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.

2 files changed, 35 insertions, 36 deletions

diff --git a/tests/clone/local.c b/tests/clone/local.c
index b90ff3107..e0bd74df7 100644
--- a/tests/clone/local.c
+++ b/tests/clone/local.c
@@ -2,42 +2,41 @@
 
 #include "git2/clone.h"
 #include "clone.h"
-#include "buffer.h"
 #include "path.h"
 #include "posix.h"
 #include "futils.h"
 
-static int file_url(git_buf *buf, const char *host, const char *path)
+static int file_url(git_str *buf, const char *host, const char *path)
 {
 	if (path[0] == '/')
 		path++;
 
-	git_buf_clear(buf);
-	return git_buf_printf(buf, "file://%s/%s", host, path);
+	git_str_clear(buf);
+	return git_str_printf(buf, "file://%s/%s", host, path);
 }
 
 #ifdef GIT_WIN32
-static int git_style_unc_path(git_buf *buf, const char *host, const char *path)
+static int git_style_unc_path(git_str *buf, const char *host, const char *path)
 {
-	git_buf_clear(buf);
+	git_str_clear(buf);
 
 	if (host)
-		git_buf_printf(buf, "//%s/", host);
+		git_str_printf(buf, "//%s/", host);
 
 	if (path[0] == '/')
 		path++;
 
 	if (git__isalpha(path[0]) && path[1] == ':' && path[2] == '/') {
-		git_buf_printf(buf, "%c$/", path[0]);
+		git_str_printf(buf, "%c$/", path[0]);
 		path += 3;
 	}
 
-	git_buf_puts(buf, path);
+	git_str_puts(buf, path);
 
-	return git_buf_oom(buf) ? -1 : 0;
+	return git_str_oom(buf) ? -1 : 0;
 }
 
-static int unc_path(git_buf *buf, const char *host, const char *path)
+static int unc_path(git_str *buf, const char *host, const char *path)
 {
 	char *c;
 
@@ -54,7 +53,7 @@ static int unc_path(git_buf *buf, const char *host, const char *path)
 
 void test_clone_local__should_clone_local(void)
 {
-	git_buf buf = GIT_BUF_INIT;
+	git_str buf = GIT_STR_INIT;
 
 	/* we use a fixture path because it needs to exist for us to want to clone */
 	const char *path = cl_fixture("testrepo.git");
@@ -79,8 +78,8 @@ void test_clone_local__should_clone_local(void)
 
 	/* Ensure that file:/// urls are percent decoded: .git == %2e%67%69%74 */
 	cl_git_pass(file_url(&buf, "", path));
-	git_buf_shorten(&buf, 4);
-	cl_git_pass(git_buf_puts(&buf, "%2e%67%69%74"));
+	git_str_shorten(&buf, 4);
+	cl_git_pass(git_str_puts(&buf, "%2e%67%69%74"));
 	cl_assert_equal_i(0, git_clone__should_clone_local(buf.ptr, GIT_CLONE_LOCAL_AUTO));
 	cl_assert_equal_i(1,  git_clone__should_clone_local(buf.ptr, GIT_CLONE_LOCAL));
 	cl_assert_equal_i(1,  git_clone__should_clone_local(buf.ptr, GIT_CLONE_LOCAL_NO_LINKS));
@@ -91,14 +90,14 @@ void test_clone_local__should_clone_local(void)
 	cl_assert_equal_i(1,  git_clone__should_clone_local(path, GIT_CLONE_LOCAL_NO_LINKS));
 	cl_assert_equal_i(0, git_clone__should_clone_local(path, GIT_CLONE_NO_LOCAL));
 
-	git_buf_dispose(&buf);
+	git_str_dispose(&buf);
 }
 
 void test_clone_local__hardlinks(void)
 {
 	git_repository *repo;
 	git_clone_options opts = GIT_CLONE_OPTIONS_INIT;
-	git_buf buf = GIT_BUF_INIT;
+	git_str buf = GIT_STR_INIT;
 	struct stat st;
 
 	/*
@@ -117,21 +116,21 @@ void test_clone_local__hardlinks(void)
 	cl_git_pass(git_clone(&repo, cl_git_path_url("clone.git"), "./clone2.git", &opts));
 
 #ifndef GIT_WIN32
-	git_buf_clear(&buf);
-	cl_git_pass(git_buf_join_n(&buf, '/', 4, git_repository_path(repo), "objects", "08", "b041783f40edfe12bb406c9c9a8a040177c125"));
+	git_str_clear(&buf);
+	cl_git_pass(git_str_join_n(&buf, '/', 4, git_repository_path(repo), "objects", "08", "b041783f40edfe12bb406c9c9a8a040177c125"));
 
 	cl_git_pass(p_stat(buf.ptr, &st));
 	cl_assert_equal_i(2, st.st_nlink);
 #endif
 
 	git_repository_free(repo);
-	git_buf_clear(&buf);
+	git_str_clear(&buf);
 
 	opts.local = GIT_CLONE_LOCAL_NO_LINKS;
 	cl_git_pass(git_clone(&repo, cl_git_path_url("clone.git"), "./clone3.git", &opts));
 
