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<?phpfunction get_file_extension($file) {  $i = strrpos($file,".");  if (!$i) { return ""; }  $l = strlen($file) - $i;  $ext = substr($file,$i+1,$l);  return strtolower($ext);}$filename = '$_FILES["file"]["name"]';$ext = 'get_file_extension';if (($ext($filename)=="zip")|| ($ext($filename)=="rar")|| ($ext($filename)=="pk3")|| ($ext($filename)=="wad"))  {  if ($_FILES["file"]["error"] > 0)    {    echo "Error: " . $_FILES["file"]["error"] . "<br />";    }  else    {    echo "Your file has been uploaded.<br />";    if (file_exists("." . $_FILES["file"]["name"]))      {      echo $_FILES["file"]["name"] . " already exists. ";      }    else      {      move_uploaded_file($_FILES["file"]["tmp_name"],      "" . $_FILES["file"]["name"]);      echo "Stored in: " . "/" . $_FILES["file"]["name"];      }    }  }else  {  echo "You are only allowed to upload ZIP, RAR, PK3, or WAD files!";  }?>