ストリーム(IStream)のサイズの取得

    // shlwapi.dll version 5.0 or later 互換

    // CStreamHelper::GetStreamSize()と同等

    static HRESULT Emulete_IStream_Size(

        IStream *pstm,

        ULARGE_INTEGER *pui)

    {

        if (pstm == NULL)

        {

            return E_FAIL;

        }

        if (pui == NULL)

        {

            return E_POINTER;

        }

        HRESULT hr = S_OK;

        try

        {

            ULARGE_INTEGER zero = {0, 0};

            *pui = zero;

            STATSTG stat;

            memset(&stat, 0, sizeof(stat));

            hr = pstm->Stat(&stat, STATFLAG_NONAME);

            if (FAILED(hr))

            {

                return hr;

            }

            *pui = stat.cbSize;

        }

        catch (...)

        {

            return E_FAIL;

        }

        return hr;

    }