/* Copyright (C) 2008-2018 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 <errno.h>

#include <sys/times.h>

#include <sysdep.h>

clock_t

__times (struct tms *buf)

{

  INTERNAL_SYSCALL_DECL (err);

  clock_t ret = INTERNAL_SYSCALL (times, err, 1, buf);

  if (INTERNAL_SYSCALL_ERROR_P (ret, err)

      && __builtin_expect (INTERNAL_SYSCALL_ERRNO (ret, err) == EFAULT, 0)

      && buf)

    {

      /* This might be an error or not.  For architectures which have no

	 separate return value and error indicators we cannot

	 distinguish a return value of e.g. (clock_t) -14 from -EFAULT.

	 Therefore the only course of action is to dereference the user

	 -supplied structure on a return of (clock_t) -14.  This will crash

	 applications which pass in an invalid non-NULL BUF pointer.

	 Note that Linux allows BUF to be NULL in which case we skip this.  */

#define touch(v) \

      do {								      \

	clock_t temp = v;						      \

	asm volatile ("" : "+r" (temp));				      \

	v = temp;							      \

      } while (0)

      touch (buf->tms_utime);

      touch (buf->tms_stime);

      touch (buf->tms_cutime);

      touch (buf->tms_cstime);

      /* If we come here the memory is valid and the kernel did not

	 return an EFAULT error, but rather e.g. (clock_t) -14.

	 Return the value given by the kernel.  */

    }

  /* On Linux this function never fails except with EFAULT.

     POSIX says that returning a value (clock_t) -1 indicates an error,

     but on Linux this is simply one of the valid clock values after

     clock_t wraps.  Therefore when we would return (clock_t) -1, we

     instead return (clock_t) 0, and loose a tick of accuracy (having

     returned 0 for two consecutive calls even though the clock

     advanced).  */

  if (ret == (clock_t) -1)

    return (clock_t) 0;

  return ret;

}

weak_alias (__times, times)