MemoryMap Application Problem

NTFSD
1

Hi
Could anyone please tell me that appart from IRP_MJ_READ and FastIoRead is there any other way by which memory mapped application can update it’s buffer from it’s mapped file. Is dereferencing (->) to any mapped file can cause IRP_MJ_READ or FastIORead to fire or there has some other way too ?

Thanks
Raghwendra

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2

Memory mapping does not use fast I/O. Only readfile/writefile use the
fast I/O path. Memory mapping, by its very nature, only uses the
in-memory copy of the data.

My guess is that you are missing the paging I/O because the file is
closed by the application before the paging I/O is sent to disk, and you
think that the close by the application somehow means that the file is
no longer in use.

You might want to write a test program to do this: open a file, map it,
close the file, modify the mapping, then watch the behavior in your
filter.

Regards,

Tony

Tony Mason

Consulting Partner

OSR Open Systems Resources, Inc.

http://www.osr.com http:</http:>

From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Raghwendra
Sent: Wednesday, June 01, 2005 7:56 AM
To: ntfsd redirect
Subject: [ntfsd] MemoryMap Application Problem

Hi

Could anyone please tell me that appart from IRP_MJ_READ and FastIoRead
is there any other way by which memory mapped application can update
it’s buffer from it’s mapped file. Is dereferencing (->) to any mapped
file can cause IRP_MJ_READ or FastIORead to fire or there has some other
way too ?

Thanks

Raghwendra

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

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Disclaimer:
The contents of this E-mail (including the contents of the enclosure(s)
or attachment(s) if any) are privileged and confidential material of MBT
and should not be disclosed to, used by or copied in any manner by
anyone other than the intended addressee(s). In case you are not the
desired addressee, you should delete this message and/or re-direct it to
the sender. The views expressed in this E-mail message (including the
enclosure(s) or attachment(s) if any) are those of the individual
sender, except where the sender expressly, and with authority, states
them to be the views of MBT.

This e-mail message including attachment/(s), if any, is believed to be
free of any virus. However, it is the responsibility of the recipient to
ensure that it is virus free and MBT is not responsible for any loss or
damage arising in any way from its use

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3

> You might want to write a test program to do this:

open a file, map it, close the file, modify the mapping,
then watch the behavior in your filter.

Or, use the FIleTest tool from the OSR, it can
do this interactively.

L.