difference between \\\\.\\%c:" & "\\\\.\\PHYSICALDRIVE%d"

In application we call the creafile as follows
where pVolumeInfo->Extents[0].DiskNumber is the value obtained from
IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS ioctl.

swprintf(pathBuff, L"\\\\.\\PHYSICALDRIVE%d",
pVolumeInfo->Extents[0].DiskNumber);
hDevice = CreateFile(
pathBuff,
GENERIC_READ|GENERIC_WRITE,
FILE_SHARE_READ|FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);

If we open the device like this the IOCTL doesnt pass thru our filter driver
whereas if we open it using "\\\\.\\%c:" in place of
"\\\\.\\PHYSICALDRIVE%d"as the input parameter then the IOCTL passes thru our
filter driver.
If I use "\\\\.\\%c:" the ioctls path is something like below(I havent
mentioned all the drivers in the path below)
1.NTFS
2.our filter driver
3.volsnap
4.partmgr

But if I use "\\\\.\\PHYSICALDRIVE%d" the ioctl path it shows is
1.\Device\Harddisk2\DR3

I dont see any other driver in the path.

can any one explain me the difference between the two calls.I thought that
both are opening the same object.
I checked the IOCTLs path using IRP Tracker.

Thanks in advance

Alexander
Wed May 07 09:13:23 CDT 2008

On what class is your filter installed?

"qwert" <qwert@discussions.microsoft.com> wrote in message
news:38FA63DB-E347-41B6-952D-22C7FA2B7B27@microsoft.com...
>
> In application we call the creafile as follows
> where pVolumeInfo->Extents[0].DiskNumber is the value obtained from
> IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS ioctl.
>
> swprintf(pathBuff, L"\\\\.\\PHYSICALDRIVE%d",
> pVolumeInfo->Extents[0].DiskNumber);
> hDevice = CreateFile(
> pathBuff,
> GENERIC_READ|GENERIC_WRITE,
> FILE_SHARE_READ|FILE_SHARE_WRITE,
> NULL,
> OPEN_EXISTING,
> FILE_ATTRIBUTE_NORMAL,
> NULL);
>
> If we open the device like this the IOCTL doesnt pass thru our filter
> driver
> whereas if we open it using "\\\\.\\%c:" in place of
> "\\\\.\\PHYSICALDRIVE%d"as the input parameter then the IOCTL passes thru
> our
> filter driver.
> If I use "\\\\.\\%c:" the ioctls path is something like below(I havent
> mentioned all the drivers in the path below)
> 1.NTFS
> 2.our filter driver
> 3.volsnap
> 4.partmgr
>
> But if I use "\\\\.\\PHYSICALDRIVE%d" the ioctl path it shows is
> 1.\Device\Harddisk2\DR3
>
> I dont see any other driver in the path.
>
> can any one explain me the difference between the two calls.I thought that
> both are opening the same object.
> I checked the IOCTLs path using IRP Tracker.
>
> Thanks in advance

Maxim
Wed May 07 10:51:33 CDT 2008

\\.\c: is a volume, if this is a simple partition - then the DO is created
by FtDisk and is named like \Device\HarddiskVolume%d

\\.\PhysicalDrive%d is the whole physical disk with all partitions on it.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com

"qwert" <qwert@discussions.microsoft.com> wrote in message
news:38FA63DB-E347-41B6-952D-22C7FA2B7B27@microsoft.com...
>
> In application we call the creafile as follows
> where pVolumeInfo->Extents[0].DiskNumber is the value obtained from
> IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS ioctl.
>
> swprintf(pathBuff, L"\\\\.\\PHYSICALDRIVE%d",
> pVolumeInfo->Extents[0].DiskNumber);
> hDevice = CreateFile(
> pathBuff,
> GENERIC_READ|GENERIC_WRITE,
> FILE_SHARE_READ|FILE_SHARE_WRITE,
> NULL,
> OPEN_EXISTING,
> FILE_ATTRIBUTE_NORMAL,
> NULL);
>
> If we open the device like this the IOCTL doesnt pass thru our filter driver
> whereas if we open it using "\\\\.\\%c:" in place of
> "\\\\.\\PHYSICALDRIVE%d"as the input parameter then the IOCTL passes thru our
> filter driver.
> If I use "\\\\.\\%c:" the ioctls path is something like below(I havent
> mentioned all the drivers in the path below)
> 1.NTFS
> 2.our filter driver
> 3.volsnap
> 4.partmgr
>
> But if I use "\\\\.\\PHYSICALDRIVE%d" the ioctl path it shows is
> 1.\Device\Harddisk2\DR3
>
> I dont see any other driver in the path.
>
> can any one explain me the difference between the two calls.I thought that
> both are opening the same object.
> I checked the IOCTLs path using IRP Tracker.
>
> Thanks in advance