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/*++
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;
}
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