/* xnanosleep.c -- a more convenient interface to nanosleep
- Copyright (C) 2002-2007, 2009-2011 Free Software Foundation, Inc.
+ Copyright (C) 2002-2007, 2009-2013 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
#include "xnanosleep.h"
-#include <limits.h>
-#include <stdbool.h>
-#include <stdio.h>
-#include <assert.h>
+#include <timespec.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
+ 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 };
-
- /* For overflow checking, use naive comparison if possible, widening
- to long double if double is not wide enough. Otherwise, use <=,
- not <, to avoid problems when TIME_T_MAX is less than SECONDS but
- compares equal to SECONDS after loss of precision when coercing
- from time_t to long double. This mishandles near-maximal values
- in some rare (perhaps theoretical) cases but that is better than
- undefined behavior. */
- bool overflow = ((time_t) ((double) TIME_T_MAX / 2) == TIME_T_MAX / 2
- ? TIME_T_MAX < seconds
- : (time_t) ((long double) TIME_T_MAX / 2) == TIME_T_MAX / 2
- ? TIME_T_MAX < (long double) seconds
- : TIME_T_MAX <= (long double) seconds);
-
- struct timespec ts_sleep;
-
- assert (0 <= seconds);
-
- /* Separate whole seconds from nanoseconds. */
- if (! overflow)
- {
- time_t floor_seconds = seconds;
- double ns = BILLION * (seconds - floor_seconds);
- ts_sleep.tv_sec = floor_seconds;
-
- /* 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 = ns;
- ts_sleep.tv_nsec += (ts_sleep.tv_nsec < ns);
-
- /* Normalize the interval length. nanosleep requires this. */
- if (BILLION <= ts_sleep.tv_nsec)
- {
- if (ts_sleep.tv_sec == TIME_T_MAX)
- overflow = true;
- else
- {
- ts_sleep.tv_sec++;
- ts_sleep.tv_nsec -= BILLION;
- }
- }
- }
+ struct timespec ts_sleep = dtotimespec (seconds);
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