fxrequestsystembufferkm.cpp

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/*++
 
Copyright (c) Microsoft Corporation
 
Module Name:
 
    FxRequestSystemBuffer.cpp
 
Abstract:
 
    This module implements class representing the system buffer in an FxRequest
 
Author:
 
 
 
 
Environment:
 
    Kernel mode only
 
Revision History:
 
 
 
 
--*/
 
#include "coreprivshared.hpp"
 
// Tracing support
extern "C" {
// #include "FxRequestSystemBufferKm.tmh"
}
 
_Must_inspect_result_
PVOID
FxRequestSystemBuffer::GetBuffer(
    VOID
    )
/*++
 
Routine Description:
    Returns the system buffer that has been cached away by the call to SetBuffer()
 
Arguments:
    None
 
Return Value:
    Valid memory or NULL on error
 
  --*/
{
    FxDevice* pDevice;
    FxIrp* irp = GetRequest()->GetFxIrp();
    WDF_DEVICE_IO_TYPE ioType;
 
    switch (irp->GetMajorFunction()) {
    case IRP_MJ_DEVICE_CONTROL:
    case IRP_MJ_INTERNAL_DEVICE_CONTROL:
        return m_Buffer;
 
    case IRP_MJ_READ:
    case IRP_MJ_WRITE:
        pDevice = FxDevice::GetFxDevice(irp->GetDeviceObject());
        ioType = pDevice->GetIoType();
 
        switch (ioType) {
        case WdfDeviceIoBuffered:
            return m_Buffer;
 
        case WdfDeviceIoDirect:
            //
            // FxRequest::GetMemoryObject has already called MmGetSystemAddressForMdlSafe
            // and returned success, so we know that we can safely call
            // MmGetSystemAddressForMdlSafe again to get a valid VA pointer.
            //
            return Mx::MxGetSystemAddressForMdlSafe(m_Mdl, NormalPagePriority);
 
        case WdfDeviceIoNeither:
            return m_Buffer;
 
        default:
            ASSERT(FALSE);
            return NULL;
        }
 
    default:
        ASSERT(FALSE);
        return NULL;
    }
}