bug#72232: "make dist" is not reproducible

[Pádraig Brady]

On 21/07/2024 17:18, Bruno Haible wrote:
> Hi,
>
> Subsequent runs of "make dist" in the same environment produce tarballs with
> different contents.
>
> How to reproduce:
>
> In a git checkout of coreutils, do:
>
> $ echo snapshot > .tarball-version
> $ ./configure; make -k maintainer-clean
> $ ./bootstrap
> $ ./configure; make dist
> $ mkdir 1; (cd 1 && tar xf ../*.tar.gz)
> $ make; make dist
> $ mkdir 2; (cd 2 && tar xf ../*.tar.gz)
> $ diff -r -q 1 2
>
> The last command produces a difference:
>
> $ diff -r -q 1 2
> Files 1/coreutils-snapshot/.timestamp and 2/coreutils-snapshot/.timestamp differ
> $ cat 1/coreutils-snapshot/.timestamp
> 1721577765
> $ cat 2/coreutils-snapshot/.timestamp
> 1721577832
>
> Can this be avoided? Can the contents of '.timestamp' always be the same?
> (Wouldn't it be enough to give it a different modification time, each time?)

Right, we should be able to adjust this.
The .timestamp file was added to support reproducible _builds_:
https://github.com/coreutils/coreutils/commit/c1b3d6587
https://reproducible-builds.org/docs/source-date-epoch/

We can just rely on the timestamp of the .tarball-version
to support reproducible _tarballs_.
That's done in the attached, which I'll apply later.

Marking this as done.

thanks,
Pádraig

coreutils-repro-dist.patch
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