Hi Tim,

Sorry for the delay!

Tim Gesthuizen <tim.gesthuizen@yahoo.de> skribis:

> as discussed before I have looked into the problems of timestamps in the
> zip files.
> I looked at the way this is solved in ant-build-system with jar files
> and thought that this could be done in a more elegant way.
> Because of this I wrote a simple frontend for LibArchive in C that
> repacks archives and sets their timestamps to zero and disables
> compression as it is done in the ant-build-system.
> Creative as I am the program is called repack.
> You find a git repository attached with the history of the repack program.
> The attached patches add repack to Guix and use it for pwsafe and the
> ant-build-system.

Nice work!  It’s great that libarchive doesn’t need to actually extract
the zip file to operate on it.

Overall I think the approach of factorizing archive-timestamp-resetting
in one place and using it everywhere (‘ant-build-system’ and all) is the
right thing to do.

However, I’m not sure whether we should introduce a new program for this
purpose.  I believe ‘strip-nondeterminism’¹ (in Perl) by fellow
Reproducible Builds hackers also addresses this problem, so it may be
wiser to use it.

But really, since (guix build utils) already implements a significant
subset of ‘strip-nondeterminism’, it would be even better if could avoid
to shell out to a C or Perl program.

I played a bit with this idea and, as an example, the attached file
allows you to traverse the list of entries in a zip file (it uses
‘guile-bytestructures’).  Specifically, you can get the list of file
names in a zip file by running:

  (call-with-input-file "something.zip"
    (lambda (port)
      (fold-entries cons '() port)))

Resetting timestamps should be just as simple.

How about taking this route?

Thanks,
Ludo’.

¹ https://salsa.debian.org/reproducible-builds/strip-nondeterminism