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Re: Ghost items in the end of a dir listing

To: xfs@xxxxxxxxxxx
Subject: Re: Ghost items in the end of a dir listing
From: Felipe Monteiro de Carvalho <felipemonteiro.carvalho@xxxxxxxxx>
Date: Thu, 4 Sep 2014 12:14:39 +0200
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Hello,

No ideas about this? =(

Any kind of tip would be really appreciated =)

thanks,

Felipe Monteiro de Carvalho

On Wed, Aug 27, 2014 at 12:20 PM, Felipe Monteiro de Carvalho
<felipemonteiro.carvalho@xxxxxxxxx> wrote:
> Hello,
>
> I am writing a program that reads XFS partitions and I am having
> trouble with some dir listings. In some directories in the block that
> starts with XD2B there is first the list of all directory items, which
> I read without problems, and then there is a free item, for example:
>
>   xfs_dir2_data_unused
>     freetag -> XFS_DIR2_DATA_FREE_TAG */
>     length -> 9A0
>     tag -> zero
>
> But after this free item there is still room in the block, so my
> program will try to read the next item. I cannot stop the reading
> because it is possible to have valid items, then a free item and then
> more valid items.
>
> The next item start might be something like:
>
> 00 00 00 2E 00 00 00 02 16
>
> So it is not a free item, as it doesn't start with FF = XFS_DIR2_DATA_FREE_TAG
> But it isn't valid either, as its name is a bunch of trash =(
>
> So my questions are:
> 1> What are those ghost items in the end of the block?
> 2> Which criteria should be utilized to differentiate them from valid
> items? I tried some guesses but nothing really works so far...
>
> Here are screenshots of the actual data involved, here showing the
> item with XFS_DIR2_DATA_FREE_TAG:
>
> http://magnifier.sourceforge.net/temp/xfs/xfs_dir_listing_XD2B_FREE_item.png
>
> And here showing the area in the end of the block with wierd items:
>
> http://magnifier.sourceforge.net/temp/xfs/xfs_dir_listing_XD2B_after_FREE.png
>
> thanks for any tips =)
> --
> Felipe Monteiro de Carvalho



-- 
Felipe Monteiro de Carvalho

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