PHP 去掉路径中的 "/./" 或者 “/../”

<?php
$filename = ‘/mnt/hgfs/workspace/weituibao/app/config/../../public/files/36/temp/201410/21/1413873853598.jpg‘;
function getRealPath($filename, $split = ‘/‘)
{
    while(true) {
        if (FALSE === strpos($filename, $split . ‘.‘)) {
            break;
        }
        $filename = explode($split, $filename);
        foreach($filename as $k => $f) {
            if (($k && $f == ‘‘) || $f == ‘.‘) {
                unset($filename[$k]);　　　　　　　　　 break;
            }
            elseif ($f == ‘..‘) {
                unset($filename[$k]);
                if(isset($filename[$k-1]))
                    unset($filename[$k-1]);
                break;
            }
        }
        $filename = implode($split, $filename);
    }
    return $filename;
}
echo getRealPath($filename);

---------- php ----------
/mnt/hgfs/workspace/weituibao/public/files/36/temp/201410/21/1413873853598.jpg
输出完成 (耗时 0 秒) - 正常终止