1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #pragma ident "%Z%%M% %I% %E% SMI"
28
29 /*
30 * xsem.c: to provide a semaphore system (used by the smq routines)
31 *
32 * these routines come from the libxposix library.
33 */
34
35 #include <pthread.h>
36 #include <time.h>
37
38 #include "xsem.h"
39
40
41 int
xsem_init(xsem_t * sem,int pshared,unsigned int value)42 xsem_init(xsem_t *sem, int pshared, unsigned int value)
43 {
44 if (pshared != 0)
45 return (-1);
46
47 pthread_mutex_init(&sem->semMutex, NULL);
48 pthread_cond_init(&sem->semCV, NULL);
49 sem->semaphore = value;
50
51 return (0);
52 }
53
54 void
xsem_destroy(xsem_t * sem)55 xsem_destroy(xsem_t *sem)
56 {
57 pthread_mutex_destroy(&sem->semMutex);
58 pthread_cond_destroy(&sem->semCV);
59 sem->semaphore = 0;
60 }
61
62 int
xsem_wait(xsem_t * sem)63 xsem_wait(xsem_t *sem)
64 {
65 pthread_mutex_lock(&sem->semMutex);
66
67 if (sem->semaphore < 0) {
68 sem->semaphore = 0;
69 pthread_mutex_unlock(&sem->semMutex);
70 return (XSEM_ERROR);
71 }
72
73 if (sem->semaphore > 0) {
74 sem->semaphore--;
75 } else {
76 while (sem->semaphore == 0)
77 pthread_cond_wait(&sem->semCV, &sem->semMutex);
78
79 if (sem->semaphore != 0) {
80 sem->semaphore--;
81 } else {
82 pthread_mutex_unlock(&sem->semMutex);
83 return (XSEM_ERROR);
84 }
85 }
86
87 pthread_mutex_unlock(&sem->semMutex);
88 return (0);
89 }
90
91
92 int
xsem_trywait(xsem_t * sem)93 xsem_trywait(xsem_t *sem)
94 {
95 pthread_mutex_lock(&sem->semMutex);
96
97 if (sem->semaphore < 0) {
98 sem->semaphore = 0;
99 pthread_mutex_unlock(&sem->semMutex);
100 return (XSEM_ERROR);
101 }
102
103 if (sem->semaphore == 0) {
104 pthread_mutex_unlock(&sem->semMutex);
105 return (XSEM_EBUSY);
106 } else {
107 sem->semaphore--;
108 }
109
110 pthread_mutex_unlock(&sem->semMutex);
111 return (0);
112 }
113
114
115 int
xsem_post(xsem_t * sem)116 xsem_post(xsem_t *sem)
117 {
118 pthread_mutex_lock(&sem->semMutex);
119 sem->semaphore++;
120 pthread_cond_signal(&sem->semCV);
121 pthread_mutex_unlock(&sem->semMutex);
122
123 return (0);
124 }
125
126
127 void
xsem_getvalue(xsem_t * sem,int * sval)128 xsem_getvalue(xsem_t *sem, int *sval)
129 {
130 *sval = sem->semaphore;
131 }
132
133
134
135 int
xsem_xwait(xsem_t * sem,int timeout,timestruc_t * mytime)136 xsem_xwait(xsem_t *sem, int timeout, timestruc_t *mytime)
137 {
138 int status;
139 timestruc_t delay;
140
141 if (timeout == 0)
142 return (xsem_wait(sem));
143 else {
144 pthread_mutex_lock(&sem->semMutex);
145
146 if (sem->semaphore < 0) {
147 sem->semaphore = 0;
148 pthread_mutex_unlock(&sem->semMutex);
149 return (XSEM_ERROR);
150 }
151
152 if (sem->semaphore > 0) {
153 sem->semaphore--;
154 } else {
155 status = 0;
156
157 delay = *mytime;
158 delay.tv_sec = delay.tv_sec + time(NULL);
159 while ((sem->semaphore == 0) && (status == 0)) {
160 status = pthread_cond_timedwait(&sem->semCV,
161 &sem->semMutex, &delay);
162 }
163
164 /*
165 * Check one more time in case thread didn't have a
166 * chance to check before timeout ??? TBD
167 */
168
169 if (status != 0) {
170 pthread_mutex_unlock(&sem->semMutex);
171 return (XSEM_ETIME);
172 } else if (sem->semaphore != 0) {
173 sem->semaphore--;
174 } else {
175 pthread_mutex_unlock(&sem->semMutex);
176 return (XSEM_ERROR);
177 }
178 }
179
180 pthread_mutex_unlock(&sem->semMutex);
181 }
182
183 return (0);
184 }
185