1 /*
2 * pthread_mutex_destroy.c
3 *
4 * Description:
5 * This translation unit implements mutual exclusion (mutex) 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 "pthread.h"
38 #include "implement.h"
39
40
41 int
pthread_mutex_destroy(pthread_mutex_t * mutex)42 pthread_mutex_destroy (pthread_mutex_t * mutex)
43 {
44 int result = 0;
45 pthread_mutex_t mx;
46
47 /*
48 * Let the system deal with invalid pointers.
49 */
50
51 /*
52 * Check to see if we have something to delete.
53 */
54 if (*mutex < PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
55 {
56 mx = *mutex;
57
58 result = pthread_mutex_trylock (&mx);
59
60 /*
61 * If trylock succeeded and the mutex is not recursively locked it
62 * can be destroyed.
63 */
64 if (result == 0)
65 {
66 if (mx->kind != PTHREAD_MUTEX_RECURSIVE || 1 == mx->recursive_count)
67 {
68 /*
69 * FIXME!!!
70 * The mutex isn't held by another thread but we could still
71 * be too late invalidating the mutex below since another thread
72 * may already have entered mutex_lock and the check for a valid
73 * *mutex != NULL.
74 *
75 * Note that this would be an unusual situation because it is not
76 * common that mutexes are destroyed while they are still in
77 * use by other threads.
78 */
79 *mutex = NULL;
80
81 result = pthread_mutex_unlock (&mx);
82
83 if (result == 0)
84 {
85 if (!CloseHandle (mx->event))
86 {
87 *mutex = mx;
88 result = EINVAL;
89 }
90 else
91 {
92 free (mx);
93 }
94 }
95 else
96 {
97 /*
98 * Restore the mutex before we return the error.
99 */
100 *mutex = mx;
101 }
102 }
103 else /* mx->recursive_count > 1 */
104 {
105 /*
106 * The mutex must be recursive and already locked by us (this thread).
107 */
108 mx->recursive_count--; /* Undo effect of pthread_mutex_trylock() above */
109 result = EBUSY;
110 }
111 }
112 }
113 else
114 {
115 /*
116 * See notes in ptw32_mutex_check_need_init() above also.
117 */
118 EnterCriticalSection (&ptw32_mutex_test_init_lock);
119
120 /*
121 * Check again.
122 */
123 if (*mutex >= PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
124 {
125 /*
126 * This is all we need to do to destroy a statically
127 * initialised mutex that has not yet been used (initialised).
128 * If we get to here, another thread
129 * waiting to initialise this mutex will get an EINVAL.
130 */
131 *mutex = NULL;
132 }
133 else
134 {
135 /*
136 * The mutex has been initialised while we were waiting
137 * so assume it's in use.
138 */
139 result = EBUSY;
140 }
141
142 LeaveCriticalSection (&ptw32_mutex_test_init_lock);
143 }
144
145 return (result);
146 }
147