1 /*
2 * -------------------------------------------------------------
3 *
4 * Module: sem_timedwait.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 typedef struct {
50 sem_t sem;
51 int * resultPtr;
52 } sem_timedwait_cleanup_args_t;
53
54
55 static void PTW32_CDECL
ptw32_sem_timedwait_cleanup(void * args)56 ptw32_sem_timedwait_cleanup (void * args)
57 {
58 sem_timedwait_cleanup_args_t * a = (sem_timedwait_cleanup_args_t *)args;
59 sem_t s = a->sem;
60
61 if (pthread_mutex_lock (&s->lock) == 0)
62 {
63 /*
64 * We either timed out or were cancelled.
65 * If someone has posted between then and now we try to take the semaphore.
66 * Otherwise the semaphore count may be wrong after we
67 * return. In the case of a cancellation, it is as if we
68 * were cancelled just before we return (after taking the semaphore)
69 * which is ok.
70 */
71 if (WaitForSingleObject(s->sem, 0) == WAIT_OBJECT_0)
72 {
73 /* We got the semaphore on the second attempt */
74 *(a->resultPtr) = 0;
75 }
76 else
77 {
78 /* Indicate we're no longer waiting */
79 s->value++;
80 #if defined(NEED_SEM)
81 if (s->value > 0)
82 {
83 s->leftToUnblock = 0;
84 }
85 #else
86 /*
87 * Don't release the W32 sema, it doesn't need adjustment
88 * because it doesn't record the number of waiters.
89 */
90 #endif
91 }
92 (void) pthread_mutex_unlock (&s->lock);
93 }
94 }
95
96
97 int
sem_timedwait(sem_t * sem,const struct timespec * abstime)98 sem_timedwait (sem_t * sem, const struct timespec *abstime)
99 /*
100 * ------------------------------------------------------
101 * DOCPUBLIC
102 * This function waits on a semaphore possibly until
103 * 'abstime' time.
104 *
105 * PARAMETERS
106 * sem
107 * pointer to an instance of sem_t
108 *
109 * abstime
110 * pointer to an instance of struct timespec
111 *
112 * DESCRIPTION
113 * This function waits on a semaphore. If the
114 * semaphore value is greater than zero, it decreases
115 * its value by one. If the semaphore value is zero, then
116 * the calling thread (or process) is blocked until it can
117 * successfully decrease the value or until interrupted by
118 * a signal.
119 *
120 * If 'abstime' is a NULL pointer then this function will
121 * block until it can successfully decrease the value or
122 * until interrupted by a signal.
123 *
124 * RESULTS
125 * 0 successfully decreased semaphore,
126 * -1 failed, error in errno
127 * ERRNO
128 * EINVAL 'sem' is not a valid semaphore,
129 * ENOSYS semaphores are not supported,
130 * EINTR the function was interrupted by a signal,
131 * EDEADLK a deadlock condition was detected.
132 * ETIMEDOUT abstime elapsed before success.
133 *
134 * ------------------------------------------------------
135 */
136 {
137 int result = 0;
138 sem_t s = *sem;
139
140 pthread_testcancel();
141
142 if (sem == NULL)
143 {
144 result = EINVAL;
145 }
146 else
147 {
148 DWORD milliseconds;
149
150 if (abstime == NULL)
151 {
152 milliseconds = INFINITE;
153 }
154 else
155 {
156 /*
157 * Calculate timeout as milliseconds from current system time.
158 */
159 milliseconds = ptw32_relmillisecs (abstime);
160 }
161
162 if ((result = pthread_mutex_lock (&s->lock)) == 0)
163 {
164 int v;
165
166 /* See sem_destroy.c
167 */
168 if (*sem == NULL)
169 {
170 (void) pthread_mutex_unlock (&s->lock);
171 errno = EINVAL;
172 return -1;
173 }
174
175 v = --s->value;
176 (void) pthread_mutex_unlock (&s->lock);
177
178 if (v < 0)
179 {
180 #if defined(NEED_SEM)
181 int timedout;
182 #endif
183 sem_timedwait_cleanup_args_t cleanup_args;
184
185 cleanup_args.sem = s;
186 cleanup_args.resultPtr = &result;
187
188 #if defined(_MSC_VER) && _MSC_VER < 1400
189 #pragma inline_depth(0)
190 #endif
191 /* Must wait */
192 pthread_cleanup_push(ptw32_sem_timedwait_cleanup, (void *) &cleanup_args);
193 #if defined(NEED_SEM)
194 timedout =
195 #endif
196 result = pthreadCancelableTimedWait (s->sem, milliseconds);
197 pthread_cleanup_pop(result);
198 #if defined(_MSC_VER) && _MSC_VER < 1400
199 #pragma inline_depth()
200 #endif
201
202 #if defined(NEED_SEM)
203
204 if (!timedout && pthread_mutex_lock (&s->lock) == 0)
205 {
206 if (*sem == NULL)
207 {
208 (void) pthread_mutex_unlock (&s->lock);
209 errno = EINVAL;
210 return -1;
211 }
212
213 if (s->leftToUnblock > 0)
214 {
215 --s->leftToUnblock;
216 SetEvent(s->sem);
217 }
218 (void) pthread_mutex_unlock (&s->lock);
219 }
220
221 #endif /* NEED_SEM */
222
223 }
224 }
225
226 }
227
228 if (result != 0)
229 {
230
231 errno = result;
232 return -1;
233
234 }
235
236 return 0;
237
238 } /* sem_timedwait */
239