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.

4 files changed, 53 insertions, 52 deletions

diff --git a/tests/pack/filelimit.c b/tests/pack/filelimit.c
index 5e0b77e9b..2b7bf6e95 100644
--- a/tests/pack/filelimit.c
+++ b/tests/pack/filelimit.c
@@ -34,12 +34,12 @@ void test_pack_filelimit__initialize_unlimited(void)
 
 void test_pack_filelimit__cleanup(void)
 {
-	git_buf path = GIT_BUF_INIT;
+	git_str path = GIT_STR_INIT;
 	cl_git_pass(git_libgit2_opts(GIT_OPT_SET_MWINDOW_FILE_LIMIT, original_mwindow_file_limit));
 
-	cl_git_pass(git_buf_joinpath(&path, clar_sandbox_path(), "repo.git"));
+	cl_git_pass(git_str_joinpath(&path, clar_sandbox_path(), "repo.git"));
 	cl_fixture_cleanup(path.ptr);
-	git_buf_dispose(&path);
+	git_str_dispose(&path);
 }
 
 /*
@@ -54,7 +54,7 @@ void create_packfile_commit(
 		size_t commit_index,
 		size_t commit_count)
 {
-	git_buf file_contents = GIT_BUF_INIT;
+	git_str file_contents = GIT_STR_INIT;
 	git_treebuilder *treebuilder;
 	git_packbuilder *packbuilder;
 	git_signature *s;
@@ -67,7 +67,7 @@ void create_packfile_commit(
 	cl_git_pass(git_blob_create_from_buffer(&oid, repo, "", 0));
 	cl_git_pass(git_treebuilder_insert(NULL, treebuilder, "README.md", &oid, 0100644));
 
-	cl_git_pass(git_buf_printf(&file_contents, "Commit %zd/%zd", commit_index, commit_count));
+	cl_git_pass(git_str_printf(&file_contents, "Commit %zd/%zd", commit_index, commit_count));
 	cl_git_pass(git_blob_create_from_buffer(&oid, repo, file_contents.ptr, file_contents.size));
 	cl_git_pass(git_treebuilder_insert(NULL, treebuilder, "file.txt", &oid, 0100644));
 
@@ -82,7 +82,7 @@ void create_packfile_commit(
 
 	cl_git_pass(git_oid_cpy(out_commit_id, &commit_id));
 
-	git_buf_dispose(&file_contents);
+	git_str_dispose(&file_contents);
 	git_treebuilder_free(treebuilder);
 	git_packbuilder_free(packbuilder);
 	git_signature_free(s);
@@ -90,7 +90,7 @@ void create_packfile_commit(
 
 void test_pack_filelimit__open_repo_with_multiple_packfiles(void)
 {
-	git_buf path = GIT_BUF_INIT;
+	git_str path = GIT_STR_INIT;
 	git_mwindow_ctl *ctl = &git_mwindow__mem_ctl;
 	git_repository *repo;
 	git_revwalk *walk;
@@ -103,7 +103,7 @@ void test_pack_filelimit__open_repo_with_multiple_packfiles(void)
 	 * Create a repository and populate it with 16 commits, each in its own
 	 * packfile.
 	 */
-	cl_git_pass(git_buf_joinpath(&path, clar_sandbox_path(), "repo.git"));
+	cl_git_pass(git_str_joinpath(&path, clar_sandbox_path(), "repo.git"));
 	cl_git_pass(git_repository_init(&repo, path.ptr, true));
 	for (i = 0; i < commit_count; ++i) {
 		create_packfile_commit(repo, &id, parent_id, i + 1, commit_count);
@@ -130,7 +130,7 @@ void test_pack_filelimit__open_repo_with_multiple_packfiles(void)
 
 	cl_assert_equal_i(expected_open_mwindow_files, open_windows);
 
-	git_buf_dispose(&path);
+	git_str_dispose(&path);
 	git_revwalk_free(walk);
 	git_repository_free(repo);
 }
diff --git a/tests/pack/indexer.c b/tests/pack/indexer.c
index 422c3def4..5958bc4ba 100644
--- a/tests/pack/indexer.c
+++ b/tests/pack/indexer.c
@@ -279,10 +279,10 @@ void test_pack_indexer__out_of_order_with_connectivity_checks(void)
 	git_indexer_free(idx);
 }
 
