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/*
* Server-side semaphore management
*
* Copyright (C) 1998 Alexandre Julliard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include "winnt.h"
#include "handle.h"
#include "thread.h"
#include "request.h"
struct semaphore
{
struct object obj; /* object header */
unsigned int count; /* current count */
unsigned int max; /* maximum possible count */
};
static void semaphore_dump( struct object *obj, int verbose );
static int semaphore_signaled( struct object *obj, struct thread *thread );
static int semaphore_satisfied( struct object *obj, struct thread *thread );
static const struct object_ops semaphore_ops =
{
sizeof(struct semaphore), /* size */
semaphore_dump, /* dump */
add_queue, /* add_queue */
remove_queue, /* remove_queue */
semaphore_signaled, /* signaled */
semaphore_satisfied, /* satisfied */
NULL, /* get_poll_events */
NULL, /* poll_event */
no_get_fd, /* get_fd */
no_flush, /* flush */
no_get_file_info, /* get_file_info */
NULL, /* queue_async */
no_destroy /* destroy */
};
static struct semaphore *create_semaphore( const WCHAR *name, size_t len,
unsigned int initial, unsigned int max )
{
struct semaphore *sem;
if (!max || (initial > max))
{
set_error( STATUS_INVALID_PARAMETER );
return NULL;
}
if ((sem = create_named_object( &semaphore_ops, name, len )))
{
if (get_error() != STATUS_OBJECT_NAME_COLLISION)
{
/* initialize it if it didn't already exist */
sem->count = initial;
sem->max = max;
}
}
return sem;
}
static unsigned int release_semaphore( handle_t handle, unsigned int count )
{
struct semaphore *sem;
unsigned int prev = 0;
if ((sem = (struct semaphore *)get_handle_obj( current->process, handle,
SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
{
prev = sem->count;
if (sem->count + count < sem->count || sem->count + count > sem->max)
{
set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
}
else if (sem->count)
{
/* there cannot be any thread waiting if the count is != 0 */
assert( !sem->obj.head );
sem->count += count;
}
else
{
sem->count = count;
wake_up( &sem->obj, count );
}
release_object( sem );
}
return prev;
}
static void semaphore_dump( struct object *obj, int verbose )
{
struct semaphore *sem = (struct semaphore *)obj;
assert( obj->ops == &semaphore_ops );
fprintf( stderr, "Semaphore count=%d max=%d ", sem->count, sem->max );
dump_object_name( &sem->obj );
fputc( '\n', stderr );
}
static int semaphore_signaled( struct object *obj, struct thread *thread )
{
struct semaphore *sem = (struct semaphore *)obj;
assert( obj->ops == &semaphore_ops );
return (sem->count > 0);
}
static int semaphore_satisfied( struct object *obj, struct thread *thread )
{
struct semaphore *sem = (struct semaphore *)obj;
assert( obj->ops == &semaphore_ops );
assert( sem->count );
sem->count--;
return 0; /* not abandoned */
}
/* create a semaphore */
DECL_HANDLER(create_semaphore)
{
struct semaphore *sem;
reply->handle = 0;
if ((sem = create_semaphore( get_req_data(), get_req_data_size(),
req->initial, req->max )))
{
reply->handle = alloc_handle( current->process, sem, SEMAPHORE_ALL_ACCESS, req->inherit );
release_object( sem );
}
}
/* open a handle to a semaphore */
DECL_HANDLER(open_semaphore)
{
reply->handle = open_object( get_req_data(), get_req_data_size(),
&semaphore_ops, req->access, req->inherit );
}
/* release a semaphore */
DECL_HANDLER(release_semaphore)
{
reply->prev_count = release_semaphore( req->handle, req->count );
}
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