From f4c69140e3f77afb3d46026390309ac1e1c2fc12 Mon Sep 17 00:00:00 2001
From: Richard Steinmetz <richard@steinmetz.cloud>
Date: Wed, 21 Aug 2024 21:21:51 +0200
Subject: [PATCH] repo: implement git_repository_commondir

---
 libgit2-sys/lib.rs |  1 +
 src/repo.rs        | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/libgit2-sys/lib.rs b/libgit2-sys/lib.rs
index f7175f4140..0909d15994 100644
--- a/libgit2-sys/lib.rs
+++ b/libgit2-sys/lib.rs
@@ -2148,6 +2148,7 @@ extern "C" {
     pub fn git_repository_is_empty(repo: *mut git_repository) -> c_int;
     pub fn git_repository_is_shallow(repo: *mut git_repository) -> c_int;
     pub fn git_repository_path(repo: *const git_repository) -> *const c_char;
+    pub fn git_repository_commondir(repo: *const git_repository) -> *const c_char;
     pub fn git_repository_state(repo: *mut git_repository) -> c_int;
     pub fn git_repository_workdir(repo: *const git_repository) -> *const c_char;
     pub fn git_repository_set_workdir(
diff --git a/src/repo.rs b/src/repo.rs
index b94b4007db..13a5fb8670 100644
--- a/src/repo.rs
+++ b/src/repo.rs
@@ -456,6 +456,16 @@ impl Repository {
         }
     }
 
+    /// If the repository is bare, it is the root directory for the repository.
+    /// If the repository is a worktree, it is the parent repo's gitdir.
+    /// Otherwise, it is the gitdir.
+    pub fn commondir(&self) -> &Path {
+        unsafe {
+            let ptr = raw::git_repository_commondir(self.raw);
+            util::bytes2path(crate::opt_bytes(self, ptr).unwrap())
+        }
+    }
+
     /// Returns the current state of this repository
     pub fn state(&self) -> RepositoryState {
         let state = unsafe { raw::git_repository_state(self.raw) };
@@ -4304,4 +4314,22 @@ Committer Name <committer.proper@email> <committer@email>"#,
             .unwrap();
         assert_eq!(tag.id(), found_tag.id());
     }
+
+    #[test]
+    fn smoke_commondir() {
+        let (td, repo) = crate::test::repo_init();
+        assert_eq!(
+            crate::test::realpath(repo.path()).unwrap(),
+            crate::test::realpath(repo.commondir()).unwrap()
+        );
+
+        let worktree = repo
+            .worktree("test", &td.path().join("worktree"), None)
+            .unwrap();
+        let worktree_repo = Repository::open_from_worktree(&worktree).unwrap();
+        assert_eq!(
+            crate::test::realpath(repo.path()).unwrap(),
+            crate::test::realpath(worktree_repo.commondir()).unwrap()
+        );
+    }
 }