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 <errno.h>
38 #include <limits.h>
39
40 #include "pthread.h"
41 #include "implement.h"
42
43 int
pthread_rwlock_timedrdlock(pthread_rwlock_t * rwlock,const struct timespec * abstime)44 pthread_rwlock_timedrdlock (pthread_rwlock_t * rwlock,
45 const struct timespec *abstime)
46 {
47 int result;
48 pthread_rwlock_t rwl;
49
50 if (rwlock == NULL || *rwlock == NULL)
51 {
52 return EINVAL;
53 }
54
55 /*
56 * We do a quick check to see if we need to do more work
57 * to initialise a static rwlock. We check
58 * again inside the guarded section of ptw32_rwlock_check_need_init()
59 * to avoid race conditions.
60 */
61 if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
62 {
63 result = ptw32_rwlock_check_need_init (rwlock);
64
65 if (result != 0 && result != EBUSY)
66 {
67 return result;
68 }
69 }
70
71 rwl = *rwlock;
72
73 if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
74 {
75 return EINVAL;
76 }
77
78 if ((result =
79 pthread_mutex_timedlock (&(rwl->mtxExclusiveAccess), abstime)) != 0)
80 {
81 return result;
82 }
83
84 if (++rwl->nSharedAccessCount == INT_MAX)
85 {
86 if ((result =
87 pthread_mutex_timedlock (&(rwl->mtxSharedAccessCompleted),
88 abstime)) != 0)
89 {
90 if (result == ETIMEDOUT)
91 {
92 ++rwl->nCompletedSharedAccessCount;
93 }
94 (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
95 return result;
96 }
97
98 rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
99 rwl->nCompletedSharedAccessCount = 0;
100
101 if ((result =
102 pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted))) != 0)
103 {
104 (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
105 return result;
106 }
107 }
108
109 return (pthread_mutex_unlock (&(rwl->mtxExclusiveAccess)));
110 }
111