Filter Manager: Opening a handle using MY filter instance

NTFSD
1

Is it possible to get a file handle thru FltCreateFile which will re-enter
MY filter instance, not be passed down the chain (as passing my own Instance
would), nor restarting at the top (as passing NULL would)?

The reason I want to do this is that my name canonicalisation callback is
logically equivalent to my filter’s implementation of
ZwQueryDirectoryFile( …, FileNamesInformation, …) and the code would be
far simpler and easier to maintain if I could simply CALL
ZwQueryDirectoryFile, knowing it will come to me. For now, I am passing a
NULL Instance parameter, trusting it to be passed thru, but I suspect I am
exposing myself to some risk here.

Brian

2

No, there is no way to do this. The best I can suggest is to have a
common routine which both your name canonicalisation callback and your
QueryDirectory, FileNamesInformation callback call.

Thanks,
Molly Brown
Microsoft Corporation

This posting is provided “AS IS” with no warranties and confers no
rights.

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Brian Collins
Sent: Tuesday, June 01, 2004 1:32 AM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] Filter Manager: Opening a handle using MY filter
instance

Is it possible to get a file handle thru FltCreateFile which will
re-enter MY filter instance, not be passed down the chain (as passing my
own Instance would), nor restarting at the top (as passing NULL would)?

The reason I want to do this is that my name canonicalisation callback
is logically equivalent to my filter’s implementation of
ZwQueryDirectoryFile( …, FileNamesInformation, …) and the code would
be far simpler and easier to maintain if I could simply CALL
ZwQueryDirectoryFile, knowing it will come to me. For now, I am passing
a NULL Instance parameter, trusting it to be passed thru, but I suspect
I am exposing myself to some risk here.

Brian

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

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3

Thanks Molly.

I guessed that - but I thought it worth asking just in case.

Brian

“Molly Brown” wrote in message
news:xxxxx@ntfsd…
No, there is no way to do this. The best I can suggest is to have a
common routine which both your name canonicalisation callback and your
QueryDirectory, FileNamesInformation callback call.

Thanks,
Molly Brown
Microsoft Corporation

This posting is provided “AS IS” with no warranties and confers no
rights.

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Brian Collins
Sent: Tuesday, June 01, 2004 1:32 AM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] Filter Manager: Opening a handle using MY filter
instance

Is it possible to get a file handle thru FltCreateFile which will
re-enter MY filter instance, not be passed down the chain (as passing my
own Instance would), nor restarting at the top (as passing NULL would)?

The reason I want to do this is that my name canonicalisation callback
is logically equivalent to my filter’s implementation of
ZwQueryDirectoryFile( …, FileNamesInformation, …) and the code would
be far simpler and easier to maintain if I could simply CALL
ZwQueryDirectoryFile, knowing it will come to me. For now, I am passing
a NULL Instance parameter, trusting it to be passed thru, but I suspect
I am exposing myself to some risk here.

Brian

—
Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: xxxxx@windows.microsoft.com
To unsubscribe send a blank email to xxxxx@lists.osr.com