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, 22 insertions, 24 deletions

diff --git a/src/blob.c b/src/blob.c
index 09b5b5d91..6f57d09e4 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -12,6 +12,7 @@
 #include "git2/repository.h"
 #include "git2/odb_backend.h"
 
+#include "buf.h"
 #include "filebuf.h"
 #include "filter.h"
 
@@ -35,12 +36,12 @@ git_object_size_t git_blob_rawsize(const git_blob *blob)
 		return (git_object_size_t)git_odb_object_size(blob->data.odb);
 }
 
-int git_blob__getbuf(git_buf *buffer, git_blob *blob)
+int git_blob__getbuf(git_str *buffer, git_blob *blob)
 {
 	git_object_size_t size = git_blob_rawsize(blob);
 
 	GIT_ERROR_CHECK_BLOBSIZE(size);
-	return git_buf_set(buffer, git_blob_rawcontent(blob), (size_t)size);
+	return git_str_set(buffer, git_blob_rawcontent(blob), (size_t)size);
 }
 
 void git_blob__free(void *_blob)
@@ -142,9 +143,9 @@ static int write_file_filtered(
 	git_repository* repo)
 {
 	int error;
-	git_buf tgt = GIT_BUF_INIT;
+	git_str tgt = GIT_STR_INIT;
 
-	error = git_filter_list_apply_to_file(&tgt, fl, repo, full_path);
+	error = git_filter_list__apply_to_file(&tgt, fl, repo, full_path);
 
 	/* Write the file to disk if it was properly filtered */
 	if (!error) {
@@ -153,7 +154,7 @@ static int write_file_filtered(
 		error = git_odb_write(id, odb, tgt.ptr, tgt.size, GIT_OBJECT_BLOB);
 	}
 
-	git_buf_dispose(&tgt);
+	git_str_dispose(&tgt);
 	return error;
 }
 
@@ -193,7 +194,7 @@ int git_blob__create_from_paths(
 	git_odb *odb = NULL;
 	git_object_size_t size;
 	mode_t mode;
-	git_buf path = GIT_BUF_INIT;
+	git_str path = GIT_STR_INIT;
 
 	GIT_ASSERT_ARG(hint_path || !try_load_filters);
 
@@ -261,7 +262,7 @@ int git_blob__create_from_paths(
 
 done:
 	git_odb_free(odb);
-	git_buf_dispose(&path);
+	git_str_dispose(&path);
 
 	return error;
 }
@@ -276,11 +277,11 @@ int git_blob_create_from_disk(
 	git_oid *id, git_repository *repo, const char *path)
 {
 	int error;
-	git_buf full_path = GIT_BUF_INIT;
+	git_str full_path = GIT_STR_INIT;
 	const char *workdir, *hintpath = NULL;
 
 	if ((error = git_path_prettify(&full_path, path, NULL)) < 0) {
-		git_buf_dispose(&full_path);
+		git_str_dispose(&full_path);
 		return error;
 	}
 
@@ -290,9 +291,9 @@ int git_blob_create_from_disk(
 		hintpath = full_path.ptr + strlen(workdir);
 
 	error = git_blob__create_from_paths(
-		id, NULL, repo, git_buf_cstr(&full_path), hintpath, 0, !!hintpath);
+		id, NULL, repo, git_str_cstr(&full_path), hintpath, 0, !!hintpath);
 
-	git_buf_dispose(&full_path);
+	git_str_dispose(&full_path);
 	return error;
 }
 
@@ -330,7 +331,7 @@ static int blob_writestream_write(git_writestream *_stream, const char *buffer,
 int git_blob_create_from_stream(git_writestream **out, git_repository *repo, const char *hintpath)
 {
 	int error;
-	git_buf path = GIT_BUF_INIT;
+	git_str path = GIT_STR_INIT;
 	blob_writestream *stream;
 
 	GIT_ASSERT_ARG(out);
@@ -349,11 +350,11 @@ int git_blob_create_from_stream(git_writestream **out, git_repository *repo, con
 	stream->parent.close = blob_writestream_close;
 	stream->parent.free  = blob_writestream_free;
 
-	if ((error = git_repository_item_path(&path, repo, GIT_REPOSITORY_ITEM_OBJECTS)) < 0
-		|| (error = git_buf_joinpath(&path, path.ptr, "streamed")) < 0)
+	if ((error = git_repository__item_path(&path, repo, GIT_REPOSITORY_ITEM_OBJECTS)) < 0
+		|| (error = git_str_joinpath(&path, path.ptr, "streamed")) < 0)
 		goto cleanup;
 
-	if ((error = git_filebuf_open_withsize(&stream->fbuf, git_buf_cstr(&path), GIT_FILEBUF_TEMPORARY,
+	if ((error = git_filebuf_open_withsize(&stream->fbuf, git_str_cstr(&path), GIT_FILEBUF_TEMPORARY,
 					       0666, 2 * 1024 * 1024)) < 0)
 		goto cleanup;
 
@@ -363,7 +364,7 @@ cleanup:
 	if (error < 0)
 		blob_writestream_free((git_writestream *) stream);
 
-	git_buf_dispose(&path);
+	git_str_dispose(&path);
 	return error;
 }
 
@@ -391,16 +392,16 @@ cleanup:
 
 int git_blob_is_binary(const git_blob *blob)
 {
-	git_buf content = GIT_BUF_INIT;
+	git_str content = GIT_STR_INIT;
 	git_object_size_t size;
 
 	GIT_ASSERT_ARG(blob);
 
 	size = git_blob_rawsize(blob);
 
-	git_buf_attach_notowned(&content, git_blob_rawcontent(blob),
+	git_str_attach_notowned(&content, git_blob_rawcontent(blob),
 		(size_t)min(size, GIT_FILTER_BYTES_TO_CHECK_NUL));
-	return git_buf_is_binary(&content);
+	return git_str_is_binary(&content);
 }
 
 int git_blob_filter_options_init(
@@ -418,10 +419,10 @@ int git_blob_filter(
 	const char *path,
 	git_blob_filter_options *given_opts)
 {
-	int error = 0;
-	git_filter_list *fl = NULL;
 	git_blob_filter_options opts = GIT_BLOB_FILTER_OPTIONS_INIT;
 	git_filter_options filter_opts = GIT_FILTER_OPTIONS_INIT;
+	git_filter_list *fl = NULL;
+	int error = 0;
 
 	GIT_ASSERT_ARG(blob);
 	GIT_ASSERT_ARG(path);
@@ -430,9 +431,6 @@ int git_blob_filter(
 	GIT_ERROR_CHECK_VERSION(
 		given_opts, GIT_BLOB_FILTER_OPTIONS_VERSION, "git_blob_filter_options");
 
-	if (git_buf_sanitize(out) < 0)
-		return -1;
-
 	if (given_opts != NULL)
 		memcpy(&opts, given_opts, sizeof(git_blob_filter_options));