/* $Id$
 * reactos Cache Manager (Cc*) I/O W32 interface of libcaptive
 * Copyright (C) 2003 Jan Kratochvil <project-captive@jankratochvil.net>
 * 
 * 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; exactly version 2 of June 1991 is required
 * 
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */


#include "config.h"

#include "io.h"	/* self */
#include <glib/gmessages.h>
#include "reactos/ddk/mmfuncs.h"
#include "reactos/ddk/kefuncs.h"
#include "reactos/ddk/iofuncs.h"


ULONG captive_Cc_IoPageRead(FILE_OBJECT *FileObject,gpointer address,ULONG length,LARGE_INTEGER *FileOffset)
{
MDL *Mdl;
KEVENT Event;
IO_STATUS_BLOCK IoStatus;
NTSTATUS err;

	g_return_val_if_fail(FileObject!=NULL,0);
	g_return_val_if_fail(address!=0,0);
	g_return_val_if_fail(length!=0,0);
	g_return_val_if_fail(FileOffset!=NULL,0);

	/* VolumeRead on ext2fsd.sys will return IoStatus.Information==0 although it
	 * successfuly read the data. Workaround it - preclear (not postclear) the
	 * buffer and do not make any other assumptions about the data read.
	 */
	memset(address,0,length);	/* pre-clear the buffer */
	Mdl=MmCreateMdl(NULL,address,length);	/* FIXME: Deprecated in favor of IoAllocateMdl() */
	g_assert(Mdl!=NULL);
	MmBuildMdlForNonPagedPool(Mdl);
	KeInitializeEvent(&Event,NotificationEvent,FALSE);
	IoStatus.Information=0;	/* preventive pre-clear for buggy filesystems */
	err=IoPageRead(FileObject,Mdl,FileOffset,&Event,&IoStatus);
	g_assert(NT_SUCCESS(err));
	g_assert(NT_SUCCESS(IoStatus.Status));
	/* It is not == as the file may be shorter than requested */
	g_assert(IoStatus.Information<=length);
	IoFreeMdl(Mdl);

	/* Forbidden, see the comment above about ext2fsd.sys.
	 * memset(((char *)address)+IoStatus.Information,0,(length-IoStatus.Information));
	 */

	return IoStatus.Information;	/* may be shorter than real! */
}


void captive_Cc_IoPageWrite(FILE_OBJECT *FileObject,gpointer address,ULONG length,LARGE_INTEGER *FileOffset)
{
MDL *Mdl;
KEVENT Event;
IO_STATUS_BLOCK IoStatus;
NTSTATUS err;

	/* We can get 0=='FileObject->DeviceObject->SectorSize' during mount of ext2fsd.sys.
	 * We are unable to find the correct sectorsize for a filesystem as
	 * even the 'CommonFcb' below contains invalid information.
	 * As we need to have sectorsize <=filesystem_blocksize at least for ext2fsd.sys
	 * we choose PAGE_SIZE - the maximum libcaptive can with its design and also the maximum
	 * size ever needed for ext2fsd.sys (PAGE_SIZE is the maximum ext2 block size).
	 */

	Mdl=MmCreateMdl(NULL,address,length);
	g_assert(Mdl!=NULL);
	MmBuildMdlForNonPagedPool(Mdl);

	KeInitializeEvent(&Event,NotificationEvent,FALSE);

	/* Use rather IoSynchronousPageWrite() than IoPageWrite() to prevent STATUS_PENDING. */
	err=IoSynchronousPageWrite(FileObject,Mdl,FileOffset,&Event,&IoStatus);
	g_assert(NT_SUCCESS(err));
	g_assert(NT_SUCCESS(IoStatus.Status));

	/* Also we can get just value 0 if the write is considered 'not dirty'
	 * during FAT write by fastfat.sys.
	 * We can also get just value 8 during write of PAGE_SIZE aligned block
	 * of MappedLength 512 during flush of LSNed buffer on captive_leave(),
	 * probably no assumptions can be made about the returned value at all.
	 */
#if 0
	g_assert(IoStatus.Information==0 || IoStatus.Information>=CAPTIVE_ROUND_DOWN_EXCEEDING(address,PAGE_SIZE)+length);
#endif
	g_assert(IoStatus.Information<=length);
}