How to preprocess buffer and pass through

Question

how to send the request to the next driver in the stack to further completion?

In my filter driver driver I register a queue for EventWrite with callback EvtDeviceIoWrite as follows:

VOID
EvtDeviceIoWrite(
    IN WDFQUEUE  Queue,
    IN WDFREQUEST  Request,
    IN size_t Length
)
{
    WDFMEMORY memory;
    NTSTATUS status;
    PUCHAR characters;
    UCHAR currentChar;
    UNREFERENCED_PARAMETER(Queue);

    status = WdfRequestRetrieveInputMemory(Request, &memory);
    if (!NT_SUCCESS(status)) {
        KdPrint(("RetreiveInputMemo:  failed 0x%x\n", status));
        return;
    }
    characters = (PUCHAR)WdfMemoryGetBuffer(memory, NULL);
    while (Length != 0) {
        Length--;
        currentChar = *(characters++);
        // Here I would like to edit the buffer
        // copy it to output buffer WdfMemoryCopyFromBuffer
    }
  **// what should be here for send** 
}

I just want do something like this, but for the request.

Sorry I am newbiee in kernel developing, and it will be greatful if someone could point me to the right way to achieve this. Any sugestions will be appreciated.

Answer 1

in Windows-driver-samples exist huge count of examples how do Forwarding I/O Requests. take for example first simply code like in filter.c - here this done by FilterForwardRequest or FilterForwardRequestWithCompletionRoutine - so in general called

WdfRequestSend(Request, WdfDeviceGetIoTarget(WdfIoQueueGetDevice(Queue)),WDF_NO_SEND_OPTIONS);