Hello,
While trying to compile abiword, and so gnome-vfs, on GNU/Hurd, I've
seen that it uses POSIX semaphore, that we don't implement yet.
So, I've done an implementation of POSIX semaphores using a pthread_mutex
and a pthread_cond. I didn't test it yet, but it compiles, and I'm pretty
confident in it (but I'm sure of the correct behavior of the destroy
function if some threads are locked on the semaphore).
Anyway, here it is. I think it should be merged in libpthreads as soon
as someone reviewed it.
/* Copyright (C) 2000,02 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Gaël Le Mignot <[EMAIL PROTECTED]>
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/*
* POSIX Threads Extension: Semaphores <semaphore.c>
*/
#include <semaphore.h>
#include <stdlib.h>
/* Initialize the semaphore and set the initial value - as in LinuxThreads
pshared must be zero right now. */
int
sem_init (sem_t *sem, int pshared, unsigned int value)
{
if (pshared)
return -1;
sem = malloc (sizeof (*sem));
if (sem == NULL)
return -1;
sem->count = value;
pthread_cond_init (&sem->lock, NULL);
pthread_mutex_init (&sem->count_lock, NULL);
return 0;
}
/* Destroys the semaphore */
int
sem_destroy (sem_t *sem)
{
pthread_mutex_destroy (&sem->count_lock);
pthread_cond_destroy (&sem->lock);
free (sem);
return 0;
}
/* Wait until the count is > 0, and then decrease it */
int
sem_wait (sem_t *sem)
{
pthread_mutex_lock (&sem->count_lock);
while (1)
{
if (sem->count)
{
sem->count--;
pthread_mutex_unlock (&sem->count_lock);
return 0;
}
pthread_cond_wait (&sem->lock, &sem->count_lock);
}
pthread_mutex_unlock (&sem->count_lock);
}
/* Non-blocking variant of sem_wait. Returns -1 if count == 0. */
int
sem_trywait (sem_t *sem)
{
int res = -1;
pthread_mutex_lock (&sem->count_lock);
if (sem->count)
{
res = 0;
sem->count--;
}
pthread_mutex_unlock (&sem->count_lock);
return res;
}
/* Increments the count */
int
sem_post (sem_t *sem)
{
pthread_mutex_lock (&sem->count_lock);
sem->count++;
pthread_cond_signal (&sem->lock);
pthread_mutex_unlock (&sem->count_lock);
return 0;
}
/* Return the value of the semaphore */
int
sem_getvalue (sem_t *sem, int *sval)
{
pthread_mutex_lock (&sem->count_lock);
*sval = sem->count;
pthread_mutex_unlock (&sem->count_lock);
return 0;
}
/* Copyright (C) 2000,02 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Gaël Le Mignot <[EMAIL PROTECTED]>
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/*
* POSIX Threads Extension: Semaphores <semaphore.h>
*/
#ifndef _SEMAPHORE_H
#define _SEMAPHORE_H 1
#include <pthread.h>
__BEGIN_DECLS
struct __sem_t
{
unsigned int count;
pthread_mutex_t count_lock;
pthread_cond_t lock;
};
typedef struct __sem_t sem_t;
/* Initialize the semaphore and set the initial value - as in LinuxThreads
pshared must be zero right now. */
extern int sem_init (sem_t *sem, int pshared, unsigned int value);
/* Destroys the semaphore */
extern int sem_destroy (sem_t *sem);
/* Wait until the count is > 0, and then decrease it */
extern int sem_wait (sem_t *sem);
/* Non-blocking variant of sem_wait. Returns -1 if count == 0. */
extern int sem_trywait (sem_t *sem);
/* Increments the count */
extern int sem_post (sem_t *sem);
/* Return the value of the semaphore */
extern int sem_getvalue (sem_t *sem, int *sval);
__END_DECLS
#endif /* pthread.h */
--
Gael Le Mignot "Kilobug" - [EMAIL PROTECTED] - http://kilobug.free.fr
GSM : 06.71.47.18.22 (in France) ICQ UIN : 7299959
Fingerprint : 1F2C 9804 7505 79DF 95E6 7323 B66B F67B 7103 C5DA
Member of HurdFr: http://hurdfr.org - The GNU Hurd: http://hurd.gnu.org
