Let's move on now to the file handling system. As we have seen in previous chapters, the user interface for the file handling system was changed significantly. For example, a Drupal 7 site can now use both private and public files within the same site. We can also now add files to our site using file fields in addition to the file uploads that were provided in previous versions of Drupal. To enable these changes, the APIs related to file handling were significantly revised.
Let's start by looking at the new hooks that your modules may want to implement in Drupal 7.
hook_file_copy($file, $source)
This hook is called after a file has been copied in the system. You can use this hook to update related information or add new information to the database.