wp_upload_dir() multsite fix

wpms_fix_upload_paths.php

<?php
/***************************************************
* Filter the results of wp_upload_dir()
* 
* In WordPress Multisite systems that were installed prior to 3.5 the system uses the folder structure /wp-content/blogs.dir/XX to store uploaded files for each blog. 
*
* The URL used to access these files follows the format /SITENAME/files/ but the function wp_upload_dir() does not match this format 
***************************************************/
function wpms_fix_upload_paths($data) {

	// Check if the base URL matches the format 'wp-content/blogs.dir/00/files'
	$needs_fixing = preg_match("/wp-content\/blogs\.dir\/(\d+)\/files/", $data['baseurl'], $uri_part);

	if ($needs_fixing) {

		$data['url'] 		= str_replace($uri_part[0], 'files', $data['url']);
		$data['baseurl'] 	= str_replace($uri_part[0], 'files', $data['baseurl']);

	}
	
	return $data;
}

// Fix upload paths
add_filter('upload_dir', 'wpms_fix_upload_paths');