-static int find_tmp_file_recurs(void *opaque, git_buf *path)
+static int find_tmp_file_recurs(void *opaque, git_str *path)
 {
 	int error = 0;
-	git_buf *first_tmp_file = opaque;
+	git_str *first_tmp_file = opaque;
 	struct stat st;
 
 	if ((error = p_lstat_posixly(path->ptr, &st)) < 0)
@@ -292,8 +292,8 @@ static int find_tmp_file_recurs(void *opaque, git_buf *path)
 		return git_path_direach(path, 0, find_tmp_file_recurs, opaque);
 
 	/* This is the template that's used in git_futils_mktmp. */
-	if (strstr(git_buf_cstr(path), "_git2_") != NULL)
-		return git_buf_sets(first_tmp_file, git_buf_cstr(path));
+	if (strstr(git_str_cstr(path), "_git2_") != NULL)
+		return git_str_sets(first_tmp_file, git_str_cstr(path));
 
 	return 0;
 }
@@ -301,21 +301,21 @@ static int find_tmp_file_recurs(void *opaque, git_buf *path)
 void test_pack_indexer__no_tmp_files(void)
 {
 	git_indexer *idx = NULL;
-	git_buf path = GIT_BUF_INIT;
-	git_buf first_tmp_file = GIT_BUF_INIT;
+	git_str path = GIT_STR_INIT;
+	git_str first_tmp_file = GIT_STR_INIT;
 
 	/* Precondition: there are no temporary files. */
-	cl_git_pass(git_buf_sets(&path, clar_sandbox_path()));
+	cl_git_pass(git_str_sets(&path, clar_sandbox_path()));
 	cl_git_pass(find_tmp_file_recurs(&first_tmp_file, &path));
-	git_buf_dispose(&path);
-	cl_assert(git_buf_len(&first_tmp_file) == 0);
+	git_str_dispose(&path);
+	cl_assert(git_str_len(&first_tmp_file) == 0);
 
 	cl_git_pass(git_indexer_new(&idx, ".", 0, NULL, NULL));
 	git_indexer_free(idx);
 
-	cl_git_pass(git_buf_sets(&path, clar_sandbox_path()));
+	cl_git_pass(git_str_sets(&path, clar_sandbox_path()));
 	cl_git_pass(find_tmp_file_recurs(&first_tmp_file, &path));
-	git_buf_dispose(&path);
-	cl_assert(git_buf_len(&first_tmp_file) == 0);
-	git_buf_dispose(&first_tmp_file);
+	git_str_dispose(&path);
+	cl_assert(git_str_len(&first_tmp_file) == 0);
+	git_str_dispose(&first_tmp_file);
 }
diff --git a/tests/pack/midx.c b/tests/pack/midx.c
index d5b91d28b..9dd949363 100644
--- a/tests/pack/midx.c
+++ b/tests/pack/midx.c
@@ -12,12 +12,12 @@ void test_pack_midx__parse(void)
 	struct git_midx_file *idx;
 	struct git_midx_entry e;
 	git_oid id;
-	git_buf midx_path = GIT_BUF_INIT;
+	git_str midx_path = GIT_STR_INIT;
 
 	cl_git_pass(git_repository_open(&repo, cl_fixture("testrepo.git")));
-	cl_git_pass(git_buf_joinpath(&midx_path, git_repository_path(repo), "objects/pack/multi-pack-index"));
-	cl_git_pass(git_midx_open(&idx, git_buf_cstr(&midx_path)));
-	cl_assert_equal_i(git_midx_needs_refresh(idx, git_buf_cstr(&midx_path)), 0);
+	cl_git_pass(git_str_joinpath(&midx_path, git_repository_path(repo), "objects/pack/multi-pack-index"));
+	cl_git_pass(git_midx_open(&idx, git_str_cstr(&midx_path)));
+	cl_assert_equal_i(git_midx_needs_refresh(idx, git_str_cstr(&midx_path)), 0);
 
