/* High-resolution sleep with the specified clock.
   Copyright (C) 2000-2012 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
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <assert.h>
#include <errno.h>
#include <time.h>
#include <sys/time.h>

__typeof__(clock_nanosleep) __clock_nanosleep;

/* This implementation assumes that these is only a `nanosleep' system
   call.  So we have to remap all other activities.  */
int
__clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req, struct timespec *rem)
{
    struct timespec now;

    if (__builtin_expect (req->tv_nsec, 0) < 0 || __builtin_expect (req->tv_nsec, 0) >= 1000000000){
        return EINVAL;
    }

    /* If we got an absolute time, remap it.  */
    if (flags == TIMER_ABSTIME)
    {
        long int nsec;
        long int sec;

        /* Make sure we use safe data types.  */
        assert (sizeof (sec) >= sizeof (now.tv_sec));

        /* Get the current time for this clock.  */
        if (__builtin_expect (clock_gettime (clock_id, &now), 0) != 0){
            return errno;
        }

        /* Compute the difference.  */
        nsec = req->tv_nsec - now.tv_nsec;
        sec = req->tv_sec - now.tv_sec - (nsec < 0);

        if (sec < 0){
            /* The time has already elapsed.  */
            return 0;
        }

        now.tv_sec = sec;
        now.tv_nsec = nsec + (nsec < 0 ? 1000000000 : 0);

        /* From now on this is our time.  */
        req = &now;

        /* Make sure we are not modifying the struct pointed to by REM.  */
        rem = NULL;
    }
    else if (__builtin_expect (flags, 0) != 0){
        return EINVAL;
    }
    else if ((clock_id != CLOCK_REALTIME) && clock_id != CLOCK_MONOTONIC){
        /* Not supported.  */
        return ENOTSUP;
    }

    return __builtin_expect (nanosleep (req, rem), 0) ? errno : 0;
}

weak_alias (__clock_nanosleep, clock_nanosleep)
