WdfObjectGetTypedContext macro

Article
03/01/2023

[Applies to KMDF and UMDF]

The WdfObjectGetTypedContext macro returns a pointer to an object's context space.

Syntax

PVOID WdfObjectGetTypedContext(
    Handle,
    Type
);

Parameters

Handle
A handle to a framework object.

Type
The symbol name of a driver-defined structure that describes an object's context space.

Return value

WdfObjectGetTypedContext returns a pointer to the specified object's context space.

Remarks

You can use the WdfObjectGetTypedContext macro to obtain a pointer to any framework object's context space. Use this macro as an alternative to calling an object-specific context accessor method that is created by the WDF_DECLARE_CONTEXT_TYPE macro or the WDF_DECLARE_CONTEXT_TYPE_WITH_NAME macro. Note that if you use WdfObjectGetTypedContext, you still must use WDF_DECLARE_CONTEXT_TYPE or WDF_DECLARE_CONTEXT_TYPE_WITH_NAME to declare your object context.

For more information about these macros, see Framework Object Context Space.

Examples

The following code example defines a context structure (MY_REQUEST_CONTEXT) for a request object and then registers the structure.

typedef struct _MY_REQUEST_CONTEXT {
  LIST_ENTRY ListEntry;
  WDFMEMORY Memory;
} MY_REQUEST_CONTEXT, *PMY_REQUEST_CONTEXT;

WDF_DECLARE_CONTEXT_TYPE(MY_REQUEST_CONTEXT)

The following code example creates a request object and obtains a pointer to its context space.

WDFREQUEST Request;
WDF_OBJECT_ATTRIBUTES MyRequestObjectAttributes;
PMY_REQUEST_CONTEXT pMyContext;

WDF_OBJECT_ATTRIBUTES_INIT(&MyRequestObjectAttributes);
WDF_OBJECT_ATTRIBUTES_SET_CONTEXT_TYPE(
                                       &MyRequestObjectAttributes,
                                       MY_REQUEST_CONTEXT
                                       );
status = WdfRequestCreate(
                          &MyRequestObjectAttributes,
                          NULL,
                          &Request
                          );

if (!NT_SUCCESS(status)) {
    return status;
}
pMyContext = WdfObjectGetTypedContext(
                                      Request,
                                      MY_REQUEST_CONTEXT
                                      );

Requirements

Target platform	Universal
Minimum KMDF version	1.0
Minimum UMDF version	2.0
Header	Wdfobject.h (include Wdf.h)
Library	Wdf01000.sys (KMDF); WUDFx02000.dll (UMDF)
IRQL	Any level