misleading timestamps in binnmus

[Niko Tyni]

On Thu, Nov 10, 2016 at 10:34:33AM +0000, Holger Levsen wrote:
> On Thu, Nov 10, 2016 at 08:24:38AM -0200, Johannes Schauer wrote:
> > > I certainly hope it's part of the .buildinfo file as well, else, for
> > > reproducing binNMUs we would also need to store the .changes files in an
> > > easily accessable manner… (which we plan to do for .buildinfo files, but
> > > not for .changes files atm…)
> > 
> > for binary-only uploads, dpkg-genbuildinfo will add the Binary-Only-Changes
> > field to the .buildinfo file which contains the text of the last changelog
> > entry together with the maintainer name and date.
> 
> can someone please point at a real life/archive example of such a file?
> (a binNMU .changes file with Binary-Only-Changes field…)

That's in the .buildinfo file (not .changes), and I don't think they are
stored in the archive yet? But just try building a binNMU with sbuild
and look at the resulting .buildinfo. Something like

  sbuild --make-binNMU="test rebuild" -m"Niko Tyni <ntyni at debian.org>" --binNMU=2 libxml-parser-perl_2.44-2

results in a .buildinfo file with

  Format: 0.1
  Source: libxml-parser-perl (2.44-2)
  Binary: libxml-parser-perl
  Architecture: amd64
  Version: 2.44-2+b2
  Binary-Only-Changes:
   libxml-parser-perl (2.44-2+b2) unstable; urgency=low, binary-only=yes
   .
     * Binary-only non-maintainer upload for amd64; no source changes.
     * test rebuild
   .
    -- Niko Tyni <ntyni at debian.org>  Tue, 05 Jul 2016 21:55:41 +0200
  Checksums-Md5:
 [...]

> I'm still confused, thinking that this Binary-Only-Changes field needs
> to be assembled into a file, called changelog.$arch, which is then put
> into the debian directory of the unpacked source package. (And which is
> then not included in the resulting binary packages…)

When asked to make a binNMU, sbuild will append an entry to
debian/changelog in the source, containing "binary-only=yes". During
package build, dh_installchangelogs (so debhelper not dpkg!) will
then extract that debian/changelog entry and install that in the
binary package as /usr/share/doc/<package>/changelog.Debian.<arch>,
separately from the rest of the changelog which goes to
/usr/share/doc/<package>/changelog.Debian. (This is done to not break
M-A:same coinstallability.)

As Johannes wrote, dpkg-genbuildinfo will also read debian/changelog in
the source and write out a corresponding Binary-Only-Changes field in the
resulting .buildinfo if the changelog entry contains "binary-only=yes".

To reproduce a binNMU from a .buildinfo file, one would need to parse
the Binary-Only-Changes field and extract the parts that needs to be
passed to sbuild. This currently seems rather fragile as noted by Ian
in #843773: the binNMU version needs to be parsed from the +bX notation,
and the message needs to be separated from the "Binary-only [...]" text
that's hardcoded in sbuild and might even change in the future. And then
there's the timestamp issue where I'll defer to others :)

But all that seems fixable on the sbuild side, and I think Johannes is
actively working on this stuff (thanks!)

Hope this clarifies a bit,
-- 
Niko Tyni   ntyni at debian.org