1 /*
2 * -------------------------------------------------------------
3 *
4 * Module: sem_destroy.c
5 *
6 * Purpose:
7 * Semaphores aren't actually part of the PThreads standard.
8 * They are defined by the POSIX Standard:
9 *
10 * POSIX 1003.1b-1993 (POSIX.1b)
11 *
12 * -------------------------------------------------------------
13 *
14 * --------------------------------------------------------------------------
15 *
16 * Pthreads-win32 - POSIX Threads Library for Win32
17 * Copyright(C) 1998 John E. Bossom
18 * Copyright(C) 1999,2005 Pthreads-win32 contributors
19 *
20 * Contact Email: rpj@callisto.canberra.edu.au
21 *
22 * The current list of contributors is contained
23 * in the file CONTRIBUTORS included with the source
24 * code distribution. The list can also be seen at the
25 * following World Wide Web location:
26 * http://sources.redhat.com/pthreads-win32/contributors.html
27 *
28 * This library is free software; you can redistribute it and/or
29 * modify it under the terms of the GNU Lesser General Public
30 * License as published by the Free Software Foundation; either
31 * version 2 of the License, or (at your option) any later version.
32 *
33 * This library is distributed in the hope that it will be useful,
34 * but WITHOUT ANY WARRANTY; without even the implied warranty of
35 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
36 * Lesser General Public License for more details.
37 *
38 * You should have received a copy of the GNU Lesser General Public
39 * License along with this library in the file COPYING.LIB;
40 * if not, write to the Free Software Foundation, Inc.,
41 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
42 */
43
44 #include "pthread.h"
45 #include "semaphore.h"
46 #include "implement.h"
47
48
49 int
sem_destroy(sem_t * sem)50 sem_destroy (sem_t * sem)
51 /*
52 * ------------------------------------------------------
53 * DOCPUBLIC
54 * This function destroys an unnamed semaphore.
55 *
56 * PARAMETERS
57 * sem
58 * pointer to an instance of sem_t
59 *
60 * DESCRIPTION
61 * This function destroys an unnamed semaphore.
62 *
63 * RESULTS
64 * 0 successfully destroyed semaphore,
65 * -1 failed, error in errno
66 * ERRNO
67 * EINVAL 'sem' is not a valid semaphore,
68 * ENOSYS semaphores are not supported,
69 * EBUSY threads (or processes) are currently
70 * blocked on 'sem'
71 *
72 * ------------------------------------------------------
73 */
74 {
75 int result = 0;
76 sem_t s = NULL;
77
78 if (sem == NULL || *sem == NULL)
79 {
80 result = EINVAL;
81 }
82 else
83 {
84 s = *sem;
85
86 if ((result = pthread_mutex_lock (&s->lock)) == 0)
87 {
88 if (s->value < 0)
89 {
90 (void) pthread_mutex_unlock (&s->lock);
91 result = EBUSY;
92 }
93 else
94 {
95 /* There are no threads currently blocked on this semaphore. */
96
97 if (!CloseHandle (s->sem))
98 {
99 (void) pthread_mutex_unlock (&s->lock);
100 result = EINVAL;
101 }
102 else
103 {
104 /*
105 * Invalidate the semaphore handle when we have the lock.
106 * Other sema operations should test this after acquiring the lock
107 * to check that the sema is still valid, i.e. before performing any
108 * operations. This may only be necessary before the sema op routine
109 * returns so that the routine can return EINVAL - e.g. if setting
110 * s->value to SEM_VALUE_MAX below does force a fall-through.
111 */
112 *sem = NULL;
113
114 /* Prevent anyone else actually waiting on or posting this sema.
115 */
116 s->value = SEM_VALUE_MAX;
117
118 (void) pthread_mutex_unlock (&s->lock);
119
120 do
121 {
122 /* Give other threads a chance to run and exit any sema op
123 * routines. Due to the SEM_VALUE_MAX value, if sem_post or
124 * sem_wait were blocked by us they should fall through.
125 */
126 Sleep(0);
127 }
128 while (pthread_mutex_destroy (&s->lock) == EBUSY);
129 }
130 }
131 }
132 }
133
134 if (result != 0)
135 {
136 errno = result;
137 return -1;
138 }
139
140 free (s);
141
142 return 0;
143
144 } /* sem_destroy */
145