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posix_sem.cpp
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1999-10-03
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/*
* posix_sem.cpp - POSIX.4 semaphores "emulation"
* Copyright (C) 1999 Orlando Bassotto
*
* Basilisk II (C) 1997-1999 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 <stdio.h>
#include <sys/types.h>
#include <errno.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_lock = NULL;
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;
}
}