We don't support using an index object from multiple threads at the same
time, so the locking doesn't have any effect when following the
rules. If not following the rules, things are going to break down
anyway.
Note that we're not checking whether the resize succeeds; in OOM cases,
we let it run with a "small" vector and hash table and see if by chance
we can grow it dynamically as we insert the new entries. Nothing to
lose really.
Instead of calling `git_index_add` in a loop, use the new
`git_index_fill` internal API to fill the index with the initial staged
entries.
The new `fill` helper assumes that all the entries will be unique and
valid, so it can append them at the end of the entries vector and only
sort it once at the end. It performs no validation checks.
This prevents the quadratic behavior caused by having to sort the
entries list once after every insertion.
When replacing an index with a new one, we need to iterate
through all index entries in order to determine which entries are
equal. When it is not possible to re-use old entries for the new
index, we move it into a list of entries that are to be removed
and thus free'd.
When we encounter a non-zero error code, though, we skip adding
the current index entry to the remove-queue. `INSERT_MAP_EX`,
which is the function last run before adding to the remove-queue,
may return a positive non-zero code that indicates what exactly
happened while inserting the element. In this case we skip adding
the entry to the remove-queue but still continue the current
operation, leading to a leak of the current entry.
Fix this by checking for a negative return value instead of a
non-zero one when we want to add the current index entry to the
remove-queue.
When adding to the index, we look to see if a portion of the given
path matches a portion of a path in the index. If so, we will use
the existing path information. For example, when adding `foo/bar.c`,
if there is an index entry to `FOO/other` and the filesystem is case
insensitive, then we will put `bar.c` into the existing tree instead
of creating a new one with a different case.
Use `strncmp` to do that instead of `memcmp`. When we `bsearch`
into the index, we locate the position where the new entry would
go. The index entry at that position does not necessarily have
a relation to the entry we're adding, so we cannot make assumptions
and use `memcmp`. Instead, compare them as strings.
When canonicalizing paths, we look for the first index entry that
matches a given substring.
When examining the working directory and determining whether it's
up-to-date, only consider the nanoseconds in the index entry when
built with `GIT_USE_NSEC`. This prevents us from believing that
the working directory is always dirty when the index was originally
written with a git client that uinderstands nsecs (like git 2.x).
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.
The uptodate bit should have a lifecycle of a single read->write
on the index. Once the index is written, the files within it should
be scanned for racy timestamps against the new index timestamp.
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.
When we insert a conflict in a case-insensitive index, accept the
new entry's path as the correct case instead of leaving the path we
already had.
This puts `git_index_conflict_add()` on the same level as
`git_index_add()` in this respect.
Inserting new REUC entries can quickly become pathological given that
each insert unsorts the REUC vector, and both subsequent lookups *and*
insertions will require sorting it again before being successful.
To avoid this, we're switching to `git_vector_insert_sorted`: this keeps
the REUC vector constantly sorted and lets us use the `on_dup` callback
to skip an extra binary search on each insertion.
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.
This allows us to remove OS checks from source code, instead relying
on CMake to detect whether or not `struct stat` has the nanoseconds
members we rely on.
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 an entry has a racy timestamp, we need to check whether the file
itself has changed since we put its entry in the index. Only then do we
smudge the size field to force a check the next time around.
This is used by the submodule in order to figure out if the index has
changed since it last read it. Using a timestamp is racy, so let's make
it use the checksum, just like we now do for reloading the index itself.
We currently use a timetamp to check whether an index file has been
modified since we last read it, but this is racy. If two updates happen
in the same second and we read after the first one, we won't detect the
second one.
Instead read the SHA-1 checksum of the file, which are its last 20 bytes which
gives us a sure-fire way to detect whether the file has changed since we
last read it.
As we're now keeping track of it, expose an accessor to this data.
If a file entry has the same timestamp as the index itself, it is
considered racily-clean, as it may have been modified after the index
was written, but during the same second. We take extra steps to check
the contents, but this is just one part of avoiding races.
For files which do have changes but have not been updated in the index,
updating the on-disk index means updating its timestamp, which means we
would no longer recognise these entries as racy and we would trust the
timestamp to tell us whether they have changed.
In order to work around this, git zeroes out the file-size field in
entries with the same timestamp as the index in order to force the next
diff to check the contents. Do so in libgit2 as well.
Introduce a new binary diff callback to provide the actual binary
delta contents to callers. Create this data from the diff contents
(instead of directly from the ODB) to support binary diffs including
the workdir, not just things coming out of the ODB.
If there exists a conflict in the index, but no file in the working
directory, this implies that the user wants to accept the resolution
by removing the file. Thus, remove the conflict entry from the
index, instead of trying to add a (nonexistent) file.
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.
