<?php
class Foo
{
        private $bar = "boo";
        private $baz = "buz";
}

$foo = new Foo();
$tmp = serialize($foo);
$nul = preg_quote(chr(0));
$reg = "/s\:([0-9]+)\:\"$nul(.*?)$nul/";
preg_match_all($reg, $tmp, $matches);
foreach ($matches[0] as $i => $match) {
        $class = $matches[2][$i];
        $clen = strlen($class);
        $len = intval($matches[1][$i]) - ($clen + 2);
        $tmp = str_replace($match, "s:$len:\"", $tmp);
        $tmp = str_replace("O:$clen:\"$class\"", "O:8:\"stdClass\"", $tmp);
}
$tmp = unserialize($tmp);
echo $tmp->bar;
echo "\n";
die;