WdfDeviceCreate之WDFDEVICE_INIT对象

WdfAddDevice回调函数中会调用WdfDeviceCreate创建设备对象WDFDEVICE，设备创建包含2个重要的参数：

• WDF_OBJECT_ATTRIBUTES：仅用于描述符设备对象的扩展空间大小

WDF_OBJECT_ATTRIBUTES               attributes;
WDF_OBJECT_ATTRIBUTES_INIT_CONTEXT_TYPE(&attributes, REQUEST_CONTEXT);
WdfDeviceInitSetRequestAttributes(DeviceInit, &attributes);

结构体的定义如下：

//
// This context is associated with every request received by the driver from the app.
//
typedef struct _REQUEST_CONTEXT {

    WDFMEMORY         UrbMemory;
    PMDL              Mdl;
    ULONG             Length;         // remaining to xfer
    ULONG             Numxfer;
    ULONG_PTR         VirtualAddress; // va for next segment of xfer.
    BOOLEAN           Read; // TRUE if Read
} REQUEST_CONTEXT, * PREQUEST_CONTEXT;

WDF_DECLARE_CONTEXT_TYPE_WITH_NAME(REQUEST_CONTEXT, GetRequestContext)

• WDFDEVICE_INIT 则描述符设备对象的相关回调和属性信息

WDFDEVICE_INIT (DeviceInit)
├── PnP 事件回调 (对应 WDM: IRP_MJ_PNP 处理例程)
│   ├── EvtDevicePrepareHardware   ← IRP_MN_START_DEVICE (初始化硬件)
│   ├── EvtDeviceReleaseHardware   ← IRP_MN_STOP_DEVICE (释放硬件资源)
│   ├── EvtDeviceD0Entry           ← IRP_MN_POWER_SET (进入D0状态)
│   ├── EvtDeviceD0Exit            ← IRP_MN_POWER_SET (离开D0状态)
│   ├── EvtDeviceQueryRemove       ← IRP_MN_QUERY_REMOVE_DEVICE
│   ├── EvtDeviceRemoveComplete    ← IRP_MN_REMOVE_DEVICE
│   └── EvtDeviceSurpriseRemoval   ← IRP_MN_SURPRISE_REMOVAL
│
├── Power 事件回调 (对应 WDM: IRP_MJ_POWER 处理例程)
│   ├── EvtDevicePowerPolicyStateChange ← 电源策略状态变化
│   ├── EvtDeviceSelfManagedIoInit     ← 自管理I/O初始化
│   └── EvtDeviceSelfManagedIoCleanup  ← 自管理I/O清理
│
├── 文件对象配置 (对应 WDM: IRP_MJ_CREATE/CLOSE/CLEANUP)
│   ├── EvtDeviceFileCreate    ← IRP_MJ_CREATE (打开设备)
│   ├── EvtDeviceFileClose     ← IRP_MJ_CLOSE (关闭设备)
│   ├── EvtDeviceFileCleanup   ← IRP_MJ_CLEANUP (清理操作)
│   └── FILE_CONTEXT           ← WDM: FsContext/FsContext2 (每句柄上下文)
│
├── I/O 请求配置 (对应 WDM: IoCreateDevice 标志)
│   ├── RequestAttributes
│   │   └── REQUEST_CONTEXT    ← 每个IRP的私有上下文
│   ├── IoType
│   │   ├── WdfDeviceIoBuffered   ← DO_BUFFERED_IO
│   │   ├── WdfDeviceIoDirect     ← DO_DIRECT_IO
│   │   └── WdfDeviceIoNeither    ← 无标志(Neither模式)
│   └── Exclusive               ← DO_EXCLUSIVE
│
├── 设备类型与特性 (对应 WDM: IoCreateDevice 参数)
│   ├── DeviceType             ← DeviceType 参数
│   ├── DeviceCharacteristics  ← DeviceCharacteristics 参数
│   ├── Exclusive              ← Exclusive 参数
│   └── SecurityDescriptor     ← 安全描述符
│
├── 命名空间配置 (对应 WDM: IoCreateDevice 设备名称)
│   ├── DeviceName             ← \Device\XXX
│   └── SymbolicLinkName       ← \DosDevices\XXX (用户态可见名称)
│
├── 驱动对象引用 (对应 WDM: DriverObject)
│   └── WdfDriver              ← 框架驱动对象(封装DriverObject)
│
└── 低层设备信息 (对应 WDM: 设备栈信息)
    ├── LowerDevice            ← 下层设备对象指针
    └── DeviceStackSize        ← 设备栈大小

创建设备：

 status = WdfDeviceCreate(&DeviceInit, &attributes, &device);
 if (!NT_SUCCESS(status)) {
     UsbSamp_DbgPrint(1, ("WdfDeviceCreate failed with Status code 0x%x\n", status));
     return status;
 }

pDevContext = GetDeviceContext(device);