1 /*
2  * Copyright (c) 2006-2008 Amit Singh/Google Inc.
3  * Copyright (c) 2012 Anatol Pomozov
4  * Copyright (c) 2011-2013 Benjamin Fleischer
5  */
6 
7 #include "darwin_compat.h"
8 
9 #include <assert.h>
10 #include <errno.h>
11 #include <sys/types.h>
12 
13 /*
14  * Semaphore implementation based on:
15  *
16  * Copyright (C) 2000,02 Free Software Foundation, Inc.
17  * This file is part of the GNU C Library.
18  * Written by Ga<EB>l Le Mignot <address@hidden>
19  *
20  * The GNU C Library is free software; you can redistribute it and/or
21  * modify it under the terms of the GNU Library General Public License as
22  * published by the Free Software Foundation; either version 2 of the
23  * License, or (at your option) any later version.
24  *
25  * The GNU C Library is distributed in the hope that it will be useful,
26  * but WITHOUT ANY WARRANTY; without even the implied warranty of
27  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
28  * Library General Public License for more details.
29  *
30  * You should have received a copy of the GNU Library General Public
31  * License along with the GNU C Library; see the file COPYING.LIB.  If not,
32  * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
33  * Boston, MA 02111-1307, USA.
34  */
35 
36 /* Semaphores */
37 
38 #define __SEM_ID_NONE  ((int)0x0)
39 #define __SEM_ID_LOCAL ((int)0xcafef00d)
40 
41 /* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_init.html */
42 int
darwin_sem_init(darwin_sem_t * sem,int pshared,unsigned int value)43 darwin_sem_init(darwin_sem_t *sem, int pshared, unsigned int value)
44 {
45     if (pshared) {
46         errno = ENOSYS;
47         return -1;
48     }
49 
50     sem->id = __SEM_ID_NONE;
51 
52     if (pthread_cond_init(&sem->__data.local.count_cond, NULL)) {
53         goto cond_init_fail;
54     }
55 
56     if (pthread_mutex_init(&sem->__data.local.count_lock, NULL)) {
57         goto mutex_init_fail;
58     }
59 
60     sem->__data.local.count = value;
61     sem->id = __SEM_ID_LOCAL;
62 
63     return 0;
64 
65 mutex_init_fail:
66 
67     pthread_cond_destroy(&sem->__data.local.count_cond);
68 
69 cond_init_fail:
70 
71     return -1;
72 }
73 
74 /* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_destroy.html */
75 int
darwin_sem_destroy(darwin_sem_t * sem)76 darwin_sem_destroy(darwin_sem_t *sem)
77 {
78     int res = 0;
79 
80     pthread_mutex_lock(&sem->__data.local.count_lock);
81 
82     sem->id = __SEM_ID_NONE;
83     pthread_cond_broadcast(&sem->__data.local.count_cond);
84 
85     if (pthread_cond_destroy(&sem->__data.local.count_cond)) {
86         res = -1;
87     }
88 
89     pthread_mutex_unlock(&sem->__data.local.count_lock);
90 
91     if (pthread_mutex_destroy(&sem->__data.local.count_lock)) {
92         res = -1;
93     }
94 
95     return res;
96 }
97 
98 int
darwin_sem_getvalue(darwin_sem_t * sem,unsigned int * sval)99 darwin_sem_getvalue(darwin_sem_t *sem, unsigned int *sval)
100 {
101     int res = 0;
102 
103     pthread_mutex_lock(&sem->__data.local.count_lock);
104 
105     if (sem->id != __SEM_ID_LOCAL) {
106         res = -1;
107         errno = EINVAL;
108     } else {
109         *sval = sem->__data.local.count;
110     }
111 
112     pthread_mutex_unlock(&sem->__data.local.count_lock);
113 
114     return res;
115 }
116 
117 /* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_post.html */
118 int
darwin_sem_post(darwin_sem_t * sem)119 darwin_sem_post(darwin_sem_t *sem)
120 {
121     int res = 0;
122 
123     pthread_mutex_lock(&sem->__data.local.count_lock);
124 
125     if (sem->id != __SEM_ID_LOCAL) {
126         res = -1;
127         errno = EINVAL;
