Re: [PATCH 1/2] config: allow config_with_options() to handle any repo

From: Matheus Tavares Bernardino <matheus.bernardino@usp.br>
Date: Aug 29, 2019, 16:44 UTC
Message-ID: <CAHd-oW6JdTSWHy6UwGhL5PUoiscayh9xVqs5ktsXzotg_vexmQ@mail.gmail.com>
In-Reply-To: <20190829140013.GC1797@sigill.intra.peff.net>

On Thu, Aug 29, 2019 at 11:00 AM Jeff King <peff@peff.net> wrote:

Show 19 quoted lines

>
> On Thu, Aug 29, 2019 at 04:31:34PM +0700, Duy Nguyen wrote:
>
> > > If so, how could we get R there? I mean, we could pass it through this
> > > chain, but the chain already passes a "struct config_options", which
> > > carries the "commondir" and "git_dir" fields. So it would probably be
> > > confusing to have them and an extra repository parameter (which also
> > > has "commondir" and "git_dir"), right? Any ideas on how to better
> > > approach this?
> >
> > I would change 'struct config_options' to carry 'struct repository'
> > which also contains git_dir and other info inside. Though I have no
> > idea how big that change would be (didn't check the code). Config code
> > relies on plenty callbacks without "void *cb_data" so relying on
> > global state is the only way in some cases.
>
> I'm not sure about that, at least for this particular git_pathdup(). We
> pass along the git_dir because we might not have a repository struct yet
> (i.e., when reading config before repo discovery has happened).

Yes, I think read_early_config(), for example, may call config_with_options() before the_repo is initialized.

> So it might be that this case should actually be making a path out of
> $git_dir/config.worktree (but I'm not 100% sure, as I don't know the ins
> and outs of worktree config files).

Makes sense, config.worktree files are per-worktree, which have different git_dir's, right?

Show 6 quoted lines

> I'm sure there are other gotchas in the config code, though, related to
> things for which we _do_ need a repository. E.g., include_by_branch()
> looks at the_repository, and should use a repository struct matching the
> git_dir we're looking at (though it may be acceptable to bail during
> early pre-repo-initialization config and just disallow branch includes,
> which is what happens now).

I think config_with_options() is another example of a place where we should have a reference to a repo (but we currently don't). When configuring from a given blob, it will call git_config_from_blob_ref(), which calls get_oid() and read_object_file(). Both of these functions will use the_repo by default. But the git_dir and commondir fields passed to config_with_options() through 'struct config_options' may not refer to the_repo, right?

I'm not sure what is the best solution to this, though. I mean, we could add a 'struct repository' in 'struct config_options', but as you already pointed out, some callers might not have a repository struct yet...

> -Peff