src/Unix/posix_sem.cpp

/*
 *  posix_sem.cpp - POSIX.4 semaphores "emulation"
 *  Copyright (C) 1999 Orlando Bassotto
 *
 *  Basilisk II (C) 1997-2001 Christian Bauer
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 * OK, I had really big problems with SysV semaphores :/
 * I rewrote those one giving a look to the source of linuxthreads
 * with mutex. Seems to be working correctly now.
 */

#include <sys/types.h>
#include <stdio.h>
#include <errno.h>
#include <time.h>
#include <pthread.h>

#include "semaphore.h"

extern "C" {

int sem_init(sem_t* sem, int pshared, unsigned int value)
{
        if(sem==NULL||value>SEM_VALUE_MAX) {
                errno = EINVAL;
                return -1;
        }
        if(pshared) {   
                errno = ENOSYS;
                return -1;
        }
        pthread_mutex_init(&sem->sem_lock, NULL);
        sem->sem_value = value;
        sem->sem_waiting = 0;
        return 0;       
}


int sem_destroy(sem_t* sem)
{
        if(sem==NULL) {
                errno = EINVAL;
                return -1;
        }
        if(sem->sem_waiting) {
                errno = EBUSY;
                return -1;
        }
        pthread_mutex_destroy(&sem->sem_lock);
        sem->sem_waiting = 0;
        sem->sem_value = 0;
        return 0;
}

sem_t sem_open(const char* name, int oflag, ...)
{
        errno = ENOSYS;
        return *(sem_t*)NULL;
}

int sem_close(sem_t* sem)
{
        errno = ENOSYS;
        return -1;
}

int sem_unlink(const char* name)
{
        errno = ENOSYS;
        return -1;
}

int sem_wait(sem_t* sem)
{
        struct timespec req = { 1, 0 };

        if(sem==NULL) {
                errno = EINVAL;
                return -1;
        }
        pthread_mutex_lock(&sem->sem_lock);
        sem->sem_waiting++;
        if(sem->sem_value > 0) {
                --sem->sem_value;
                return 0;
        }
        while(!sem->sem_value) nanosleep(NULL, &req);
        pthread_mutex_unlock(&sem->sem_lock);
        return 0;       
}

int sem_trywait(sem_t* sem)
{
        errno = ENOSYS;
        return -1;
}

int sem_post(sem_t* sem)
{
        if(sem==NULL) {
                errno = EINVAL;
                return -1;
        }
        if(!sem->sem_waiting) {
                if(sem->sem_value >= SEM_VALUE_MAX) {
                        errno = ERANGE;
                        pthread_mutex_unlock(&sem->sem_lock);
                        return -1;
                }
                ++sem->sem_value;
                pthread_mutex_unlock(&sem->sem_lock);
        }
        else {
                sem->sem_waiting--;
                ++sem->sem_value;
//              pthread_mutex_unlock(&sem->sem_lock);
        }
        return 0;
}

int sem_getvalue(sem_t* sem, int* sval)
{
        errno = ENOSYS;
        return -1;
}

}
Revision:	1.4
Committed:	2001-02-02T20:52:57Z (23 years, 5 months ago) by cebix
Branch:	MAIN
CVS Tags:	snapshot-17022001, snapshot-29052001, release-0_9-1
Changes since 1.3:	+1 -1 lines
Log Message:	- bumped version number to 0.9 - updated copyright dates
#	User	Rev	Content
1	cebix	1.1	/*
2			* posix_sem.cpp - POSIX.4 semaphores "emulation"
3			* Copyright (C) 1999 Orlando Bassotto
4			*
5	cebix	1.4	* Basilisk II (C) 1997-2001 Christian Bauer
6	cebix	1.1	*
7			* This program is free software; you can redistribute it and/or modify
8			* it under the terms of the GNU General Public License as published by
9			* the Free Software Foundation; either version 2 of the License, or
10			* (at your option) any later version.
11			*
12			* This program is distributed in the hope that it will be useful,
13			* but WITHOUT ANY WARRANTY; without even the implied warranty of
14			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15			* GNU General Public License for more details.
16			*
17			* You should have received a copy of the GNU General Public License
18			* along with this program; if not, write to the Free Software
19			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20			*/
21
22			/*
23			* OK, I had really big problems with SysV semaphores :/
24			* I rewrote those one giving a look to the source of linuxthreads
25			* with mutex. Seems to be working correctly now.
26			*/
27
28	cebix	1.3	#include <sys/types.h>
29	cebix	1.1	#include <stdio.h>
30			#include <errno.h>
31	cebix	1.3	#include <time.h>
32	cebix	1.1	#include <pthread.h>
33	cebix	1.3
34	cebix	1.1	#include "semaphore.h"
35
36			extern "C" {
37
38			int sem_init(sem_t* sem, int pshared, unsigned int value)
39			{
40			if(sem==NULL\|\|value>SEM_VALUE_MAX) {
41			errno = EINVAL;
42			return -1;
43			}
44			if(pshared) {
45			errno = ENOSYS;
46			return -1;
47			}
48			pthread_mutex_init(&sem->sem_lock, NULL);
49			sem->sem_value = value;
50			sem->sem_waiting = 0;
51			return 0;
52			}
53
54
55			int sem_destroy(sem_t* sem)
56			{
57			if(sem==NULL) {
58			errno = EINVAL;
59			return -1;
60			}
61			if(sem->sem_waiting) {
62			errno = EBUSY;
63			return -1;
64			}
65			pthread_mutex_destroy(&sem->sem_lock);
66			sem->sem_waiting = 0;
67			sem->sem_value = 0;
68			return 0;
69			}
70
71			sem_t sem_open(const char* name, int oflag, ...)
72			{
73			errno = ENOSYS;
74			return (sem_t)NULL;
75			}
76
77			int sem_close(sem_t* sem)
78			{
79			errno = ENOSYS;
80			return -1;
81			}
82
83			int sem_unlink(const char* name)
84			{
85			errno = ENOSYS;
86			return -1;
87			}
88
89			int sem_wait(sem_t* sem)
90			{
91			struct timespec req = { 1, 0 };
92
93			if(sem==NULL) {
94			errno = EINVAL;
95			return -1;
96			}
97			pthread_mutex_lock(&sem->sem_lock);
98			sem->sem_waiting++;
99			if(sem->sem_value > 0) {
100			--sem->sem_value;
101			return 0;
102			}
103			while(!sem->sem_value) nanosleep(NULL, &req);
104			pthread_mutex_unlock(&sem->sem_lock);
105			return 0;
106			}
107
108			int sem_trywait(sem_t* sem)
109			{
110			errno = ENOSYS;
111			return -1;
112			}
113
114			int sem_post(sem_t* sem)
115			{
116			if(sem==NULL) {
117			errno = EINVAL;
118			return -1;
119			}
120			if(!sem->sem_waiting) {
121			if(sem->sem_value >= SEM_VALUE_MAX) {
122			errno = ERANGE;
123			pthread_mutex_unlock(&sem->sem_lock);
124			return -1;
125			}
126			++sem->sem_value;
127			pthread_mutex_unlock(&sem->sem_lock);
128			}
129			else {
130			sem->sem_waiting--;
131			++sem->sem_value;
132			// pthread_mutex_unlock(&sem->sem_lock);
133			}
134			return 0;
135			}
136
137			int sem_getvalue(sem_t* sem, int* sval)
138			{
139			errno = ENOSYS;
140			return -1;
141			}
142
143			}