Re: [PATCH 11/12] receive-pack: treat namespace .have lines like alternates

From: Lukas Fleischer <lfleischer@lfos.de>
Date: Jan 27, 2017, 17:45 UTC
Message-ID: <148553912610.7898.1319453517642036857@typhoon>
In-Reply-To: <xmqqa8aec40a.fsf@gitster.mtv.corp.google.com>

On Wed, 25 Jan 2017 at 20:51:17, Junio C Hamano wrote:

Show 18 quoted lines

> [...]
> > diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
> > index 8f8762e4a..c55e2f993 100644
> > --- a/builtin/receive-pack.c
> > +++ b/builtin/receive-pack.c
> > @@ -251,8 +251,9 @@ static void show_ref(const char *path, const unsigned char *sha1)
> [...]
> >       if (ref_is_hidden(path, path_full))
> [...]
> This is an unrelated tangent, but there may want to be a knob to
> make the code return here without even showing, to make the
> advertisement even smaller and also to stop miniscule information
> leakage?  If the namespaced multiple projects are totally unrelated
> (i.e. "My sysadmin gave me a write access only to this single
> directory, so I am using the namespace feature to host these three
> projects that have nothing to do with each other"), showing objects
> of other namespaces will buy us nothing and the user is better off
> without this code showing these refs as ".have".

I think this is already possible using receive.hideRefs (which causes the ref_is_hidden() branch above to return if applicable).

Having support for suppressing .have lines corresponding to different namespaces was actually the reason I implemented 78a766ab6 (hideRefs: add support for matching full refs, 2015-11-03). We have been using namespaces for hosting the package Git repositories of the Arch Linux User Repository [1] with a shared object storage for several months now. See [2] for *some* technical details on how things are implemented; the last section explains how the hideRefs mechanism can be used to limit ref advertisement to the "active" namespace.

Regards, Lukas

[1] https://aur.archlinux.org/ [2] https://git.archlinux.org/aurweb.git/plain/doc/git-interface.txt