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196 lines
5.7 KiB
C
196 lines
5.7 KiB
C
/*
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* Server-side USER handles
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*
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* Copyright (C) 2001 Alexandre Julliard
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#include "thread.h"
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#include "user.h"
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#include "request.h"
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struct user_handle
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{
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void *ptr; /* pointer to object */
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unsigned short type; /* object type (0 if free) */
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unsigned short generation; /* generation counter */
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};
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static struct user_handle *handles;
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static struct user_handle *freelist;
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static int nb_handles;
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static int allocated_handles;
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static struct user_handle *handle_to_entry( user_handle_t handle )
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{
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unsigned short generation;
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int index = ((handle & 0xffff) - FIRST_USER_HANDLE) >> 1;
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if (index < 0 || index >= nb_handles) return NULL;
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if (!handles[index].type) return NULL;
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generation = handle >> 16;
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if (generation == handles[index].generation || !generation || generation == 0xffff)
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return &handles[index];
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return NULL;
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}
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static inline user_handle_t entry_to_handle( struct user_handle *ptr )
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{
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unsigned int index = ptr - handles;
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return (index << 1) + FIRST_USER_HANDLE + (ptr->generation << 16);
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}
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static inline struct user_handle *alloc_user_entry(void)
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{
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struct user_handle *handle;
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if (freelist)
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{
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handle = freelist;
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freelist = handle->ptr;
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return handle;
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}
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if (nb_handles >= allocated_handles) /* need to grow the array */
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{
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struct user_handle *new_handles;
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/* grow array by 50% (but at minimum 32 entries) */
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int growth = max( 32, allocated_handles / 2 );
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int new_size = min( allocated_handles + growth, (LAST_USER_HANDLE-FIRST_USER_HANDLE+1) >> 1 );
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if (new_size <= allocated_handles) return NULL;
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if (!(new_handles = realloc( handles, new_size * sizeof(*handles) )))
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return NULL;
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handles = new_handles;
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allocated_handles = new_size;
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}
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handle = &handles[nb_handles++];
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handle->generation = 0;
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return handle;
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}
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static inline void *free_user_entry( struct user_handle *ptr )
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{
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void *ret;
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ret = ptr->ptr;
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ptr->ptr = freelist;
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ptr->type = 0;
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freelist = ptr;
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return ret;
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}
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/* allocate a user handle for a given object */
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user_handle_t alloc_user_handle( void *ptr, enum user_object type )
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{
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struct user_handle *entry = alloc_user_entry();
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if (!entry) return 0;
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entry->ptr = ptr;
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entry->type = type;
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if (++entry->generation >= 0xffff) entry->generation = 1;
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return entry_to_handle( entry );
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}
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/* return a pointer to a user object from its handle */
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void *get_user_object( user_handle_t handle, enum user_object type )
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{
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struct user_handle *entry;
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if (!(entry = handle_to_entry( handle )) || entry->type != type) return NULL;
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return entry->ptr;
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}
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/* get the full handle for a possibly truncated handle */
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user_handle_t get_user_full_handle( user_handle_t handle )
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{
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struct user_handle *entry;
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if (handle >> 16) return handle;
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if (!(entry = handle_to_entry( handle ))) return handle;
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return entry_to_handle( entry );
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}
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/* same as get_user_object plus set the handle to the full 32-bit value */
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void *get_user_object_handle( user_handle_t *handle, enum user_object type )
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{
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struct user_handle *entry;
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if (!(entry = handle_to_entry( *handle )) || entry->type != type) return NULL;
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*handle = entry_to_handle( entry );
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return entry->ptr;
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}
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/* free a user handle and return a pointer to the object */
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void *free_user_handle( user_handle_t handle )
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{
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struct user_handle *entry;
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if (!(entry = handle_to_entry( handle )))
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{
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set_error( STATUS_INVALID_HANDLE );
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return NULL;
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}
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return free_user_entry( entry );
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}
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/* return the next user handle after 'handle' that is of a given type */
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void *next_user_handle( user_handle_t *handle, enum user_object type )
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{
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struct user_handle *entry;
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if (!*handle) entry = handles;
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else
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{
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int index = ((*handle & 0xffff) - FIRST_USER_HANDLE) >> 1;
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if (index < 0 || index >= nb_handles) return NULL;
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entry = handles + index + 1; /* start from the next one */
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}
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while (entry < handles + nb_handles)
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{
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if (!type || entry->type == type)
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{
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*handle = entry_to_handle( entry );
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return entry->ptr;
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}
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entry++;
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}
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return NULL;
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}
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/* free client-side user handles managed by the process */
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void free_process_user_handles( struct process *process )
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{
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unsigned int i;
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for (i = 0; i < nb_handles; i++)
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if (handles[i].type == USER_CLIENT && handles[i].ptr == process)
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free_user_entry( &handles[i] );
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}
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/* allocate an arbitrary user handle */
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DECL_HANDLER(alloc_user_handle)
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{
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reply->handle = alloc_user_handle( current->process, USER_CLIENT );
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}
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/* free an arbitrary user handle */
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DECL_HANDLER(free_user_handle)
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{
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struct user_handle *entry;
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if ((entry = handle_to_entry( req->handle )) && entry->type == USER_CLIENT)
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free_user_entry( entry );
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else
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set_error( STATUS_INVALID_HANDLE );
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}
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