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, 23 insertions, 24 deletions

diff --git a/src/tag.c b/src/tag.c
index ee91e5091..7a155147d 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -9,7 +9,6 @@
 
 #include "commit.h"
 #include "signature.h"
-#include "message.h"
 #include "wildmatch.h"
 #include "git2/object.h"
 #include "git2/repository.h"
@@ -176,7 +175,7 @@ int git_tag__parse(void *_tag, git_odb_object *odb_obj)
 
 static int retrieve_tag_reference(
 	git_reference **tag_reference_out,
-	git_buf *ref_name_out,
+	git_str *ref_name_out,
 	git_repository *repo,
 	const char *tag_name)
 {
@@ -185,7 +184,7 @@ static int retrieve_tag_reference(
 
 	*tag_reference_out = NULL;
 
-	if (git_buf_joinpath(ref_name_out, GIT_REFS_TAGS_DIR, tag_name) < 0)
+	if (git_str_joinpath(ref_name_out, GIT_REFS_TAGS_DIR, tag_name) < 0)
 		return -1;
 
 	error = git_reference_lookup(&tag_ref, repo, ref_name_out->ptr);
@@ -199,11 +198,11 @@ static int retrieve_tag_reference(
 
 static int retrieve_tag_reference_oid(
 	git_oid *oid,
-	git_buf *ref_name_out,
+	git_str *ref_name_out,
 	git_repository *repo,
 	const char *tag_name)
 {
-	if (git_buf_joinpath(ref_name_out, GIT_REFS_TAGS_DIR, tag_name) < 0)
+	if (git_str_joinpath(ref_name_out, GIT_REFS_TAGS_DIR, tag_name) < 0)
 		return -1;
 
 	return git_reference_name_to_id(oid, repo, ref_name_out->ptr);
@@ -217,16 +216,16 @@ static int write_tag_annotation(
 		const git_signature *tagger,
 		const char *message)
 {
-	git_buf tag = GIT_BUF_INIT;
+	git_str tag = GIT_STR_INIT;
 	git_odb *odb;
 
 	git_oid__writebuf(&tag, "object ", git_object_id(target));
-	git_buf_printf(&tag, "type %s\n", git_object_type2string(git_object_type(target)));
-	git_buf_printf(&tag, "tag %s\n", tag_name);
+	git_str_printf(&tag, "type %s\n", git_object_type2string(git_object_type(target)));
+	git_str_printf(&tag, "tag %s\n", tag_name);
 	git_signature__writebuf(&tag, "tagger ", tagger);
-	git_buf_putc(&tag, '\n');
+	git_str_putc(&tag, '\n');
 
-	if (git_buf_puts(&tag, message) < 0)
+	if (git_str_puts(&tag, message) < 0)
 		goto on_error;
 
 	if (git_repository_odb__weakptr(&odb, repo) < 0)
@@ -235,11 +234,11 @@ static int write_tag_annotation(
 	if (git_odb_write(oid, odb, tag.ptr, tag.size, GIT_OBJECT_TAG) < 0)
 		goto on_error;
 
-	git_buf_dispose(&tag);
+	git_str_dispose(&tag);
 	return 0;
 
 on_error:
-	git_buf_dispose(&tag);
+	git_str_dispose(&tag);
 	git_error_set(GIT_ERROR_OBJECT, "failed to create tag annotation");
 	return -1;
 }
@@ -255,7 +254,7 @@ static int git_tag_create__internal(
 		int create_tag_annotation)
 {
 	git_reference *new_ref = NULL;
-	git_buf ref_name = GIT_BUF_INIT;
+	git_str ref_name = GIT_STR_INIT;
 
 	int error;
 
@@ -276,7 +275,7 @@ static int git_tag_create__internal(
 	/** Ensure the tag name doesn't conflict with an already existing
 	 *	reference unless overwriting has explicitly been requested **/
 	if (error == 0 && !allow_ref_overwrite) {
-		git_buf_dispose(&ref_name);
+		git_str_dispose(&ref_name);
 		git_error_set(GIT_ERROR_TAG, "tag already exists");
 		return GIT_EEXISTS;
 	}
@@ -291,7 +290,7 @@ static int git_tag_create__internal(
 
 cleanup:
 	git_reference_free(new_ref);
-	git_buf_dispose(&ref_name);
+	git_str_dispose(&ref_name);
 	return error;
 }
 
@@ -344,7 +343,7 @@ int git_tag_create_from_buffer(git_oid *oid, git_repository *repo, const char *b
 	git_odb_object *target_obj;
 
 	git_reference *new_ref = NULL;
-	git_buf ref_name = GIT_BUF_INIT;
+	git_str ref_name = GIT_STR_INIT;
 
 	GIT_ASSERT_ARG(oid);
 	GIT_ASSERT_ARG(buffer);
@@ -395,7 +394,7 @@ int git_tag_create_from_buffer(git_oid *oid, git_repository *repo, const char *b
 	git_odb_stream_free(stream);
 
 	if (error < 0) {
-		git_buf_dispose(&ref_name);
+		git_str_dispose(&ref_name);
 		return error;
 	}
 
@@ -403,7 +402,7 @@ int git_tag_create_from_buffer(git_oid *oid, git_repository *repo, const char *b
 		&new_ref, repo, ref_name.ptr, oid, allow_ref_overwrite, NULL);
 
 	git_reference_free(new_ref);
-	git_buf_dispose(&ref_name);
+	git_str_dispose(&ref_name);
 
 	return error;
 
@@ -418,12 +417,12 @@ on_error:
 int git_tag_delete(git_repository *repo, const char *tag_name)
 {
 	git_reference *tag_ref;
-	git_buf ref_name = GIT_BUF_INIT;
+	git_str ref_name = GIT_STR_INIT;
 	int error;
 
 	error = retrieve_tag_reference(&tag_ref, &ref_name, repo, tag_name);
 
-	git_buf_dispose(&ref_name);
+	git_str_dispose(&ref_name);
 
 	if (error < 0)
 		return error;
@@ -535,7 +534,7 @@ int git_tag_peel(git_object **tag_target, const git_tag *tag)
 
 int git_tag_name_is_valid(int *valid, const char *name)
 {
-	git_buf ref_name = GIT_BUF_INIT;
+	git_str ref_name = GIT_STR_INIT;
 	int error = 0;
 
 	GIT_ASSERT(valid);
@@ -547,14 +546,14 @@ int git_tag_name_is_valid(int *valid, const char *name)
 	if (!name || name[0] == '-')
 		goto done;
 
-	if ((error = git_buf_puts(&ref_name, GIT_REFS_TAGS_DIR)) < 0 ||
-	    (error = git_buf_puts(&ref_name, name)) < 0)
+	if ((error = git_str_puts(&ref_name, GIT_REFS_TAGS_DIR)) < 0 ||
+	    (error = git_str_puts(&ref_name, name)) < 0)
 		goto done;
 
 	error = git_reference_name_is_valid(valid, ref_name.ptr);
 
 done:
-	git_buf_dispose(&ref_name);
+	git_str_dispose(&ref_name);
 	return error;
 }