1 files changed, 43 insertions, 0 deletions
diff --git a/object/storer/loose/paths.go b/object/storer/loose/paths.go
new file mode 100644
index 00000000..73cb0cf3
--- /dev/null
+++ b/object/storer/loose/paths.go
@@ -0,0 +1,43 @@
+package loose
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+
+	objectid "codeberg.org/lindenii/furgit/object/id"
+	"codeberg.org/lindenii/furgit/object/storer"
+)
+
+// objectPath returns the loose object path for id relative to the objects root.
+func (store *Store) objectPath(id objectid.ObjectID) (string, error) {
+	if id.Algorithm() != store.algo {
+		return "", fmt.Errorf("objectstorer/loose: object id algorithm mismatch: got %s want %s", id.Algorithm(), store.algo)
+	}
+
+	hex := id.String()
+
+	return filepath.Join(hex[:2], hex[2:]), nil
+}
+
+// openObject opens the loose object file for id.
+// Missing files cause objectstorer.ErrObjectNotFound.
+func (store *Store) openObject(id objectid.ObjectID) (*os.File, error) {
+	relPath, err := store.objectPath(id)
+	if err != nil {
+		return nil, err
+	}
+
+	file, err := store.root.Open(relPath)
+	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			return nil, objectstorer.ErrObjectNotFound
+		}
+
+		return nil, err
+	}
+
+	return file, nil
+}