[ros-dev] About ReactOS hive files and end_pages in header being possibly wrong

[Aleksey Bragin]

Hi,
thanks a lot for your comment, I'm quite interested in it!

Certainly, since ReactOS's hive file format [should be] is the same  
as NT one, we need to fix ReactOS. It would be very very helpful if  
you could find other differences.

In the meanwhile, I will try to see that end of last page thing.


WBR,
Aleksey Bragin.


On May 31, 2011, at 4:47 PM, Richard W.M. Jones wrote:

>
> Hi, I'm one of the authors of hivex, a program for reading Windows
> registry hive files:
>
> http://libguestfs.org/hivex.3.html
>
> The library can't currently read ReactOS hive files.  I'm *very*
> hestitant to say anyone is "wrong" here since the documentation for
> hive files is obviously non-existent, but it appears that ReactOS
> doesn't fill in the end_pages field in the header, and instead relies
> on the size of the file itself.
>
> For example, a hive downloaded from a fresh ReactOS install:
>
>   hivex_open: header fields:
>     file version             1.3
>     sequence nos             3 3
>       (sequences nos should match if hive was synched at shutdown)
>     original file name
>       (only 32 chars are stored, name is probably truncated)
>     root offset              0x70 + 0x1000
> **  end of last page         0x1000 + 0x1000 (total file size 0x22000)
>     checksum                 0x8dc38fdf (calculated 0x8dc38fdf)
>
> Notice that "end of last page" field is 0x1000, versus a completely
> different file size.
>
> hivex currently refuses to read past the end_pages limit, and we are
> able to read every Windows hive that has ever been thrown at us.
>
> If I hack hivex so that it ignores end_pages and simply uses the size
> of the file as a guide, then hivex can successfully read the whole of
> the file.
>
> However I'm a bit unwilling to make this change to hivex just for
> ReactOS, since it works fine with real Windows already.
>
> So I wonder if this could just be a mistake in ReactOS or if there's
> some deeper reason that I'm missing.
>
> TIA,
>
> Rich.
>
> -- 
> Richard Jones, Virtualization Group, Red Hat http:// 
> people.redhat.com/~rjones
> virt-df lists disk usage of guests without needing to install any
> software inside the virtual machine.  Supports Linux and Windows.
> http://et.redhat.com/~rjones/virt-df/
>
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