How to emulate file size

NTFSD
1

Hi, All
I am trying to emulate the file size by trying to catch the
IRP_MJ_QUERY_INFORMATION
then setting its completion routin to IrpQueryCompletion().
In Completion routine we are using
currentIrpStack->Parameters.QueryFile.FileInformationClass
to find the class.
And placing the same FileInformationClass with our virtual
allocationsize and EndofFile in Irp->AssociatedIrp.SystemBuffer.
The obve logic does not seems to be working .
Whats has gone wrong.
What are the ways by which OS can Query File Size.

Thanks & Regards,

2

Look at CcInitializeCacheMap. The file system reports the sizes of
files to the cache manager using this API. This is not done via an IRP
and thus it is outside the ability of a file system filter driver to
modify or change.

Then look at CcSetFileSizes. File systems use this to report the new
(updated) size of a file. Again, this is not done via an IRP and thus
it is outside the ability of a file system driver to modify or change.

Regards,

Tony

Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of rakesh thakur
Sent: Sunday, April 03, 2005 9:21 AM
To: ntfsd redirect
Subject: [ntfsd] How to emulate file size

Hi, All
I am trying to emulate the file size by trying to catch the
IRP_MJ_QUERY_INFORMATION
then setting its completion routin to IrpQueryCompletion().
In Completion routine we are using
currentIrpStack->Parameters.QueryFile.FileInformationClass
to find the class.
And placing the same FileInformationClass with our virtual
allocationsize and EndofFile in Irp->AssociatedIrp.SystemBuffer.
The obve logic does not seems to be working .
Whats has gone wrong.
What are the ways by which OS can Query File Size.

Thanks & Regards,

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

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