QueryDosDevice() for Dynamic Disks

NTFSD
1

Hi all,

In Windows 2003, QueryDosDevice() returns a name different from that displayed by fltmc volumes for dynamic disks.

fltmc volumes->
C:->\Device\HarddiskDmVolumes\PhysicalDmVolumes\BlockVolume1
QueryDosDevice()->
C:->\Device\HarddiskDmVolumes\Win2k3-32-2Dg0\Volume1

I know that the latter is yet another symbolic link to the former.
What is the correct way to get the first one from a disk letter in the user space?

Thanks in advance,
Greg.

2

Multiple (nested) symbolic links are generally allowed.
You have to keep translating the symbolic link until there
is none.

L.

3

Hi Ladislav,

Thanks for the reply.
If I pass the output of the first QueryDosDevice() to the next, I get an error.
Isn’t it supposed to accept only the drive names like “c:”?

Greg.

4

I solved this problem by opening and querying the symbolic link object -
NtOpenSymbolicLink and NtQuerySymbolicLinkObject. There was a post to this
list some time ago about a better method but I haven’t had the chance to try
it. A search for QueryDosDevice might turn it up.

Bill

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of xxxxx@gmail.com
Sent: Thursday, May 31, 2012 10:24 AM
To: Windows File Systems Devs Interest List
Subject: RE:[ntfsd] QueryDosDevice() for Dynamic Disks

Hi Ladislav,

Thanks for the reply.
If I pass the output of the first QueryDosDevice() to the next, I get an
error.
Isn’t it supposed to accept only the drive names like “c:”?

Greg.

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5

Thanks Bill,

I will try to find it.
In the meantime, it seems that there is a way to do it, albeit a cumbersome one.

  • Enumerate volumes using FilterVolumeFindFirst/Next()
  • Query drive letters using FilterGetDosName()
  • Do the reverse look-up for the drive letter in question

I haven’t checked it yet, but it should work.

Greg.

6

Hi Greg,

I really don’t like QueryDosDevice(). I’d say use the MountMgr interface (if you’re in kernel mode) or the Volume Management Functions (http://msdn.microsoft.com/en-us/library/windows/desktop/aa365730(v=vs.85).aspx) if you’re in user mode (and in particular GetVolumePathNamesForVolumeName() if you actually care about drive letters) .

I have a blog post about this http://fsfilters.blogspot.com/2012/03/volume-names.html where I also have some sample code.

Thanks,
Alex.

7

Great! Thanks Alex.

On May 31, 2012, at 18:01, xxxxx@gmail.com wrote:

Hi Greg,

I really don’t like QueryDosDevice(). I’d say use the MountMgr interface (if you’re in kernel mode) or the Volume Management Functions (http://msdn.microsoft.com/en-us/library/windows/desktop/aa365730(v=vs.85).aspx) if you’re in user mode (and in particular GetVolumePathNamesForVolumeName() if you actually care about drive letters) .

I have a blog post about this http://fsfilters.blogspot.com/2012/03/volume-names.html where I also have some sample code.

Thanks,
Alex.

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8

> I will try to find it.

Use \?\Volume{guid} as unique volume ID.

Do not pay attention to the above-mentioned symlinks, they are the undocumented details.

–
Maxim S. Shatskih
Windows DDK MVP
xxxxx@storagecraft.com
http://www.storagecraft.com

9

Thank Maxim.

On Jun 1, 2012, at 8:50, “Maxim S. Shatskih” wrote:

>> I will try to find it.
>
> Use \?\Volume{guid} as unique volume ID.
>
> Do not pay attention to the above-mentioned symlinks, they are the undocumented details.
>
> –
> Maxim S. Shatskih
> Windows DDK MVP
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
>
> —
> NTFSD is sponsored by OSR
>
> For our schedule of debugging and file system seminars visit:
> http://www.osr.com/seminars
>
> To unsubscribe, visit the List Server section of OSR Online at http://www.osronline.com/page.cfm?name=ListServer