#580798 fuseiso fails to mount .ISZ images

Package:
fuseiso
Source:
fuseiso
Description:
FUSE module to mount ISO filesystem images
Submitter:
Dmitry Katsubo
Date:
2010-05-12 11:48:10 UTC
Severity:
normal
#580798#5
Date:
2010-05-08 17:38:50 UTC
From:
To:
When trying to mount .ISZ image, created by UltraISO, the image cannot
be mounted and the following is reported:

# fuseiso image.isz ./iso
init: wrong standard identifier in volume descriptor 0, skipping..
init: wrong standard identifier in volume descriptor 1, skipping..
init: wrong standard identifier in volume descriptor 2, skipping..
init: wrong standard identifier in volume descriptor 3, skipping..
init: wrong standard identifier in volume descriptor 4, skipping..
init: wrong standard identifier in volume descriptor 5, skipping..
init: wrong standard identifier in volume descriptor 6, skipping..
init: wrong standard identifier in volume descriptor 7, skipping..
init: wrong standard identifier in volume descriptor 8, skipping..
init: wrong standard identifier in volume descriptor 9, skipping..
init: wrong standard identifier in volume descriptor 10, skipping..
init: wrong standard identifier in volume descriptor 11, skipping..
init: wrong standard identifier in volume descriptor 12, skipping..
init: wrong standard identifier in volume descriptor 13, skipping..
init: wrong standard identifier in volume descriptor 14, skipping..
init: wrong standard identifier in volume descriptor 15, skipping..
init: wrong standard identifier in volume descriptor 16, skipping..
init: wrong standard identifier in volume descriptor 17, exiting..

The image can be mounted with UltraISO v9.3.6 and with DaemonTools v4.35.

#580798#10
Date:
2010-05-11 20:12:49 UTC
From:
To:
Hello,

What does file(1) report about image.isz?

However, fuseiso doesn't claim to be able to mount those kind of images.

Kindly,
David

#580798#15
Date:
2010-05-11 21:57:48 UTC
From:
To:
tags 580798 + confirmed
thanks

Hello,

I didn't understand they simply are gzip-compressed-ISOs.
I'm confirming this bug.

Kindly,
David

#580798#22
Date:
2010-05-11 22:39:09 UTC
From:
To:
tags 580798 = wontfix
thanks

Hello,

After some thinking, and brainstorming with some friends on IRC about the issue
and possible solutions, I've come to the conclusion that .isz files
(or .iso.gz, or any similar format) is not efficiently mountable. This is
because, for example, if you want to cat a file, and this happens to be at the
end of the archive, the OS needs to decompress the whole of it before being
able to give it back to the user.

A workaround might be decompressing your .isz, and mount the resulting file, if
it's a proper ISO.

Kindly,
David

#580798#29
Date:
2010-05-12 11:30:49 UTC
From:
To:
Hi David!

You are right: after reading the help again I have realized that fuseiso
really does not claim to support ISZ [1] images - I was confused with
"zisofs" which is RockRidge extension and is not the same as ISZ.

It is possible to mount ISZ files, at least in Windows world there are
two products, that can do it: UltraISO [2] and DaemonTools [3]. I agree,
that as ISZ format was introduced by commercial company there might be
licence problems, etc. But if you talk to EZB Systems folks I am pretty
sure they will be happy to make decoding of ISZ opensource (and maybe
even the compression/decompression utility).

ISZ is not simply gzip-compressed file, as if ISO would have been
compressed like that, you indeed cannot seek the image. The idea is that
the image is divided into fixed-sized blocks (say, 512K) which are
compressed. The offset of each compressed block is saved in a directory,
so if you need to seek to a given sector, it is easy to calculate the
compressed block you need, uncompress it and get the content. Pretty
strightforward to program, and such features as volume splitting and
encrypting may wait for better times.

I have asked the community about the support of this format in Linux
world [4], and it seems like there is no working solution. So fuseiso is
the only hope to support this. Therefore I request you to kindly change
the status of the bug from "issue" to "feature request".

[1] http://www.ezbsystems.com/isz/iszspec.txt
[2] http://en.wikipedia.org/wiki/UltraISO
[3] http://en.wikipedia.org/wiki/Daemon_Tools
[4]
http://superuser.com/questions/139759/how-to-mount-a-compressed-iso-image

David Paleino wrote on 12/05/2010 00:39: