linux-ext4 - Re: Which features should I implement in my ext4 reader?

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Message-ID: <CACyNnZOXOZ-uL+TO8HOuO4DoWsBKuBOX5RLQrZzyoeG1L2a9yg@mail.gmail.com>
Date:	Wed, 28 Aug 2013 22:09:42 +0200
From:	Felipe Monteiro de Carvalho <felipemonteiro.carvalho@...il.com>
To:	Felipe Monteiro de Carvalho <felipemonteiro.carvalho@...il.com>,
	"Theodore Ts'o" <tytso@....edu>, linux-ext4@...r.kernel.org
Subject: Re: Which features should I implement in my ext4 reader?

Hello,

Any idea where to find the extra data over 60 bytes in a very small
file (for example 120 bytes) would be greatly appreciated ... I
already tried the extra space after the inode but there was nothing
useful there! =/ Or at least nothing that matched the description of
the extended attributes. It should start with a magic number, but
started with many zeroes =/

thanks,

Felipe Monteiro de Carvalho

On Fri, Aug 23, 2013 at 2:54 PM, Felipe Monteiro de Carvalho
<felipemonteiro.carvalho@...il.com> wrote:
> Hello,
>
> I went forward trying to implement this myself, but I am having trouble.
>
> Files up to 60 bytes work great, and large files too. But a file with
> 61 bytes does not.
>
> Reading ignoring the inline results in zero on all bytes, which can't
> be right, so I guess it is inlined.
>
> After the first 60 bytes I try to get the extended attribute, but
> i_file_acl_lo == FData.l_i_file_acl_high == 0
>
> And I think that it cannot possibly have the extended attribute data
> in block zero =/ (it contains DEADBEEF or something like that)
>
> Any ideas where I got this wrong or any tips about how to figure out
> in debugfs where the data is?
>
> thanks,
> --
> Felipe Monteiro de Carvalho



-- 
Felipe Monteiro de Carvalho
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