diff --git a/exec/file.py b/exec/file.py
index 00653aa..c677e09 100644
--- a/exec/file.py
+++ b/exec/file.py
@@ -4,7 +4,7 @@ import os
 import stat
 import subprocess
 
-from shutil import rmtree
+from shutil import copyfile, rmtree
 from tempfile import mkdtemp
 from typing import Optional, Union
 
@@ -41,7 +41,7 @@ def chown(path: str, user: Optional[Union[str, int]] = None, group: Optional[Uni
             raise Exception(f"Failed to change owner of '{path}' to '{owner}'")
 
 
-def chmod(path, mode: Union[int, str] = 0o0755, force_sticky=True, privileged: bool = True):
+def chmod(path: str, mode: Union[int, str] = 0o0755, force_sticky=True, privileged: bool = True):
     if not isinstance(mode, str):
         octal = oct(mode)[2:]
     else:
@@ -60,11 +60,14 @@ def chmod(path, mode: Union[int, str] = 0o0755, force_sticky=True, privileged: b
             raise Exception(f"Failed to set mode of '{path}' to '{chmod}'")
 
 
-def root_check_exists(path):
+copy_file = copyfile
+
+
+def root_check_exists(path: str):
     return os.path.exists(path) or run_root_cmd(['[', '-e', path, ']']).returncode == 0
 
 
-def root_check_is_dir(path):
+def root_check_is_dir(path: str):
     return os.path.isdir(path) or run_root_cmd(['[', '-d', path, ']'])