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  • From: Bor Kraljič <pyrobor AT ver.si>
  • To: sm-discuss AT lists.ibiblio.org
  • Subject: Re: [SM-Discuss] libpng 1.4 devel branch
  • Date: Wed, 22 Sep 2010 16:33:54 +0200

Is there any progress ? I think quite few of us tested libpng14 tested it and
report problems and solve most of them. What needs to be tested before the
merge into the test grimoire ? Any idea when the merge will happen ?

regards,
Bor

On Wednesday 11 of August 2010 16:57:36 Remko van der Vossen wrote:
> Hi everyone,
>
> SHORT VERSION
>
> Please test libpng 1.4:
> - scribe add libpng from
> git://download.sourcemage.org/smgl/grimoire.git:libpng:devel-libpng
> - cast libpng
> - report success and failure on the wiki page
>
> For more info see: http://sourcemage.org/Grimoire/libpng14
>
> LONG VERSION
>
> libpng 1.4 has been out for a while now, but upgrading to 1.4 isn't as
> easy as any old version bump. The problem is that 1.4 is both API as
> well as ABI incompatible with 1.2. This means that we need to develop a
> seemless upgrade path where all spells that need a recast will be recast
> upon a libpng upgrade. Additionally we need to find and fix any spells
> that are incompatible with libpng 1.4.
>
> The libpng spell was made multiversion for both 1.2 and 1.4 in master.
> This has been reverted in lieu of a devel-libpng git branch for several
> reasons, (disclaimer; this is just my opinion, feel free to disagree):
>
> 1. The spell didn't include any upgrade path, if a user simply did a
> cast libpng all dependees of libpng (even indirect ones due to the
> lovely libtool mess) would break because they can't link to
> libpng12.so.0 which is suddenly gone. Users can't be expected to
> run a cast -B -c for a simple spell upgrade. And of course even if
> they were it wouldn't happen on a sorcery -s and then still our
> dependency tree isn't as complete as it should be, so a cast -B
> could easily miss spells that need to be recast.
>
> 2. libpng 1.4 should not go to stable grimoire as long as there are
> spells that fail on it. Meaning that the libpng commit, as well as
> all related fix commits of other spells would need to be reverted
> each time a stable-rc is branched off as long as we aren't done
> with libpng testing.
>
> 3. By making the libpng spell multiversion we need to support both
> version 1.2 and 1.4. So instead of just making sure the other
> spells work with 1.4 we need to also have it keep working with
> 1.2. By moving the libpng development to a git branch and simply
> doing a straight upgrade instead of a multiversion we sidestep
> this issue.
>
> 4. Test grimoire ins't a dumping ground for new developments, yes,
> test can from time to time contain things that don't work,
> especially compatibiluty problems between upgraded spells and
> other spells, that is what test is for. But we shouldn't knowingly
> put broken spells, or spells with known collateral damage into
> test. This is such a case; this is an ABI and API incompatible
> upgrade of a package which a lot of other packages depend on
> directly or indirectly, we expect major breakage here. We need to
> flesh out most of the problems we expect to see before we shoot it
> out to a larger audience.
>
> So, I made a devel-libpng branch, and in it updated the libpng spell to
> version 1.4.3 and included an UP_TRIGGERS script that checks all
> installed spells for ELF dynamic objects that link to libpng and
> triggers a cast self on those that do.
>
> I tested it on my home box, and found a few spells incompatible with
> libpng 1.4 and fixed as much as I could. The current status can be found
> on the libpng 1.4 wiki project page:
>
> http://sourcemage.org/Grimoire/libpng14
>
> Please help out and test the devel-libpng14 branch, let's prove we can
> work with branches effectively. All you need to do is install a grimoire
> based on the devel-libpng branch as described in the short version above
> and cast libpng. Naturally if you already have a git based repo you can
> also just switch it to the libpng branch.
>
> Please report any success and failure on the wiki page. And if you can
> and have the time, please commit any libpng 1.4 related fixes to the
> devel-libpng branch. see http://sourcemage.org/Git_Guide for info on
> working with git branches.
>
> Regards,
>
> Remko van der Vossen
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