Re: reproducible tar archives

[Bruno Haible]

Simon Josefsson wrote:
> 1) Some of the suggested flags probably requires a newer GNU tar.  ...
> running 'make distcheck' on old
> systems is useful for ironing out platform-dependent problems.

I always run
  - 'make distcheck' only on my development machine,
  - 'make check' on various platforms.
What is the kind of bugs I could detect by running 'make distcheck'
on Alpine Linux or Android?

> 2) Some choices may be opinionated, but I'm not sure which ones.  Maybe
> PAX archives as in --format=posix?  I recall seeing some people
> recommend --format=ustar for greater compatibility

I use --format=ustar because I want the oldest (= most compatible) format
that fits my needs.
  - The default is --format=v7 (with Automake).
  - But with it I got errors such as
    tar: 
gettext-0.19.8.1.74-72e49-dirty/gettext-tools/gnulib-tests/test-term-ostream-xterm-linux-mandriva.out:
 file name is too long (max 99); not dumped
    tar: 
gettext-0.19.8.1.74-72e49-dirty/gettext-runtime/intl-csharp/doc/GNU_Gettext_GettextResourceManager.html:
 file name is too long (max 99); not dumped

Looking at [1], --format=posix brings only features that most GNU package
tarballs will never need.

> +             touch -m -d @"$$(git log -1 --format=%ct)" $(srcdir)/NEWS; \

Looks fine to me. --format=%ct prints the CommitDate, as seconds since the
Epoch.

Bruno

[1] https://www.gnu.org/software/tar/manual/html_node/Formats.html