Sweden-Number/server/semaphore.c

228 lines
7.2 KiB
C

/*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
#include "config.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include "ntstatus.h"
#define WIN32_NO_STATUS
#include "windef.h"
#include "winternl.h"
#include "handle.h"
#include "thread.h"
#include "request.h"
#include "security.h"
static const WCHAR semaphore_name[] = {'S','e','m','a','p','h','o','r','e'};
struct type_descr semaphore_type =
{
{ semaphore_name, sizeof(semaphore_name) }, /* name */
SEMAPHORE_ALL_ACCESS, /* valid_access */
{ /* mapping */
STANDARD_RIGHTS_READ | SEMAPHORE_QUERY_STATE,
STANDARD_RIGHTS_WRITE | SEMAPHORE_MODIFY_STATE,
STANDARD_RIGHTS_EXECUTE | SYNCHRONIZE,
SEMAPHORE_ALL_ACCESS
},
};
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 wait_queue_entry *entry );
static void semaphore_satisfied( struct object *obj, struct wait_queue_entry *entry );
static int semaphore_signal( struct object *obj, unsigned int access );
static const struct object_ops semaphore_ops =
{
sizeof(struct semaphore), /* size */
&semaphore_type, /* type */
semaphore_dump, /* dump */
add_queue, /* add_queue */
remove_queue, /* remove_queue */
semaphore_signaled, /* signaled */
semaphore_satisfied, /* satisfied */
semaphore_signal, /* signal */
no_get_fd, /* get_fd */
default_map_access, /* map_access */
default_get_sd, /* get_sd */
default_set_sd, /* set_sd */
default_get_full_name, /* get_full_name */
no_lookup_name, /* lookup_name */
directory_link_name, /* link_name */
default_unlink_name, /* unlink_name */
no_open_file, /* open_file */
no_kernel_obj_list, /* get_kernel_obj_list */
no_close_handle, /* close_handle */
no_destroy /* destroy */
};
static struct semaphore *create_semaphore( struct object *root, const struct unicode_str *name,
unsigned int attr, unsigned int initial, unsigned int max,
const struct security_descriptor *sd )
{
struct semaphore *sem;
if (!max || (initial > max))
{
set_error( STATUS_INVALID_PARAMETER );
return NULL;
}
if ((sem = create_named_object( root, &semaphore_ops, name, attr, sd )))
{
if (get_error() != STATUS_OBJECT_NAME_EXISTS)
{
/* initialize it if it didn't already exist */
sem->count = initial;
sem->max = max;
}
}
return sem;
}
static int release_semaphore( struct semaphore *sem, unsigned int count,
unsigned int *prev )
{
if (prev) *prev = sem->count;
if (sem->count + count < sem->count || sem->count + count > sem->max)
{
set_error( STATUS_SEMAPHORE_LIMIT_EXCEEDED );
return 0;
}
else if (sem->count)
{
/* there cannot be any thread to wake up if the count is != 0 */
sem->count += count;
}
else
{
sem->count = count;
wake_up( &sem->obj, count );
}
return 1;
}
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\n", sem->count, sem->max );
}
static int semaphore_signaled( struct object *obj, struct wait_queue_entry *entry )
{
struct semaphore *sem = (struct semaphore *)obj;
assert( obj->ops == &semaphore_ops );
return (sem->count > 0);
}
static void semaphore_satisfied( struct object *obj, struct wait_queue_entry *entry )
{
struct semaphore *sem = (struct semaphore *)obj;
assert( obj->ops == &semaphore_ops );
assert( sem->count );
sem->count--;
}
static int semaphore_signal( struct object *obj, unsigned int access )
{
struct semaphore *sem = (struct semaphore *)obj;
assert( obj->ops == &semaphore_ops );
if (!(access & SEMAPHORE_MODIFY_STATE))
{
set_error( STATUS_ACCESS_DENIED );
return 0;
}
return release_semaphore( sem, 1, NULL );
}
/* create a semaphore */
DECL_HANDLER(create_semaphore)
{
struct semaphore *sem;
struct unicode_str name;
struct object *root;
const struct security_descriptor *sd;
const struct object_attributes *objattr = get_req_object_attributes( &sd, &name, &root );
if (!objattr) return;
if ((sem = create_semaphore( root, &name, objattr->attributes, req->initial, req->max, sd )))
{
if (get_error() == STATUS_OBJECT_NAME_EXISTS)
reply->handle = alloc_handle( current->process, sem, req->access, objattr->attributes );
else
reply->handle = alloc_handle_no_access_check( current->process, sem,
req->access, objattr->attributes );
release_object( sem );
}
if (root) release_object( root );
}
/* open a handle to a semaphore */
DECL_HANDLER(open_semaphore)
{
struct unicode_str name = get_req_unicode_str();
reply->handle = open_object( current->process, req->rootdir, req->access,
&semaphore_ops, &name, req->attributes );
}
/* release a semaphore */
DECL_HANDLER(release_semaphore)
{
struct semaphore *sem;
if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
{
release_semaphore( sem, req->count, &reply->prev_count );
release_object( sem );
}
}
/* query details about the semaphore */
DECL_HANDLER(query_semaphore)
{
struct semaphore *sem;
if ((sem = (struct semaphore *)get_handle_obj( current->process, req->handle,
SEMAPHORE_QUERY_STATE, &semaphore_ops )))
{
reply->current = sem->count;
reply->max = sem->max;
release_object( sem );
}
}