phpseclib\Net\SFTP::truncate PHP Method

    function truncate($filename, $new_size)
    {
        $attr = pack('N3', NET_SFTP_ATTR_SIZE, $new_size / 4294967296, $new_size);
        // 4294967296 == 0x100000000 == 1<<32
        return $this->_setstat($filename, $attr, false);
    }