libgit2 has two distinct requirements that were previously solved by
`git_buf`. We require:
1. A general purpose string class that provides a number of utility APIs
for manipulating data (eg, concatenating, truncating, etc).
2. A structure that we can use to return strings to callers that they
can take ownership of.
By using a single class (`git_buf`) for both of these purposes, we have
confused the API to the point that refactorings are difficult and
reasoning about correctness is also difficult.
Move the utility class `git_buf` to be called `git_str`: this represents
its general purpose, as an internal string buffer class. The name also
is an homage to Junio Hamano ("gitstr").
The public API remains `git_buf`, and has a much smaller footprint. It
is generally only used as an "out" param with strict requirements that
follow the documentation. (Exceptions exist for some legacy APIs to
avoid breaking callers unnecessarily.)
Utility functions exist to convert a user-specified `git_buf` to a
`git_str` so that we can call internal functions, then converting it
back again.
Makes usage of CLOCK_MONOTONIC conditional and makes functions that uses git__timer handle clock resynchronization. Call gettimeofday with tzp set to NULL as required by https://pubs.opengroup.org/onlinepubs/9699919799/functions/gettimeofday.html
Clarify the `git_atomic` type and functions now that we have a 64 bit version as well (`git_atomic64`).
The code worked under the assumption that anything under `refs/tags` are tag objects, and all the rest would be peelable to a commit. As it is completely valid to have tags to blobs under a non `refs/tags` ref, this would cause failures when trying to peel a tag to a commit. Fix the broken filtering by switching to `git_revwalk_push_glob`, which already handles this case.
Ensure that the server has not sent us overly-large sideband messages (ensure that they are no more than `INT_MAX` bytes), then cast to `int`.
The only function that is named `issomething` (without underscore) was `git_oid_iszero`. Rename it to `git_oid_is_zero` for consistency with the rest of the library.
The `git_push_transfer_progress` is a callback and as such should be suffixed with `_cb` for consistency. Rename `git_push_transfer_progress` to `git_push_transfer_progress_cb`.