Drupal file_copy won't work outside of the Drupal install

The selected file could not be uploaded, because the destination is not properly configured

This “feature” has bitten me before. It’s one of those annoying Drupal things which would be fine if the error message wasn’t so misleading.

What’s happening is that file_copy() calls file_create_path()

While file_copy() doesn’t declare that it only works in the Drupal folders - file_create_path() is clear about this.

<?php

/**
 * Make sure the destination is a complete path and resides in the file system
 * directory, if it is not prepend the file system directory.
 *
 * @param $dest A string containing the path to verify. If this value is
 *   omitted, Drupal's 'files' directory will be used.
 * @return A string containing the path to file, with file system directory
 *   appended if necessary, or FALSE if the path is invalid (i.e. outside the
 *   configured 'files' or temp directories).
 */
function file_create_path($dest = 0) {

?>

I need to copy files outside of the DocumentRoot to keep them private

Yes I could put them in the DocumentRoot and restrict access to the folder but that is just perverse (and easy to get wrong).

So I need to avoid these functions.