/*
 *  ReactOS W32 Subsystem
 *  Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 ReactOS Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
/* $Id$
 *
 * COPYRIGHT:      See COPYING in the top level directory
 * PROJECT:        ReactOS kernel
 * PURPOSE:        User object manager
 * FILE:           subsys/win32k/misc/object.c
 * PROGRAMMERS:    David Welch (welch@cwcom.net)
 *                 Casper S. Hornstrup (chorns@users.sourceforge.net)
 * UPDATE HISTORY:
 *     06-06-2001  CSH  Ported kernel object manager
 */
/* INCLUDES ******************************************************************/

#include <ddk/ntddk.h>
#include <include/object.h>

#define NDEBUG
#include <debug.h>

/* FUNCTIONS *****************************************************************/

PVOID FASTCALL
HEADER_TO_BODY(PUSER_OBJECT_HEADER ObjectHeader)
{
  return (((PUSER_OBJECT_HEADER)ObjectHeader) + 1);
}

PUSER_OBJECT_HEADER FASTCALL
BODY_TO_HEADER(PVOID ObjectBody)
{
  return (((PUSER_OBJECT_HEADER)ObjectBody) - 1);
}

VOID STATIC FASTCALL
ObmpLockHandleTable(PUSER_HANDLE_TABLE HandleTable)
{
  ExAcquireFastMutex(&HandleTable->ListLock);
}

VOID STATIC FASTCALL
ObmpUnlockHandleTable(PUSER_HANDLE_TABLE HandleTable)
{
  ExReleaseFastMutex(&HandleTable->ListLock);
}

VOID FASTCALL
ObmpPerformRetentionChecks(PUSER_OBJECT_HEADER ObjectHeader)
{
  if (ObjectHeader->RefCount < 0)
    {
      DbgPrint("ObjectHeader 0x%X has invalid reference count (%d)\n",
	       ObjectHeader, ObjectHeader->RefCount);
    }
  
  if (ObjectHeader->HandleCount < 0)
    {
      DbgPrint("Object 0x%X has invalid handle count (%d)\n",
	       ObjectHeader, ObjectHeader->HandleCount);
    }
  
  if ((ObjectHeader->RefCount == 0) && (ObjectHeader->HandleCount == 0))
    {
      ExFreePool(ObjectHeader);
    }
}

PUSER_HANDLE FASTCALL
ObmpGetObjectByHandle(PUSER_HANDLE_TABLE HandleTable,
		      HANDLE Handle)
/*
 * FUNCTION: Get the data structure for a handle
 * ARGUMENTS:
 *   HandleTable = Table to search
 *   Handle      = Handle to get data structure for
 * RETURNS:
 *   Pointer to the data structure identified by the handle on success,
 *   NULL on failure
 */
{
  ULONG Index = (((ULONG)Handle) >> 2) - 1;
  ULONG Count = Index / HANDLE_BLOCK_ENTRIES;
  PUSER_HANDLE_BLOCK Block = NULL;
  PLIST_ENTRY Current;
  ULONG i;
  
  Current = HandleTable->ListHead.Flink;
  
  for (i = 0; i < Count; i++)
    {
      Current = Current->Flink;
      if (Current == &(HandleTable->ListHead))
	{
	  return NULL;
	}
    }
  
  Block = CONTAINING_RECORD(Current, USER_HANDLE_BLOCK, ListEntry);
  return &(Block->Handles[Index % HANDLE_BLOCK_ENTRIES]);
}

VOID FASTCALL
ObmpCloseAllHandles(PUSER_HANDLE_TABLE HandleTable)
{
  PLIST_ENTRY CurrentEntry;
  PUSER_HANDLE_BLOCK Current;
  PVOID ObjectBody;
  ULONG i;

  ObmpLockHandleTable(HandleTable);
  
  CurrentEntry = HandleTable->ListHead.Flink;

  while (CurrentEntry != &HandleTable->ListHead)
    {
      Current = CONTAINING_RECORD(CurrentEntry, USER_HANDLE_BLOCK, ListEntry);
      
      for (i = 0; i < HANDLE_BLOCK_ENTRIES; i++)
	{
	  ObjectBody = Current->Handles[i].ObjectBody;
	  
	  if (ObjectBody != NULL)
	    {
	      PUSER_OBJECT_HEADER ObjectHeader = BODY_TO_HEADER(ObjectBody);
	      
