section, variables modified on the occurrence
of the signal are examined to determine that there is no work
to be done, and the process pauses awaiting work by using
.I sigsuspend
with the previous mask returned by
.IR sigprocmask .
.SH SEE ALSO
sigprocmask(2), sigaction(2), sigsetops(3)