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, 48 insertions, 48 deletions

diff --git a/src/checkout.c b/src/checkout.c
index 3a171066b..b31918fc8 100644
--- a/src/checkout.c
+++ b/src/checkout.c
@@ -61,9 +61,9 @@ typedef struct {
 	git_vector update_conflicts;
 	git_vector *update_reuc;
 	git_vector *update_names;
-	git_buf target_path;
+	git_str target_path;
 	size_t target_len;
-	git_buf tmp;
+	git_str tmp;
 	unsigned int strategy;
 	int can_symlink;
 	int respect_filemode;
@@ -321,11 +321,11 @@ static int checkout_action_no_wd(
 }
 
 static int checkout_target_fullpath(
-	git_buf **out, checkout_data *data, const char *path)
+	git_str **out, checkout_data *data, const char *path)
 {
-	git_buf_truncate(&data->target_path, data->target_len);
+	git_str_truncate(&data->target_path, data->target_len);
 
-	if (path && git_buf_puts(&data->target_path, path) < 0)
+	if (path && git_str_puts(&data->target_path, path) < 0)
 		return -1;
 
 	if (git_path_validate_workdir_buf(data->repo, &data->target_path) < 0)
@@ -339,7 +339,7 @@ static int checkout_target_fullpath(
 static bool wd_item_is_removable(
 	checkout_data *data, const git_index_entry *wd)
 {
-	git_buf *full;
+	git_str *full;
 
 	if (wd->mode != GIT_FILEMODE_TREE)
 		return true;
@@ -423,7 +423,7 @@ static int checkout_action_wd_only(
 
 		/* copy the entry for issuing notification callback later */
 		git_index_entry saved_wd = *wd;
-		git_buf_sets(&data->tmp, wd->path);
+		git_str_sets(&data->tmp, wd->path);
 		saved_wd.path = data->tmp.ptr;
 
 		error = git_iterator_advance_over(
@@ -476,7 +476,7 @@ static bool submodule_is_config_only(
 
 static bool checkout_is_empty_dir(checkout_data *data, const char *path)
 {
-	git_buf *fullpath;
+	git_str *fullpath;
 
 	if (checkout_target_fullpath(&fullpath, data, path) < 0)
 		return false;
@@ -1584,7 +1584,7 @@ static int blob_content_to_link(
 	git_blob *blob,
 	const char *path)
 {
-	git_buf linktarget = GIT_BUF_INIT;
+	git_str linktarget = GIT_STR_INIT;
 	int error;
 
 	if ((error = mkpath2file(data, path, data->opts.dir_mode)) < 0)
@@ -1594,10 +1594,10 @@ static int blob_content_to_link(
 		return error;
 
 	if (data->can_symlink) {
-		if ((error = p_symlink(git_buf_cstr(&linktarget), path)) < 0)
+		if ((error = p_symlink(git_str_cstr(&linktarget), path)) < 0)
 			git_error_set(GIT_ERROR_OS, "could not create symlink %s", path);
 	} else {
-		error = git_futils_fake_symlink(git_buf_cstr(&linktarget), path);
+		error = git_futils_fake_symlink(git_str_cstr(&linktarget), path);
 	}
 
 	if (!error) {
@@ -1609,7 +1609,7 @@ static int blob_content_to_link(
 		st->st_mode = GIT_FILEMODE_LINK;
 	}
 
-	git_buf_dispose(&linktarget);
+	git_str_dispose(&linktarget);
 
 	return error;
 }
@@ -1636,7 +1636,7 @@ static int checkout_submodule_update_index(
 	checkout_data *data,
 	const git_diff_file *file)
 {
-	git_buf *fullpath;
+	git_str *fullpath;
 	struct stat st;
 
 	/* update the index unless prevented */
@@ -1772,7 +1772,7 @@ static int checkout_blob(
 	checkout_data *data,
 	const git_diff_file *file)
 {
-	git_buf *fullpath;
+	git_str *fullpath;
 	struct stat st;
 	int error = 0;
 
@@ -1809,7 +1809,7 @@ static int checkout_remove_the_old(
 	git_diff_delta *delta;
 	const char *str;
 	size_t i;
-	git_buf *fullpath;
+	git_str *fullpath;
 	uint32_t flg = GIT_RMDIR_EMPTY_PARENTS |
 		GIT_RMDIR_REMOVE_FILES | GIT_RMDIR_REMOVE_BLOCKERS;
 
