The reflog append function was overzealous in its checking. When passed
an old and new ids, it should not do any checking, but just serialize
the data to a reflog entry.
The existing ones lack checking zeroed ids when switching back from an
unborn branch as well as what happens when detaching.
The reflog appending function mistakenly wrote zeros when dealing with a
detached HEAD. This explicitly checks for those situations and fixes
them.
When we update the current branch, we must also append to HEAD's reflog
to keep them in sync.
This is a bit of a hack, but as git.git says, it covers 100% of
default cases.
This is not something anybody would ever do; removing HEAD makes the
.git/ directory no longer be a repository, so we wouldn't be expected to
handle such a situation.
If the pqueue comparison fn returned just 0 or 1 (think "a<b")
then the sort order of returned items could be wrong because there
was a "< 0" that really needed to be "<= 0". Yikes!!!
The git_odb_exists_prefix API was not dealing correctly when a
later backend returned GIT_ENOTFOUND even if an earlier backend
had found the object.
Additionally, the unit tests were not properly exercising the API
and had a couple mistakes in checking the results.
Lastly, since the backends are not expected to behavior correctly
unless all bytes of the short id are zero except for the prefix,
this makes the ODB prefix APIs explicitly clear out the extra
bytes so the user doesn't have to be as careful.
We look up a reference in order to figure out if it's the current
branch, which we need to free once we're done with the check.
As a bonus, only perform the check when we're passed the force flag, as
it's a useless check otherwise.
We can make use of git_object_dup to use refcounting instead of pointer
comparison to make sure we don't free the caller's object.
This also lets us simplify the case for '~0' which is now just an
assignment instead of looking up the object we have at hand.
Previously the hunk_byfinalline_search_cmp function was called with different
data types (size_t and uint32_t) for the key argument but expected only the
former resulting in an invalid memory access when passed the latter on a 64 bit
machine.
The following patch makes sure that the function is called and works with the
same type (size_t).
