hglobalstream.c

这是一个开放源代码的与WINNT/WIN2K/WIN2003兼容的操作系统

      break;
    case STREAM_SEEK_CUR:
      newPosition = This->currentPosition;
      break;
    case STREAM_SEEK_END:
      newPosition = This->streamSize;
      break;
    default:
      return STG_E_INVALIDFUNCTION;
  }

  /*
   * Move the actual file pointer
   * If the file pointer ends-up after the end of the stream, the next Write operation will
   * make the file larger. This is how it is documented.
   */
  if (dlibMove.QuadPart < 0 && newPosition.QuadPart < -dlibMove.QuadPart) return STG_E_INVALIDFUNCTION;

  newPosition.QuadPart = RtlLargeIntegerAdd(newPosition.QuadPart, dlibMove.QuadPart);

  if (plibNewPosition) *plibNewPosition = newPosition;
  This->currentPosition = newPosition;

  return S_OK;
}

/***
 * This method is part of the IStream interface.
 *
 * It will change the size of a stream.
 *
 * TODO: Switch from small blocks to big blocks and vice versa.
 *
 * See the documentation of IStream for more info.
 */
static HRESULT WINAPI HGLOBALStreamImpl_SetSize(
				     IStream*      iface,
				     ULARGE_INTEGER  libNewSize)   /* [in] */
{
  HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
  HGLOBAL supportHandle;

  TRACE("(%p, %d)\n", iface, libNewSize.u.LowPart);

  /*
   * HighPart is ignored as shown in tests
   */

  if (This->streamSize.u.LowPart == libNewSize.u.LowPart)
    return S_OK;

  /*
   * Re allocate the HGlobal to fit the new size of the stream.
   */
  supportHandle = GlobalReAlloc(This->supportHandle, libNewSize.u.LowPart, 0);

  if (supportHandle == 0)
    return E_OUTOFMEMORY;

  This->supportHandle = supportHandle;
  This->streamSize.u.LowPart = libNewSize.u.LowPart;

  return S_OK;
}

/***
 * This method is part of the IStream interface.
 *
 * It will copy the 'cb' Bytes to 'pstm' IStream.
 *
 * See the documentation of IStream for more info.
 */
static HRESULT WINAPI HGLOBALStreamImpl_CopyTo(
				    IStream*      iface,
				    IStream*      pstm,         /* [unique][in] */
				    ULARGE_INTEGER  cb,           /* [in] */
				    ULARGE_INTEGER* pcbRead,      /* [out] */
				    ULARGE_INTEGER* pcbWritten)   /* [out] */
{
  HRESULT        hr = S_OK;
  BYTE           tmpBuffer[128];
  ULONG          bytesRead, bytesWritten, copySize;
  ULARGE_INTEGER totalBytesRead;
  ULARGE_INTEGER totalBytesWritten;

  TRACE("(%p, %p, %d, %p, %p)\n", iface, pstm,
	cb.u.LowPart, pcbRead, pcbWritten);

  /*
   * Sanity check
   */
  if ( pstm == 0 )
    return STG_E_INVALIDPOINTER;

  totalBytesRead.u.LowPart = totalBytesRead.u.HighPart = 0;
  totalBytesWritten.u.LowPart = totalBytesWritten.u.HighPart = 0;

  /*
   * use stack to store data temporarly
   * there is surely more performant way of doing it, for now this basic
   * implementation will do the job
   */
  while ( cb.u.LowPart > 0 )
  {
    if ( cb.u.LowPart >= 128 )
      copySize = 128;
    else
      copySize = cb.u.LowPart;

    hr = IStream_Read(iface, tmpBuffer, copySize, &bytesRead);
    if (FAILED(hr))
        break;

    totalBytesRead.u.LowPart += bytesRead;

    if (bytesRead)
    {
        hr = IStream_Write(pstm, tmpBuffer, bytesRead, &bytesWritten);
        if (FAILED(hr))
            break;

        totalBytesWritten.u.LowPart += bytesWritten;
    }

    if (bytesRead!=copySize)
      cb.u.LowPart = 0;
    else
      cb.u.LowPart -= bytesRead;
  }