 	cl_git_pass(git_oid_fromstr(&id, "5001298e0c09ad9c34e4249bc5801c75e9754fa5"));
 	cl_git_pass(git_midx_entry_find(&e, idx, &id, GIT_OID_HEXSZ));
@@ -28,7 +28,7 @@ void test_pack_midx__parse(void)
 
 	git_midx_free(idx);
 	git_repository_free(repo);
-	git_buf_dispose(&midx_path);
+	git_str_dispose(&midx_path);
 }
 
 void test_pack_midx__lookup(void)
@@ -51,27 +51,28 @@ void test_pack_midx__writer(void)
 {
 	git_repository *repo;
 	git_midx_writer *w = NULL;
-	git_buf midx = GIT_BUF_INIT, expected_midx = GIT_BUF_INIT, path = GIT_BUF_INIT;
+	git_buf midx = GIT_BUF_INIT;
+	git_str expected_midx = GIT_STR_INIT, path = GIT_STR_INIT;
 
 	cl_git_pass(git_repository_open(&repo, cl_fixture("testrepo.git")));
 
-	cl_git_pass(git_buf_joinpath(&path, git_repository_path(repo), "objects/pack"));
-	cl_git_pass(git_midx_writer_new(&w, git_buf_cstr(&path)));
+	cl_git_pass(git_str_joinpath(&path, git_repository_path(repo), "objects/pack"));
+	cl_git_pass(git_midx_writer_new(&w, git_str_cstr(&path)));
 
 	cl_git_pass(git_midx_writer_add(w, "pack-d7c6adf9f61318f041845b01440d09aa7a91e1b5.idx"));
 	cl_git_pass(git_midx_writer_add(w, "pack-d85f5d483273108c9d8dd0e4728ccf0b2982423a.idx"));
 	cl_git_pass(git_midx_writer_add(w, "pack-a81e489679b7d3418f9ab594bda8ceb37dd4c695.idx"));
 
 	cl_git_pass(git_midx_writer_dump(&midx, w));
-	cl_git_pass(git_buf_joinpath(&path, git_repository_path(repo), "objects/pack/multi-pack-index"));
-	cl_git_pass(git_futils_readbuffer(&expected_midx, git_buf_cstr(&path)));
+	cl_git_pass(git_str_joinpath(&path, git_repository_path(repo), "objects/pack/multi-pack-index"));
+	cl_git_pass(git_futils_readbuffer(&expected_midx, git_str_cstr(&path)));
 
-	cl_assert_equal_i(git_buf_len(&midx), git_buf_len(&expected_midx));
-	cl_assert_equal_strn(git_buf_cstr(&midx), git_buf_cstr(&expected_midx), git_buf_len(&midx));
+	cl_assert_equal_i(midx.size, git_str_len(&expected_midx));
+	cl_assert_equal_strn(midx.ptr, git_str_cstr(&expected_midx), midx.size);
 
 	git_buf_dispose(&midx);
-	git_buf_dispose(&expected_midx);
-	git_buf_dispose(&path);
+	git_str_dispose(&expected_midx);
+	git_str_dispose(&path);
 	git_midx_writer_free(w);
 	git_repository_free(repo);
 }
@@ -81,30 +82,30 @@ void test_pack_midx__odb_create(void)
 	git_repository *repo;
 	git_odb *odb;
 	git_clone_options opts = GIT_CLONE_OPTIONS_INIT;
-	git_buf midx = GIT_BUF_INIT, expected_midx = GIT_BUF_INIT, midx_path = GIT_BUF_INIT;
+	git_str midx = GIT_STR_INIT, expected_midx = GIT_STR_INIT, midx_path = GIT_STR_INIT;
 	struct stat st;
 
 	opts.bare = true;
 	opts.local = GIT_CLONE_LOCAL;
 	cl_git_pass(git_clone(&repo, cl_fixture("testrepo/.gitted"), "./clone.git", &opts));
-	cl_git_pass(git_buf_joinpath(&midx_path, git_repository_path(repo), "objects/pack/multi-pack-index"));
-	cl_git_fail(p_stat(git_buf_cstr(&midx_path), &st));
+	cl_git_pass(git_str_joinpath(&midx_path, git_repository_path(repo), "objects/pack/multi-pack-index"));
+	cl_git_fail(p_stat(git_str_cstr(&midx_path), &st));
 
 	cl_git_pass(git_repository_odb(&odb, repo));
 	cl_git_pass(git_odb_write_multi_pack_index(odb));
 	git_odb_free(odb);
 
