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/* xnanosleep.c -- a more convenient interface to nanosleep
Copyright (C) 2002-2007, 2009-2020 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 3 of the License, 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, see <https://www.gnu.org/licenses/>. */
/* Mostly written (for sleep.c) by Paul Eggert.
Factored out (creating this file) by Jim Meyering. */
#include <config.h>
#include "xnanosleep.h"
#include <intprops.h>
#include <timespec.h>
#include <errno.h>
#include <time.h>
#include <unistd.h>
/* 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)
{
#if HAVE_PAUSE
if (1.0 + TYPE_MAXIMUM (time_t) <= seconds)
{
do
pause ();
while (errno == EINTR);
/* pause failed (!); fall back on repeated nanosleep calls. */
}
#endif
struct timespec ts_sleep = dtotimespec (seconds);
for (;;)
{
/* 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).
Gnulib's replacement nanosleep sometimes does not update
TS_SLEEP, and it is possible some kernels have a similar bug.
However, this merely causes xnanosleep to sleep longer than
necessary, which is not a correctness bug. */
errno = 0;
if (nanosleep (&ts_sleep, &ts_sleep) == 0)
break;
if (errno != EINTR && errno != 0)
return -1;
}
return 0;
}
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