  /*
   * Update number of bytes read and written
   */
  if (pcbRead)
  {
    pcbRead->u.LowPart = totalBytesRead.u.LowPart;
    pcbRead->u.HighPart = totalBytesRead.u.HighPart;
  }

  if (pcbWritten)
  {
    pcbWritten->u.LowPart = totalBytesWritten.u.LowPart;
    pcbWritten->u.HighPart = totalBytesWritten.u.HighPart;
  }
  return hr;
}

/***
 * This method is part of the IStream interface.
 *
 * For streams supported by HGLOBALS, this function does nothing.
 * This is what the documentation tells us.
 *
 * See the documentation of IStream for more info.
 */
static HRESULT WINAPI HGLOBALStreamImpl_Commit(
		  IStream*      iface,
		  DWORD         grfCommitFlags)  /* [in] */
{
  return S_OK;
}

/***
 * This method is part of the IStream interface.
 *
 * For streams supported by HGLOBALS, this function does nothing.
 * This is what the documentation tells us.
 *
 * See the documentation of IStream for more info.
 */
static HRESULT WINAPI HGLOBALStreamImpl_Revert(
		  IStream* iface)
{
  return S_OK;
}

/***
 * This method is part of the IStream interface.
 *
 * For streams supported by HGLOBALS, this function does nothing.
 * This is what the documentation tells us.
 *
 * See the documentation of IStream for more info.
 */
static HRESULT WINAPI HGLOBALStreamImpl_LockRegion(
		  IStream*       iface,
		  ULARGE_INTEGER libOffset,   /* [in] */
		  ULARGE_INTEGER cb,          /* [in] */
		  DWORD          dwLockType)  /* [in] */
{
  return STG_E_INVALIDFUNCTION;
}

/*
 * This method is part of the IStream interface.
 *
 * For streams supported by HGLOBALS, this function does nothing.
 * This is what the documentation tells us.
 *
 * See the documentation of IStream for more info.
 */
static HRESULT WINAPI HGLOBALStreamImpl_UnlockRegion(
		  IStream*       iface,
		  ULARGE_INTEGER libOffset,   /* [in] */
		  ULARGE_INTEGER cb,          /* [in] */
		  DWORD          dwLockType)  /* [in] */
{
  return S_OK;
}

/***
 * This method is part of the IStream interface.
 *
 * This method returns information about the current
 * stream.
 *
 * See the documentation of IStream for more info.
 */
static HRESULT WINAPI HGLOBALStreamImpl_Stat(
		  IStream*     iface,
		  STATSTG*     pstatstg,     /* [out] */
		  DWORD        grfStatFlag)  /* [in] */
{
  HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;

  memset(pstatstg, 0, sizeof(STATSTG));

  pstatstg->pwcsName = NULL;
  pstatstg->type     = STGTY_STREAM;
  pstatstg->cbSize   = This->streamSize;

  return S_OK;
}

static HRESULT WINAPI HGLOBALStreamImpl_Clone(
		  IStream*     iface,
		  IStream**    ppstm) /* [out] */
{
  ULARGE_INTEGER dummy;
  LARGE_INTEGER offset;
  HRESULT hr;
  HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
  TRACE(" Cloning %p (deleteOnRelease=%d seek position=%ld)\n",iface,This->deleteOnRelease,(long)This->currentPosition.QuadPart);
  hr=CreateStreamOnHGlobal(This->supportHandle, FALSE, ppstm);
  if(FAILED(hr))
    return hr;
  offset.QuadPart=(LONGLONG)This->currentPosition.QuadPart;
  HGLOBALStreamImpl_Seek(*ppstm,offset,STREAM_SEEK_SET,&dummy);
  return S_OK;
}

