From: ludo@gnu.org (Ludovic Courtès)
To: Mark H Weaver <mhw@netris.org>
Cc: guix-devel@gnu.org
Subject: Re: Timestamps in tarballs created by 'patch-and-repack'
Date: Wed, 15 Jul 2015 16:30:19 +0200 [thread overview]
Message-ID: <87k2u1mr2c.fsf@gnu.org> (raw)
In-Reply-To: <87lheithka.fsf@netris.org> (Mark H. Weaver's message of "Tue, 14 Jul 2015 20:01:25 -0400")
Mark H Weaver <mhw@netris.org> skribis:
> Mark H Weaver <mhw@netris.org> writes:
>
>> Mark H Weaver <mhw@netris.org> writes:
>>
>>> However, this raises a deeper problem: all of the outputs of
>>> 'patch-and-repack' contain non-deterministic timestamps, and these
>>> timestamps can cause problems with future builds.
>>>
>>> Would it be sufficient to simply zero out all of the timestamps before
>>> repacking?
>>
>> I looked into this a bit more. In addition to timestamps, the other
>> impure bits getting into tar files are the names and numeric ids of the
>> owner and groups. Section 4.3.1 (Overriding File Metadata) of the GNU
>> tar manual describes how to override these when creating an archive.
>>
>> My guess is that the following options would be sufficient to make the
>> generated tar archives deterministic:
>>
>> --mtime=@0 --owner=root:0 --group=root:0
>
> This seems to work well, so I've added these flags when creating
> tarballs in commits 2e9511dfbdb5ddd78c2f205c4ca7fc23738d79f8 and
> c09e6a5f5e2a77beff89d68069f3037c1b6310e5 in core-updates.
That sounds like the right thing (it’s also what is used in
gnu/system/install.scm for the binary tarball.)
Thanks for noticing and fixing it!
Ludo’.
prev parent reply other threads:[~2015-07-15 14:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-14 19:15 Timestamps in tarballs created by 'patch-and-repack' Mark H Weaver
2015-07-14 20:25 ` Mark H Weaver
2015-07-15 0:01 ` Mark H Weaver
2015-07-15 14:30 ` Ludovic Courtès [this message]
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