str: introduce `git_str` for internal, `git_buf` is external

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.

3 files changed, 21 insertions, 21 deletions

diff --git a/tests/iterator/index.c b/tests/iterator/index.c
index 25d8c2990..69b795f5c 100644
--- a/tests/iterator/index.c
+++ b/tests/iterator/index.c
@@ -279,12 +279,12 @@ static const char *expected_index_ci[] = {
 
 void test_iterator_index__case_folding(void)
 {
-	git_buf path = GIT_BUF_INIT;
+	git_str path = GIT_STR_INIT;
 	int fs_is_ci = 0;
 
-	cl_git_pass(git_buf_joinpath(&path, cl_fixture("icase"), ".gitted/CoNfIg"));
+	cl_git_pass(git_str_joinpath(&path, cl_fixture("icase"), ".gitted/CoNfIg"));
 	fs_is_ci = git_path_exists(path.ptr);
-	git_buf_dispose(&path);
+	git_str_dispose(&path);
 
 	index_iterator_test(
 		"icase", NULL, NULL, 0, ARRAY_SIZE(expected_index_cs),
@@ -978,22 +978,22 @@ void test_iterator_index__pathlist_with_directory(void)
 
 static void create_paths(git_index *index, const char *root, int depth)
 {
-	git_buf fullpath = GIT_BUF_INIT;
+	git_str fullpath = GIT_STR_INIT;
 	git_index_entry entry;
 	size_t root_len;
 	int i;
 
 	if (root) {
-		cl_git_pass(git_buf_puts(&fullpath, root));
-		cl_git_pass(git_buf_putc(&fullpath, '/'));
+		cl_git_pass(git_str_puts(&fullpath, root));
+		cl_git_pass(git_str_putc(&fullpath, '/'));
 	}
 
 	root_len = fullpath.size;
 
 	for (i = 0; i < 8; i++) {
 		bool file = (depth == 0 || (i % 2) == 0);
-		git_buf_truncate(&fullpath, root_len);
-		cl_git_pass(git_buf_printf(&fullpath, "item%d", i));
+		git_str_truncate(&fullpath, root_len);
+		cl_git_pass(git_str_printf(&fullpath, "item%d", i));
 
 		if (file) {
 			memset(&entry, 0, sizeof(git_index_entry));
@@ -1007,7 +1007,7 @@ static void create_paths(git_index *index, const char *root, int depth)
 		}
 	}
 
-	git_buf_dispose(&fullpath);
+	git_str_dispose(&fullpath);
 }
 
 void test_iterator_index__pathlist_for_deeply_nested_item(void)
diff --git a/tests/iterator/tree.c b/tests/iterator/tree.c
index f7fb9a7ee..4145c8dea 100644
--- a/tests/iterator/tree.c
+++ b/tests/iterator/tree.c
@@ -623,7 +623,7 @@ static void build_test_tree(
 	const char *scan = fmt, *next;
 	char type, delimiter;
 	git_filemode_t mode = GIT_FILEMODE_BLOB;
-	git_buf name = GIT_BUF_INIT;
+	git_str name = GIT_STR_INIT;
 	va_list arglist;
 
 	cl_git_pass(git_treebuilder_new(&builder, repo, NULL)); /* start builder */
@@ -640,7 +640,7 @@ static void build_test_tree(
 		delimiter = *scan++; /* read and skip delimiter */
 		for (next = scan; *next && *next != delimiter; ++next)
 			/* seek end */;
-		cl_git_pass(git_buf_set(&name, scan, (size_t)(next - scan)));
+		cl_git_pass(git_str_set(&name, scan, (size_t)(next - scan)));
 		for (scan = next; *scan && (*scan == delimiter || *scan == ','); ++scan)
 			/* skip delimiter and optional comma */;
 
@@ -653,7 +653,7 @@ static void build_test_tree(
 	cl_git_pass(git_treebuilder_write(out, builder));
 
 	git_treebuilder_free(builder);
-	git_buf_dispose(&name);
+	git_str_dispose(&name);
 }
 
 void test_iterator_tree__case_conflicts_0(void)
diff --git a/tests/iterator/workdir.c b/tests/iterator/workdir.c
index 82ee363f9..7ca726c24 100644
--- a/tests/iterator/workdir.c
+++ b/tests/iterator/workdir.c
@@ -643,7 +643,7 @@ void test_iterator_workdir__filesystem2(void)
  */
 void test_iterator_workdir__filesystem_gunk(void)
 {
-	git_buf parent = GIT_BUF_INIT;
+	git_str parent = GIT_STR_INIT;
 	git_iterator *i;
 	int n;
 
@@ -653,8 +653,8 @@ void test_iterator_workdir__filesystem_gunk(void)
 	g_repo = cl_git_sandbox_init("testrepo");
 
 	for (n = 0; n < 100000; n++) {
-		git_buf_clear(&parent);
-		cl_git_pass(git_buf_printf(&parent, "%s/refs/heads/foo/%d/subdir", git_repository_path(g_repo), n));
+		git_str_clear(&parent);
+		cl_git_pass(git_str_printf(&parent, "%s/refs/heads/foo/%d/subdir", git_repository_path(g_repo), n));
 		cl_git_pass(git_futils_mkdir(parent.ptr, 0775, GIT_MKDIR_PATH));
 	}
 
@@ -667,7 +667,7 @@ void test_iterator_workdir__filesystem_gunk(void)
 	expect_iterator_items(i, 17, NULL, 16, NULL);
 
 	git_iterator_free(i);
-	git_buf_dispose(&parent);
+	git_str_dispose(&parent);
 }
 
 void test_iterator_workdir__skips_unreadable_dirs(void)
@@ -1019,19 +1019,19 @@ void test_iterator_workdir__pathlist_with_dirs(void)
 
 static void create_paths(const char *root, int depth)
 {
-	git_buf fullpath = GIT_BUF_INIT;
+	git_str fullpath = GIT_STR_INIT;
 	size_t root_len;
 	int i;
 
-	cl_git_pass(git_buf_puts(&fullpath, root));
+	cl_git_pass(git_str_puts(&fullpath, root));
 	cl_git_pass(git_path_to_dir(&fullpath));
 
 	root_len = fullpath.size;
 
 	for (i = 0; i < 8; i++) {
 		bool file = (depth == 0 || (i % 2) == 0);
-		git_buf_truncate(&fullpath, root_len);
-		cl_git_pass(git_buf_printf(&fullpath, "item%d", i));
+		git_str_truncate(&fullpath, root_len);
+		cl_git_pass(git_str_printf(&fullpath, "item%d", i));
 
 		if (file) {
 			cl_git_rewritefile(fullpath.ptr, "This is a file!\n");
@@ -1043,7 +1043,7 @@ static void create_paths(const char *root, int depth)
 		}
 	}
 
-	git_buf_dispose(&fullpath);
+	git_str_dispose(&fullpath);
 }
 
 void test_iterator_workdir__pathlist_for_deeply_nested_item(void)