/* Try to Lock a mutex.  Generic version.

   Copyright (C) 2002-2018 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 <pthread.h>

#include <pt-internal.h>

#define LOSE do { * (int *) 0 = 0; } while (1)

/* Lock MUTEX, return EBUSY if we can't get it.  */

int

__pthread_mutex_trylock (struct __pthread_mutex *mutex)

{

  int err;

  struct __pthread *self;

  const struct __pthread_mutexattr *attr = mutex->__attr;

  if (attr == __PTHREAD_ERRORCHECK_MUTEXATTR)

    attr = &__pthread_errorcheck_mutexattr;

  if (attr == __PTHREAD_RECURSIVE_MUTEXATTR)

    attr = &__pthread_recursive_mutexattr;

  __pthread_spin_lock (&mutex->__lock);

  if (__pthread_spin_trylock (&mutex->__held) == 0)

    /* Acquired the lock.  */

    {

#if defined(ALWAYS_TRACK_MUTEX_OWNER)

# ifndef NDEBUG

      self = _pthread_self ();

      if (self != NULL)

	/* The main thread may take a lock before the library is fully

	   initialized, in particular, before the main thread has a

	   TCB.  */

	{

	  assert (mutex->__owner == NULL);

	  mutex->__owner = _pthread_self ();

	}

# endif

#endif

      if (attr != NULL)

	switch (attr->__mutex_type)

	  {

	  case PTHREAD_MUTEX_NORMAL:

	    break;

	  case PTHREAD_MUTEX_RECURSIVE:

	    mutex->__locks = 1;

	  case PTHREAD_MUTEX_ERRORCHECK:

	    mutex->__owner = _pthread_self ();

	    break;

	  default:

	    LOSE;

	  }

      __pthread_spin_unlock (&mutex->__lock);

      return 0;

    }

  err = EBUSY;

  if (attr != NULL)

    {

      self = _pthread_self ();

      switch (attr->__mutex_type)

	{

	case PTHREAD_MUTEX_NORMAL:

	  break;

	case PTHREAD_MUTEX_ERRORCHECK:

	  /* We could check if MUTEX->OWNER is SELF, however, POSIX

	     does not permit pthread_mutex_trylock to return EDEADLK

	     instead of EBUSY, only pthread_mutex_lock.  */

	  break;

	case PTHREAD_MUTEX_RECURSIVE:

	  if (mutex->__owner == self)

	    {

	      mutex->__locks++;

	      err = 0;

	    }

	  break;

	default:

	  LOSE;

	}

    }

  __pthread_spin_unlock (&mutex->__lock);

  return err;

}

strong_alias (__pthread_mutex_trylock, _pthread_mutex_trylock);

strong_alias (__pthread_mutex_trylock, pthread_mutex_trylock);