/*
 * Virtual function table for the HGLOBALStreamImpl class.
 */
static const IStreamVtbl HGLOBALStreamImpl_Vtbl =
{
    HGLOBALStreamImpl_QueryInterface,
    HGLOBALStreamImpl_AddRef,
    HGLOBALStreamImpl_Release,
    HGLOBALStreamImpl_Read,
    HGLOBALStreamImpl_Write,
    HGLOBALStreamImpl_Seek,
    HGLOBALStreamImpl_SetSize,
    HGLOBALStreamImpl_CopyTo,
    HGLOBALStreamImpl_Commit,
    HGLOBALStreamImpl_Revert,
    HGLOBALStreamImpl_LockRegion,
    HGLOBALStreamImpl_UnlockRegion,
    HGLOBALStreamImpl_Stat,
    HGLOBALStreamImpl_Clone
};

/******************************************************************************
** HGLOBALStreamImpl implementation
*/

/***
 * This is the constructor for the HGLOBALStreamImpl class.
 *
 * Params:
 *    hGlobal          - Handle that will support the stream. can be NULL.
 *    fDeleteOnRelease - Flag set to TRUE if the HGLOBAL will be released
 *                       when the IStream object is destroyed.
 */
static HGLOBALStreamImpl* HGLOBALStreamImpl_Construct(
		HGLOBAL  hGlobal,
		BOOL     fDeleteOnRelease)
{
  HGLOBALStreamImpl* newStream;

  newStream = HeapAlloc(GetProcessHeap(), 0, sizeof(HGLOBALStreamImpl));

  if (newStream!=0)
  {
    /*
     * Set-up the virtual function table and reference count.
     */
    newStream->lpVtbl = &HGLOBALStreamImpl_Vtbl;
    newStream->ref    = 0;

    /*
     * Initialize the support.
     */
    newStream->supportHandle = hGlobal;
    newStream->deleteOnRelease = fDeleteOnRelease;

    /*
     * This method will allocate a handle if one is not supplied.
     */
    if (!newStream->supportHandle)
    {
      newStream->supportHandle = GlobalAlloc(GMEM_MOVEABLE | GMEM_NODISCARD |
					     GMEM_SHARE, 0);
    }

    /*
     * Start the stream at the beginning.
     */
    newStream->currentPosition.u.HighPart = 0;
    newStream->currentPosition.u.LowPart = 0;

    /*
     * Initialize the size of the stream to the size of the handle.
     */
    newStream->streamSize.u.HighPart = 0;
    newStream->streamSize.u.LowPart  = GlobalSize(newStream->supportHandle);
  }

  return newStream;
}


/***********************************************************************
 *           CreateStreamOnHGlobal     [OLE32.@]
 */
HRESULT WINAPI CreateStreamOnHGlobal(
		HGLOBAL   hGlobal,
		BOOL      fDeleteOnRelease,
		LPSTREAM* ppstm)
{
  HGLOBALStreamImpl* newStream;

  newStream = HGLOBALStreamImpl_Construct(hGlobal,
					  fDeleteOnRelease);

  if (newStream!=NULL)
  {
    return IUnknown_QueryInterface((IUnknown*)newStream,
				   &IID_IStream,
				   (void**)ppstm);
  }

  return E_OUTOFMEMORY;
}

/***********************************************************************
 *           GetHGlobalFromStream     [OLE32.@]
 */
HRESULT WINAPI GetHGlobalFromStream(IStream* pstm, HGLOBAL* phglobal)
{
  HGLOBALStreamImpl* pStream;

  if (pstm == NULL)
    return E_INVALIDARG;

  pStream = (HGLOBALStreamImpl*) pstm;

  /*
   * Verify that the stream object was created with CreateStreamOnHGlobal.
   */
  if (pStream->lpVtbl == &HGLOBALStreamImpl_Vtbl)
    *phglobal = pStream->supportHandle;
  else
  {
    *phglobal = 0;
    return E_INVALIDARG;
  }

  return S_OK;
}