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