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, 22 deletions

diff --git a/src/pack-objects.c b/src/pack-objects.c
index d89a4e780..e5fc625a4 100644
--- a/src/pack-objects.c
+++ b/src/pack-objects.c
@@ -7,6 +7,7 @@
 
 #include "pack-objects.h"
 
+#include "buf.h"
 #include "zstream.h"
 #include "delta.h"
 #include "iterator.h"
@@ -33,7 +34,7 @@ struct unpacked {
 
 struct tree_walk_context {
 	git_packbuilder *pb;
-	git_buf buf;
+	git_str buf;
 };
 
 struct pack_write_context {
@@ -685,8 +686,8 @@ done:
 
 static int write_pack_buf(void *buf, size_t size, void *data)
 {
-	git_buf *b = (git_buf *)data;
-	return git_buf_put(b, buf, size);
+	git_str *b = (git_str *)data;
+	return git_str_put(b, buf, size);
 }
 
 static int type_size_sort(const void *_a, const void *_b)
@@ -947,7 +948,7 @@ static int find_deltas(git_packbuilder *pb, git_pobject **list,
 	size_t *list_size, size_t window, size_t depth)
 {
 	git_pobject *po;
-	git_buf zbuf = GIT_BUF_INIT;
+	git_str zbuf = GIT_STR_INIT;
 	struct unpacked *array;
 	size_t idx = 0, count = 0;
 	size_t mem_usage = 0;
@@ -1045,7 +1046,7 @@ static int find_deltas(git_packbuilder *pb, git_pobject **list,
 
 			memcpy(po->delta_data, zbuf.ptr, zbuf.size);
 			po->z_delta_size = zbuf.size;
-			git_buf_clear(&zbuf);
+			git_str_clear(&zbuf);
 
 			GIT_ASSERT(git_packbuilder__cache_lock(pb) == 0);
 			pb->delta_cache_size -= po->delta_size;
@@ -1093,7 +1094,7 @@ on_error:
 		git__free(array[i].data);
 	}
 	git__free(array);
-	git_buf_dispose(&zbuf);
+	git_str_dispose(&zbuf);
 
 	return error;
 }
@@ -1360,18 +1361,18 @@ int git_packbuilder_foreach(git_packbuilder *pb, int (*cb)(void *buf, size_t siz
 	return write_pack(pb, cb, payload);
 }
 
-int git_packbuilder_write_buf(git_buf *buf, git_packbuilder *pb)
+int git_packbuilder__write_buf(git_str *buf, git_packbuilder *pb)
 {
-	int error;
-
-	if ((error = git_buf_sanitize(buf)) < 0)
-		return error;
-
 	PREPARE_PACK;
 
 	return write_pack(pb, &write_pack_buf, buf);
 }
 
+int git_packbuilder_write_buf(git_buf *buf, git_packbuilder *pb)
+{
+	GIT_BUF_WRAP_PRIVATE(buf, git_packbuilder__write_buf, pb);
+}
+
 static int write_cb(void *buf, size_t len, void *payload)
 {
 	struct pack_write_context *ctx = payload;
@@ -1386,7 +1387,7 @@ int git_packbuilder_write(
 	void *progress_cb_payload)
 {
 	int error = -1;
-	git_buf object_path = GIT_BUF_INIT;
+	git_str object_path = GIT_STR_INIT;
 	git_indexer_options opts = GIT_INDEXER_OPTIONS_INIT;
 	git_indexer *indexer = NULL;
 	git_indexer_progress stats;
@@ -1396,11 +1397,11 @@ int git_packbuilder_write(
 	PREPARE_PACK;
 
 	if (path == NULL) {
-		if ((error = git_repository_item_path(&object_path, pb->repo, GIT_REPOSITORY_ITEM_OBJECTS)) < 0)
+		if ((error = git_repository__item_path(&object_path, pb->repo, GIT_REPOSITORY_ITEM_OBJECTS)) < 0)
 			goto cleanup;
-		if ((error = git_buf_joinpath(&object_path, git_buf_cstr(&object_path), "pack")) < 0)
+		if ((error = git_str_joinpath(&object_path, git_str_cstr(&object_path), "pack")) < 0)
 			goto cleanup;
-		path = git_buf_cstr(&object_path);
+		path = git_str_cstr(&object_path);
 	}
 
 	opts.progress_cb = progress_cb;
@@ -1425,7 +1426,7 @@ int git_packbuilder_write(
 
 cleanup:
 	git_indexer_free(indexer);
-	git_buf_dispose(&object_path);
+	git_str_dispose(&object_path);
 	return error;
 }
 
@@ -1447,10 +1448,10 @@ static int cb_tree_walk(
 	if (git_tree_entry_type(entry) == GIT_OBJECT_COMMIT)
 		return 0;
 
-	if (!(error = git_buf_sets(&ctx->buf, root)) &&
-		!(error = git_buf_puts(&ctx->buf, git_tree_entry_name(entry))))
+	if (!(error = git_str_sets(&ctx->buf, root)) &&
+		!(error = git_str_puts(&ctx->buf, git_tree_entry_name(entry))))
 		error = git_packbuilder_insert(
-			ctx->pb, git_tree_entry_id(entry), git_buf_cstr(&ctx->buf));
+			ctx->pb, git_tree_entry_id(entry), git_str_cstr(&ctx->buf));
 
 	return error;
 }
@@ -1474,14 +1475,14 @@ int git_packbuilder_insert_tree(git_packbuilder *pb, const git_oid *oid)
 {
 	int error;
 	git_tree *tree = NULL;
-	struct tree_walk_context context = { pb, GIT_BUF_INIT };
+	struct tree_walk_context context = { pb, GIT_STR_INIT };
 
 	if (!(error = git_tree_lookup(&tree, pb->repo, oid)) &&
 	    !(error = git_packbuilder_insert(pb, oid, NULL)))
 		error = git_tree_walk(tree, GIT_TREEWALK_PRE, cb_tree_walk, &context);
 
 	git_tree_free(tree);
-	git_buf_dispose(&context.buf);
+	git_str_dispose(&context.buf);
 	return error;
 }