1 /*
2 * ptw32_semwait.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 #if !defined(_UWIN)
38 /*# include <process.h> */
39 #endif
40 #include "pthread.h"
41 #include "implement.h"
42
43
44 int
ptw32_semwait(sem_t * sem)45 ptw32_semwait (sem_t * sem)
46 /*
47 * ------------------------------------------------------
48 * DESCRIPTION
49 * This function waits on a POSIX semaphore. If the
50 * semaphore value is greater than zero, it decreases
51 * its value by one. If the semaphore value is zero, then
52 * the calling thread (or process) is blocked until it can
53 * successfully decrease the value.
54 *
55 * Unlike sem_wait(), this routine is non-cancelable.
56 *
57 * RESULTS
58 * 0 successfully decreased semaphore,
59 * -1 failed, error in errno.
60 * ERRNO
61 * EINVAL 'sem' is not a valid semaphore,
62 * ENOSYS semaphores are not supported,
63 * EINTR the function was interrupted by a signal,
64 * EDEADLK a deadlock condition was detected.
65 *
66 * ------------------------------------------------------
67 */
68 {
69 int result = 0;
70 sem_t s = *sem;
71
72 if (s == NULL)
73 {
74 result = EINVAL;
75 }
76 else
77 {
78 if ((result = pthread_mutex_lock (&s->lock)) == 0)
79 {
80 int v;
81
82 /* See sem_destroy.c
83 */
84 if (*sem == NULL)
85 {
86 (void) pthread_mutex_unlock (&s->lock);
87 errno = EINVAL;
88 return -1;
89 }
90
91 v = --s->value;
92 (void) pthread_mutex_unlock (&s->lock);
93
94 if (v < 0)
95 {
96 /* Must wait */
97 if (WaitForSingleObject (s->sem, INFINITE) == WAIT_OBJECT_0)
98 {
99 #if defined(NEED_SEM)
100 if (pthread_mutex_lock (&s->lock) == 0)
101 {
102 if (*sem == NULL)
103 {
104 (void) pthread_mutex_unlock (&s->lock);
105 errno = EINVAL;
106 return -1;
107 }
108
109 if (s->leftToUnblock > 0)
110 {
111 --s->leftToUnblock;
112 SetEvent(s->sem);
113 }
114 (void) pthread_mutex_unlock (&s->lock);
115 }
116 #endif
117 return 0;
118 }
119 }
120 else
121 {
122 return 0;
123 }
124 }
125 }
126
127 if (result != 0)
128 {
129 errno = result;
130 return -1;
131 }
132
133 return 0;
134
135 } /* ptw32_semwait */
136