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
42int
43pthread_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}
94