WdfRequestRetrieveUnsafeUserOutputBuffer - NtDoc
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// wdfrequest.h
NTSTATUS WdfRequestRetrieveUnsafeUserOutputBuffer(
[in] WDFREQUEST Request,
[in] size_t MinimumRequiredLength,
[out] PVOID *OutputBuffer,
[out, optional] size_t *Length
);
View the official Windows Driver Kit DDI referenceNo description available.
[Applies to KMDF only]
The WdfRequestRetrieveUnsafeUserOutputBuffer method retrieves an I/O request's output buffer, if the request's technique for accessing data buffers is neither buffered nor direct I/O.
Request [in]A handle to a framework request object.
MinimumRequiredLength [in]The minimum buffer size, in bytes, that the driver needs to process the I/O request.
OutputBuffer [out]A pointer to a location that receives the buffer's address.
Length [out, optional]A pointer to a location that receives the buffer's size, in bytes. This parameter is optional and can be NULL.
WdfRequestRetrieveUnsafeUserOutputBuffer 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_INVALID_DEVICE_REQUEST | This value is returned if one of the following occurs: * The method was not called from within the driver's EvtIoInCallerContext callback function. * The I/O request's I/O control code is IRP_MJ_WRITE or IRP_MJ_INTERNAL_DEVICE_CONTROL. * The request specifies buffered I/O or direct I/O. |
| STATUS_BUFFER_TOO_SMALL | The MinimumRequiredLength parameter specifies a buffer size that is larger than the buffer's actual size. |
This method might also return other NTSTATUS values.
A bug check occurs if the driver supplies an invalid object handle.
The WdfRequestRetrieveUnsafeUserOutputBuffer method must be called from an EvtIoInCallerContext callback function. After calling WdfRequestRetrieveUnsafeUserOutputBuffer, the driver must call WdfRequestProbeAndLockUserBufferForWrite.
The driver can call WdfRequestRetrieveUnsafeUserOutputBuffer if a request's I/O control code is IRP_MJ_READ or IRP_MJ_DEVICE_CONTROL.
The driver can access the retrieved buffer until it completes the I/O request that the Request parameter represents.
For more information about WdfRequestRetrieveUnsafeUserOutputBuffer, see Accessing Data Buffers in Framework-Based Drivers.
For a code example that uses WdfRequestRetrieveUnsafeUserOutputBuffer, see WdfRequestProbeAndLockUserBufferForRead.
WdfRequestProbeAndLockUserBufferForWrite
WdfRequestRetrieveUnsafeUserInputBuffer