@@ -1927,40 +1927,40 @@ static int checkout_lookup_head_tree(git_tree **out, git_repository *repo)
 
 
 static int conflict_entry_name(
-	git_buf *out,
+	git_str *out,
 	const char *side_name,
 	const char *filename)
 {
-	if (git_buf_puts(out, side_name) < 0 ||
-		git_buf_putc(out, ':') < 0 ||
-		git_buf_puts(out, filename) < 0)
+	if (git_str_puts(out, side_name) < 0 ||
+		git_str_putc(out, ':') < 0 ||
+		git_str_puts(out, filename) < 0)
 		return -1;
 
 	return 0;
 }
 
-static int checkout_path_suffixed(git_buf *path, const char *suffix)
+static int checkout_path_suffixed(git_str *path, const char *suffix)
 {
 	size_t path_len;
 	int i = 0, error = 0;
 
-	if ((error = git_buf_putc(path, '~')) < 0 || (error = git_buf_puts(path, suffix)) < 0)
+	if ((error = git_str_putc(path, '~')) < 0 || (error = git_str_puts(path, suffix)) < 0)
 		return -1;
 
-	path_len = git_buf_len(path);
+	path_len = git_str_len(path);
 
-	while (git_path_exists(git_buf_cstr(path)) && i < INT_MAX) {
-		git_buf_truncate(path, path_len);
+	while (git_path_exists(git_str_cstr(path)) && i < INT_MAX) {
+		git_str_truncate(path, path_len);
 
-		if ((error = git_buf_putc(path, '_')) < 0 ||
-			(error = git_buf_printf(path, "%d", i)) < 0)
+		if ((error = git_str_putc(path, '_')) < 0 ||
+			(error = git_str_printf(path, "%d", i)) < 0)
 			return error;
 
 		i++;
 	}
 
 	if (i == INT_MAX) {
-		git_buf_truncate(path, path_len);
+		git_str_truncate(path, path_len);
 
 		git_error_set(GIT_ERROR_CHECKOUT, "could not write '%s': working directory file exists", path->ptr);
 		return GIT_EEXISTS;
@@ -1974,8 +1974,8 @@ static int checkout_write_entry(
 	checkout_conflictdata *conflict,
 	const git_index_entry *side)
 {
-	const char *hint_path, *suffix;
-	git_buf *fullpath;
+	const char *hint_path = NULL, *suffix;
+	git_str *fullpath;
 	struct stat st;
 	int error;
 
@@ -2025,7 +2025,7 @@ static int checkout_write_entries(
 }
 
 static int checkout_merge_path(
-	git_buf *out,
+	git_str *out,
 	checkout_data *data,
 	checkout_conflictdata *conflict,
 	git_merge_file_result *result)
@@ -2033,7 +2033,7 @@ static int checkout_merge_path(
 	const char *our_label_raw, *their_label_raw, *suffix;
 	int error = 0;
 
-	if ((error = git_buf_joinpath(out, data->opts.target_directory, result->path)) < 0 ||
+	if ((error = git_str_joinpath(out, data->opts.target_directory, result->path)) < 0 ||
 	    (error = git_path_validate_workdir_buf(data->repo, out)) < 0)
 		return error;
 
@@ -2056,9 +2056,9 @@ static int checkout_write_merge(
 	checkout_data *data,
 	checkout_conflictdata *conflict)
 {
-	git_buf our_label = GIT_BUF_INIT, their_label = GIT_BUF_INIT,
-		path_suffixed = GIT_BUF_INIT, path_workdir = GIT_BUF_INIT,
-		in_data = GIT_BUF_INIT, out_data = GIT_BUF_INIT;
+	git_str our_label = GIT_STR_INIT, their_label = GIT_STR_INIT,
+		path_suffixed = GIT_STR_INIT, path_workdir = GIT_STR_INIT,
+		in_data = GIT_STR_INIT, out_data = GIT_STR_INIT;
 	git_merge_file_options opts = GIT_MERGE_FILE_OPTIONS_INIT;
 	git_merge_file_result result = {0};
 	git_filebuf output = GIT_FILEBUF_INIT;
@@ -2088,8 +2088,8 @@ static int checkout_write_merge(
 			&their_label, opts.their_label, conflict->theirs->path)) < 0)
 			goto done;
 
