repo: add paths.git_dir repo info key

Introduce a new repo info key `paths.git_dir` to expose the
repository's gitdir path, equivalent to `git rev-parse --git-dir`.

This improves consistency and allows tools to retrieve the gitdir
path without invoking external commands.

The implementation adds support in repo.c and integrates it into
the repo info reporting mechanism. Documentation is updated to
describe the new key, and tests are added to verify that the value
matches the output of `git rev-parse --git-dir`.

Signed-off-by: jayesh0104 <jayeshdaga99@gmail.com>

Author: jayesh0104

Documentation/git-repo.adoc

@@ -95,6 +95,11 @@ In order to obtain a set of values from `git repo info`, you should provide
 the keys that identify them. Here's a list of the available keys and the
 values that they return:
 
+`paths.git_dir`::
+	The path to the Git directory for the repository (equivalent to
+	`git rev-parse --git-dir`).
+
+
 `layout.bare`::
 	`true` if this is a bare repository, otherwise `false`.
 

builtin/repo.c

@@ -66,11 +66,18 @@ static int get_references_format(struct repository *repo, struct strbuf *buf)
 	return 0;
 }
 
+static int get_paths_git_dir(struct repository *repo, struct strbuf *buf)
+{
+	strbuf_addstr(buf, repo_get_git_dir(repo));
+	return 0;
+}
+
 /* repo_info_field keys must be in lexicographical order */
 static const struct repo_info_field repo_info_field[] = {
 	{ "layout.bare", get_layout_bare },
 	{ "layout.shallow", get_layout_shallow },
 	{ "object.format", get_object_format },
+	{ "paths.git_dir", get_paths_git_dir },
 	{ "references.format", get_references_format },
 };
 

t/t1900-repo-info.sh

@@ -149,4 +149,14 @@ test_expect_success 'git repo info --keys uses lines as its default output forma
 	test_cmp expect actual
 '
 
+test_expect_success 'paths.git_dir matches rev-parse --git-dir' '
+	git init repo &&
+	(
+		cd repo &&
+		git repo info paths.git_dir >actual &&
+		echo "paths.git_dir=$(git rev-parse --git-dir)" >expect &&
+		test_cmp expect actual
+	)
+'
+
 test_done