function untar($tarfile)
{
    $tarfile=fopen($tarfile,"r");
    $datainfo="";
    $data="";
    while (!feof($tarfile))
        {
            $readdata=fread($tarfile,512);
            if (substr($readdata,257,5)=="ustar")
                {
                    if (!empty($datainfo))
                        {
                            $poscount=0;
                            $name="";
                            while (substr($datainfo,$poscount,1)!=chr(0))
                                {
                                    $name.=substr($datainfo,$poscount,1);
                                    $poscount++;
                                }
                            if (!empty($name))
                                {
                                    if (substr($name,-1)=="/")
                                        {
                                            echo "Creating ".$name."<br>";
                                            mkdir($name);
                                        }
                                    else
                                        {
                                            echo "Extracting ".$name."<br>";
                                            $datasize=strlen($data)-1;
                                            while ((substr($data,$datasize,1)==chr(0)) && ($datasize>-1))
                                                {
                                                    $datasize--;
                                                }
                                            $datasize++;
                                            $filedata="";
                                            for ($datacount=0;$datacount<$datasize;$datacount++)
                                                {
                                                    $filedata.=substr($data,$datacount,1);
                                                }
                                            $file=fopen($name,"w");
                                            fwrite($file,$filedata);
                                            fclose($file);
                                        }
                                }
                            $datainfo=$readdata;
                            $data="";
                        }
                    else
                        {
                            $datainfo=$readdata;
                        }
                }
            else
                {
                    $data.=$readdata;
                }
        }
    if (!empty($datainfo))
        {
            $poscount=0;
            $name="";
            while (substr($datainfo,$poscount,1)!=chr(0))
                {
                    $name.=substr($datainfo,$poscount,1);
                    $poscount++;
                }
            if (!empty($name))
                {
                    if (substr($name,-1)=="/")
                        {
                            echo "Creating ".$name."<br>";
                            mkdir($name);
                        }
                    else
                        {
                            echo "Extracting ".$name."<br>";
                            $datasize=strlen($data)-1;
                            while ((substr($data,$datasize,1)==chr(0)) && ($datasize>-1))
                                {
                                    $datasize--;
                                }
                            $datasize++;
                            $filedata="";
                            for ($datacount=0;$datacount<$datasize;$datacount++)
                                {
                                    $filedata.=substr($data,$datacount,1);
                                }
                            $file=fopen($name,"w");
                            fwrite($file,$filedata);
                            fclose($file);
                        }
                }
            $datainfo=$readdata;
            $data="";
        }    
    fclose($tarfile);
}