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, 4 insertions, 4 deletions

diff --git a/tests/online/fetchhead.c b/tests/online/fetchhead.c
index b61993138..30cce3a90 100644
--- a/tests/online/fetchhead.c
+++ b/tests/online/fetchhead.c
@@ -52,7 +52,7 @@ static void fetchhead_test_fetch(const char *fetchspec, const char *expected_fet
 {
 	git_remote *remote;
 	git_fetch_options fetch_opts = GIT_FETCH_OPTIONS_INIT;
-	git_buf fetchhead_buf = GIT_BUF_INIT;
+	git_str fetchhead_buf = GIT_STR_INIT;
 	int equals = 0;
 	git_strarray array, *active_refs = NULL;
 
@@ -72,7 +72,7 @@ static void fetchhead_test_fetch(const char *fetchspec, const char *expected_fet
 
 	equals = (strcmp(fetchhead_buf.ptr, expected_fetchhead) == 0);
 
-	git_buf_dispose(&fetchhead_buf);
+	git_str_dispose(&fetchhead_buf);
 
 	cl_assert(equals);
 }
@@ -157,7 +157,7 @@ void test_online_fetchhead__colon_only_dst_refspec_creates_no_branch(void)
 
 void test_online_fetchhead__creds_get_stripped(void)
 {
-	git_buf buf = GIT_BUF_INIT;
+	git_str buf = GIT_STR_INIT;
 	git_remote *remote;
 
 	cl_git_pass(git_repository_init(&g_repo, "./foo", 0));
@@ -169,5 +169,5 @@ void test_online_fetchhead__creds_get_stripped(void)
 		"49322bb17d3acc9146f98c97d078513228bbf3c0\t\thttps://github.com/libgit2/TestGitRepository\n");
 
 	git_remote_free(remote);
-	git_buf_dispose(&buf);
+	git_str_dispose(&buf);
 }