FltWriteFile and FILE_WRITE_TO_END_OF_FILE

NTFSD
1

Hi, if I use FltWriteFile and wish to append data, can I also use the
following trick which is working for ZwWriteFile ?
“It is also possible to cause a write operation to start at the current end
of file by specifying for ByteOffset a pointer to a LARGE_INTEGER value with
HighPart set to -1 and LowPart set to FILE_WRITE_TO_END_OF_FILE. This works
whether or not the I/O Manager is maintaining the current file position”.

Thanks,

/Daniel

2

Yes, this works.

Ken

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Daniel Terhell
Sent: Friday, December 29, 2006 10:15 AM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] FltWriteFile and FILE_WRITE_TO_END_OF_FILE

Hi, if I use FltWriteFile and wish to append data, can I also use the
following trick which is working for ZwWriteFile ?
"It is also possible to cause a write operation to start at the current end
of file by specifying for ByteOffset a pointer to a LARGE_INTEGER value with

HighPart set to -1 and LowPart set to FILE_WRITE_TO_END_OF_FILE. This works
whether or not the I/O Manager is maintaining the current file position".

Thanks,

/Daniel

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

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3

Just for the record:

I have had some problems with using FILE_WRITE_TO_END_OF_FILE and FltWrite
under one particular version of filtermanager (unfortunately I don’t have
the details as to which version). As I remember the filtermanager code was
looking at the offset, deciding it was too large and refusing to send the
IRP down. I ended up keeping my own end of file cursor so as to be able to
run on all platforms.

Rod