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
41int
42xsem_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
54void
55xsem_destroy(xsem_t *sem)
56{
57	pthread_mutex_destroy(&sem->semMutex);
58	pthread_cond_destroy(&sem->semCV);
59	sem->semaphore = 0;
60}
61
62int
63xsem_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
92int
93xsem_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
115int
116xsem_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
127void
128xsem_getvalue(xsem_t *sem, int *sval)
129{
130	*sval = sem->semaphore;
131}
132
133
134
135int
136xsem_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