fix: resolve submodule worktrees

src/main.rs

@@ -66,7 +66,7 @@ fn main() {
     });
 
     for repo in rx {
-        let repo_path = repo.path().parent().expect("GIT_DIR cannot be root").display();
+        let repo_path = repo.workdir().unwrap_or_else(|| repo.commondir()).display();
 
         println!("{repo_path}");
 
@@ -126,16 +126,16 @@ impl Walker {
                 continue;
             }
 
-            let git_dir = entry_path.join(GIT_DIR);
-
-            if !git_dir.is_dir() {
+            match ok_or_continue!(try_get_git_dir(&entry_path)) {
+                Some(git_dir) => tx
+                    .send(ok_or_continue!(Repository::open(git_dir)))
+                    .expect("main thread paniced"),
+                None => {
                     // Descend deeper into directories that are not git repositories.
                     ok_or_continue!(self.walk(&entry_path, tx.clone()));
                     continue;
                 }
-
-            tx.send(ok_or_continue!(Repository::open(git_dir)))
-                .expect("main thread paniced");
+            }
         }
 
         Ok(())
@@ -154,6 +154,44 @@ fn is_cache_dir(path: &Path) -> io::Result<bool> {
     Ok(CACHE_DIR_TAG_HEADER == buf)
 }
 
+fn try_get_git_dir(path: &Path) -> io::Result<Option<PathBuf>> {
+    let git_dir = path.join(GIT_DIR);
+
+    if git_dir.is_dir() {
+        return Ok(Some(git_dir));
+    }
+
+    if !git_dir.is_file() {
+        return Ok(None);
+    }
+
+    let mut buf = [0u8; 1024 * 8];
+    let mut file = File::open(&git_dir)?;
+    let n = file.read(&mut buf)?;
+
+    let Some(str) = buf[0..n].strip_prefix(b"gitdir: ") else {
+        log::info!("ingoring .git: unreleated contents: {}", git_dir.display());
+        return Ok(None);
+    };
+
+    let Ok(str) = String::from_utf8(str.trim_ascii().into()) else {
+        log::info!("ingoring .git: non-utf8 gitdir path: {}", git_dir.display());
+        return Ok(None);
+    };
+
+    let parent_git_dir = git_dir
+        .parent()
+        .expect("GIT_DIR cannot be at root")
+        .join(str);
+
+    if parent_git_dir.is_dir() {
+        return Ok(Some(parent_git_dir));
+    }
+
+    log::info!("ingoring .git: orphan worktree: {}", git_dir.display());
+    Ok(None)
+}
+
 fn is_hidden_file(path: &Path) -> bool {
     let Some(str) = path.file_name() else {
         return false;