Update: rename f_file_change_owner() to f_file_change_role().

Update: rename f_file_change_owner() to f_file_change_role().

Change owner implies changing the owner.
This is not strictly true, due to how the chown() and similar POSIX functions works.

Instead, these change owner and/or group.
To avoid confusion with thinking this function exclusively changes owner, use a completely different word.
The chosen word is "role".