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

   1 /*
   2  * pthread_rwlock_timedrdlock.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_timedrdlock (pthread_rwlock_t * rwlock,
  44                             const struct timespec *abstime)
  45 {
  46   int result;
  47   pthread_rwlock_t rwl;
  48
  49   if (rwlock == NULL || *rwlock == NULL)
  50     {
  51       return EINVAL;
  52     }
  53
  54   /*
  55    * We do a quick check to see if we need to do more work
  56    * to initialise a static rwlock. We check
  57    * again inside the guarded section of ptw32_rwlock_check_need_init()
  58    * to avoid race conditions.
  59    */
  60   if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
  61     {
  62       result = ptw32_rwlock_check_need_init (rwlock);
  63
  64       if (result != 0 && result != EBUSY)
  65         {
  66           return result;
  67         }
  68     }
  69
  70   rwl = *rwlock;
  71
  72   if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
  73     {
  74       return EINVAL;
  75     }
  76
  77   if ((result =
  78        pthread_mutex_timedlock (&(rwl->mtxExclusiveAccess), abstime)) != 0)
  79     {
  80       return result;
  81     }
  82
  83   if (++rwl->nSharedAccessCount == INT_MAX)
  84     {
  85       if ((result =
  86            pthread_mutex_timedlock (&(rwl->mtxSharedAccessCompleted),
  87                                     abstime)) != 0)
  88         {
  89           if (result == ETIMEDOUT)
  90             {
  91               ++rwl->nCompletedSharedAccessCount;
  92             }
  93           (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
  94           return result;
  95         }
  96
  97       rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
  98       rwl->nCompletedSharedAccessCount = 0;
  99
 100       if ((result =
 101            pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted))) != 0)
 102         {
 103           (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
 104           return result;
 105         }
 106     }
 107
 108   return (pthread_mutex_unlock (&(rwl->mtxExclusiveAccess)));
 109 }