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, 4 insertions, 4 deletions

diff --git a/src/attr_file.h b/src/attr_file.h
index d634e6da9..08630d1a6 100644
--- a/src/attr_file.h
+++ b/src/attr_file.h
@@ -13,7 +13,7 @@
 #include "git2/attr.h"
 #include "vector.h"
 #include "pool.h"
-#include "buffer.h"
+#include "str.h"
 #include "futils.h"
 
 #define GIT_ATTR_FILE			".gitattributes"
@@ -118,7 +118,7 @@ struct git_attr_file_entry {
 };
 
 typedef struct {
-	git_buf  full;
+	git_str  full;
 	char    *path;
 	char    *basename;
 	int      is_dir;
@@ -132,8 +132,8 @@ typedef struct {
 	int key;
 	unsigned int init_setup:1,
 		init_sysdir:1;
-	git_buf sysdir;
-	git_buf tmp;
+	git_str sysdir;
+	git_str tmp;
 } git_attr_session;
 
 extern int git_attr_session__init(git_attr_session *attr_session, git_repository *repo);