PIBIO_STORAGE_CONTROL_UNIT_PRIVILEGED_FN callback function (winbio_adapter.h)

Called by the Windows Biometric Framework to perform a vendor-defined control operation that requires elevated privilege. Call the StorageAdapterControlUnit function to perform a vendor-defined control operation that does not require elevated privilege.

Syntax

PIBIO_STORAGE_CONTROL_UNIT_PRIVILEGED_FN PibioStorageControlUnitPrivilegedFn;

HRESULT PibioStorageControlUnitPrivilegedFn(
  [in, out] PWINBIO_PIPELINE Pipeline,
  [in]      ULONG ControlCode,
  [in]      PUCHAR SendBuffer,
  [in]      SIZE_T SendBufferSize,
  [in]      PUCHAR ReceiveBuffer,
  [in]      SIZE_T ReceiveBufferSize,
  [out]     PSIZE_T ReceiveDataSize,
  [out]     PULONG OperationStatus
)
{...}

Parameters

[in, out] Pipeline

A pointer to the WINBIO_PIPELINE structure associated with the biometric unit performing the operation.

[in] ControlCode

A ULONG value that specifies the vendor-defined operation to perform.

[in] SendBuffer

A pointer to a buffer that contains the control information sent to the storage adapter. The format and content of the buffer is vendor defined.

[in] SendBufferSize

The size, in bytes, of the buffer specified by the SendBuffer parameter.

[in] ReceiveBuffer

A pointer to a buffer that receives information returned by the storage adapter in response to the control operation. The format of the buffer is vendor defined.

[in] ReceiveBufferSize

The size, in bytes, of the buffer specified by the ReceiveBuffer parameter.

[out] ReceiveDataSize

A pointer to a variable that receives the size, in bytes, of the data written to the buffer specified by the ReceiveBuffer parameter.

[out] OperationStatus

A pointer to a variable that receives a vendor-defined status code that specifies the outcome of the control operation.

Return value

If the function succeeds, it returns S_OK. If the function fails, it must return one of the following HRESULT values to indicate the error.

Return code Description
E_POINTER
A mandatory pointer argument is NULL.
E_INVALIDARG
The size or format of the buffer specified by the SendBuffer parameter is not correct, or the value specified in the ControlCode parameter is not recognized by the adapter.
E_NOT_SUFFICIENT_BUFFER
The buffer specified by the ReceiveBuffer parameter is too small.
WINBIO_E_CANCELED
The operation was canceled.
WINBIO_E_DEVICE_FAILURE
There was a hardware failure.
WINBIO_E_INVALID_CONTROL_CODE
The value specified in the ControlCode parameter is not recognized by the adapter.
Note  Beginning with Windows 8, use only E_INVALIDARG to signal this condition.
 

Remarks

Your implementation of this function should be identical to your implementation of the StorageAdapterControlUnit function except that elevated privileges are required to perform the operations specified by the ControlCode parameter. You are responsible for defining the operations and deciding which will require elevated privilege.

This function must check the value of the ReceiveBufferSize parameter to be certain that the buffer specified by the ReceiveBuffer parameter is large enough to hold the data being returned.

Examples

The following pseudocode shows one possible implementation of this function. The example does not compile. You must adapt it to suit your purpose.

/////////////////////////////////////////////////////////////////////////////////////////
//
// StorageAdapterControlUnitPrivileged
//
// Purpose:
//      Performs a vendor-defined control operation that requires elevated privilege.
//
// Parameters:
//      Pipeline            - Pointer to a WINBIO_PIPELINE structure associated 
//                            with the biometric unit performing the operation
//      ControlCode         - Specifies the vendor-defined operation to perform
//      SendBuffer          - Contains the control information sent to the 
//                            storage adapter
//      SendBufferSize      - Size, in bytes, of the buffer specified by the 
//                            SendBuffer parameter
//      ReceiveBuffer       - Receives information returned by the storage adapter
//                            in response to the control operation
//      ReceiveBufferSize   - Size, in bytes, of the buffer specified by the 
//                            ReceiveBuffer parameter.
//      ReceiveDataSize     - Receives the size, in bytes, of the data written to 
//                            the buffer specified by the ReceiveBuffer parameter
//      OperationStatus     - Receives a vendor-defined status code that specifies 
//                            the outcome of the control operation.
//
static HRESULT
WINAPI
StorageAdapterControlUnitPrivileged(
    __inout PWINBIO_PIPELINE Pipeline,
    __in ULONG ControlCode,
    __in PUCHAR SendBuffer,
    __in SIZE_T SendBufferSize,
    __in PUCHAR ReceiveBuffer,
    __in SIZE_T ReceiveBufferSize,
    __out PSIZE_T ReceiveDataSize,
    __out PULONG OperationStatus
    )
{
    HRESULT hr = S_OK;
    BOOL result = TRUE;

