/*++

Copyright (C) Microsoft Corporation, All Rights Reserved.

Module Name:

    util.cpp

Abstract:

    This module contains the implementation of the driver

Environment:

    Windows Driver Framework (WDF)

--*/

#include "vhidmini.h"

//
// HID minidriver IOCTL uses HID_XFER_PACKET which contains an embedded pointer.
//
//   typedef struct _HID_XFER_PACKET {
//     PUCHAR reportBuffer;
//     ULONG  reportBufferLen;
//     UCHAR  reportId;
//   } HID_XFER_PACKET, *PHID_XFER_PACKET;
//
// UMDF cannot handle embedded pointers when marshalling buffers between processes.
// Therefore a special driver mshidumdf.sys is introduced to convert such IRPs to
// new IRPs (with new IOCTL name like IOCTL_UMDF_HID_Xxxx) where:
//
//   reportBuffer - passed as one buffer inside the IRP
//   reportId     - passed as a second buffer inside the IRP
//
// The new IRP is then passed to UMDF host and driver for further processing.
//

NTSTATUS
RequestGetHidXferPacket_ToReadFromDevice(
    _In_  WDFREQUEST        Request,
    _Out_ HID_XFER_PACKET  *Packet
    )
{
    //
    // Driver need to write to the output buffer (so that App can read from it)
    //
    //   Report Buffer: Output Buffer
    //   Report Id    : Input Buffer
    //

    NTSTATUS                status;
    WDFMEMORY               inputMemory;
    WDFMEMORY               outputMemory;
    size_t                  inputBufferLength;
    size_t                  outputBufferLength;
    PVOID                   inputBuffer;
    PVOID                   outputBuffer;

    //
    // Get report Id from input buffer
    //
    status = WdfRequestRetrieveInputMemory(Request, &inputMemory);
    if( !NT_SUCCESS(status) ) {
        KdPrint(("WdfRequestRetrieveInputMemory failed 0x%x\n",status));
        return status;
    }
    inputBuffer = WdfMemoryGetBuffer(inputMemory, &inputBufferLength);

    if (inputBufferLength < sizeof(UCHAR)) {
        status = STATUS_INVALID_BUFFER_SIZE;
        KdPrint(("WdfRequestRetrieveInputMemory: invalid input buffer. size %d, expect %d\n",
                            (int)inputBufferLength, (int)sizeof(UCHAR)));
        return status;
    }

    Packet->reportId        = *(PUCHAR)inputBuffer;

    //
    // Get report buffer from output buffer
    //
    status = WdfRequestRetrieveOutputMemory(Request, &outputMemory);
    if( !NT_SUCCESS(status) ) {
        KdPrint(("WdfRequestRetrieveOutputMemory failed 0x%x\n",status));
        return status;
    }

    outputBuffer = WdfMemoryGetBuffer(outputMemory, &outputBufferLength);

    Packet->reportBuffer    = (PUCHAR) outputBuffer;
    Packet->reportBufferLen = (ULONG)  outputBufferLength;

    return status;
}

NTSTATUS
RequestGetHidXferPacket_ToWriteToDevice(
    _In_  WDFREQUEST        Request,
    _Out_ HID_XFER_PACKET  *Packet
    )
{
    //
    // Driver need to read from the input buffer (which was written by App)
    //
    //   Report Buffer: Input Buffer
    //   Report Id    : Output Buffer Length
    //
    // Note that the report id is not stored inside the output buffer, as the
    // driver has no read-access right to the output buffer, and trying to read
    // from the buffer will cause an access violation error.
    //
    // The workaround is to store the report id in the OutputBufferLength field,
    // to which the driver does have read-access right.
    //

    NTSTATUS                status;
    WDFMEMORY               inputMemory;
    WDFMEMORY               outputMemory;
    size_t                  inputBufferLength;
    size_t                  outputBufferLength;
    PVOID                   inputBuffer;

    //
    // Get report Id from output buffer length
    //
    status = WdfRequestRetrieveOutputMemory(Request, &outputMemory);
    if( !NT_SUCCESS(status) ) {
        KdPrint(("WdfRequestRetrieveOutputMemory failed 0x%x\n",status));
        return status;
    }
    WdfMemoryGetBuffer(outputMemory, &outputBufferLength);
    Packet->reportId        = (UCHAR) outputBufferLength;

    //
    // Get report buffer from input buffer
    //
    status = WdfRequestRetrieveInputMemory(Request, &inputMemory);
    if( !NT_SUCCESS(status) ) {
        KdPrint(("WdfRequestRetrieveInputMemory failed 0x%x\n",status));
        return status;
    }
    inputBuffer = WdfMemoryGetBuffer(inputMemory, &inputBufferLength);

    Packet->reportBuffer    = (PUCHAR) inputBuffer;
    Packet->reportBufferLen = (ULONG)  inputBufferLength;

    return status;
}