How to Decode eval(gzinflate

Simple Script how to decode :
1) eval(gzinflate(base64_decode(
2) eval(gzinflate(str_rot13(base64_decode(
3) eval(gzinflate(base64_decode(base64_decode(str_rot13(
4) eval(gzinflate(base64_decode(str_rot13(

<?php
/*
This code was taken from http://wordpress.macosbrain.com/2006/08/17/decode-function-eval-gzinflate-base64_decode-str_rot13/

Directions:
1. Save this code to a PHP file (e.g. decode.php)
2. Copy the encoded PHP code and place it in encoded.php
3. Execute this script by visiting decode.php in your browser
4. You will be prompted to download the decrypted file (e.g. decode_test.php)

Notice:
Do not use this to violate copyright. This is intended for educational and security purposes only.
*/

class decode
{
    function __construct($file)
    {
        $this->org_data = file_get_contents($file);
        $this->result = $this->org_data;
        $this->done = false;
        $this->file = $file;
    }

    function strip_php_tags($str)
    {
        $str_del = Array('');
        return str_replace($str_del,'',$str);
    }

    function strip_what_to_execute()
    {
        $possible_code = substr($this->result,0,strpos($this->result,"'"));
        $possible_code_end = strrpos($this->result,"'");
        if($this->test_possible_code($possible_code) && count($this->execute)> 0)
        {
            $possible_code_start = strlen($possible_code)+1;
            $this->result = substr($this->result,$possible_code_start,$possible_code_end-$possible_code_start);
        }
    }

    function clean_string($str)
    {
        $str = trim($str,"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f");
        $str = trim($str,"\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff");
        $str = trim($str);
        return $str;
    }

    function test_possible_code($str)
    {
        $str = $this->clean_string($this->strip_php_tags($str));
        //echo $str."\n";
        $functions = explode('(',$str);
        $this->execute = array();
        if(!in_array('eval',$functions))
        {
            $this->done = true;
            return false;
        }
        foreach($functions as $function)
        {
            if($function!='' && $function!='eval')
            {
                if(!function_exists($function))
                $this->error('sorry but i can not access the function:"'.$function.'"');
                else
                $this->execute[] = $function;
            }
        }
        return true;
    }

    function execute()
    {
        $cmd_str = '';
        $cmd_end = '';
        foreach($this->execute as $cmd)
        {
            $cmd_str .= $cmd.'(';
            $cmd_end .= ')';
        }
        $eval = $cmd_str."'".$this->result."'".$cmd_end;
        eval ("\$this->result = ".$eval.";");
    }

    function error($msg)
    {
        die($msg);
    }

    function decode()
    {
        $this->strip_what_to_execute();
        if($this->done==false && count($this->execute)> 0)
        {
            $this->execute();
            $this->decode();
        }
        else
        {
            //i think this is the "decrypted", you may see two little errors, correct them.
            $this->download();
        }
    }

    function download()
    {
        header('Content-Disposition: attachment; filename="decrypted_'.$this->file.'"');
        header('Content-Type: application/php');
        header('Content-Length: '.strlen($this->result));
        die($this->result);
    }
}
//put your encoded PHP code in encoded.php
$decode = new decode('encoded.php');
$decode->decode();
?>