str: introduce `git_str` for internal, `git_buf` is externalethomson/gitstr

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.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/net.h b/src/net.h
index 322d0bda9..728add3d0 100644
--- a/src/net.h
+++ b/src/net.h
@@ -52,10 +52,10 @@ extern int git_net_url_apply_redirect(
 extern void git_net_url_swap(git_net_url *a, git_net_url *b);
 
 /** Places the URL into the given buffer. */
-extern int git_net_url_fmt(git_buf *out, git_net_url *url);
+extern int git_net_url_fmt(git_str *out, git_net_url *url);
 
 /** Place the path and query string into the given buffer. */
-extern int git_net_url_fmt_path(git_buf *buf, git_net_url *url);
+extern int git_net_url_fmt_path(git_str *buf, git_net_url *url);
 
 /** Determines if the url matches given pattern or pattern list */
 extern bool git_net_url_matches_pattern(