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/* Copyright (C) 1991, 1992, 1993, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
/* SIGALRM signal handler for `sleep'. This does nothing but return,
but SIG_IGN isn't supposed to break `pause'. */
static void
sleep_handler (sig)
int sig;
{
return;
}
/* Make the process sleep for SECONDS seconds, or until a signal arrives
and is not ignored. The function returns the number of seconds less
than SECONDS which it actually slept (zero if it slept the full time).
If a signal handler does a `longjmp' or modifies the handling of the
SIGALRM signal while inside `sleep' call, the handling of the SIGALRM
signal afterwards is undefined. There is no return value to indicate
error, but if `sleep' returns SECONDS, it probably didn't work. */
unsigned int
sleep (seconds)
unsigned int seconds;
{
unsigned int remaining, slept;
time_t before, after;
sigset_t set, oset;
struct sigaction act, oact;
int save = errno;
if (seconds == 0)
return 0;
/* Block SIGALRM signals while frobbing the handler. */
if (sigemptyset (&set) < 0 ||
sigaddset (&set, SIGALRM) < 0 ||
sigprocmask (SIG_BLOCK, &set, &oset))
return seconds;
act.sa_handler = sleep_handler;
act.sa_flags = 0;
act.sa_mask = oset; /* execute handler with original mask */
if (sigaction (SIGALRM, &act, &oact) < 0)
return seconds;
before = time ((time_t *) NULL);
remaining = alarm (seconds);
if (remaining > 0 && remaining < seconds)
{
/* The user's alarm will expire before our own would.
Restore the user's signal action state and let his alarm happen. */
(void) sigaction (SIGALRM, &oact, (struct sigaction *) NULL);
alarm (remaining); /* Restore sooner alarm. */
sigsuspend (&oset); /* Wait for it to go off. */
after = time ((time_t *) NULL);
}
else
{
/* Atomically restore the old signal mask
(which had better not block SIGALRM),
and wait for a signal to arrive. */
sigsuspend (&oset);
after = time ((time_t *) NULL);
/* Restore the old signal action state. */
(void) sigaction (SIGALRM, &oact, (struct sigaction *) NULL);
}
/* Notice how long we actually slept. */
slept = after - before;
/* Restore the user's alarm if we have not already past it.
If we have, be sure to turn off the alarm in case a signal
other than SIGALRM was what woke us up. */
(void) alarm (remaining > slept ? remaining - slept : 0);
/* Restore the original signal mask. */
(void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
/* Restore the `errno' value we started with.
Some of the calls we made might have failed, but we didn't care. */
__set_errno (save);
return slept > seconds ? 0 : seconds - slept;
}
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