Ensure correct permissions for copied files, even if an error happens during copying

Author: tuncbkose

nbgrader/exchange/default/exchange.py

@@ -97,31 +97,36 @@ def do_copy(self, src, dest, log=None):
             self.log.error("Directory size is too big")
             raise RuntimeError(f"Directory size is too big. Size is {dir_size}, maximum size is {1000 * max_dir_size}")
 
-        shutil.copytree(src, dest,
-                        ignore=ignore_patterns(exclude=self.coursedir.ignore,
-                                               include=self.coursedir.include,
-                                               max_file_size=self.coursedir.max_file_size,
-                                               log=self.log))
-        # copytree copies access mode too - so we must add go+rw back to it if
-        # we are in groupshared.
-        if self.coursedir.groupshared:
-            for dirname, _, filenames in os.walk(dest):
-                # dirs become ug+rwx
-                st_mode = os.stat(dirname).st_mode
-                if st_mode & 0o2770 != 0o2770:
-                    try:
-                        os.chmod(dirname, (st_mode|0o2770) & 0o2777)
-                    except PermissionError:
-                        self.log.warning("Could not update permissions of %s to make it groupshared", dirname)
-
-                for filename in filenames:
-                    filename = os.path.join(dirname, filename)
-                    st_mode = os.stat(filename).st_mode
-                    if st_mode & 0o660 != 0o660:
+        try:
+            shutil.copytree(src, dest,
+                            ignore=ignore_patterns(exclude=self.coursedir.ignore,
+                                                   include=self.coursedir.include,
+                                                   max_file_size=self.coursedir.max_file_size,
+                                                   log=self.log))
+        except OSError as err:
+            raise err
+        # Set permissions for copied files, even if some failed to copy
+        finally:
+            # copytree copies access mode too - so we must add go+rw back to it if
+            # we are in groupshared.
+            if self.coursedir.groupshared:
+                for dirname, _, filenames in os.walk(dest):
+                    # dirs become ug+rwx
+                    st_mode = os.stat(dirname).st_mode
+                    if st_mode & 0o2770 != 0o2770:
                         try:
-                            os.chmod(filename, (st_mode|0o660) & 0o777)
+                            os.chmod(dirname, (st_mode|0o2770) & 0o2777)
                         except PermissionError:
-                            self.log.warning("Could not update permissions of %s to make it groupshared", filename)
+                            self.log.warning("Could not update permissions of %s to make it groupshared", dirname)
+
+                    for filename in filenames:
+                        filename = os.path.join(dirname, filename)
+                        st_mode = os.stat(filename).st_mode
+                        if st_mode & 0o660 != 0o660:
+                            try:
+                                os.chmod(filename, (st_mode|0o660) & 0o777)
+                            except PermissionError:
+                                self.log.warning("Could not update permissions of %s to make it groupshared", filename)
 
     def start(self):
         if sys.platform == 'win32':