IUnknown_QueryService function

Retrieves an interface for a service from a specified object.

Syntax

HRESULT IUnknown_QueryService(
  _In_  IUnknown *punk,
  _In_  REFGUID  guidService,
  _In_  REFIID   riid,
  _Out_ void     **ppvOut
);

Parameters

punk [in]

Type: IUnknown*

A pointer to the IUnknown instance of the COM object that supports the service.

guidService [in]

Type: REFGUID

The service's unique identifier (SID).

riid [in]

Type: REFIID

The IID of the desired service interface.

ppvOut [out]

Type: void**

When this method returns, contains the interface pointer requested riid. If successful, the calling application is responsible for calling IUnknown::Release using this value when the service is no longer needed. In the case of failure, this value is NULL.

Return value

Type: HRESULT

Returns S_OK if successful. Returns E_FAIL if the object does not support IServiceProvider. Otherwise, the function returns the HRESULT returned by the object's QueryService method.

Remarks

If the object passed in the punk parameter supports the IServiceProvider interface, then its QueryService method is invoked, passing the guidService, riid, and ppvOut parameters and propagating the return value. Otherwise, the function returns E_FAIL.

For those versions of Windows that do not include IUnknown_QueryService in Shlwapi.h, this function must be called directly from Shlwapi.dll using ordinal 176.

Requirements

See also

IServiceProvider

QueryService