On Wed, Jul 26, 2017 at 05:49:47PM -0700, Junio C Hamano wrote:
> Michael Haggerty <mhagger@xxxxxxxxxxxx> writes:
>
> > I think the most natural thing would be to use different encoding
> > rules for pseudo-refs (references like "HEAD" and "FETCH_HEAD") and
> > for other references (those starting with "refs/").
> >
> > Pseudo-refs (with the partial exception of "HEAD") are quite peculiar
> > beasts....
>
> I agree with the reasoning, but what I am worried about is that
> their handling in the existing refs.c code may be leaky and/or
> inconsistent.
>
> What I saw was that a test have ended up with .git/%46%4F%4F when it
> was told to create a ref "FOO" (which indicates that "FOO" was
> passed to the files backend), which later failed to read it back
> because the pseudo_ref handling refs.c wanted to see ".git/FOO" on
> the reading side.
>
> Perhaps it is only a bug in t/t1405-main-ref-store.sh?
An interesting related issue for pseudo-refs: if you encode HEAD as
.git/%48%45%41%44, how will we recognize that directory as a git
repository? Detecting (and doing a sanity check on) "HEAD" is one of the
key mechanisms for deciding whether we are in a git repository.
Obviously an older version of git that doesn't know about the new
encoding scheme wouldn't work on this repository anyway. But:
1. It should say "this is a git repo, but not a vintage I understand".
Not "this isn't a git repo, I'll keep looking".
2. How does a git version of the correct vintage decide "this is a git
repo, so I'll check its config for extensions.refBackend, and a-ha,
they _do_ have a HEAD". There's a chicken-and-egg problem.
Obviously for (2) we could teach that mechanism to look for the encoded
HEAD file, too. But this is just one backend. What about a reftable or
other non-filesystem store that keeps "HEAD" inside a file?
I kind of wonder if more exotic ref storage backends should always just
place a dummy "HEAD" file that is enough to bootstrap the "this is a git
repo" process (for both new and old versions).
This is orthogonal to the rest of the pseudo-refs discussion, but just
something I thought of while reading the thread.
-Peff
