You can feed absolute garbage to symbolic-ref as a target like:
git symbolic-ref HEAD refs/heads/foo..bar
While this doesn't technically break the repo entirely (our "is it a git
directory" detector looks only for "refs/" at the start), we would never
resolve such a ref, as the ".." is invalid within a refname.
Let's flag these as invalid at creation time to help the caller realize
that what they're asking for is bogus.
A few notes:
- We use REFNAME_ALLOW_ONELEVEL here, which lets:
git update-ref refs/heads/foo FETCH_HEAD
continue to work. It's unclear whether anybody wants to do something
so odd, but it does work now, so this is erring on the conservative
side. There's a test to make sure we didn't accidentally break this,
but don't take that test as an endorsement that it's a good idea, or
something we might not change in the future.
- The test in t4202-log.sh checks how we handle such an invalid ref on
the reading side, so it has to be updated to touch the HEAD file
directly.
- We need to keep our HEAD-specific check for "does it start with
refs/". The ALLOW_ONELEVEL flag means we won't be enforcing that for
other refs, but HEAD is special here because of the checks in
validate_headref().
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
04ede97211