reactos操作系统实现(80)

下面的函数主要初始化PnP发现的设备，并为它安装服务，代码如下：

#001  NTSTATUS

#002  IopInitializePnpServices(IN PDEVICE_NODEDeviceNode)

#003  {

#004     DEVICETREE_TRAVERSE_CONTEXT Context;

#005 

#006    DPRINT("IopInitializePnpServices(%p)/n", DeviceNode);

#007 

 

构造一个响应子服务发现的操作。

#008     IopInitDeviceTreeTraverseContext(

#009        &Context,

#010        DeviceNode,

#011        IopActionInitChildServices,

#012        DeviceNode);

#013 

 

开始遍历整个设备树。

#014     returnIopTraverseDeviceTree(&Context);

#015  }

#016 

 

初始化每个设备节点，如下：

#001  NTSTATUS

#002  IopActionInitChildServices(PDEVICE_NODEDeviceNode,

#003                             PVOID Context)

#004  {

#005     PDEVICE_NODE ParentDeviceNode;

#006     NTSTATUS Status;

#007     BOOLEAN BootDrivers = !PnpSystemInit;

#008 

#009    DPRINT("IopActionInitChildServices(%p, %p)/n", DeviceNode,Context);

#010 

 

取父节点设备。

#011     ParentDeviceNode = (PDEVICE_NODE)Context;

#012 

#013     /*

#014      * We are called for the parent too, butwe don't need to do special

#015      *handling for this node

#016      */

 

如果下一个节点等于父节点，没有子节点，就直接返回。

#017     if (DeviceNode == ParentDeviceNode)

#018     {

#019        DPRINT("Success/n");

#020        return STATUS_SUCCESS;

#021     }

#022 

#023     /*

#024      * Make sure this device node is a directchild of the parent device node

#025      * that is given as an argument

#026      */

#027  #if 0

#028     if (DeviceNode->Parent !=ParentDeviceNode)

#029     {

#030        /*

#031         * Stop the traversal immediately andindicate unsuccessful operation

#032         */

#033        DPRINT("Stop/n");

#034        return STATUS_UNSUCCESSFUL;

#035     }

#036  #endif

#037 

 

判断这个节点是否可以安装服务。

#038     if (!IopDeviceNodeHasFlag(DeviceNode,DNF_DISABLED) &&

#039         !IopDeviceNodeHasFlag(DeviceNode,DNF_ADDED) &&

#040         !IopDeviceNodeHasFlag(DeviceNode,DNF_STARTED))

#041     {

#042        PLDR_DATA_TABLE_ENTRY ModuleObject;

#043        PDRIVER_OBJECT DriverObject;

#044 

 

获取已经存在驱动程序指针。

#045        /* Get existing DriverObject pointer(in case the driver has

#046           already been loaded and initialized)*/

#047        Status = IopGetDriverObject(

#048            &DriverObject,

#049            &DeviceNode->ServiceName,

#050            FALSE);

#051 

#052        if (!NT_SUCCESS(Status))

#053        {

#054           /* Driver is not initialized, try toload it */

#055           Status =IopLoadServiceModule(&DeviceNode->ServiceName, &ModuleObject);

#056 

#057           if (NT_SUCCESS(Status) || Status ==STATUS_IMAGE_ALREADY_LOADED)

#058           {

#059              /* STATUS_IMAGE_ALREADY_LOADEDmeans this driver

#060                 was loaded by the bootloader*/

#061              if ((Status !=STATUS_IMAGE_ALREADY_LOADED) ||

#062                  (Status ==STATUS_IMAGE_ALREADY_LOADED && !DriverObject))

#063              {

 

初始化这个设备的驱动程序。

#064                 /* Initialize the driver */

#065                 Status =IopInitializeDriverModule(DeviceNode, ModuleObject,

#066                   &DeviceNode->ServiceName, FALSE, &DriverObject);

#067              }

#068              else

#069              {

#070                 Status = STATUS_SUCCESS;

#071              }

#072           }

#073           else

#074           {

#075             DPRINT1("IopLoadServiceModule(%wZ) failed with status0x%08x/n",

#076                     &DeviceNode->ServiceName, Status);

#077           }

#078        }

#079 

 

设备驱动程序已经加载，开始初始化入口点。

#080        /* Driver is loaded and initialized atthis point */

#081        if (NT_SUCCESS(Status))

#082        {

 

添加低层次的过滤驱动程序。

#083           /* Attach lower level filterdrivers. */

#084           IopAttachFilterDrivers(DeviceNode,TRUE);

 

初始化设备。

#085           /* Initialize the function driverfor the device node */

#086           Status =IopInitializeDevice(DeviceNode, DriverObject);

#087 

#088           if (NT_SUCCESS(Status))

#089           {

#090              /* Attach upper level filterdrivers. */

#091             IopAttachFilterDrivers(DeviceNode, FALSE);

#092              IopDeviceNodeSetFlag(DeviceNode,DNF_STARTED);

#093 

 

启动这个设备。

#094              Status =IopStartDevice(DeviceNode);

#095           }

#096           else

#097           {

#098             DPRINT1("IopInitializeDevice(%wZ) failed with status0x%08x/n",

#099                     &DeviceNode->InstancePath, Status);

#100           }

#101        }

#102        else

#103        {

 

设置引导驱动程序不可以再加载。

#104           /*

#105            * Don't disable when trying to loadonly boot drivers

#106            */

#107           if (!BootDrivers)

#108           {

#109              IopDeviceNodeSetFlag(DeviceNode,DNF_DISABLED);

#110              IopDeviceNodeSetFlag(DeviceNode,DNF_START_FAILED);

#111              /* FIXME: Log the error (possiblyin IopInitializeDeviceNodeService) */

#112              DPRINT1("Initialization ofservice %S failed (Status %x)/n",

#113               DeviceNode->ServiceName.Buffer, Status);

#114           }

#115        }

#116     }

#117     else

#118     {

#119        DPRINT("Device %wZ is disabled oralready initialized/n",

#120           &DeviceNode->InstancePath);

#121     }

#122 

#123     return STATUS_SUCCESS;

#124  }