We sometimes call lock_ref_sha1_basic with REF_NODEREF
to operate directly on a symbolic ref. This is used, for
example, to move to a detached HEAD, or when updating
the contents of HEAD via checkout or symbolic-ref.
However, the first step of the function is to resolve the
refname to get the "old" sha1, and we do so without telling
resolve_ref_unsafe() that we are only interested in the
symref. As a result, we may detect a problem there not with
the symref itself, but with something it points to.
The real-world example I found (and what is used in the test
suite) is a HEAD pointing to a ref that cannot exist,
because it would cause a directory/file conflict with other
existing refs. This situation is somewhat broken, of
course, as trying to _commit_ on that HEAD would fail. But
it's not explicitly forbidden, and we should be able to move
away from it. However, neither "git checkout" nor "git
symbolic-ref" can do so. We try to take the lock on HEAD,
which is pointing to a non-existent ref. We bail from
resolve_ref_unsafe() with errno set to EISDIR, and the lock
code thinks we are attempting to create a d/f conflict.
Of course we're not. The problem is that the lock code has
no idea what level we were at when we got EISDIR, so trying
to diagnose or remove empty directories for HEAD is not
useful.
To make things even more complicated, we only get EISDIR in
the loose-ref case. If the refs are packed, the resolution
may "succeed", giving us the pointed-to ref in "refname",
but a null oid. Later, we say "ah, the null oid means we are
creating; let's make sure there is room for it", but
mistakenly check against the _resolved_ refname, not the
original.
We can fix this by making two tweaks:
1. Call resolve_ref_unsafe() with RESOLVE_REF_NO_RECURSE
when REF_NODEREF is set. This means any errors
we get will be from the orig_refname, and we can act
accordingly.
We already do this in the REF_DELETING case, but we
should do it for update, too.
2. If we do get a "refname" return from
resolve_ref_unsafe(), even with RESOLVE_REF_NO_RECURSE
it may be the name of the ref pointed-to by a symref.
We already normalize this back to orig_refname before
taking the lockfile, but we need to do so before the
null_oid check.
While we're rearranging the REF_NODEREF handling, we can
also bump the initialization of lflags to the top of the
function, where we are setting up other flags. This saves us
from having yet another conditional block on REF_NODEREF
just to set it later.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It's unlikely that we would fail to create or update a
symbolic ref (especially HEAD), but if we do, we should
notice and complain. Note that there's no need to give more
details in our error message; create_symref will already
have done so.
While we're here, let's also fix a minor memory leak in
clone.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There is no need to duplicate the definition of $_z40 and $_x40 that
test-lib.sh supplies the test scripts.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git checkout -b newbranch $commit^{tree}" mistakenly created a new branch
rooted at the current HEAD, because in that case, the two structure fields
used to see if the command was invoked without any argument (hence it
needs to default to checking out the HEAD) were populated incorrectly.
Upon seeing a command line argument that we took as a rev, we should store
that string in new.name, even if that does not name a commit. This will
correctly trigger the existing safety logic.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Daniel Barkalow <barkalow@iabervon.org>
When using alternates, it is possible for HEAD to end up pointing to
an invalid commit. git checkout should be able to recover from that
situation without crashing.
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
