Always lock the index when we begin the merge, before we write
any of the metdata files. This prevents a race where another
client may run a commit after we have written the MERGE_HEAD but
before we have updated the index, which will produce a merge
commit that is treesame to one parent. The merge will finish and
update the index and the resultant commit would not be a merge at
all.
Make our overflow checking look more like gcc and clang's, so that
we can substitute it out with the compiler instrinsics on platforms
that support it. This means dropping the ability to pass `NULL` as
an out parameter.
As a result, the macros also get updated to reflect this as well.
Passing 0 as the length of the paths to check to git_diff_index_to_workdir
results in all files being treated as conflicting, that is, all untracked or
modified files in the worktree is reported as conflicting
We always calculate multiple merge bases, but up to now we had only
exposed the "best" merge base.
Introduce git_oidarray which analogously to git_strarray lets us return
multiple ids.
git_checkout_index can now check out other git_index's (that are not
necessarily the repository index). This allows checkout_index to use
the repository's index for stat cache information instead of the index
data being checked out. git_merge and friends now check out their
indexes directly instead of trying to blend it into the running index.
This makes the lock management on the index a little bit broader,
having a number of routines hold the lock across looking up the
item to be modified and actually making the modification. Still
not true thread safety, but more pure index modifications are now
safe which allows the simple cases (such as starting up a diff
while index modifications are underway) safe enough to get the
snapshot without hitting allocation problems.
As part of this, I simplified the allocation of index entries to
use a flex array and just put the path at the end of the index
entry. This makes every entry self-contained and makes it a
little easier to feel sure that pointers to strings aren't
being accidentally copied and freed while other references are
still being held.
This makes the index iterator honor the GIT_ITERATOR_IGNORE_CASE
and GIT_ITERATOR_DONT_IGNORE_CASE flags without modifying the
index data itself. To take advantage of this, I had to export a
number of the internal index entry comparison functions. I also
wrote some new tests to exercise the capability.
As a way to speed up the cases where we need to hide some commits, we
find out what the merge bases are so we know to stop marking commits as
uninteresting and avoid walking down a potentially very large amount of
commits which we will never see. There are however two oversights in
current code.
The merge-base finding algorithm fails to recognize that if it is only
given one commit, there can be no merge base. It instead walks down the
whole ancestor chain needlessly. Make it return an empty list
immediately in this situation.
The revwalk does not know whether the user has asked to hide any commits
at all. In situation where the user pushes multiple commits but doesn't
hide any, the above fix wouldn't do the trick. Keep track of whether the
user wants to hide any commits and only run the merge-base finding
algorithm when it's needed.
