/* Copyright (C) 1992-2018 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 <unistd.h>

#include <sys/resource.h>

/* Increment the scheduling priority of the calling process by INCR.

   The superuser may use a negative INCR to decrement the priority.  */

int

nice (int incr)

{

  int save;

  int prio;

  int result;

  /* -1 is a valid priority, so we use errno to check for an error.  */

  save = errno;

  __set_errno (0);

  prio = __getpriority (PRIO_PROCESS, 0);

  if (prio == -1)

    {

      if (errno != 0)

	return -1;

    }

  result = __setpriority (PRIO_PROCESS, 0, prio + incr);

  if (result == -1)

    {

      if (errno == EACCES)

	__set_errno (EPERM);

      return -1;

    }

  __set_errno (save);

  return __getpriority (PRIO_PROCESS, 0);

}