git_buf_clear does not free allocated memory associated with a
git_buf. Use `git_buf_free` instead to correctly free its memory
and plug the memory leak.
If the underlying filesystem doesn't support better than one
second resolution, then don't expect that turning on `GIT_USE_NSEC`
does anything magical to change that.
The index::nsec::staging_maintains_other_nanos test was created to
ensure that when we stage an entry when GIT_USE_NSECS is *unset* that
we truncate the index entry and do not persist the (old, invalid)
nanosec values. Ensure that when GIT_USE_NSECS is *set* that we do
not do that, and actually write the correct nanosecond values.
Ensure that `git_index_read_index` clears the uptodate bit on
files that it modifies.
Further, do not propagate the cache from an on-disk index into
another on-disk index. Although this should not be done, as
`git_index_read_index` is used to bring an in-memory index into
another index (that may or may not be on-disk), ensure that we do
not accidentally bring in these bits when misused.
Test that entries are only smudged when we write the index: the
entry smudging is to prevent us from updating an index in a way
that it would be impossible to tell that an item was racy.
Consider when we load an index: any entries that have the same
(or newer) timestamp than the index itself are considered racy,
and are subject to further scrutiny.
If we *save* that index with the same entries that we loaded,
then the index would now have a newer timestamp than the entries,
and they would no longer be given that additional scrutiny, failing
our racy detection! So test that we smudge those entries only on
writing the new index, but that we can detect them (in diff) without
having to write.
Keep track of entries that we believe are up-to-date, because we
added the index entries since the index was loaded. This prevents
us from unnecessarily examining files that we wrote during the
cleanup of racy entries (when we smudge racily clean files that have
a timestamp newer than or equal to the index's timestamp when we
read it). Without keeping track of this, we would examine every
file that we just checked out for raciness, since all their timestamps
would be newer than the index's timestamp.
Test that on platforms without `core.symlinks`, we preserve symlinks
in `git_index_add_bypath`. (Users should correct the actual index
entry's mode to change a link to a regular file.)
Test that nanoseconds are round-tripped correctly when we read
an index file that contains them. We should, however, ignore them
because we don't understand them, and any new entries in the index
should contain a `0` nsecs field, while existing preserving entries.
When we do not trust the on-disk mode, we use the mode of an existing
index entry. This allows us to preserve executable bits on platforms
that do not honor them on the filesystem.
If there is no stage 0 index entry, also look at conflicts to attempt
to answer this question: prefer the data from the 'ours' side, then
the 'theirs' side before falling back to the common ancestor.
Untangle git_futils_mkdir from git_futils_mkdir_ext - the latter
assumes that we own everything beneath the base, as if it were
being called with a base of the repository or working directory,
and is tailored towards checkout and ensuring that there is no
bogosity beneath the base that must be cleaned up.
This is (at best) slow and (at worst) unsafe in the larger context
of a filesystem where we do not own things and cannot do things like
unlink symlinks that are in our way.
On case insensitive platforms, allow `git_index_add` to provide a new
path for an existing index entry. Previously, we would maintain the
case in an index entry without the ability to change it (except by
removing an entry and re-adding it.)
Higher-level functions (like `git_index_add_bypath` and
`git_index_add_frombuffers`) continue to keep the old path for easier
usage.
On case insensitive systems, when given a user-provided path in the
higher-level index addition functions (eg `git_index_add_bypath` /
`git_index_add_frombuffer`), examine the index to try to match the
given path to an existing directory.
Various mechanisms can cause the on-disk representation of a folder
to not match the representation in HEAD or the index - for example,
a case changing rename of some file `a/file.txt` to `A/file.txt`
will update the paths in the index, but not rename the folder on
disk.
If a user subsequently adds `a/other.txt`, then this should be stored
in the index as `A/other.txt`.
When we pass the path of a repository to `_bypath()`, we should behave
like git and stage it as a `_COMMIT` regardless of whether it is
registered a a submodule.
When confronted with a conflict in the index, `git_index_add_all`
should stage the working directory copy. If there is no file in the
working directory, the conflict should simply be removed.
It's not always obvious the mapping between stage level and
conflict-ness. More importantly, this can lead otherwise sane
people to write constructs like `if (!git_index_entry_stage(entry))`,
which (while technically correct) is unreadable.
Provide a nice method to help avoid such messy thinking.
