repo: add path.toplevel with absolute and relative suffix formatting

Scripts frequently need to find the root directory of a repository's
working tree. Currently, this requires using `git rev-parse --show-toplevel`
or inferring it from other repository information.

Introduce `path.toplevel.absolute` and `path.toplevel.relative` keys
to `git repo info`. This allows scripts to retrieve the top-level
working tree path in a predictable, strictly formatted manner without
relying on `rev-parse`.

If requested in a bare repository where no working tree exists, the
command returns an empty string.

Mentored-by: Justin Tobler <jltobler@gmail.com>
Mentored-by: Lucas Seiki Oshiro <lucasseikioshiro@gmail.com>
Signed-off-by: K Jayatheerth <jayatheerthkulkarni2005@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-repo.adoc

@@ -119,6 +119,16 @@ values that they return:
 `path.gitdir.relative`::
 	The path to the Git repository directory relative to the current working directory.
 
+`path.toplevel.absolute`::
+	The canonical absolute path to the top-level directory of the
+	repository's working tree. Outputs an empty string if the repository
+	is bare.
+
+`path.toplevel.relative`::
+	The path to the top-level directory of the repository's working
+	tree relative to the current working directory. Outputs an empty
+	string if the repository is bare.
+
 `references.format`::
 	The reference storage format. The valid values are:
 +

builtin/repo.c

@@ -121,6 +121,28 @@ static int get_path_gitdir_relative(struct repository *repo, struct strbuf *buf)
 	return 0;
 }
 
+static int get_path_toplevel_absolute(struct repository *repo, struct strbuf *buf)
+{
+	const char *work_tree = repo_get_work_tree(repo);
+
+	if (!work_tree)
+		return 0;
+
+	format_path(buf, work_tree, "", PATH_FORMAT_CANONICAL);
+	return 0;
+}
+
+static int get_path_toplevel_relative(struct repository *repo, struct strbuf *buf)
+{
+	const char *work_tree = repo_get_work_tree(repo);
+
+	if (!work_tree)
+		return 0;
+
+	format_path(buf, work_tree, repo->prefix, PATH_FORMAT_RELATIVE);
+	return 0;
+}
+
 static int get_references_format(struct repository *repo, struct strbuf *buf)
 {
 	strbuf_addstr(buf,
@@ -137,6 +159,8 @@ static const struct repo_info_field repo_info_field[] = {
 	{ "path.commondir.relative", get_path_commondir_relative },
 	{ "path.gitdir.absolute", get_path_gitdir_absolute },
 	{ "path.gitdir.relative", get_path_gitdir_relative },
+	{ "path.toplevel.absolute", get_path_toplevel_absolute },
+	{ "path.toplevel.relative", get_path_toplevel_relative },
 	{ "references.format", get_references_format },
 };
 

t/t1900-repo-info.sh

@@ -213,4 +213,39 @@ test_repo_info_path 'gitdir with explicit GIT_DIR' 'gitdir' \
 	'.git' \
 	'GIT_DIR="../.git" && export GIT_DIR'
 
+test_expect_success 'path.toplevel absolute and relative' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		mkdir -p repo/sub &&
+		cd repo/sub &&
+
+		ROOT="$(test-tool path-utils real_path ..)" &&
+
+		echo "path.toplevel.absolute=$ROOT" >expect.abs &&
+		git repo info path.toplevel.absolute >actual.abs &&
+		test_cmp expect.abs actual.abs &&
+
+		echo "path.toplevel.relative=../" >expect.rel &&
+		git repo info path.toplevel.relative >actual.rel &&
+		test_cmp expect.rel actual.rel
+	)
+'
+
+test_expect_success 'path.toplevel absolute and relative in a bare repository' '
+	test_when_finished "rm -rf bare.git" &&
+	git init --bare bare.git &&
+	(
+		cd bare.git &&
+
+		echo "path.toplevel.absolute=" >expect.abs &&
+		git repo info path.toplevel.absolute >actual.abs &&
+		test_cmp expect.abs actual.abs &&
+
+		echo "path.toplevel.relative=" >expect.rel &&
+		git repo info path.toplevel.relative >actual.rel &&
+		test_cmp expect.rel actual.rel
+	)
+'
+
 test_done