	      ObmReferenceObjectByPointer(ObjectBody, otUnknown);
	      ObjectHeader->HandleCount--;
	      Current->Handles[i].ObjectBody = NULL;
	      
	      ObmpUnlockHandleTable(HandleTable);
	      
	      ObmDereferenceObject(ObjectBody);

	      ObmpLockHandleTable(HandleTable);
	      CurrentEntry = &HandleTable->ListHead;
	      break;
	    }
	}
      
      CurrentEntry = CurrentEntry->Flink;
    }
  
  ObmpUnlockHandleTable(HandleTable);
}

VOID FASTCALL
ObmpDeleteHandleTable(PUSER_HANDLE_TABLE HandleTable)
{
  PUSER_HANDLE_BLOCK Current;
  PLIST_ENTRY CurrentEntry;

  ObmpCloseAllHandles(HandleTable);
  
  CurrentEntry = RemoveHeadList(&HandleTable->ListHead);
  
  while (CurrentEntry != &HandleTable->ListHead)
  {
    Current = CONTAINING_RECORD(CurrentEntry,
				USER_HANDLE_BLOCK,
				ListEntry);

    ExFreePool(Current);
    
    CurrentEntry = RemoveHeadList(&HandleTable->ListHead);
  }
}

PVOID FASTCALL
ObmpDeleteHandle(PUSER_HANDLE_TABLE HandleTable,
		 HANDLE Handle)
{
  PUSER_OBJECT_HEADER ObjectHeader;
  PUSER_HANDLE Entry;
  PVOID ObjectBody;

  ObmpLockHandleTable(HandleTable);
  
  Entry = ObmpGetObjectByHandle(HandleTable, Handle);
  if (Entry == NULL)
    {
      ObmpUnlockHandleTable(HandleTable);
      return NULL;
    }

  ObjectBody = Entry->ObjectBody;
  
  if (ObjectBody != NULL)
    {
      ObjectHeader = BODY_TO_HEADER(ObjectBody);
      ObjectHeader->HandleCount--;
      ObmReferenceObjectByPointer(ObjectBody, otUnknown);
      Entry->ObjectBody = NULL;
    }
  
  ObmpUnlockHandleTable(HandleTable);

  return ObjectBody;
}

NTSTATUS FASTCALL
ObmpInitializeObject(PUSER_HANDLE_TABLE HandleTable,
		     PUSER_OBJECT_HEADER ObjectHeader,
		     PHANDLE Handle,
		     USER_OBJECT_TYPE ObjectType,
		     ULONG ObjectSize)
{
  DWORD Status = STATUS_SUCCESS;
  
  ObjectHeader->Type = ObjectType;
  ObjectHeader->HandleCount = 0;
  ObjectHeader->RefCount = 1;
  ObjectHeader->Size = ObjectSize;

  if (Handle != NULL)
    {
      Status = ObmCreateHandle(HandleTable,
			       HEADER_TO_BODY(ObjectHeader),
			       Handle);
    }

  return Status;
}


ULONG FASTCALL
ObmGetReferenceCount(PVOID ObjectBody)
{
  PUSER_OBJECT_HEADER ObjectHeader = BODY_TO_HEADER(ObjectBody);

  return ObjectHeader->RefCount;
}

ULONG FASTCALL
ObmGetHandleCount(PVOID ObjectBody)
{
  PUSER_OBJECT_HEADER ObjectHeader = BODY_TO_HEADER(ObjectBody);

  return ObjectHeader->HandleCount;
}

VOID FASTCALL
ObmReferenceObject(PVOID ObjectBody)
/*
 * FUNCTION: Increments a given object's reference count and performs
 *           retention checks
 * ARGUMENTS:
 *   ObjectBody = Body of the object
 */
{
  PUSER_OBJECT_HEADER ObjectHeader;
  
  if (!ObjectBody)
    {
      return;
    }
  
  ObjectHeader = BODY_TO_HEADER(ObjectBody);
  