-		opts.our_label = git_buf_cstr(&our_label);
-		opts.their_label = git_buf_cstr(&their_label);
+		opts.our_label = git_str_cstr(&our_label);
+		opts.their_label = git_str_cstr(&their_label);
 	}
 
 	if ((error = git_merge_file_from_index(&result, data->repo,
@@ -2106,7 +2106,7 @@ static int checkout_write_merge(
 		goto done;
 
 	if ((data->strategy & GIT_CHECKOUT_UPDATE_ONLY) != 0 &&
-		(error = checkout_safe_for_update_only(data, git_buf_cstr(&path_workdir), result.mode)) <= 0)
+		(error = checkout_safe_for_update_only(data, git_str_cstr(&path_workdir), result.mode)) <= 0)
 		goto done;
 
 	if (!data->opts.disable_filters) {
@@ -2127,7 +2127,7 @@ static int checkout_write_merge(
 	}
 
 	if ((error = mkpath2file(data, path_workdir.ptr, data->opts.dir_mode)) < 0 ||
-		(error = git_filebuf_open(&output, git_buf_cstr(&path_workdir), GIT_FILEBUF_DO_NOT_BUFFER, result.mode)) < 0 ||
+		(error = git_filebuf_open(&output, git_str_cstr(&path_workdir), GIT_FILEBUF_DO_NOT_BUFFER, result.mode)) < 0 ||
 		(error = git_filebuf_write(&output, out_data.ptr, out_data.size)) < 0 ||
 		(error = git_filebuf_commit(&output)) < 0)
 		goto done;
@@ -2135,13 +2135,13 @@ static int checkout_write_merge(
 done:
 	git_filter_list_free(fl);
 
-	git_buf_dispose(&out_data);
-	git_buf_dispose(&our_label);
-	git_buf_dispose(&their_label);
+	git_str_dispose(&out_data);
+	git_str_dispose(&our_label);
+	git_str_dispose(&their_label);
 
 	git_merge_file_result_free(&result);
-	git_buf_dispose(&path_workdir);
-	git_buf_dispose(&path_suffixed);
+	git_str_dispose(&path_workdir);
+	git_str_dispose(&path_suffixed);
 
 	return error;
 }
@@ -2321,8 +2321,8 @@ static void checkout_data_clear(checkout_data *data)
 	git__free(data->pfx);
 	data->pfx = NULL;
 
-	git_buf_dispose(&data->target_path);
-	git_buf_dispose(&data->tmp);
+	git_str_dispose(&data->target_path);
+	git_str_dispose(&data->tmp);
 
 	git_index_free(data->index);
 	data->index = NULL;
@@ -2506,12 +2506,12 @@ static int checkout_data_init(
 	    (error = git_vector_init(&data->removes, 0, git__strcmp_cb)) < 0 ||
 	    (error = git_vector_init(&data->remove_conflicts, 0, NULL)) < 0 ||
 	    (error = git_vector_init(&data->update_conflicts, 0, NULL)) < 0 ||
-	    (error = git_buf_puts(&data->target_path, data->opts.target_directory)) < 0 ||
+	    (error = git_str_puts(&data->target_path, data->opts.target_directory)) < 0 ||
 	    (error = git_path_to_dir(&data->target_path)) < 0 ||
 	    (error = git_strmap_new(&data->mkdir_map)) < 0)
 		goto cleanup;
 
-	data->target_len = git_buf_len(&data->target_path);
+	data->target_len = git_str_len(&data->target_path);
 
 	git_attr_session__init(&data->attr_session, data->repo);
 
@@ -2623,7 +2623,7 @@ int git_checkout_iterator(
 
 	if (data.strategy & GIT_CHECKOUT_DRY_RUN)
 		goto cleanup;
-	
+
 	data.total_steps = counts[CHECKOUT_ACTION__REMOVE] +
 		counts[CHECKOUT_ACTION__REMOVE_CONFLICT] +
 		counts[CHECKOUT_ACTION__UPDATE_BLOB] +