-	cl_git_pass(p_stat(git_buf_cstr(&midx_path), &st));
+	cl_git_pass(p_stat(git_str_cstr(&midx_path), &st));
 
 	cl_git_pass(git_futils_readbuffer(&expected_midx, cl_fixture("testrepo.git/objects/pack/multi-pack-index")));
-	cl_git_pass(git_futils_readbuffer(&midx, git_buf_cstr(&midx_path)));
-	cl_assert_equal_i(git_buf_len(&midx), git_buf_len(&expected_midx));
-	cl_assert_equal_strn(git_buf_cstr(&midx), git_buf_cstr(&expected_midx), git_buf_len(&midx));
+	cl_git_pass(git_futils_readbuffer(&midx, git_str_cstr(&midx_path)));
+	cl_assert_equal_i(git_str_len(&midx), git_str_len(&expected_midx));
+	cl_assert_equal_strn(git_str_cstr(&midx), git_str_cstr(&expected_midx), git_str_len(&midx));
 
 	git_repository_free(repo);
-	git_buf_dispose(&midx);
-	git_buf_dispose(&midx_path);
-	git_buf_dispose(&expected_midx);
+	git_str_dispose(&midx);
+	git_str_dispose(&midx_path);
+	git_str_dispose(&expected_midx);
 
 	cl_git_pass(git_futils_rmdir_r("./clone.git", NULL, GIT_RMDIR_REMOVE_FILES));
-}
\ No newline at end of file
+}
diff --git a/tests/pack/packbuilder.c b/tests/pack/packbuilder.c
index 5d93ede06..b4c655c5e 100644
--- a/tests/pack/packbuilder.c
+++ b/tests/pack/packbuilder.c
@@ -96,7 +96,7 @@ static int feed_indexer(void *ptr, size_t len, void *payload)
 void test_pack_packbuilder__create_pack(void)
 {
 	git_indexer_progress stats;
-	git_buf buf = GIT_BUF_INIT, path = GIT_BUF_INIT;
+	git_str buf = GIT_STR_INIT, path = GIT_STR_INIT;
 	git_hash_ctx ctx;
 	git_oid hash;
 	char hex[GIT_OID_HEXSZ+1]; hex[GIT_OID_HEXSZ] = '\0';
@@ -108,7 +108,7 @@ void test_pack_packbuilder__create_pack(void)
 	cl_git_pass(git_indexer_commit(_indexer, &stats));
 
 	git_oid_fmt(hex, git_indexer_hash(_indexer));
-	git_buf_printf(&path, "pack-%s.pack", hex);
+	git_str_printf(&path, "pack-%s.pack", hex);
 
 	/*
 	 * By default, packfiles are created with only one thread.
@@ -124,15 +124,15 @@ void test_pack_packbuilder__create_pack(void)
 	 *
 	 */
 
-	cl_git_pass(git_futils_readbuffer(&buf, git_buf_cstr(&path)));
+	cl_git_pass(git_futils_readbuffer(&buf, git_str_cstr(&path)));
 
 	cl_git_pass(git_hash_ctx_init(&ctx, GIT_HASH_ALGORITHM_SHA1));
 	cl_git_pass(git_hash_update(&ctx, buf.ptr, buf.size));
 	cl_git_pass(git_hash_final(hash.id, &ctx));
 	git_hash_ctx_cleanup(&ctx);
 
-	git_buf_dispose(&path);
-	git_buf_dispose(&buf);
+	git_str_dispose(&path);
+	git_str_dispose(&buf);
 
 	git_oid_fmt(hex, &hash);