Sweden-Number/server/semaphore.c

161 lines
4.2 KiB
C

/*
* Server-side semaphore management
*
* Copyright (C) 1998 Alexandre Julliard
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include "winerror.h"
#include "winnt.h"
#include "handle.h"
#include "thread.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 void semaphore_destroy( struct object *obj );
static const struct object_ops semaphore_ops =
{
semaphore_dump,
add_queue,
remove_queue,
semaphore_signaled,
semaphore_satisfied,
no_read_fd,
no_write_fd,
no_flush,
no_get_file_info,
semaphore_destroy
};
static struct object *create_semaphore( const char *name, unsigned int initial, unsigned int max )
{
struct semaphore *sem;
if (!max || (initial > max))
{
SET_ERROR( ERROR_INVALID_PARAMETER );
return NULL;
}
if (!(sem = (struct semaphore *)create_named_object( name, &semaphore_ops, sizeof(*sem) )))
return NULL;
if (GET_ERROR() != ERROR_ALREADY_EXISTS)
{
/* initialize it if it didn't already exist */
sem->count = initial;
sem->max = max;
}
return &sem->obj;
}
static int release_semaphore( int handle, unsigned int count, unsigned int *prev_count )
{
struct semaphore *sem;
if (!(sem = (struct semaphore *)get_handle_obj( current->process, handle,
SEMAPHORE_MODIFY_STATE, &semaphore_ops )))
return 0;
*prev_count = sem->count;
if (sem->count + count < sem->count || sem->count + count > sem->max)
{
SET_ERROR( ERROR_TOO_MANY_POSTS );
return 0;
}
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 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 name='%s'\n",
sem->count, sem->max, get_object_name( &sem->obj ) );
}
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 */
}
static void semaphore_destroy( struct object *obj )
{
struct semaphore *sem = (struct semaphore *)obj;
assert( obj->ops == &semaphore_ops );
free( sem );
}
/* create a semaphore */
DECL_HANDLER(create_semaphore)
{
struct create_semaphore_reply reply = { -1 };
struct object *obj;
char *name = (char *)data;
if (!len) name = NULL;
else CHECK_STRING( "create_semaphore", name, len );
obj = create_semaphore( name, req->initial, req->max );
if (obj)
{
reply.handle = alloc_handle( current->process, obj, SEMAPHORE_ALL_ACCESS, req->inherit );
release_object( obj );
}
send_reply( current, -1, 1, &reply, sizeof(reply) );
}
/* open a handle to a semaphore */
DECL_HANDLER(open_semaphore)
{
struct open_semaphore_reply reply;
char *name = (char *)data;
if (!len) name = NULL;
else CHECK_STRING( "open_semaphore", name, len );
reply.handle = open_object( name, &semaphore_ops, req->access, req->inherit );
send_reply( current, -1, 1, &reply, sizeof(reply) );
}
/* release a semaphore */
DECL_HANDLER(release_semaphore)
{
struct release_semaphore_reply reply;
if (release_semaphore( req->handle, req->count, &reply.prev_count )) CLEAR_ERROR();
send_reply( current, -1, 1, &reply, sizeof(reply) );
}