128     } else if (sem->__data.local.count < DARWIN_SEM_VALUE_MAX) {
129         sem->__data.local.count++;
130         if (sem->__data.local.count == 1) {
131             pthread_cond_signal(&sem->__data.local.count_cond);
132         }
133     } else {
134         errno = ERANGE;
135         res = -1;
136     }
137 
138     pthread_mutex_unlock(&sem->__data.local.count_lock);
139 
140     return res;
141 }
142 
143 /* http://www.opengroup.org/onlinepubs/009695399/functions/sem_timedwait.html */
144 int
darwin_sem_timedwait(darwin_sem_t * sem,const struct timespec * abs_timeout)145 darwin_sem_timedwait(darwin_sem_t *sem, const struct timespec *abs_timeout)
146 {
147     int res = 0;
148 
149     if (abs_timeout &&
150         (abs_timeout->tv_nsec < 0 || abs_timeout->tv_nsec >= 1000000000)) {
151         errno = EINVAL;
152         return -1;
153     }
154 
155     pthread_cleanup_push((void(*)(void*))&pthread_mutex_unlock,
156                  &sem->__data.local.count_lock);
157 
158     pthread_mutex_lock(&sem->__data.local.count_lock);
159 
160     if (sem->id != __SEM_ID_LOCAL) {
161         errno = EINVAL;
162         res = -1;
163     } else {
164         if (!sem->__data.local.count) {
165             res = pthread_cond_timedwait(&sem->__data.local.count_cond,
166                              &sem->__data.local.count_lock,
167                              abs_timeout);
168         }
169         if (res) {
170             assert(res == ETIMEDOUT);
171             res = -1;
172             errno = ETIMEDOUT;
173         } else if (sem->id != __SEM_ID_LOCAL) {
174             res = -1;
175             errno = EINVAL;
176         } else {
177             sem->__data.local.count--;
178         }
179     }
180 
181     pthread_cleanup_pop(1);
182 
183     return res;
184 }
185 
186 /* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_trywait.html */
187 int
darwin_sem_trywait(darwin_sem_t * sem)188 darwin_sem_trywait(darwin_sem_t *sem)
189 {
190     int res = 0;
191 
192     pthread_mutex_lock(&sem->__data.local.count_lock);
193 
194     if (sem->id != __SEM_ID_LOCAL) {
195         res = -1;
196         errno = EINVAL;
197     } else if (sem->__data.local.count) {
198         sem->__data.local.count--;
199     } else {
200         res = -1;
201         errno = EAGAIN;
202     }
203 
204     pthread_mutex_unlock (&sem->__data.local.count_lock);
205 
206     return res;
207 }
208 
209 /* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_wait.html */
210 int
darwin_sem_wait(darwin_sem_t * sem)211 darwin_sem_wait(darwin_sem_t *sem)
212 {
213     /* Must be volatile or will be clobbered by longjmp */
214     volatile int res = 0;
215 
216     pthread_cleanup_push((void(*)(void*))&pthread_mutex_unlock,
217                  &sem->__data.local.count_lock);
218 
219     pthread_mutex_lock(&sem->__data.local.count_lock);
220 
221     if (sem->id != __SEM_ID_LOCAL) {
222         errno = EINVAL;
223         res = -1;
224     } else {
225         if (!sem->__data.local.count) {
226             pthread_cond_wait(&sem->__data.local.count_cond,
227                       &sem->__data.local.count_lock);
228             if (!sem->__data.local.count) {
229                 /* spurious wakeup, assume it is an interruption */
230                 res = -1;
231                 errno = EINTR;
232                 goto out;
233             }
234         }
235         if (sem->id != __SEM_ID_LOCAL) {
236             res = -1;
237             errno = EINVAL;
238         } else {
239             sem->__data.local.count--;
240         }
241     }
242 
243 out:
244     pthread_cleanup_pop(1);
245 
246     return res;
247 }
248