WdfRequestRetrieveInputBuffer function (wdfrequest.h)

Artikel
04/18/2022

[Applies to KMDF and UMDF]

The WdfRequestRetrieveInputBuffer method retrieves an I/O request's input buffer.

Syntax

NTSTATUS WdfRequestRetrieveInputBuffer(
  [in]            WDFREQUEST Request,
                  size_t     MinimumRequiredLength,
  [out]           PVOID      *Buffer,
  [out, optional] size_t     *Length
);

Parameters

[in] Request

A handle to a framework request object.

MinimumRequiredLength

The minimum buffer size, in bytes, that the driver needs to process the I/O request.

[out] Buffer

A pointer to a location that receives the buffer's address.

[out, optional] Length

A pointer to a location that receives the buffer's size, in bytes. This parameter is optional and can be NULL.

Return value

WdfRequestRetrieveInputBuffer returns STATUS_SUCCESS if the operation succeeds. Otherwise, this method might return one of the following values:

Return code	Description
STATUS_INVALID_PARAMETER	An input parameter is invalid.
STATUS_BUFFER_TOO_SMALL	The input buffer's length is zero, or the MinimumRequiredSize parameter specifies a buffer size that is larger than the buffer's actual size.
STATUS_INVALID_DEVICE_REQUEST	The request type is not valid or the request is using neither buffered nor direct I/O. For more information about supported methods for accessing data buffers, see the following Remarks section.
STATUS_INTERNAL_ERROR	The request has already been completed.
STATUS_INSUFFICIENT_RESOURCES	There is insufficient memory.

This method might also return other NTSTATUS values.

A bug check occurs if the driver supplies an invalid object handle.

Remarks

A request's input buffer contains information, such as data to be written to a disk, that was supplied by the originator of the request. Your driver can call WdfRequestRetrieveInputBuffer to obtain the input buffer for a write request or a device I/O control request, but not for a read request (because read requests do not provide input data).

The WdfRequestRetrieveInputBuffer method retrieves the input buffer for I/O requests that use the buffered I/O method or the direct I/O method for accessing data buffers. If the request's I/O control code is IRP_MJ_INTERNAL_DEVICE_CONTROL, or if the request came from another kernel-mode driver, WdfRequestRetrieveInputBuffer also supports I/O requests that use neither buffered nor direct I/O.

If WdfRequestRetrieveInputBuffer returns STATUS_SUCCESS, the driver receives the address and, optionally, the size of the input buffer.

The driver can access the retrieved buffer until it completes the I/O request that the Request parameter represents.

Instead of calling WdfRequestRetrieveInputBuffer, the driver can call WdfRequestRetrieveInputMemory, which creates a framework memory object that represents the buffer.

For more information about WdfRequestRetrieveInputBuffer, see Accessing Data Buffers in Framework-Based Drivers.

Examples

The following code example is part of the Serial sample driver's EvtIoDeviceControl callback function. If the I/O control code is IOCTL_SERIAL_SET_TIMEOUT, the driver obtains new time-out values from the I/O request's input buffer.

VOID
SerialEvtIoDeviceControl(
    IN WDFQUEUE     Queue,
    IN WDFREQUEST   Request,
    IN size_t       OutputBufferLength,
    IN size_t       InputBufferLength,
    IN ULONG        IoControlCode
    )
{
    PVOID  buffer;
    size_t  bufSize;

    switch (IoControlCode) {
...

        case IOCTL_SERIAL_SET_TIMEOUTS: {

            PSERIAL_TIMEOUTS NewTimeouts;

            Status = WdfRequestRetrieveInputBuffer(
                                                   Request,
                                                   sizeof(SERIAL_TIMEOUTS),
                                                   &buffer,
                                                   &bufSize
                                                   );
            if (!NT_SUCCESS(Status)) {
                break;
            }

            NewTimeouts =(PSERIAL_TIMEOUTS)buffer;
    }
...
}

Requirements

Requirement	Value
Target Platform	Universal
Minimum KMDF version	1.0
Minimum UMDF version	2.0
Header	wdfrequest.h (include Wdf.h)
Library	Wdf01000.sys (KMDF); WUDFx02000.dll (UMDF)
IRQL	<=DISPATCH_LEVEL
DDI compliance rules	BufAfterReqCompletedIntIoctl(kmdf), BufAfterReqCompletedIntIoctlA(kmdf), BufAfterReqCompletedIoctl(kmdf), BufAfterReqCompletedIoctlA(kmdf), BufAfterReqCompletedRead(kmdf), BufAfterReqCompletedWrite(kmdf), BufAfterReqCompletedWriteA(kmdf), DriverCreate(kmdf), InputBufferAPI(kmdf), InvalidReqAccess(kmdf), InvalidReqAccessLocal(kmdf), KmdfIrql(kmdf), KmdfIrql2(kmdf), KmdfIrqlExplicit(kmdf)

Delen via