Re: [Info-mtools] Inconsistent results between kernel vfat and mtools

[Hamish Coleman]

It looks to me like your disc image is subtly corrupted.  When you check it
with fsck.fat, it will show up a bunch of issues.

Given the apparent age of the files on the disc, I would not be surprised
to discover that this came from the time when a lot of the fields in the
superblock were ignored as some of the Operating systems just used hard
coded values.

On Tue, Nov 21, 2023 at 08:39:03AM +0100, Alexander Huemer wrote:
> Hi
> 
> I am observing inconsistent results between the kernel vfat 
> implementation and mtools.
> The image file I am using is [1].
> Here is a simple procedure that shows what I am experiencing.
> 
> Download the image. For simplicity that'll be called 'image.img' below.
> 
> mkdir -p ~/tmp/unpack
> cd ~/tmp/unpack
> mcopy -a ~/image.img -a :: .
> sudo mount -t vfat ~/image.img /mnt
> diff -u <(md5sum *) <(cd /mnt; md5sum *)
> 
> This is the result I am getting:
> 
> --- /dev/fd/63        2023-11-21 07:21:10.930270864 +0000
> +++ /dev/fd/62        2023-11-21 07:21:10.930270864 +0000
> @@ -1,7 +1,7 @@
> -04ab6b3bd6f6689fe102a3531d15e8b1  003290.DSL
> -50bb89afd3ddb2d7fe62946ee0d780f3  013179.dsl
> -14c3e2c6c7c69d69c60e8a43b9c11ae1  023193.dsl
> +b16167d015a5a427088eb0200a5ba051  003290.DSL
> +00cd9c5a6948e029b310615b0fb074c2  013179.dsl
> +b42bd0a7f6cf5a81da57a6008436e5fa  023193.dsl
>  fe80900bee88c24fa11089a9ababcf5e  CSCMCNME.CMD
> -9c21964c22e263063f638630e66560eb  MAINTRK.DIA
> +c94fc15f7efd09966c8bbc7ced0bab9d  MAINTRK.DIA
>  e07b8d18af7fe075c74a220d3a7cda30  MRNLEV.ECN
>  428978ce5c2775926a4a1743b7af602e  VOLUME.LAB
> 
> I believe that the results yielded by vfat are correct and the results 
> yielded by mtools are incorrect.
> 
> Does the image file have some unusual properties that push mtools to 
> undesired behavior? User error? 
> 
> Thanks,
> -Alex
> 
> [1] 
> https://bitsavers.org/bits/IBM/3174/IBM_3174_DSL_FC9021_N52.0/IBM_3174_DSL_FC9021_N52.0.img
> 

-- 
Use Linux!                                                  hamish@zot.org
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