mirror of
https://github.com/coreutils/coreutils.git
synced 2024-12-14 12:23:55 +08:00
108 lines
3.2 KiB
C
108 lines
3.2 KiB
C
/* xnanosleep.c -- a more convenient interface to nanosleep
|
|
Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2, or (at your option)
|
|
any later version.
|
|
|
|
This program 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 General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software Foundation,
|
|
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
|
|
|
|
/* Mostly written (for sleep.c) by Paul Eggert.
|
|
Factored out (creating this file) by Jim Meyering. */
|
|
|
|
#if HAVE_CONFIG_H
|
|
# include <config.h>
|
|
#endif
|
|
|
|
#include "xnanosleep.h"
|
|
|
|
#include <limits.h>
|
|
#include <stdbool.h>
|
|
#include <stdio.h>
|
|
#include <assert.h>
|
|
#include <errno.h>
|
|
#include <sys/types.h>
|
|
#include <time.h>
|
|
|
|
#include "intprops.h"
|
|
|
|
#ifndef TIME_T_MAX
|
|
# define TIME_T_MAX TYPE_MAXIMUM (time_t)
|
|
#endif
|
|
|
|
/* Sleep until the time (call it WAKE_UP_TIME) specified as
|
|
SECONDS seconds after the time this function is called.
|
|
SECONDS must be non-negative. If SECONDS is so large that
|
|
it is not representable as a `struct timespec', then use
|
|
the maximum value for that interval. Return -1 on failure
|
|
(setting errno), 0 on success. */
|
|
|
|
int
|
|
xnanosleep (double seconds)
|
|
{
|
|
enum { BILLION = 1000000000 };
|
|
|
|
bool overflow = false;
|
|
double ns;
|
|
struct timespec ts_sleep;
|
|
|
|
assert (0 <= seconds);
|
|
|
|
/* Separate whole seconds from nanoseconds.
|
|
Be careful to detect any overflow. */
|
|
ts_sleep.tv_sec = seconds;
|
|
ns = BILLION * (seconds - ts_sleep.tv_sec);
|
|
overflow |= ! (ts_sleep.tv_sec <= seconds && 0 <= ns && ns <= BILLION);
|
|
ts_sleep.tv_nsec = ns;
|
|
|
|
/* Round up to the next whole number, if necessary, so that we
|
|
always sleep for at least the requested amount of time. Assuming
|
|
the default rounding mode, we don't have to worry about the
|
|
rounding error when computing 'ns' above, since the error won't
|
|
cause 'ns' to drop below an integer boundary. */
|
|
ts_sleep.tv_nsec += (ts_sleep.tv_nsec < ns);
|
|
|
|
/* Normalize the interval length. nanosleep requires this. */
|
|
if (BILLION <= ts_sleep.tv_nsec)
|
|
{
|
|
time_t t = ts_sleep.tv_sec + 1;
|
|
|
|
/* Detect integer overflow. */
|
|
overflow |= (t < ts_sleep.tv_sec);
|
|
|
|
ts_sleep.tv_sec = t;
|
|
ts_sleep.tv_nsec -= BILLION;
|
|
}
|
|
|
|
for (;;)
|
|
{
|
|
if (overflow)
|
|
{
|
|
ts_sleep.tv_sec = TIME_T_MAX;
|
|
ts_sleep.tv_nsec = BILLION - 1;
|
|
}
|
|
|
|
/* Linux-2.6.8.1's nanosleep returns -1, but doesn't set errno
|
|
when resumed after being suspended. Earlier versions would
|
|
set errno to EINTR. nanosleep from linux-2.6.10, as well as
|
|
implementations by (all?) other vendors, doesn't return -1
|
|
in that case; either it continues sleeping (if time remains)
|
|
or it returns zero (if the wake-up time has passed). */
|
|
errno = 0;
|
|
if (nanosleep (&ts_sleep, NULL) == 0)
|
|
break;
|
|
if (errno != EINTR && errno != 0)
|
|
return -1;
|
|
}
|
|
|
|
return 0;
|
|
}
|