[GSoC][PATCH 3/4] repo: add path.gitdir with absolute and relative suffix formatting

[K Jayatheerth <jayatheerthkulkarni2005@gmail.com>]

Introduce path-related metadata fields to `git repo info` by adding
explicit `path.gitdir.absolute` and `path.gitdir.relative` keys. This
replaces dynamic prefix parsing machinery with individual, predictable
lexicographically-sorted keys that map directly to dedicated formatting
callbacks.

To calculate paths relative to the current working directory, update
`builtin/repo.c` to include `setup.h` and supply `startup_info->prefix`
to the path-formatting engine. Both explicit variants automatically
populate bulk dumps via `--all` and output predictably under `--keys`.

Update `t/t1900-repo-info.sh` to use a modernized, function-based loop
helper (`test_repo_info_path`) and `test_grep` to cleanly assert separate
path variation lookups.

Signed-off-by: K Jayatheerth <jayatheerthkulkarni2005@gmail.com>
Mentored-by: Justin Tobler <jltobler@gmail.com>
Mentored-by: Lucas Seiki Oshiro <lucasseikioshiro@gmail.com>
---
 Documentation/git-repo.adoc |  6 ++++++
 builtin/repo.c              | 26 ++++++++++++++++++++++++++
 t/t1900-repo-info.sh        | 31 +++++++++++++++++++++++++++++++
 3 files changed, 63 insertions(+)

diff --git a/Documentation/git-repo.adoc b/Documentation/git-repo.adoc
index 42262c1983..a0dca7ce88 100644
--- a/Documentation/git-repo.adoc
+++ b/Documentation/git-repo.adoc
@@ -104,6 +104,12 @@ values that they return:
 `object.format`::
 	The object format (hash algorithm) used in the repository.
 
+`path.gitdir.absolute`::
+	The canonical absolute path to the Git repository directory (the `.git` directory).
+
+`path.gitdir.relative`::
+	The path to the Git repository directory relative to the current working directory.
+
 `references.format`::
 	The reference storage format. The valid values are:
 +
diff --git a/builtin/repo.c b/builtin/repo.c
index 71a5c1c29c..c141ef892a 100644
--- a/builtin/repo.c
+++ b/builtin/repo.c
@@ -7,12 +7,14 @@
 #include "hex.h"
 #include "odb.h"
 #include "parse-options.h"
+#include "path.h"
 #include "path-walk.h"
 #include "progress.h"
 #include "quote.h"
 #include "ref-filter.h"
 #include "refs.h"
 #include "revision.h"
+#include "setup.h"
 #include "strbuf.h"
 #include "string-list.h"
 #include "shallow.h"
@@ -75,6 +77,28 @@ static int get_object_format(struct repository *repo, struct strbuf *buf)
 	return 0;
 }
 
+static int get_path_gitdir_absolute(struct repository *repo, struct strbuf *buf)
+{
+	const char *git_dir = repo_get_git_dir(repo);
+
+	if (!git_dir)
+		return error(_("unable to get git directory"));
+
+	strbuf_add_path(buf, git_dir, startup_info->prefix, PATH_FORMAT_CANONICAL, PATH_DEFAULT_UNMODIFIED);
+	return 0;
+}
+
+static int get_path_gitdir_relative(struct repository *repo, struct strbuf *buf)
+{
+	const char *git_dir = repo_get_git_dir(repo);
+
+	if (!git_dir)
+		return error(_("unable to get git directory"));
+
+	strbuf_add_path(buf, git_dir, startup_info->prefix, PATH_FORMAT_RELATIVE, PATH_DEFAULT_UNMODIFIED);
+	return 0;
+}
+
 static int get_references_format(struct repository *repo, struct strbuf *buf)
 {
 	strbuf_addstr(buf,
@@ -87,6 +111,8 @@ static const struct repo_info_field repo_info_field[] = {
 	{ "layout.bare", get_layout_bare },
 	{ "layout.shallow", get_layout_shallow },
 	{ "object.format", get_object_format },
+	{ "path.gitdir.absolute", get_path_gitdir_absolute },
+	{ "path.gitdir.relative", get_path_gitdir_relative },
 	{ "references.format", get_references_format },
 };
 
diff --git a/t/t1900-repo-info.sh b/t/t1900-repo-info.sh
index 39bb77dda0..7c7dfbb052 100755
--- a/t/t1900-repo-info.sh
+++ b/t/t1900-repo-info.sh
@@ -155,4 +155,35 @@ test_expect_success 'git repo info -h shows only repo info usage' '
 	test_grep ! "git repo structure" actual
 '
 
+test_repo_info_path () {
+	field_name=$1
+	expect_relative=$2
+
+	test_expect_success "query individual key: path.$field_name.absolute" '
+		(
+			cd test-repo/sub &&
+			expect_absolute=$(cd .. && pwd)/.git &&
+			echo "path.$field_name.absolute=$expect_absolute" >expect &&
+			git repo info path.$field_name.absolute >actual &&
+			test_cmp expect actual
+		)
+	'
+
+	test_expect_success "query individual key: path.$field_name.relative" '
+		(
+			cd test-repo/sub &&
+			echo "path.$field_name.relative=$expect_relative" >expect &&
+			git repo info path.$field_name.relative >actual &&
+			test_cmp expect actual
+		)
+	'
+}
+
+test_expect_success 'setup test repository layout for path fields' '
+	git init test-repo &&
+	mkdir -p test-repo/sub
+'
+
+test_repo_info_path 'gitdir' '../.git'
+
 test_done
-- 
2.54.0