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

On Fri, Dec 14, 2018 at 6:22 PM Jacob Keller <jacob.keller@xxxxxxxxx> wrote:
> On Thu, Dec 13, 2018 at 11:38 PM Duy Nguyen <pclouds@xxxxxxxxx> 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.

> So, yea the actual file may not
> be case sensitive, but we would never create refs/head anymore for any
> reason, so there would be no ambiguity if reading the refs/head vs
> refs/HEAD on a case insensitive file system, since refs/head would no
> longer be a legitimate ref stored as a file if you used a different
> refs backend.
> Basically, we'd be looking up HEAD by checking the file, but we'd stop
> looking up head, hEAd, etc in the files, and instead use whatever
> other refs backend for non-pseudo refs. Thus, it wouldn't matter,
> since we'd never actually lookup the other spellings of HEAD as a
> file. Wouldn't that solve the ambiguity, at least once a repository
> has fully switched to some alternative refs backend for non-pseudo
> refs? (Unless I mis-understand and refs/head could be an added pseudo
> ref?)

No I think "pseudo refs" are those outside "refs" directory only. So
"refs/head" would be a "normal" ref.

> Jake