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

   1 /*
   2  * pthread_rwlock_unlock.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_unlock (pthread_rwlock_t * rwlock)
  44 {
  45   int result, result1;
  46   pthread_rwlock_t rwl;
  47
  48   if (rwlock == NULL || *rwlock == NULL)
  49     {
  50       return (EINVAL);
  51     }
  52
  53   if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
  54     {
  55       /*
  56        * Assume any race condition here is harmless.
  57        */
  58       return 0;
  59     }
  60
  61   rwl = *rwlock;
  62
  63   if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
  64     {
  65       return EINVAL;
  66     }
  67
  68   if (rwl->nExclusiveAccessCount == 0)
  69     {
  70       if ((result =
  71            pthread_mutex_lock (&(rwl->mtxSharedAccessCompleted))) != 0)
  72         {
  73           return result;
  74         }
  75
  76       if (++rwl->nCompletedSharedAccessCount == 0)
  77         {
  78           result = pthread_cond_signal (&(rwl->cndSharedAccessCompleted));
  79         }
  80
  81       result1 = pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted));
  82     }
  83   else
  84     {
  85       rwl->nExclusiveAccessCount--;
  86
  87       result = pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted));
  88       result1 = pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
  89
  90     }
  91
  92   return ((result != 0) ? result : result1);
  93 }