# IStorage::OpenStream

Opens an existing stream object within this storage object in the specified access mode.

HRESULT OpenStream(

const WCHAR * pwcsName, | //Points to name of stream to open
void * reserved1, | //Reserved; must be NULL
DWORD grfMode, | //Access mode for the new stream
DWORD reserved2, | //Reserved; must be zero
IStream ** ppstm | //Indirect pointer to opened stream object
); |

Parameters

pwcsName
  [in] Points to a wide character string that contains the name of the stream to open.
reserved1
  [in] Reserved for future use; must be NULL.
grfMode
  [in] Specifies the access mode to be assigned to the open stream. See the STGM enumeration values for descriptions of the possible values. . Whatever other modes you may choose, you must at least specify STGM_SHARE_EXCLUSIVE when calling this method.
reserved2
  [in] Reserved for future use; must be zero.
ppstm
  [out] On successful return, points to the location of an IStream pointer to the newly-opened stream object. This parameter is set to NULL if an error occurs.

Return Values

S_OK
  The stream was successfully opened.
E_PENDING
  Asynchronous Storage only: Part or all of the stream’s data is currently unavailable. For more information see IFillLockBytes and Asynchronous Storage.
STG_E_ACCESSDENIED
  Insufficient permissions to open stream.
STG_E_FILENOTFOUND
  The stream with specified name does not exist.
STG_E_INSUFFICIENTMEMORY
  The stream was not opened due to a lack of memory.
STG_E_INVALIDFLAG
  The value specified for the grfMode flag is not a valid STGM enumeration value.
STG_E_INVALIDFUNCTION
  The specified combination of grfMode flags is not supported. For example, if this method is called without the STGM_SHARE_EXCLUSIVE flag.
STG_E_INVALIDNAME
  Invalid value for pwcsName.
STG_E_INVALIDPOINTER
  The pointer specified for the stream object was invalid.
STG_E_INVALIDPARAMETER
  One of the parameters was invalid.
STG_E_REVERTED
  The storage object has been invalidated by a revert operation above it in the transaction tree.
STG_E_TOOMANYOPENFILES
  The stream was not opened because there are too many open files.

Remarks

IStorage::OpenStream opens an existing stream object within this storage object in the access mode specified in grfMode. There are restrictions on the permissions that can be given in grfMode. For example, the permissions on this storage object restrict the permissions on its streams. In general, access restrictions on streams should be stricter than those on their parent storages. Compound-file streams must be opened with STGM_SHARE_EXCLUSIVE.

See Also

IStorage - Compound File Implementation, IStorage::CreateStream, IStream