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From: Boba on 8 Feb 2010 13:22
dear all;
is there a way of using CreateFile/ReadFile
for accessing raw data of a compressed file
bypassing invocation of Rtl[De]CompressXxx?
i need it in user level on ntfs3. tia. boba


From: Kerem Gümrükcü on 8 Feb 2010 18:24
AFAIK no, not from usermode. In general
you leave that transparently to the os. Why
you need that,..? AFAIk the compressed data
is packed with LZ77 or some compression
based on that,...

Regards

Kerem

--
-----------------------
Beste Gr�sse / Best regards / Votre bien devoue
Kerem G�mr�kc�
Latest Project: http://www.pro-it-education.de/software/deviceremover
Latest Open-Source Projects: http://entwicklung.junetz.de
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"Boba" <Boba(a)somewhere.net> schrieb im Newsbeitrag
news:u1l2nuOqKHA.3848(a)TK2MSFTNGP06.phx.gbl...
> dear all;
> is there a way of using CreateFile/ReadFile
> for accessing raw data of a compressed file
> bypassing invocation of Rtl[De]CompressXxx?
> i need it in user level on ntfs3. tia. boba
>
>
From: Boba on 8 Feb 2010 22:14
"Kerem G�mr�kc�" <kareem114(a)hotmail.com> wrote in message
news:OB4upXRqKHA.4636(a)TK2MSFTNGP06.phx.gbl...
> AFAIK no, not from usermode.

allow me to disagree with you on that:
nothing prevents me from reading the file
clusters straight off of the disk.

> you leave that transparently to the os. Why
> you need that,..?

i need to increase the performance of some
code by saving time on de/compression.

> AFAIk the compressed data
> is packed with LZ77 or some compression
> based on that,...

yes, a simplified version of LZ77 is just
one of them.

so you think my only choice is to install
a filter, right?


From: Pavel A. on 8 Feb 2010 22:33
"Boba" <Boba(a)somewhere.net> wrote in message
news:u1l2nuOqKHA.3848(a)TK2MSFTNGP06.phx.gbl...
> dear all;
> is there a way of using CreateFile/ReadFile
> for accessing raw data of a compressed file
> bypassing invocation of Rtl[De]CompressXxx?
> i need it in user level on ntfs3. tia. boba
>

FILE_FLAG_BACKUP_SEMANTICS and BackupRead() ?

--pa


From: Boba on 8 Feb 2010 23:10
"Pavel A." <pavel_a(a)12fastmail34.fm> wrote in message
news:9BEC518B-4E98-4DF0-BD7C-71C4F4C637CF(a)microsoft.com...
> ...
> FILE_FLAG_BACKUP_SEMANTICS and BackupRead() ?

no. BackupRead first decompresses the $DATA stream,
then it reads and adds all other streams which makes
it even slower than just reading+decompressing data.
i need to fast copy just the raw data. any thoughts?


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