WDF_REQUEST_COMPLETION_PARAMS - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers 
// wdfrequest.h

typedef struct _WDF_REQUEST_COMPLETION_PARAMS {
  ULONG            Size;
  WDF_REQUEST_TYPE Type;
  IO_STATUS_BLOCK  IoStatus;
  union {
    struct {
      WDFMEMORY Buffer;
      size_t    Length;
      size_t    Offset;
    } Write;
    struct {
      WDFMEMORY Buffer;
      size_t    Length;
      size_t    Offset;
    } Read;
    struct {
      ULONG  IoControlCode;
      struct {
        WDFMEMORY Buffer;
        size_t    Offset;
      } Input;
      struct {
        WDFMEMORY Buffer;
        size_t    Offset;
        size_t    Length;
      } Output;
    } Ioctl;
    struct {
      union {
        PVOID     Ptr;
        ULONG_PTR Value;
      } Argument1;
      union {
        PVOID     Ptr;
        ULONG_PTR Value;
      } Argument2;
      union {
        PVOID     Ptr;
        ULONG_PTR Value;
      } Argument3;
      union {
        PVOID     Ptr;
        ULONG_PTR Value;
      } Argument4;
    } Others;
    struct {
      PWDF_USB_REQUEST_COMPLETION_PARAMS Completion;
    } Usb;
  } Parameters;
} WDF_REQUEST_COMPLETION_PARAMS, *PWDF_REQUEST_COMPLETION_PARAMS;
View the official Windows Driver Kit DDI reference

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Windows Driver Kit DDI reference (ns-wdfrequest-_wdf_request_completion_params)

_WDF_REQUEST_COMPLETION_PARAMS structure

Description

[Applies to KMDF and UMDF]

The WDF_REQUEST_COMPLETION_PARAMS structure contains parameters that are associated with the completion of an I/O request.

Members

Size

The size, in bytes, of this structure.

Type

A WDF_REQUEST_TYPE value that identifies the request type.

IoStatus

An IO_STATUS_BLOCK structure for the request.

Parameters

Request-specific values for the request.

Parameters.Write

Parameters.Write.Buffer

A handle to a framework memory object. This object identifies the buffer that the driver specified when it formatted the request and sent it to an I/O target.

Parameters.Write.Length

Length, in bytes, of the transfer.

Parameters.Write.Offset

Beginning address within the buffer for the data transfer.

Parameters.Read

Parameters.Read.Buffer

A handle to a framework memory object. This object identifies the buffer that the driver specified when it formatted the request and sent it to an I/O target.

Parameters.Read.Length

Length, in bytes, of the transfer.

Parameters.Read.Offset

Beginning address within the buffer for the data transfer.

Parameters.Ioctl

Parameters.Ioctl.IoControlCode

Parameters.Ioctl.Input

Parameters.Ioctl.Input.Buffer

A handle to a framework memory object. This object identifies the input buffer that the driver specified when it formatted the request and sent it to an I/O target.

Parameters.Ioctl.Input.Offset

Beginning address within the buffer for the data transfer.

Parameters.Ioctl.Output

Parameters.Ioctl.Output.Buffer

A handle to a framework memory object. This object identifies the output buffers that the driver specified when it formatted the request and sent it to an I/O target.

Parameters.Ioctl.Output.Offset

Beginning address within the buffer for the data transfer.

Parameters.Ioctl.Output.Length

Length, in bytes, of the transfer.

Parameters.Others

Parameters.Others.Argument1

Use of this member is defined by the driver stack. See Remarks.

Parameters.Others.Argument1.Ptr

Parameters.Others.Argument1.Value

Parameters.Others.Argument2

Use of this member is defined by the driver stack.

Parameters.Others.Argument2.Ptr

Parameters.Others.Argument2.Value

Parameters.Others.Argument3

Use of this member is defined by the driver stack.

Parameters.Others.Argument3.Ptr

Parameters.Others.Argument3.Value

Parameters.Others.Argument4

Use of this member is defined by the driver stack.

Parameters.Others.Argument4.Ptr

Parameters.Others.Argument4.Value

Parameters.Usb

For USB devices, this member contains a pointer to a WDF_USB_REQUEST_COMPLETION_PARAMS structure.

Parameters.Usb.Completion

Remarks

The WDF_REQUEST_COMPLETION_PARAMS structure is used as input to the WdfRequestGetCompletionParams method and a driver's CompletionRoutine callback function.

In both cases, the completion parameters structure contains valid information only if the driver has formatted the request by calling one of the WdfIoTargetFormatXxx methods. For example, see WdfIoTargetFormatRequestForRead.

Before calling WdfRequestGetCompletionParams to retrieve the I/O completion information for a request, the driver must first call WDF_REQUEST_COMPLETION_PARAMS_INIT to initialize the WDF_REQUEST_COMPLETION_PARAMS structure.

The Parameters.Others.Argument members are custom arguments that a driver typically passes down the stack (and can arrive back after the request is completed). They are used for non-standard, driver stack dependent data. For example, a USB driver specifies a pointer to a URB in Parameters.Others.Argument1 when it sends a IOCTL_INTERNAL_USB_SUBMIT_URB request to the USB stack. Similarly, a Bluetooth driver specifies a pointer to a BRB (Bluetooth Request Block) in Parameters.Others.Argument1 when it receives an IOCTL_INTERNAL_BTH_SUBMIT_BRB.

See also

CompletionRoutine

IO_STATUS_BLOCK

WDF_REQUEST_COMPLETION_PARAMS_INIT

WDF_REQUEST_TYPE

WdfRequestGetCompletionParams

View the official Windows Driver Kit DDI reference

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