vires_artes_sanitize_upload_filenames.php

<?php
/**
 * Sanitize upload filenames
 * For reference:
 * @See http://codex.wordpress.org/Function_Reference/wp_handle_upload
 * @See http://php.net/manual/en/function.rename.php
 */
if( !function_exists('vires_artes_sanitize_upload_filenames') ) {
    function vires_artes_sanitize_upload_filenames($vals)
    {
        // Extract the filename and URL Decode it
        $name = array_reverse(explode('/', $vals['file']));
        $name = urldecode($name[0]);
        
        // Extract the local path to the uploaded file and remove the current filename
        $url = str_replace($name, '', urldecode($vals['file']));
        
        // Extract the public URL for the uploaded file and remove the current filename
        $wurl = str_replace($name, '', urldecode($vals['url']));
        
        // Sanitize the filename replacing non UTF8 characters
        $filetype = wp_check_filetype($name);
        $name = str_replace('.'.$filetype['ext'], '', $name);
        $name = sanitize_title($name);

        $sanitized_file_name = $name . '.' . $filetype['ext'];
        
        // Update the file array with the updated filename in it, precerving the local
        // and public url, just updating the filename with the sanitized version.
        if(@rename($vals['file'], $url . $sanitized_file_name))
        {
            return array(
            'file' => $url . $sanitized_file_name,
            'url' => $wurl . $sanitized_file_name,
            'type' => $vals['type']
            );
        }
        
        // Return the filearray
        return $vals;
    }    
}
add_action('wp_handle_upload', 'vires_artes_sanitize_upload_filenames');

?>