bug#21111: possibly bogus in binary tarball

[ludo@gnu.org (Ludovic Courtès)]

Dave Love <fx@gnu.org> skribis:

> Ludovic Courtès <ludo@gnu.org> writes:
>
>> Interestingly, I do not get this message, both with ‘tar xf’ and
>> ‘tar xvf’ with GNU tar 1.28.
>>
>> I tried with different timezones, and I can’t trigger it.
>>
>> Dave: What version of GNU tar do you use, and in what timezone?
>>
>> TIA,
>> Ludo’.
>
> It was on RHEL6 in the UK zone
>
>   $ grep -I zone /etc/sysconfig/clock
>   ZONE="Europe/London"
>   
> with:
>
>   $ rpm -q tar
>   tar-1.23-11.el6.x86_64
>
> There aren't any obviously-relevant patches in the tar package changelog.

According to the 1.28 manual (info "(tar) warnings"), this specific
warning can be explicitly enabled with --warning=timestamp.

However, I tried variations of the following command with no luck:

  TZ=Europe/London tar --warning=timestamp --extract -f \
    guix-binary-0.8.3.i686-linux.tar.xz

So maybe the fact that 1.28 doesn’t emit the warning is a bug.

> I think it would be worth a note on the timestamps anyway to avoid
> confusion and make sure they're maintained, if they should be.  (Excuse
> me if that's done somewhere, but I just went to the current installation
> instructions.)

I’ve added this to the installation instructions in commit aafa0df:

   Some versions of GNU tar raise a warning about “implausibly old
   time stamps”.  This is because all the files in the archive have
   their modification time set to zero (which means January 1st,
   1970.)  This is done on purpose to make sure the archive content is
   independent of its creation time, thus making it reproducible.

Thanks!

Ludo’.