reading from file during IRP_MJ_WRITE

NTFSD
1

Hi,
I’m writing versioned filesystem and i want to do the “undo log” of
operations. The way, which i think would be the best, is reading the file
bytes, which will be written. To do this I tried FltReadFile during
preoperation callback routine for IRP_MJ_WRITE, but there was an error
(0xC0000011). I found that code running at DPC/dispatch level can’t wait
on an object, and i think that error was because of it.
My questions are:
Am I rigth?
How can I read from file during IRP_MJ_WRITE?

Waiting for replies,
malgosia

2

Try to build IRP with major code IRP_MJ_READ and send to underlying driver.

Best regards,
Fisyuk Victor
EMail/MSN: xxxxx@rambler.ru
Web: http://rockdbg.siteburg.com

“Malgorzata Bienkowska” wrote in message
news:xxxxx@ntfsd…
> Hi,
> I’m writing versioned filesystem and i want to do the “undo log” of
> operations. The way, which i think would be the best, is reading the file
> bytes, which will be written. To do this I tried FltReadFile during
> preoperation callback routine for IRP_MJ_WRITE, but there was an error
> (0xC0000011). I found that code running at DPC/dispatch level can’t wait
> on an object, and i think that error was because of it.
> My questions are:
> Am I rigth?
> How can I read from file during IRP_MJ_WRITE?
>
> Waiting for replies,
> malgosia
>

3

Did you check what status 0xC0000011 mean? You are getting
STATUS_END_OF_FILE: there is nothing to read yet - the incoming write appends
data to the file.

Thank you,
Alexei.

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com]On Behalf Of Malgorzata
Bienkowska
Sent: Wednesday, March 29, 2006 4:56 AM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] reading from file during IRP_MJ_WRITE

Hi,
I’m writing versioned filesystem and i want to do the “undo log” of
operations. The way, which i think would be the best, is reading the file
bytes, which will be written. To do this I tried FltReadFile during
preoperation callback routine for IRP_MJ_WRITE, but there was an error
(0xC0000011). I found that code running at DPC/dispatch level can’t wait
on an object, and i think that error was because of it.
My questions are:
Am I rigth?
How can I read from file during IRP_MJ_WRITE?

Waiting for replies,
malgosia

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

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

4

Dnia Wed, 29 Mar 2006 14:13:14 -0800, Alexei Jelvis
napisa³:

> Did you check what status 0xC0000011 mean? You are getting
> STATUS_END_OF_FILE: there is nothing to read yet - the incoming write
> appends
> data to the file.

Thanks, I couldn’t find what that error mean (now I know where should i
search it:), if there is nothing in the file why does FltReadFile return
an error and not success and 0 bytes read?
At what level does code of prewrite callback routine run?

Sorry, if my questions are obvious, but it’s my first filesystem, which
i’m writing.
Thanks,
malgosia

>
> Thank you,
> Alexei.
>
> -----Original Message-----
> From: xxxxx@lists.osr.com
> [mailto:xxxxx@lists.osr.com]On Behalf Of Malgorzata
> Bienkowska
> Sent: Wednesday, March 29, 2006 4:56 AM
> To: Windows File Systems Devs Interest List
> Subject: [ntfsd] reading from file during IRP_MJ_WRITE
>
>
> Hi,
> I’m writing versioned filesystem and i want to do the “undo log” of
> operations. The way, which i think would be the best, is reading the file
> bytes, which will be written. To do this I tried FltReadFile during
> preoperation callback routine for IRP_MJ_WRITE, but there was an error
> (0xC0000011). I found that code running at DPC/dispatch level can’t wait
> on an object, and i think that error was because of it.
> My questions are:
> Am I rigth?
> How can I read from file during IRP_MJ_WRITE?
>
> Waiting for replies,
> malgosia
>
> —
> Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@vmware.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>