index: Check git_vector_dup error in write_entries

This is for extra safety within write_entries

If allocating case_sorted.contents fails, git_vector_sort will segfault.

To prevent a race condition, these wlock/rlock calls should probably be checked
for errors.

Invert the workflow conditionals so that a workflow_dispatch event acts
like an on: push build.

Add new bindings for the R language

Update .gitignore

patch: add owner accessor

commit-graph: Introduce a parser for commit-graph files

revspec: rename git_revparse_mode_t to git_revspec_t

mwindow: Fix a bug in the LRU window finding code

The information about the type of a revision spec is not information
about the parser.  Name it accordingly, so that `git_revparse_mode_t`
is now `git_revspec_t`.  Deprecate the old name.

Only exclude tags files/folders and build folders at the repository root.

Our test resources shouldn't count toward our language statistics.  We
have some PHP checked in to the test resources, but I assure you that we
do not have any production code in PHP and we shouldn't be blamed for
the test data.

This change now updates the `lru_window` variable to match the current
file's MRU window. This makes it such that it doesn't always choose the
file that happened to come last in the list of window files, and instead
should now correctly choose the file with the least-recently-used one.

ci: don't use ninja on macOS

Ninja is not installed by default on the macOS machines; stop trying to
use it.  Instead use `make -j` which should be roughly equivalent in
performance but supported everywhere.

midx: Fix a bug in `git_midx_needs_refresh()`

clone: set refs/remotes/origin/HEAD when branch is specified

This change is the first in a series to add support for git's
commit-graph. This should speed up commit graph traversals by avoiding
object parsing and allowing some operations to terminate earlier.

Part of: #5757

When a branch is specified to check out in clone, update the remote
tracking `HEAD` to point to it.  This mimics git's behavior, when
`git clone -b <name>` is used.

Use `p_pwrite`/`p_pread` consistently throughout the codebase

README: instructions for using libgit2 without compiling

Cope with empty default branch

This change stops using the seek+read/write combo to perform I/O with an
offset, since this is faster by one system call (and also more atomic
and therefore safer).

The very last check in the freshness check for the midx was wrong ><
This was also because this function was not tested.

github-actions: Also rename the main branch here

This should fix the CI.

The init.defaultbranch option may be set, but empty.  In this case, we
should ignore it instead of trying to set our default branch to
`refs/heads/`.

If a symbolic reference points to something invalid, then do not try to
update it.

When HEAD points to a nonexistent or invalid branch - for example, to
`refs/heads/` - the fetch should be permitted to continue, but we should
not use it when creating the `for merge` option in the FETCH_HEAD file.

(This emulates git's behavior.)

blob: fix name of `GIT_BLOB_FILTER_ATTRIBUTES_FROM_HEAD`

Add documentation for git_blob_filter_options.version

Adds info about initializing options with git_blob_filter_options_init

`GIT_BLOB_FILTER_ATTTRIBUTES_FROM_HEAD` is misspelled, it should be
`GIT_BLOB_FILTER_ATTRIBUTES_FROM_HEAD`, and it would be if it were not
for the MacBook Pro keyboard and my inattentiveness.

The `git_blob_filter_options_init` function should be included, to allow
callers in FFI environments to let us initialize an options structure
for them.