internal override unsafe Int64 GetTotalLength()
        {
            Int64 totalLen = 0;

            for (int i = 0; i < this.m_srcList.Count; i++)
            {
                NativeBlockStream ns = this.GetStream(i, FileAccess.Read);
                totalLen += ns.GetTotalLength();
                ns.Close();
            }
            return(totalLen);
        }