WDF_DECLARE_CONTEXT_TYPE_WITH_NAME macro

Artikkeli
03/01/2023

[Applies to KMDF and UMDF]

The WDF_DECLARE_CONTEXT_TYPE_WITH_NAME macro creates an accessor method with a specified name for a driver's object-specific context space.

Syntax

void WDF_DECLARE_CONTEXT_TYPE_WITH_NAME(
    _contexttype,
    _castingfunction
);

Parameters

_contexttype
The structure type name of a driver-defined structure that describes the contents of an object's context space.

_castingfunction
A C-language routine name. The macro uses this name as the name for the accessor method that it creates for the object's context space.

Return value

This macro does not return a value.

Remarks

For more information about using this macro, see Framework Object Context Space.

Examples

The following code example defines a context structure (MY_REQUEST_CONTEXT) for a request object. Then, the example invokes the WDF_DECLARE_CONTEXT_TYPE_WITH_NAME macro to register the structure and specify that the context accessor method will be named RequestGetMyContext.

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

WDF_DECLARE_CONTEXT_TYPE_WITH_NAME(MY_REQUEST_CONTEXT, RequestGetMyContext)

The following code example creates a request object and then uses the RequestGetMyContext accessor method to obtain a pointer to the object's 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 = RequestGetMyContext(Request);

Requirements

Target platform	Universal
Minimum KMDF version	1.0
Minimum UMDF version	2.0
Header	Wdfobject.h (include Wdf.h)

Jaa