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/* Try to Lock a mutex. Generic version.
Copyright (C) 2002-2019 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
<https://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);
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