  ObjectHeader->RefCount++;

  ObmpPerformRetentionChecks(ObjectHeader);
}

VOID FASTCALL
ObmDereferenceObject(PVOID ObjectBody)
/*
 * FUNCTION: Decrements a given object's reference count and performs
 *           retention checks
 * ARGUMENTS:
 *   ObjectBody = Body of the object
 */
{
  PUSER_OBJECT_HEADER ObjectHeader;
  
  if (!ObjectBody)
    {
      return;
    }
  
  ObjectHeader = BODY_TO_HEADER(ObjectBody);
  
  ObjectHeader->RefCount--;

  ObmpPerformRetentionChecks(ObjectHeader);
}

NTSTATUS FASTCALL
ObmReferenceObjectByPointer(PVOID ObjectBody,
			    USER_OBJECT_TYPE ObjectType)
/*
 * FUNCTION: Increments the pointer reference count for a given object
 * ARGUMENTS:
 *         ObjectBody = Object's body
 *         ObjectType = Object type
 * RETURNS: Status
 */
{
  PUSER_OBJECT_HEADER ObjectHeader;
  
  ObjectHeader = BODY_TO_HEADER(ObjectBody);
  
  if ((ObjectType != otUnknown) && (ObjectHeader->Type != ObjectType))
    {
      return STATUS_INVALID_PARAMETER;
    }
  
  ObjectHeader->RefCount++;
  
  return STATUS_SUCCESS;
}

PVOID FASTCALL
ObmCreateObject(PUSER_HANDLE_TABLE HandleTable,
		PHANDLE Handle,
		USER_OBJECT_TYPE ObjectType,
		ULONG ObjectSize)
{
  PUSER_OBJECT_HEADER ObjectHeader;
  PVOID ObjectBody;
  DWORD Status;
  
  ObjectHeader = (PUSER_OBJECT_HEADER)ExAllocatePool(NonPagedPool, 
				     ObjectSize + sizeof(USER_OBJECT_HEADER));
  if (!ObjectHeader)
    {
      return NULL;
    }
  
  ObjectBody = HEADER_TO_BODY(ObjectHeader);
  
  RtlZeroMemory(ObjectBody, ObjectSize);
  
  Status = ObmpInitializeObject(HandleTable,
				ObjectHeader,
				Handle,
				ObjectType,
				ObjectSize);
  
  if (!NT_SUCCESS(Status))
    {
      ExFreePool(ObjectHeader);
      return NULL;
    }
  
  return ObjectBody;
}

NTSTATUS FASTCALL
ObmCreateHandle(PUSER_HANDLE_TABLE HandleTable,
		PVOID ObjectBody,
		PHANDLE HandleReturn)
/*
 * FUNCTION: Add a handle referencing an object
 * ARGUMENTS:
 *   HandleTable = Table to put handle in
 *   ObjectBody  = Object body that the handle should refer to
 * RETURNS: The created handle
 */
{
  PUSER_HANDLE_BLOCK NewBlock;
  PLIST_ENTRY Current;
  ULONG Handle;
  ULONG i;

  if (ObjectBody != NULL) 
    {
      BODY_TO_HEADER(ObjectBody)->HandleCount++;
    }
  
  ObmpLockHandleTable(HandleTable);

  Handle = 1;
  Current = HandleTable->ListHead.Flink;
  /*
   * Scan through the currently allocated Handle blocks looking for a free
   * slot
   */
  while (Current != &(HandleTable->ListHead))
    {
      PUSER_HANDLE_BLOCK Block = 
	CONTAINING_RECORD(Current, USER_HANDLE_BLOCK, ListEntry);
           
      for (i = 0; i < HANDLE_BLOCK_ENTRIES; i++)
	{
	  if (!Block->Handles[i].ObjectBody)
	    {
	      Block->Handles[i].ObjectBody = ObjectBody;
	      ObmpUnlockHandleTable(HandleTable);
	      *HandleReturn = (HANDLE)((Handle + i) << 2);
	      return ERROR_SUCCESS;
	    }
	}

