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/*
* Server-side USER handles
*
* Copyright (C) 2001 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 "thread.h"
#include "user.h"
struct user_handle
{
void *ptr; /* pointer to object */
unsigned short type; /* object type (0 if free) */
unsigned short generation; /* generation counter */
};
static struct user_handle *handles;
static struct user_handle *freelist;
static int nb_handles;
static int allocated_handles;
static struct user_handle *handle_to_entry( user_handle_t handle )
{
unsigned short generation;
int index = (((unsigned long)handle & 0xffff) - FIRST_USER_HANDLE) >> 1;
if (index < 0 || index >= nb_handles) return NULL;
if (!handles[index].type) return NULL;
generation = (unsigned long)handle >> 16;
if (generation == handles[index].generation || !generation || generation == 0xffff)
return &handles[index];
return NULL;
}
static inline user_handle_t entry_to_handle( struct user_handle *ptr )
{
int index = ptr - handles;
return (user_handle_t)((((unsigned long)index << 1) + FIRST_USER_HANDLE) + (ptr->generation << 16));
}
static inline struct user_handle *alloc_user_entry(void)
{
struct user_handle *handle;
if (freelist)
{
handle = freelist;
freelist = handle->ptr;
return handle;
}
if (nb_handles >= allocated_handles) /* need to grow the array */
{
struct user_handle *new_handles;
/* grow array by 50% (but at minimum 32 entries) */
int growth = max( 32, allocated_handles / 2 );
int new_size = min( allocated_handles + growth, (LAST_USER_HANDLE-FIRST_USER_HANDLE+1) >> 1 );
if (new_size <= allocated_handles) return NULL;
if (!(new_handles = realloc( handles, new_size * sizeof(*handles) )))
return NULL;
handles = new_handles;
allocated_handles = new_size;
}
handle = &handles[nb_handles++];
handle->generation = 0;
return handle;
}
static inline void *free_user_entry( struct user_handle *ptr )
{
void *ret;
ret = ptr->ptr;
ptr->ptr = freelist;
ptr->type = 0;
freelist = ptr;
return ret;
}
/* allocate a user handle for a given object */
user_handle_t alloc_user_handle( void *ptr, enum user_object type )
{
struct user_handle *entry = alloc_user_entry();
if (!entry) return 0;
entry->ptr = ptr;
entry->type = type;
if (++entry->generation >= 0xffff) entry->generation = 1;
return entry_to_handle( entry );
}
/* return a pointer to a user object from its handle */
void *get_user_object( user_handle_t handle, enum user_object type )
{
struct user_handle *entry;
if (!(entry = handle_to_entry( handle )) || entry->type != type) return NULL;
return entry->ptr;
}
/* get the full handle for a possibly truncated handle */
user_handle_t get_user_full_handle( user_handle_t handle )
{
struct user_handle *entry;
if ((unsigned long)handle >> 16) return handle;
if (!(entry = handle_to_entry( handle ))) return handle;
return entry_to_handle( entry );
}
/* same as get_user_object plus set the handle to the full 32-bit value */
void *get_user_object_handle( user_handle_t *handle, enum user_object type )
{
struct user_handle *entry;
if (!(entry = handle_to_entry( *handle )) || entry->type != type) return NULL;
*handle = entry_to_handle( entry );
return entry->ptr;
}
/* free a user handle and return a pointer to the object */
void *free_user_handle( user_handle_t handle )
{
struct user_handle *entry;
if (!(entry = handle_to_entry( handle )))
{
set_error( STATUS_INVALID_HANDLE );
return NULL;
}
return free_user_entry( entry );
}
/* return the next user handle after 'handle' that is of a given type */
void *next_user_handle( user_handle_t *handle, enum user_object type )
{
struct user_handle *entry;
if (!*handle) entry = handles;
else
{
int index = (((unsigned long)*handle & 0xffff) - FIRST_USER_HANDLE) >> 1;
if (index < 0 || index >= nb_handles) return NULL;
entry = handles + index + 1; /* start from the next one */
}
while (entry < handles + nb_handles)
{
if (!type || entry->type == type)
{
*handle = entry_to_handle( entry );
return entry->ptr;
}
entry++;
}
return NULL;
}
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