native_client_sdk/src/libraries/third_party/pthreads-win32/pthread_rwlock_destroy.c

   1 /*
   2  * pthread_rwlock_destroy.c
   3  *
   4  * Description:
   5  * This translation unit implements read/write lock primitives.
   6  *
   7  * --------------------------------------------------------------------------
   8  *
   9  *      Pthreads-win32 - POSIX Threads Library for Win32
  10  *      Copyright(C) 1998 John E. Bossom
  11  *      Copyright(C) 1999,2005 Pthreads-win32 contributors
  12  *
  13  *      Contact Email: rpj@callisto.canberra.edu.au
  14  *
  15  *      The current list of contributors is contained
  16  *      in the file CONTRIBUTORS included with the source
  17  *      code distribution. The list can also be seen at the
  18  *      following World Wide Web location:
  19  *      http://sources.redhat.com/pthreads-win32/contributors.html
  20  *
  21  *      This library is free software; you can redistribute it and/or
  22  *      modify it under the terms of the GNU Lesser General Public
  23  *      License as published by the Free Software Foundation; either
  24  *      version 2 of the License, or (at your option) any later version.
  25  *
  26  *      This library is distributed in the hope that it will be useful,
  27  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  29  *      Lesser General Public License for more details.
  30  *
  31  *      You should have received a copy of the GNU Lesser General Public
  32  *      License along with this library in the file COPYING.LIB;
  33  *      if not, write to the Free Software Foundation, Inc.,
  34  *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  35  */
  36
  37 #include <limits.h>
  38
  39 #include "pthread.h"
  40 #include "implement.h"
  41
  42 int
  43 pthread_rwlock_destroy (pthread_rwlock_t * rwlock)
  44 {
  45   pthread_rwlock_t rwl;
  46   int result = 0, result1 = 0, result2 = 0;
  47
  48   if (rwlock == NULL || *rwlock == NULL)
  49     {
  50       return EINVAL;
  51     }
  52
  53   if (*rwlock != PTHREAD_RWLOCK_INITIALIZER)
  54     {
  55       rwl = *rwlock;
  56
  57       if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
  58         {
  59           return EINVAL;
  60         }
  61
  62       if ((result = pthread_mutex_lock (&(rwl->mtxExclusiveAccess))) != 0)
  63         {
  64           return result;
  65         }
  66
  67       if ((result =
  68            pthread_mutex_lock (&(rwl->mtxSharedAccessCompleted))) != 0)
  69         {
  70           (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
  71           return result;
  72         }
  73
  74       /*
  75        * Check whether any threads own/wait for the lock (wait for ex.access);
  76        * report "BUSY" if so.
  77        */
  78       if (rwl->nExclusiveAccessCount > 0
  79           || rwl->nSharedAccessCount > rwl->nCompletedSharedAccessCount)
  80         {
  81           result = pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted));
  82           result1 = pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
  83           result2 = EBUSY;
  84         }
  85       else
  86         {
  87           rwl->nMagic = 0;
  88
  89           if ((result =
  90                pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted))) != 0)
  91             {
  92               pthread_mutex_unlock (&rwl->mtxExclusiveAccess);
  93               return result;
  94             }
  95
  96           if ((result =
  97                pthread_mutex_unlock (&(rwl->mtxExclusiveAccess))) != 0)
  98             {
  99               return result;
 100             }
 101
 102           *rwlock = NULL;       /* Invalidate rwlock before anything else */
 103           result = pthread_cond_destroy (&(rwl->cndSharedAccessCompleted));
 104           result1 = pthread_mutex_destroy (&(rwl->mtxSharedAccessCompleted));
 105           result2 = pthread_mutex_destroy (&(rwl->mtxExclusiveAccess));
 106           (void) free (rwl);
 107         }
 108     }
 109   else
 110     {
 111       ptw32_mcs_local_node_t node;
 112       /*
 113        * See notes in ptw32_rwlock_check_need_init() above also.
 114        */
 115       ptw32_mcs_lock_acquire(&ptw32_rwlock_test_init_lock, &node);
 116
 117       /*
 118        * Check again.
 119        */
 120       if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
 121         {
 122           /*
 123            * This is all we need to do to destroy a statically
 124            * initialised rwlock that has not yet been used (initialised).
 125            * If we get to here, another thread
 126            * waiting to initialise this rwlock will get an EINVAL.
 127            */
 128           *rwlock = NULL;
 129         }
 130       else
 131         {
 132           /*
 133            * The rwlock has been initialised while we were waiting
 134            * so assume it's in use.
 135            */
 136           result = EBUSY;
 137         }
 138
 139       ptw32_mcs_lock_release(&node);
 140     }
 141
 142   return ((result != 0) ? result : ((result1 != 0) ? result1 : result2));
 143 }