      Handle = Handle + HANDLE_BLOCK_ENTRIES;
      Current = Current->Flink;
    }

  /*
   * Add a new Handle block to the end of the list
   */
  NewBlock = (PUSER_HANDLE_BLOCK)ExAllocatePool(NonPagedPool, 
						sizeof(USER_HANDLE_BLOCK));
  if (!NewBlock)
    {
      *HandleReturn = (PHANDLE)NULL;
      return STATUS_INSUFFICIENT_RESOURCES;
    }
  
  RtlZeroMemory(NewBlock, sizeof(USER_HANDLE_BLOCK));
  NewBlock->Handles[0].ObjectBody = ObjectBody;
  InsertTailList(&HandleTable->ListHead, &NewBlock->ListEntry);
  ObmpUnlockHandleTable(HandleTable);
  *HandleReturn = (HANDLE)(Handle << 2);

  return STATUS_SUCCESS;
}

NTSTATUS FASTCALL
ObmReferenceObjectByHandle(PUSER_HANDLE_TABLE HandleTable,
			   HANDLE Handle,
			   USER_OBJECT_TYPE ObjectType,
			   PVOID* Object)
/*
 * FUNCTION: Increments the reference count for an object and returns a
 *           pointer to its body
 * ARGUMENTS:
 *         HandleTable = Table to search
 *         Handle = Handle for the object
 *         ObjectType = Type of object
 *         Object (OUT) = Points to the object body on return
 * RETURNS: Status
 */
{
  PUSER_OBJECT_HEADER ObjectHeader;
  PUSER_HANDLE UserHandle;
  PVOID ObjectBody;
  
  ObmpLockHandleTable(HandleTable);
  
  UserHandle = ObmpGetObjectByHandle(HandleTable, Handle);
  
  if ((UserHandle == NULL) || (UserHandle->ObjectBody == NULL))
    {
      ObmpUnlockHandleTable(HandleTable);
      return STATUS_UNSUCCESSFUL;
    }
  
  ObjectBody = UserHandle->ObjectBody;
  ObmReferenceObjectByPointer(ObjectBody, ObjectType);
  
  ObmpUnlockHandleTable(HandleTable);
  
  ObjectHeader = BODY_TO_HEADER(ObjectBody);
  
  if ((ObjectType != otUnknown) && (ObjectHeader->Type != ObjectType))
    {
      return STATUS_UNSUCCESSFUL;
    }
  
  *Object = ObjectBody;
  
  return STATUS_SUCCESS;
}

NTSTATUS FASTCALL
ObmCloseHandle(PUSER_HANDLE_TABLE HandleTable,
	       HANDLE Handle)
{
  PVOID ObjectBody;

  ObjectBody = ObmpDeleteHandle(HandleTable, Handle);
  if (ObjectBody == NULL)
    {
      return STATUS_UNSUCCESSFUL;
    }
  
  ObmDereferenceObject(ObjectBody);
  
  return STATUS_SUCCESS;
}

VOID FASTCALL
ObmInitializeHandleTable(PUSER_HANDLE_TABLE HandleTable)
{
  InitializeListHead(&HandleTable->ListHead);
  ExInitializeFastMutex(&HandleTable->ListLock);
}

VOID FASTCALL
ObmFreeHandleTable(PUSER_HANDLE_TABLE HandleTable)
{
  ObmpDeleteHandleTable(HandleTable);
}

PUSER_HANDLE_TABLE FASTCALL
ObmCreateHandleTable(VOID)
{
  PUSER_HANDLE_TABLE HandleTable;

  HandleTable = (PUSER_HANDLE_TABLE)ExAllocatePool(NonPagedPool, 
						   sizeof(USER_HANDLE_TABLE));
  if (!HandleTable)
    {
      return NULL;
    }
  
  ObmInitializeHandleTable(HandleTable);
  
  return HandleTable;
}

VOID FASTCALL
ObmDestroyHandleTable(PUSER_HANDLE_TABLE HandleTable)
{
  ObmFreeHandleTable(HandleTable);
  ExFreePool(HandleTable);
}

/* EOF */