/* Copyright (C) 1994-2018 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 <stddef.h>

#include <errno.h>

#include <sys/time.h>

#include <hurd.h>

/* XXX Temporary cheezoid implementation; see __setitmr.c.  */

/* These are defined in __setitmr.c.  */

extern spin_lock_t _hurd_itimer_lock;

extern struct itimerval _hurd_itimerval;

extern struct timeval _hurd_itimer_started;

static inline void

subtract_timeval (struct timeval *from, const struct timeval *subtract)

{

  from->tv_usec -= subtract->tv_usec;

  from->tv_sec -= subtract->tv_sec;

  while (from->tv_usec < 0)

    {

      --from->tv_sec;

      from->tv_usec += 1000000;

    }

}

/* Set *VALUE to the current setting of timer WHICH.

   Return 0 on success, -1 on errors.  */

int

__getitimer (enum __itimer_which which, struct itimerval *value)

{

  struct itimerval val;

  struct timeval elapsed;

  switch (which)

    {

    default:

      return __hurd_fail (EINVAL);

    case ITIMER_VIRTUAL:

    case ITIMER_PROF:

      return __hurd_fail (ENOSYS);

    case ITIMER_REAL:

      break;

    }

  /* Get the time now.  */

  if (__gettimeofday (&elapsed, NULL) < 0)

    return -1;

  /* Extract the current timer setting; and the time it was set, so we can

     calculate the time elapsed so far.  */

  HURD_CRITICAL_BEGIN;

  __spin_lock (&_hurd_itimer_lock);

  val = _hurd_itimerval;

  subtract_timeval (&elapsed, &_hurd_itimer_started);

  __spin_unlock (&_hurd_itimer_lock);

  HURD_CRITICAL_END;

  if ((val.it_value.tv_sec | val.it_value.tv_usec) != 0)

    {

      /* There is a pending alarm set.  VAL indicates the interval it was

	 set for, relative to the time recorded in _hurd_itimer_started.

	 Now compensate for the time elapsed since to get the user's

	 conception of the current value of the timer (as if the value

	 stored decreased every microsecond).  */

      if (timercmp (&val.it_value, &elapsed, <))

	{

	  /* Hmm.  The timer should have just gone off, but has not been

	     reset.  This is a possible timing glitch.  The alarm will signal

	     soon, so fabricate a value for how soon.  */

	  val.it_value.tv_sec = 0;

	  val.it_value.tv_usec = 10; /* Random.  */

	}

      else

	/* Subtract the time elapsed since the timer was set

	   from the current timer value the user sees.  */

	subtract_timeval (&val.it_value, &elapsed);

    }

  *value = val;

  return 0;

}

weak_alias (__getitimer, getitimer)