IStream::Clone method (objidl.h)

Article
10/13/2021

The Clone method creates a new stream object with its own seek pointer that references the same bytes as the original stream.

Syntax

HRESULT Clone(
  [out] IStream **ppstm
);

Parameters

[out] ppstm

When successful, pointer to the location of an IStream pointer to the new stream object. If an error occurs, this parameter is NULL.

Return value

This method can return one of these values.

Return code	Description
S_OK	The stream was successfully cloned.
E_PENDING	Asynchronous Storage only: Part or all of the stream's data is currently unavailable.
STG_E_INSUFFICIENTMEMORY	The stream was not cloned due to a lack of memory.
STG_E_INVALIDPOINTER	The ppStm pointer is not valid.
STG_E_REVERTED	The object has been invalidated by a revert operation above it in the transaction tree.

Remarks

The Clone method creates a new stream object for accessing the same bytes but using a separate seek pointer. The new stream object sees the same data as the source-stream object. Changes written to one object are immediately visible in the other. Range locking is shared between the stream objects.

The initial setting of the seek pointer in the cloned stream instance is the same as the current setting of the seek pointer in the original stream at the time of the clone operation.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps \| UWP apps]
Minimum supported server	Windows 2000 Server [desktop apps \| UWP apps]
Target Platform	Windows
Header	objidl.h
Library	Uuid.lib
DLL	Ole32.dll