Re: [PATCH 1/1] worktree refs: fix case sensitivity for 'head'

[Jacob Keller <jacob.keller@gmail.com>]

On Fri, Dec 14, 2018 at 9:47 AM Duy Nguyen <pclouds@gmail.com> wrote:
>
> On Fri, Dec 14, 2018 at 6:38 PM Duy Nguyen <pclouds@gmail.com> wrote:
> >
> > On Fri, Dec 14, 2018 at 6:22 PM Jacob Keller <jacob.keller@gmail.com> wrote:
> > >
> > > On Thu, Dec 13, 2018 at 11:38 PM Duy Nguyen <pclouds@gmail.com> wrote:
> > > > Even with a new ref storage, I'm pretty sure pseudo refs like HEAD,
> > > > FETCH_HEAD... will forever be backed by filesystem. HEAD for example
> > > > is part of the repository signature and must exist as a file. We could
> > > > also lookup pseudo refs with readdir() instead of lstat(). On
> > > > case-preserving-and-insensitive filesystems, we can reject "head" this
> > > > way. But that comes with a high cost.
> > > > --
> > > > Duy
> > >
> > > Once other refs are backed by something that doesn't depend on
> > > filesystem case sensitivity, you could enforce that we only accept
> > > call-caps HEAD as a psuedo ref, and always look up other spellings in
> > > the other refs backend, though, right?
> >
> > Hmm.. yes. I don't know off hand if we have any pseudo refs in
> > lowercase. Unlikely so yes this should work.
>
> One thing we could do _today_ without waiting for a new refs backend
> is, avoid looking up pseudo refs if the given ref name is not
> all-caps. So "head" (or hEAd) can match refs/head, refs/tags/head,
> refs/heads/head but never $GIT_DIR/HEAD. And yes I checked the code,
> pseudo refs must be all-caps.
> --
> Duy

Right, I think that's a good start, at least for these pseudo refs. It
doesn't solve the more general case of refs mismatching, but it
prevents the obvious one where case actually matters, by preventing
head from looking up as HEAD.

Thanks,
Jake