UsbStorage驱动开发（一）[原创]

UsbStorage, 驱动, 开发, 原创

　　前段时间发现有网友在开发驱动的过程中遇到问题，所以今天我整理了一下我在写驱动中的一点心得。希望大家指导！

win2k的UsbStorage不需要驱动程序就能运行，但是如果我们的设备有特殊功能，像前几天有网友问的那种要显示自已的标号的。那么UsbStor.sys就不能满足我们的需求。当然如果要实现自己的功能，我们也只需要UsbStor.sys的基础上修改就行了！
USB磁盘驱动程序是一个BUS DRIVER，它的主要入口如下：
NTSTATUS
DriverEntry(
         IN PDRIVER_OBJECT DriverObject,
         IN PUNICODE_STRING pRegistryPath
         )
{
#if DBG
DbgPrint("Enter UsbStore DriverEntry!\n");
#endif
DriverObject->DriverExtension->AddDevice = UsbStore_AddDevice;
DriverObject->DriverUnload = UsbStore_Unload;
DriverObject->DriverStartIo = UsbStore_StartIo;

DriverObject->MajorFunction[IRP_MJ_CREATE] =
DriverObject->MajorFunction[IRP_MJ_CLOSE]  = UsbStore_CreateClose;
DriverObject->MajorFunction[IRP_MJ_READ] =
DriverObject->MajorFunction[IRP_MJ_WRITE]  = UsbStore_ReadWrite;
DriverObject->MajorFunction[IRP_MJ_DEVICE_CONTROL] = UsbStore_DeviceIoControl;
DriverObject->MajorFunction[IRP_MJ_SCSI] = UsbStore_Scsi;
DriverObject->MajorFunction[IRP_MJ_PNP] = UsbStore_Pnp;
DriverObject->MajorFunction[IRP_MJ_SYSTEM_CONTROL] = UsbStore_SystemControl;
DriverObject->MajorFunction[IRP_MJ_POWER]  = UsbStore_Power;

return STATUS_SUCCESS;
}
USB STORAGE DRIVER对设备的主要操作MajorFunction是IRP_MJ_SCSI，而不是IRP_MJ_READ 以及IRP_MJ_WRITE 。
USB STORAGE DRIVER的上层程序是CLASS DRIVER。CLASS DRIVER对上层的USB磁盘的读写等操作转换成IRP_MJ_SCSI，USB STORAGE DRIVER根据USB CBI规范和BULK ONLY规范将上层DRIVER传送来的IRP_MJ_SCSI的SRB（SCSI_REQUEST_BLOCK）的相关部分传递给设备。
UsbStore_AddDevice的功能是建立USB STORAGE DRIVER的FDO。
NTSTATUS
UsbStore_AddDevice(
               IN PDRIVER_OBJECT DriverObject,
               IN PDEVICE_OBJECT PhysicalDeviceObject
               )
{
NTSTATUS status;
PUSB_DEVICE_EXTENSION pUsb_DeviceExtension;
PDEVICE_OBJECT USbStore_FileDeviceObject = NULL;
KEVENT Event;
#if DBG
DbgPrint("Enter AddDevice Dispatch!\n");
#endif

status = IoCreateDevice(
               DriverObject,
               sizeof(USB_DEVICE_EXTENSION),
               NULL,
               FILE_DEVICE_BUS_EXTENDER,
               FILE_AUTOGENERATED_DEVICE_NAME ,
               FALSE,
               &USbStore_FileDeviceObject
               );
if(!NT_SUCCESS(status))
{
#if DBG
      DbgPrint("IoCreateDevice Failed!\n");
#endif
      return status;
}

pUsb_DeviceExtension = (PUSB_DEVICE_EXTENSION)USbStore_FileDeviceObject->DeviceExtension;
RtlZeroMemory(pUsb_DeviceExtension,sizeof(USB_DEVICE_EXTENSION));

pUsb_DeviceExtension->DeviceType = USBSTORE_FDO;
pUsb_DeviceExtension->UsbFileDeviceObject = USbStore_FileDeviceObject;
pUsb_DeviceExtension->UsbPhysicalDeviceObject = PhysicalDeviceObject;

pUsb_DeviceExtension->SystemPowerState = PowerSystemWorking;
pUsb_DeviceExtension->CurrentPowerState = PowerDeviceD0;

pUsb_DeviceExtension->UsbStore_TopOfStackDeviceObject =
                        IoAttachDeviceToDeviceStack(
                                                      USbStore_FileDeviceObject,
                                                      PhysicalDeviceObject
                                                      );
KeInitializeEvent(
                  &Event,
                  SynchronizationEvent,
                  FALSE
                  );
pUsb_DeviceExtension->Usb_Event = Event;

UsbStore_GetDriverFlags(USbStore_FileDeviceObject);

USbStore_FileDeviceObject->Flags &= ~DO_DEVICE_INITIALIZING;
USbStore_FileDeviceObject->Flags |= DO_DIRECT_IO;
USbStore_FileDeviceObject->Flags |= DO_POWER_PAGABLE;

return STATUS_SUCCESS;
}

//UsbStore_GetDriverFlags
NTSTATUS
UsbStore_GetDriverFlags(
                     IN PDEVICE_OBJECT UsbFdo
                     )
{
PUSB_DEVICE_EXTENSION pUsb_DeviceExtension;
NTSTATUS status;
HANDLE RegHandle;
RTL_QUERY_REGISTRY_TABLE RegTable;

ULONG Value = 0;
RtlZeroMemory(&RegTable,sizeof(RTL_QUERY_REGISTRY_TABLE));
pUsb_DeviceExtension = UsbFdo->DeviceExtension;
status = IoOpenDeviceRegistryKey(
                                 pUsb_DeviceExtension->UsbPhysicalDeviceObject,
                                 PLUGPLAY_REGKEY_DRIVER,
                                 STANDARD_RIGHTS_ALL,
                                 &RegHandle
                                 );
if(NT_SUCCESS(status))
{
      RegTable.Flags = RTL_QUERY_REGISTRY_DIRECT;
      RegTable.Name = L"DriverFlags";
      RegTable.EntryContext = &Value;
      RegTable.DefaultType = REG_DWORD;
      RegTable.DefaultData = &Value;
      RegTable.DefaultLength = sizeof(ULONG);

      status = RtlQueryRegistryValues(
                                    RTL_REGISTRY_HANDLE,
                                    RegHandle,
                                    &RegTable,
                                    NULL,
                                    NULL
                                    );
      if(!NT_SUCCESS(status))
      {
#if DBG
         DbgPrint("RtlQueryRegistryValues Failed!\n");
#endif
         return status;
      }
      ZwClose(RegHandle);
}

if(Value>=4)
      Value =0;
pUsb_DeviceExtension->DriverFlags = Value;

return status;
}
在这段代码中，
status = IoCreateDevice(
               DriverObject,
               sizeof(USB_DEVICE_EXTENSION),
               NULL,
               FILE_DEVICE_BUS_EXTENDER,
               FILE_AUTOGENERATED_DEVICE_NAME ,
               FALSE,
               &USbStore_FileDeviceObject
               );
负责建立一个USB STORAGE DRIVER的FDO，请各位注意，设备的类型（DEVICE TYPE）是FILE_DEVICE_BUS_EXTENDER。
取注册表的一段代码，主要负责是取出DRIVER FLAGS,它用于标记设备是满足CBI规范还是BULK ONLY规范。

（未完待续）

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