-	git_buf_clear(&buf);
-	cl_git_pass(git_buf_join_n(&buf, '/', 4, git_repository_path(repo), "objects", "08", "b041783f40edfe12bb406c9c9a8a040177c125"));
+	git_str_clear(&buf);
+	cl_git_pass(git_str_join_n(&buf, '/', 4, git_repository_path(repo), "objects", "08", "b041783f40edfe12bb406c9c9a8a040177c125"));
 
 	cl_git_pass(p_stat(buf.ptr, &st));
 	cl_assert_equal_i(1, st.st_nlink);
@@ -142,14 +141,14 @@ void test_clone_local__hardlinks(void)
 	cl_git_pass(git_clone(&repo, "./clone.git", "./clone4.git", NULL));
 
 #ifndef GIT_WIN32
-	git_buf_clear(&buf);
-	cl_git_pass(git_buf_join_n(&buf, '/', 4, git_repository_path(repo), "objects", "08", "b041783f40edfe12bb406c9c9a8a040177c125"));
+	git_str_clear(&buf);
+	cl_git_pass(git_str_join_n(&buf, '/', 4, git_repository_path(repo), "objects", "08", "b041783f40edfe12bb406c9c9a8a040177c125"));
 
 	cl_git_pass(p_stat(buf.ptr, &st));
 	cl_assert_equal_i(3, st.st_nlink);
 #endif
 
-	git_buf_dispose(&buf);
+	git_str_dispose(&buf);
 	git_repository_free(repo);
 
 	cl_git_pass(git_futils_rmdir_r("./clone.git", NULL, GIT_RMDIR_REMOVE_FILES));
@@ -164,7 +163,7 @@ void test_clone_local__standard_unc_paths_are_written_git_style(void)
 	git_repository *repo;
 	git_remote *remote;
 	git_clone_options opts = GIT_CLONE_OPTIONS_INIT;
-	git_buf unc = GIT_BUF_INIT, git_unc = GIT_BUF_INIT;
+	git_str unc = GIT_STR_INIT, git_unc = GIT_STR_INIT;
 
 	/* we use a fixture path because it needs to exist for us to want to clone */
 	const char *path = cl_fixture("testrepo.git");
@@ -179,8 +178,8 @@ void test_clone_local__standard_unc_paths_are_written_git_style(void)
 
 	git_remote_free(remote);
 	git_repository_free(repo);
-	git_buf_dispose(&unc);
-	git_buf_dispose(&git_unc);
+	git_str_dispose(&unc);
+	git_str_dispose(&git_unc);
 
 	cl_git_pass(git_futils_rmdir_r("./clone.git", NULL, GIT_RMDIR_REMOVE_FILES));
 #endif
@@ -192,7 +191,7 @@ void test_clone_local__git_style_unc_paths(void)
 	git_repository *repo;
 	git_remote *remote;
 	git_clone_options opts = GIT_CLONE_OPTIONS_INIT;
-	git_buf git_unc = GIT_BUF_INIT;
+	git_str git_unc = GIT_STR_INIT;
 
 	/* we use a fixture path because it needs to exist for us to want to clone */
 	const char *path = cl_fixture("testrepo.git");
@@ -206,7 +205,7 @@ void test_clone_local__git_style_unc_paths(void)
 
 	git_remote_free(remote);
 	git_repository_free(repo);
-	git_buf_dispose(&git_unc);
+	git_str_dispose(&git_unc);
 
 	cl_git_pass(git_futils_rmdir_r("./clone.git", NULL, GIT_RMDIR_REMOVE_FILES));
 #endif
diff --git a/tests/clone/nonetwork.c b/tests/clone/nonetwork.c
index ec12fee18..7625a2183 100644
--- a/tests/clone/nonetwork.c
+++ b/tests/clone/nonetwork.c
@@ -145,15 +145,15 @@ void test_clone_nonetwork__cope_with_already_existing_directory(void)
 
 void test_clone_nonetwork__can_prevent_the_checkout_of_a_standard_repo(void)
 {
-	git_buf path = GIT_BUF_INIT;
+	git_str path = GIT_STR_INIT;
 
 	g_options.checkout_opts.checkout_strategy = 0;
 	cl_git_pass(git_clone(&g_repo, cl_git_fixture_url("testrepo.git"), "./foo", &g_options));
 
-	cl_git_pass(git_buf_joinpath(&path, git_repository_workdir(g_repo), "master.txt"));
-	cl_assert_equal_i(false, git_path_isfile(git_buf_cstr(&path)));
+	cl_git_pass(git_str_joinpath(&path, git_repository_workdir(g_repo), "master.txt"));
+	cl_assert_equal_i(false, git_path_isfile(git_str_cstr(&path)));
 
-	git_buf_dispose(&path);
+	git_str_dispose(&path);
 }
 
 void test_clone_nonetwork__can_checkout_given_branch(void)
@@ -304,9 +304,9 @@ static void assert_correct_reflog(const char *name)
 {
 	git_reflog *log;
 	const git_reflog_entry *entry;
-	git_buf expected_message = GIT_BUF_INIT;
+	git_str expected_message = GIT_STR_INIT;
 
-	git_buf_printf(&expected_message,
+	git_str_printf(&expected_message,
 		"clone: from %s", cl_git_fixture_url("testrepo.git"));
 
 	cl_git_pass(git_reflog_read(&log, g_repo, name));
@@ -316,7 +316,7 @@ static void assert_correct_reflog(const char *name)
 
 	git_reflog_free(log);
 
-	git_buf_dispose(&expected_message);
+	git_str_dispose(&expected_message);
 }
 
 void test_clone_nonetwork__clone_updates_reflog_properly(void)