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      1 /*
      2  * pthread_rwlock_timedwrlock.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 (at) 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_timedwrlock (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 ((result =
     84        pthread_mutex_timedlock (&(rwl->mtxSharedAccessCompleted),
     85 				abstime)) != 0)
     86     {
     87       (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
     88       return result;
     89     }
     90 
     91   if (rwl->nExclusiveAccessCount == 0)
     92     {
     93       if (rwl->nCompletedSharedAccessCount > 0)
     94 	{
     95 	  rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
     96 	  rwl->nCompletedSharedAccessCount = 0;
     97 	}
     98 
     99       if (rwl->nSharedAccessCount > 0)
    100 	{
    101 	  rwl->nCompletedSharedAccessCount = -rwl->nSharedAccessCount;
    102 
    103 	  /*
    104 	   * This routine may be a cancelation point
    105 	   * according to POSIX 1003.1j section 18.1.2.
    106 	   */
    107 #if defined(_MSC_VER) && _MSC_VER < 1400
    108 #pragma inline_depth(0)
    109 #endif
    110 	  pthread_cleanup_push (ptw32_rwlock_cancelwrwait, (void *) rwl);
    111 
    112 	  do
    113 	    {
    114 	      result =
    115 		pthread_cond_timedwait (&(rwl->cndSharedAccessCompleted),
    116 					&(rwl->mtxSharedAccessCompleted),
    117 					abstime);
    118 	    }
    119 	  while (result == 0 && rwl->nCompletedSharedAccessCount < 0);
    120 
    121 	  pthread_cleanup_pop ((result != 0) ? 1 : 0);
    122 #if defined(_MSC_VER) && _MSC_VER < 1400
    123 #pragma inline_depth()
    124 #endif
    125 
    126 	  if (result == 0)
    127 	    {
    128 	      rwl->nSharedAccessCount = 0;
    129 	    }
    130 	}
    131     }
    132 
    133   if (result == 0)
    134     {
    135       rwl->nExclusiveAccessCount++;
    136     }
    137 
    138   return result;
    139 }
    140