KsInitializeDriver详解

KsInitializeDriver是AVStream驱动的总入口：

NTSTATUS
NTAPI
KsInitializeDriver(
    IN PDRIVER_OBJECT DriverObject,
    IN PUNICODE_STRING RegistryPathName,
    IN const KSDEVICE_DESCRIPTOR* Descriptor OPTIONAL
    )

KsInitializeDriver函数内部功能如下：

• 如果Descriptor不为空，则调用IoAllocateDriverObjectExtension分配一个sizeof(KSDEVICE_DESCRIPTOR)的结构体，用于存储参数Descriptor

    if (Descriptor) 
    {
        PKSDEVICE_DESCRIPTOR* descriptorInExt;
        status = IoAllocateDriverObjectExtension(
                DriverObject,
                PVOID(KsInitializeDriver),
                sizeof(*descriptorInExt),
                reinterpret_cast<PVOID*>(&descriptorInExt));

        if (NT_SUCCESS(status))
        {
            *descriptorInExt = PKSDEVICE_DESCRIPTOR(Descriptor);
        }
    }

• 设置驱动对应的派遣例程

  DriverObject->MajorFunction[IRP_MJ_PNP] =     CKsDevice::DispatchPnp;
  DriverObject->MajorFunction[IRP_MJ_POWER] =     CKsDevice::DispatchPower;
  DriverObject->MajorFunction[IRP_MJ_SYSTEM_CONTROL] =     KsDefaultForwardIrp;
  DriverObject->DriverExtension->AddDevice = KsAddDevice;
  
  DriverObject->DriverUnload = KsNullDriverUnload;
  
  DriverObject->MajorFunction[IRP_MJ_CREATE] =    CKsDevice::DispatchCreate;
  KsSetMajorFunctionHandler(DriverObject,IRP_MJ_CLOSE);
  KsSetMajorFunctionHandler(DriverObject,IRP_MJ_DEVICE_CONTROL);
  

  KsSetMajorFunctionHandler函数做了二次分发，其主要根据是否支持快调IO来设置对应的FastIoDispatch等例程.
  如果是快速调用

  if (MajorFunction & KSDISPATCH_FASTIO)
  {
         switch (MajorFunction & ~KSDISPATCH_FASTIO)
         {
  
        case IRP_MJ_DEVICE_CONTROL:
            DriverObject->FastIoDispatch->FastIoDeviceControl = DispatchFastDeviceIoControl;
            break;
  
        case IRP_MJ_READ:
            DriverObject->FastIoDispatch->FastIoRead = DispatchFastRead;
            break;
  
        case IRP_MJ_WRITE:
            DriverObject->FastIoDispatch->FastIoWrite = DispatchFastWrite;
            break;
  
        default:
            return STATUS_INVALID_PARAMETER;
        }
  }
  

  如果不是快速调用（这里设置的是IRP_MJ_CLOSE和IRP_MJ_DEVICE_CONTROL，就不是），所以内容为：

         PDRIVER_DISPATCH    Dispatch;
  
        switch (MajorFunction) {
  
        case IRP_MJ_CREATE:
            Dispatch = DispatchCreate;
            break;
  
        case IRP_MJ_CLOSE:
            Dispatch = DispatchClose;
            break;
  
        case IRP_MJ_FLUSH_BUFFERS:
            Dispatch = DispatchFlush;
            break;
  
        case IRP_MJ_DEVICE_CONTROL:
            Dispatch = DispatchDeviceIoControl;
            break;
  
        case IRP_MJ_READ:
            Dispatch = DispatchRead;
            break;
  
        case IRP_MJ_WRITE:
            Dispatch = DispatchWrite;
            break;
  
        case IRP_MJ_QUERY_SECURITY:
            Dispatch = DispatchQuerySecurity;
            break;
  
        case IRP_MJ_SET_SECURITY:
            Dispatch = DispatchSetSecurity;
            break;
  
        default:
            return STATUS_INVALID_PARAMETER;
  
        }
        DriverObject->MajorFunction[MajorFunction] = Dispatch;
  

故最终结果为：