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Implement POSIX-generic sleep via nanosleep rather than SIGARLM.

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This commit is contained in:
Roland McGrath 2012-09-28 16:22:51 -07:00
parent 1fa1170b52
commit ea4d37b316
2 changed files with 38 additions and 65 deletions
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3
ChangeLog
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@ -1,5 +1,8 @@
2012-09-28 Roland McGrath <roland@hack.frob.com>
* sysdeps/posix/sleep.c (__sleep): Rewritten using __nanosleep
instead of SIGALRM.
* sysdeps/gnu/_G_config.h: Moved to ...
* sysdeps/unix/sysv/linux/_G_config.h: ... here.
* sysdeps/mach/hurd/_G_config.h: Moved to ...

100
sysdeps/posix/sleep.c
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@ -1,4 +1,5 @@
/* Copyright (C) 1991, 1992, 1993, 1996, 1997 Free Software Foundation, Inc.
/* Sleep for a given number of seconds. POSIX.1 version.
Copyright (C) 1991-2012 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
@ -15,20 +16,12 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
#include <sys/param.h>
/* SIGALRM signal handler for `sleep'. This does nothing but return,
but SIG_IGN isn't supposed to break `pause'. */
static void
sleep_handler (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).
@ -39,67 +32,44 @@ sleep_handler (int sig)
unsigned int
__sleep (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)
/* This is not necessary but some buggy programs depend on it. */
if (__builtin_expect (seconds == 0, 0))
{
/* 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);
#ifdef CANCELLATION_P
CANCELLATION_P (THREAD_SELF);
#endif
return 0;
}
/* Notice how long we actually slept. */
slept = after - before;
int save_errno = errno;
/* 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);
const unsigned int max
= (unsigned int) (((unsigned long int) (~((time_t) 0))) >> 1);
struct timespec ts = { 0, 0 };
do
{
if (sizeof (ts.tv_sec) <= sizeof (seconds))
{
/* Since SECONDS is unsigned assigning the value to .tv_sec can
overflow it. In this case we have to wait in steps. */
ts.tv_sec += MIN (seconds, max);
seconds -= (unsigned int) ts.tv_sec;
}
else
{
ts.tv_sec = (time_t) seconds;
seconds = 0;
}
/* Restore the original signal mask. */
(void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
if (__nanosleep (&ts, &ts) < 0)
/* We were interrupted.
Return the number of (whole) seconds we have not yet slept. */
return seconds + ts.tv_sec;
}
while (seconds > 0);
/* Restore the `errno' value we started with.
Some of the calls we made might have failed, but we didn't care. */
__set_errno (save);
__set_errno (save_errno);
return slept > seconds ? 0 : seconds - slept;
return 0;
}
weak_alias (__sleep, sleep)