Here is an optimized nanosleep.c for glibc 2.
H.J.
----
/* Copyright (C) 1998 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., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
extern int __syscall_nanosleep (const struct timespec *req,
struct timespec *rem);
int
__nanosleep(const struct timespec *req, struct timespec *rem)
{
sigset_t set, oset;
struct sigaction oact;
int saved_errno;
int ignored;
int ret;
/* Linux will wake up the system call, nanosleep, when SIGCHLD
arrives even if SIGCHLD is ignored. We have to deal with it
in libc. We block SIGCHLD first. */
if (sigemptyset (&set) < 0 ||
sigaddset (&set, SIGCHLD) < 0 ||
sigprocmask (SIG_BLOCK, &set, &oset))
return -1;
/* If SIGCHLD is already blocked, we don't have to do anything. */
if (!sigismember (&oset, SIGCHLD))
{
/* We get the signal handler for SIGCHLD. */
if (sigaction (SIGCHLD, (struct sigaction *) NULL, &oact) < 0)
{
saved_errno = errno;
/* Restore the original signal mask. */
(void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
__set_errno (saved_errno);
return -1;
}
/* Should we really block SIGCHLD? */
ignored = (oact.sa_handler == SIG_IGN);
if (!ignored)
/* Restore the original signal mask. */
(void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
ret = __syscall_nanosleep (req, rem);
if (ignored)
{
saved_errno = errno;
/* Restore the original signal mask. */
(void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
__set_errno (saved_errno);
}
}
else
ret = __syscall_nanosleep (req, rem);
return ret;
}
weak_alias (__nanosleep, nanosleep)
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