WdfRequestCreateFromIrp function (wdfrequest.h)

[Applies to KMDF only]

The WdfRequestCreateFromIrp method creates a framework request object from a specified WDM IRP.

Syntax

NTSTATUS WdfRequestCreateFromIrp(
  [in, optional] PWDF_OBJECT_ATTRIBUTES RequestAttributes,
  [in]           PIRP                   Irp,
  [in]           BOOLEAN                RequestFreesIrp,
  [out]          WDFREQUEST             *Request
);

Parameters

[in, optional] RequestAttributes

A pointer to a caller-allocated WDF_OBJECT_ATTRIBUTES structure that specifies object attributes for the request object. This parameter is optional and can be WDF_NO_OBJECT_ATTRIBUTES.

[in] Irp

A pointer to an IRP structure that contains a WDM I/O request packet.

[in] RequestFreesIrp

A Boolean value that, if TRUE, indicates that the framework removes the IRP when the request handle is destroyed. If FALSE, the driver must call IoFreeIrp to remove the IRP, using the steps that the following Examples section demonstrates.

[out] Request

A pointer to a location that receives a handle to a framework request object.

Return value

WdfRequestCreateFromIrp returns STATUS_SUCCESS if the operation succeeds. For a list of additional return values, see Framework Object Creation Errors.

This method might also return other NTSTATUS values.

Remarks

Typically, framework-based drivers call WdfRequestCreateFromIrp only if they receive WDM IRPs in a WDM dispatch routine and then forward the requests to framework I/O targets.

If a driver calls WdfRequestCreateFromIrp to create a request object, it must not call WdfRequestComplete for the request object. Instead, the driver must call WdfObjectDelete when it has finished using the request object.

In addition, the driver must not call WdfRequestRetrieveOutputMemory, WdfRequestRetrieveOutputBuffer, WdfRequestRetrieveInputBuffer, or WdfRequestRetrieveInputMemory with the new request object.

By default, the new request object's parent is the framework driver object that the WdfDriverCreate method created. You can use the ParentObject member of the WDF_OBJECT_ATTRIBUTES structure to specify a different parent. The framework deletes the request object when it deletes the parent object. If your driver does not change the default parent, the driver should delete the request object when it has finished using the object; otherwise, the request object will remain until the I/O manager unloads your driver.

For more information about creating framework request objects, see Creating Framework Request Objects.

Framework-based drivers must not use the Tail.Overlay.DriverContext member of the IRP structure, because the framework uses this member.

Examples

Example 1

The following code example creates a framework request object from a specified WDM IRP and then deletes it. This example sets the RequestFreesIrp parameter to TRUE, so the framework removes the IRP when the request handle is destroyed.

WDFREQUEST request;
PIRP irp;

//Creation
status = WdfRequestCreateFromIrp(
                                 WDF_NO_OBJECT_ATTRIBUTES,
                                 irp,
                                 TRUE,
                                 &request
                                 );
...
//Deletion
WdfObjectDelete(request);

Example 2

The following code example also creates a framework request object from a specified WDM IRP and then deletes it. This example sets the RequestFreesIrp parameter to FALSE, so the driver must call IoFreeIrp to remove the IRP. All of the function calls in the example are required.

WDF_REQUEST_REUSE_PARAMS params;
WDFREQUEST request;
PIRP irp;

//Creation
status = WdfRequestCreateFromIrp(
                                 WDF_NO_OBJECT_ATTRIBUTES,
                                 irp,
                                 FALSE,
                                 &request
                                 );
...
//Deletion
WDF_REQUEST_REUSE_PARAMS_INIT(
                              &params,
                              WDF_REQUEST_REUSE_NO_FLAGS,
                              STATUS_SUCCESS
                              );
WDF_REQUEST_REUSE_PARAMS_SET_NEW_IRP(
                                     &params,
                                     NULL
                                     );
status = WdfRequestReuse(
                         request,
                         &params
                         );
ASSERT(NT_SUCCESS(status));
IoFreeIrp(irp);
WdfObjectDelete(request);

Requirements

See also

IoFreeIrp

WDF_OBJECT_ATTRIBUTES

WdfDeviceInitSetRequestAttributes

WdfDriverCreate

WdfRequestCreate

WdfRequestReuse