genisoimage: add feature to create md5sum.txt/sha1sum.txt/other checksum file

Bug #481866 reported by zzz on 2009-11-13
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
cdrkit (Ubuntu)
Undecided
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Bug Description

Copied verbatim from a really old upstream wishlist request on mkisofs.

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=338830

Ubuntu CDs presumably pre-calculate the MD5SUMs before putting the file in the iso, but as this feature request states: it is wasteful to have to read all the files once to generate the checksum and then again to generate the iso, it'd be good to support on-the-fly creation.

https://help.ubuntu.com/community/HowToMD5SUM#MD5SUM%20on%20CD

---

It is very convenient to be able to check that the contents of a CD or
DVD are still intact by having an md5sum.txt file at the root of the
filesystem. Creating the file can, however, be somewhat cumbersome, and
also requires reading all the data twice: once for generating the checksums,
then to generate the disk image. It would be wonderful if mkisofs could
do it on the fly. Something like this:

    mkisofs -checksum-file md5sum.txt -checksum-type md5 ...

Obviously it would be good to be able to specify other checksum types
than MD5, but even just that would be good enough: this feature is meant
for checking that there is no disk corruption, not as a safeguard against
tampering or counterfeiting, and MD5 is certainly good enough to detect
corruption.

I would not even be against creating the checksum file automatically,
unless there is already a file by that name, but this may be too fancy
for many people.

To clarify, since someone asked me about this on irc: the point of the
checksum file is to make it possible to check that a disk and its files
are still working after, say, the disk has been stored for several years
in a cabinet or used as the cat's scratching post. If there is a proper
md5sum.txt file one can do this:

 cd /cdrom && md5sum -c md5sum.txt

That's quite a convenient way of doing it.

Schily (schilling-fokus) wrote :

What do you expect from such a feature?

Should this feature be compatible with the overall design of mkisofs?

There is a patch that definitely is not compatible with the design of
mkisofs as the patch will not work with mkisofs ... | cdrecord ....
Mkisofs is designed to work completely without calling lseek()
for this reason and this does not apply to the patch.

Another important question would be: why do you approach
Ubuntu? There is no development at Ubuntu and the fork
in addition is dead since 2.5 years. The development only
happens in the original software that is here:

ftp://ftp.berlios.de/pub/cdrecord/alpha/

http://cdrecord.berlios.de/

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