/* Copyright (C) 2002-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.

   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 "pthreadP.h"

#include <atomic.h>

int

__pthread_setcanceltype (int type, int *oldtype)

{

  if (type < PTHREAD_CANCEL_DEFERRED || type > PTHREAD_CANCEL_ASYNCHRONOUS)

    return EINVAL;

#ifndef SIGCANCEL

  if (type == PTHREAD_CANCEL_ASYNCHRONOUS)

    return ENOTSUP;

#endif

  volatile struct pthread *self = THREAD_SELF;

  int oldval = THREAD_GETMEM (self, cancelhandling);

  while (1)

    {

      int newval = (type == PTHREAD_CANCEL_ASYNCHRONOUS

		    ? oldval | CANCELTYPE_BITMASK

		    : oldval & ~CANCELTYPE_BITMASK);

      /* Store the old value.  */

      if (oldtype != NULL)

	*oldtype = ((oldval & CANCELTYPE_BITMASK)

		    ? PTHREAD_CANCEL_ASYNCHRONOUS : PTHREAD_CANCEL_DEFERRED);

      /* Avoid doing unnecessary work.  The atomic operation can

	 potentially be expensive if the memory has to be locked and

	 remote cache lines have to be invalidated.  */

      if (oldval == newval)

	break;

      /* Update the cancel handling word.  This has to be done

	 atomically since other bits could be modified as well.  */

      int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,

					      oldval);

      if (__glibc_likely (curval == oldval))

	{

	  if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))

	    {

	      THREAD_SETMEM (self, result, PTHREAD_CANCELED);

	      __do_cancel ();

	    }

	  break;

	}

      /* Prepare for the next round.  */

      oldval = curval;

    }

  return 0;

}

strong_alias (__pthread_setcanceltype, pthread_setcanceltype)