    // Verify that pointer arguments are not NULL.
    if (!ARGUMENT_PRESENT(Pipeline) ||
        !ARGUMENT_PRESENT(SendBuffer) ||
        !ARGUMENT_PRESENT(ReceiveBuffer) ||
        !ARGUMENT_PRESENT(ReceiveDataSize) ||
        !ARGUMENT_PRESENT(OperationStatus))
    {
        hr = E_POINTER;
        goto cleanup;
    }

    // Retrieve the context from the pipeline.
    PWINBIO_STORAGE_CONTEXT storageContext = 
           (PWINBIO_STORAGE_CONTEXT)Pipeline->StorageContext;

    // Verify the state of the pipeline.
    if (storageContext == NULL ||
        Pipeline->StorageHandle == INVALID_HANDLE_VALUE)
    {
        hr = WINBIO_E_INVALID_DEVICE_STATE;
        goto cleanup;
    }

    switch (ControlCode)
    {
    case MY_PRIVILEGED_CTRL_CODE_P1:
        {
            CTRL_CODE_P1_SEND_BUFFER *sendBuffer = (CTRL_CODE_P1_SEND_BUFFER*)SendBuffer;

            // Verify the size of the send buffer.
            if (SendBufferSize < sizeof(CTRL_CODE_P1_SEND_BUFFER))
            {
                hr = E_INVALIDARG;
                break;
            }

            // Perform any other checks that may be required on the buffer 
            // contents. Return E_INVALIDARG if any of the checks fail.
            if (sendBuffer->SomeField != SomeSpecialValue ||
                sendBuffer->SomeOtherField != SomeOtherSpecialValue)
            {
                hr = E_INVALIDARG;
                break;
            }

            if (ReceiveBufferSize < sizeof(CTRL_CODE_P1_RECEIVE_BUFFER))
            {
                hr = E_NOT_SUFFICIENT_BUFFER;
                break;
            }
        }

        // Fall through and perform the control operation after the switch
        // statement. Alternatively, depending on your requirements, you can 
        // perform the control operation here.
        break;

    case MY_PRIVILEGED_CTRL_CODE_P2:
        // Continue testing for other non-privileged control codes that your
        // adapter supports.
        {
            CTRL_CODE_P2_SEND_BUFFER *sendBuffer = (CTRL_CODE_P2_SEND_BUFFER*)SendBuffer;

            // Verify the size of the send buffer.
            if (SendBufferSize < sizeof(CTRL_CODE_P2_SEND_BUFFER))
            {
                hr = E_INVALIDARG;
                break;
            }

            // Perform any other checks that may be required on the buffer 
            // contents. Return E_INVALIDARG if any of the checks fail.
            if (sendBuffer->SomeField != SomeSpecialValue ||
                sendBuffer->SomeOtherField != SomeOtherSpecialValue)
            {
                hr = E_INVALIDARG;
                break;
            }

            if (ReceiveBufferSize < sizeof(CTRL_CODE_P2_RECEIVE_BUFFER))
            {
                hr = E_NOT_SUFFICIENT_BUFFER;
                break;
            }
        }
        break;

    default:
        // All unrecognized control code values should return an error.
        hr = WINBIO_E_INVALID_CONTROL_CODE;
        break;
    }
    if (FAILED(hr))
    {
        goto cleanup;
    }

    // If control code validation succeeds, perform the control operation. This
    // example assumes that your adapter has put an open handle to a storage 
    // device in the Pipeline structure. It also assumes that the driver performs
    // overlapped I/O and that a properly initialized OVERLAPPED structure is
    // contained in the storage context.
    result = DeviceIoControl(
                Pipeline->StorageHandle,
                ControlCode,
                SendBuffer,
                (DWORD)SendBufferSize,
                ReceiveBuffer,
                (DWORD)ReceiveBufferSize,
                (LPDWORD)ReceiveDataSize,
                &storageContext->Overlapped
                );
    if (result == FALSE && GetLastError() == ERROR_IO_PENDING)
    {
        SetLastError(ERROR_SUCCESS);

        result = GetOverlappedResult(
                    Pipeline->StorageHandle,
                    &storageContext->Overlapped,
                    (LPDWORD)ReceiveDataSize,
                    TRUE
                    );
    }
    *OperationStatus = GetLastError();

    if (!result)
    {
        hr = _AdapterGetHresultFromWin32(*OperationStatus);
    }

cleanup:

    return hr;
}

Requirements

   
Minimum supported client Windows 7 [desktop apps only]
Minimum supported server Windows Server 2008 R2 [desktop apps only]
Target Platform Windows
Header winbio_adapter.h (include Winbio_adapter.h)

See also

Plug-in Functions

StorageAdapterControlUnit