Re: [Bug-xorriso] libisofs: unsupported ECMA-119 feature (interleaved mode)

[Jonathan Dowland]

On Tue, Sep 24, 2019 at 08:34:59PM +0200, Thomas Schmitt wrote:
> Thanks for reporting.

You're welcome — we've interacted on debian-user before, and it's always
a pleasure.

> So even if you are willing to send me the whole image of 6 GB, it is
> questionable whether i will learn anything from it. (If you give me an URL
> i will download it, just for curiosity.)

I will have to look carefully at what is likely on the disc but if I can
share it with you, I will. It's possible it has confidential stuff on it
which would prevent me from doing so unfortunately. At the very least I
hope to establish exactly what software I used to write it.

I'm putting it back in my reader so I can poke at it a bit more over the
next few days.

> > DVD-R DL
>
> Those are rare. DVD+R DL are more often to see. But also not very reliable
> to my experience.

You're quite right, I just double-checked and they are DVD+R DLs.

> libburn reports to libisoburn a readable image size of about 75% of what
> the ISO Primary Volume Descriptor tells as filesystem size. So this does not
> coincide with a plausible layer limit.

Hmm ok.

> I dare to state that xorriso command -check_media is a sincere competitor
> to ddrescue:

Thanks for sharing! I'm going to add this to my draft articles on disc
importing as an alternative to ddrescue:
   https://jmtd.net/computing/imaging_discs/

>  xorriso -outdev /dev/sr0 \
>          -check_media \
>             use=outdev \
>             what=disc \
>             time_limit=7200 \
>             abort_file=/tmp/stop_check_media \
>             data_to="$HOME"/sr0_image.iso \
>             sector_map="$HOME"/sr0_image.map \
>             --
>
> This will copy readable blocks to their proper position in file
>  "$HOME"/sr0_image.iso
> and record the successfuly retrieved blocks in file
>  "$HOME"/sr0_image.map

Added to my TODO list is to check the format of the .map file. I wrote
some software "badiso" that uses xorriso in the background to match file
names to LBAs, and then correlates that with ddrescue's .log file
format, to tell you which files are corrupted or not:

   https://jmtd.net/software/badiso/

I would like to support xorriso's .map file format too, if it differs.

> The run will last at most 7200 seconds or until you touch file
>  /tmp/stop_check_media

The timeout behaviour is a very good idea. The lack of such a thing in
ddrescue really made automating or batching lots of disc imports very
hard.

--
Jonathan Dowland