Re: Git fails to detect subcommand when hook is symlinked to a builtin

From: Todd Zullinger <tmz@pobox.com>
Date: Mar 19, 2011, 01:14 UTC
Message-ID: <20110319011445.GL26236@inocybe.localdomain>
In-Reply-To: <7vhbb0rkv4.fsf@alter.siamese.dyndns.org>

Junio C Hamano wrote:

Show 9 quoted lines

> I have a suspicion that we may end up saying "don't do that", but
> let's ponder a bit with some technical background first.  The "git"
> wrapper and builtin commands are all the same binary, and as a
> consequence, their main() function needs to decide what to do based
> on argv[0].  If argv[0] is "git", we know argv[1] is the name of the
> subcommand, and if argv[0] is "git-foo", it might be the internal
> call from the "git" wrapper that was invoked with argv[] = { "git",
> "foo", ... }, but we don't expect that argv[0] to be things like
> "post-update".

I can certainly understand that. :)

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> But it is curious why the resulting behaviour changed recently.  The
> symptom hints that the link target (git-update-server-info in your
> case) used to be given as argv[0] (which still wouldn't have been
> kosher---you are not supposed to use dashed form since 1.5.4 or so
> without adding $GIT_EXEC_PATH at the beginning of your $PATH, and
> that is why I said the first sentence in this reply), but we
> recently changed something and now we are getting
> "hooks/post-update" in argv[0].
>
> I suspect the recent change to run hooks via run_command() interface
> has something to do with it.  From what version did you update to
> 1.7.4.1?

I should have mentioned it, but I failed to do so.  Sorry about that.

This was moving from 1.5.5.6 to 1.7.4.1. The packages for EPEL (extra stuff for RHEL/CentOS) lagged behind for quite some time. The fedorahosted.org system was using 1.5.5.6 for a long time with the symlinked post-update hook in place. But it's not necessarily anything that changed recently in git. It could have been changes all the way back in 1.6.0, which seems like an eternity in git time.

We already fixed up the repositories on fedorahosted for this, but I figured I should ask, in case this change was not intended and might catch other folks doing git hosting.

(The only other minor change that caught us was that some of the repos did not have core.bare = true and pushes to these oddly configured repositories failed. Clearly, that was a misconfiguration from the time the repos were setup. Otherwise, for moving from 1.5.5.6 to 1.7.4.1, things went quite smoothly. That's thanks in no small part to the great attention to detail you and the other folks on this list have. Thank you!)

-- 
Todd        OpenPGP -> KeyID: 0xBEAF0CE3 | URL: www.pobox.com/~tmz/pgp
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