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, 3 insertions, 6 deletions

diff --git a/tests/refs/branches/remote.c b/tests/refs/branches/remote.c
index 27a3b0c44..e2bd3485a 100644
--- a/tests/refs/branches/remote.c
+++ b/tests/refs/branches/remote.c
@@ -32,10 +32,9 @@ void test_refs_branches_remote__can_get_remote_for_branch(void)
 void test_refs_branches_remote__no_matching_remote_returns_error(void)
 {
 	const char *unknown = "refs/remotes/nonexistent/master";
-	git_buf buf;
+	git_buf buf = GIT_BUF_INIT;
 
 	git_error_clear();
-	memset(&buf, 0, sizeof(git_buf));
 	cl_git_fail_with(git_branch_remote_name(&buf, g_repo, unknown), GIT_ENOTFOUND);
 	cl_assert(git_error_last() != NULL);
 }
@@ -43,10 +42,9 @@ void test_refs_branches_remote__no_matching_remote_returns_error(void)
 void test_refs_branches_remote__local_remote_returns_error(void)
 {
 	const char *local = "refs/heads/master";
-	git_buf buf;
+	git_buf buf = GIT_BUF_INIT;
 
 	git_error_clear();
-	memset(&buf, 0, sizeof(git_buf));
 	cl_git_fail_with(git_branch_remote_name(&buf, g_repo, local), GIT_ERROR);
 	cl_assert(git_error_last() != NULL);
 }
@@ -54,7 +52,7 @@ void test_refs_branches_remote__local_remote_returns_error(void)
 void test_refs_branches_remote__ambiguous_remote_returns_error(void)
 {
 	git_remote *remote;
-	git_buf buf;
+	git_buf buf = GIT_BUF_INIT;
 
 	/* Create the remote */
 	cl_git_pass(git_remote_create_with_fetchspec(&remote, g_repo, "addtest", "http://github.com/libgit2/libgit2", "refs/heads/*:refs/remotes/test/*"));
@@ -62,7 +60,6 @@ void test_refs_branches_remote__ambiguous_remote_returns_error(void)
 	git_remote_free(remote);
 
 	git_error_clear();
-	memset(&buf, 0, sizeof(git_buf));
 	cl_git_fail_with(git_branch_remote_name(&buf, g_repo, remote_tracking_branch_name), GIT_EAMBIGUOUS);
 	cl_assert(git_error_last() != NULL);
 }