reactos操作系统实现(77)

因为PC里一条总线上可以连接很多设备，就像一棵树一样，需要遍历所有总线上所有子设备，并且为每一个子设备安装相应的驱动程序，下面这个函数，实现枚举所有子设备，实现代码如下：

#001 NTSTATUS

#002 IopEnumerateDevice(

#003 IN PDEVICE_OBJECT DeviceObject)

#004 {

获取设备的节点。

#005 PDEVICE_NODE DeviceNode = IopGetDeviceNode(DeviceObject);

#006 DEVICETREE_TRAVERSE_CONTEXT Context;

#007 PDEVICE_RELATIONS DeviceRelations;

#008 PDEVICE_OBJECT ChildDeviceObject;

#009 IO_STATUS_BLOCK IoStatusBlock;

#010 PDEVICE_NODE ChildDeviceNode;

#011 IO_STACK_LOCATION Stack;

#012 NTSTATUS Status;

#013 ULONG i;

#014

#015 DPRINT("DeviceObject 0x%p/n",DeviceObject);

#016

#017 DPRINT("Sending GUID_DEVICE_ARRIVAL/n");

#018

报告这个设备到用户模式的即插即用管理器。

#019 /* Report the device to the user-mode pnp manager */

#020 IopQueueTargetDeviceEvent(&GUID_DEVICE_ARRIVAL,

#021 &DeviceNode->InstancePath);

#022

#023 DPRINT("Sending IRP_MN_QUERY_DEVICE_RELATIONS to device stack/n");

#024

#025 Stack.Parameters.QueryDeviceRelations.Type = BusRelations;

#026

发送查询设备之间相互关系。

#027 Status = IopInitiatePnpIrp(

#028 DeviceObject,

#029 &IoStatusBlock,

#030 IRP_MN_QUERY_DEVICE_RELATIONS,

#031 &Stack);

#032 if (!NT_SUCCESS(Status) || Status == STATUS_PENDING)

#033 {

#034 DPRINT("IopInitiatePnpIrp() failed with status 0x%08lx/n",Status);

#035 return Status;

#036 }

#037

获取设备相互关系。

#038 DeviceRelations = (PDEVICE_RELATIONS)IoStatusBlock.Information;

#039

#040 if (!DeviceRelations)

#041 {

#042 DPRINT("No PDOs/n");

#043 return STATUS_UNSUCCESSFUL;

#044 }

#045

#046 DPRINT("Got %u PDOs/n",DeviceRelations->Count);

#047

创建所有这个根设备下面的子设备。

#048 /*

#049 * Create device nodes for all discovered devices

#050 */

#051 for (i = 0; i < DeviceRelations->Count; i++)

#052 {

#053 ChildDeviceObject = DeviceRelations->Objects[i];

#054 ASSERT((ChildDeviceObject->Flags & DO_DEVICE_INITIALIZING) == 0);

#055

获取子设备节点是否存在。

#056 ChildDeviceNode = IopGetDeviceNode(ChildDeviceObject);

#057 if (!ChildDeviceNode)

#058 {

如果不存在，就创建这个子设备节点。

#059 /* One doesn't exist,create it */

#060 Status = IopCreateDeviceNode(

#061 DeviceNode,

#062 ChildDeviceObject,

#063 NULL,

#064 &ChildDeviceNode);

#065 if (NT_SUCCESS(Status))

#066 {

#067 /* Mark the node as enumerated */

#068 ChildDeviceNode->Flags |= DNF_ENUMERATED;

#069

#070 /* Mark the DO as bus enumerated */

#071 ChildDeviceObject->Flags |= DO_BUS_ENUMERATED_DEVICE;

#072 }

#073 else

#074 {

#075 /* Ignore this DO */

#076 DPRINT1("IopCreateDeviceNode() failed with status 0x%08x. Skipping PDO %u/n",Status,i);

#077 ObDereferenceObject(ChildDeviceNode);

#078 }

#079 }

#080 else

#081 {

#082 /* Mark it as enumerated */

#083 ChildDeviceNode->Flags |= DNF_ENUMERATED;

#084 ObDereferenceObject(ChildDeviceObject);

#085 }

#086 }

#087 ExFreePool(DeviceRelations);

#088

获取这个总线驱动程序上所有设备。

#089 /*

#090 * Retrieve information about all discovered children from the bus driver

#091 */

#092 IopInitDeviceTreeTraverseContext(

#093 &Context,

#094 DeviceNode,

#095 IopActionInterrogateDeviceStack,

#096 DeviceNode);

#097

#098 Status = IopTraverseDeviceTree(&Context);

#099 if (!NT_SUCCESS(Status))

#100 {

#101 DPRINT("IopTraverseDeviceTree() failed with status 0x%08lx/n",Status);

#102 return Status;

#103 }

#104

获取这个总线驱动程序上所有注册表里的信息。

#105 /*

#106 * Retrieve configuration from the registry for discovered children

#107 */

#108 IopInitDeviceTreeTraverseContext(

#109 &Context,

#110 DeviceNode,

#111 IopActionConfigureChildServices,

#112 DeviceNode);

#113

#114 Status = IopTraverseDeviceTree(&Context);

#115 if (!NT_SUCCESS(Status))

#116 {

#117 DPRINT("IopTraverseDeviceTree() failed with status 0x%08lx/n",Status);

#118 return Status;

#119 }

#120

初始化所有发现的PnP设备驱动程序。

#121 /*

#122 * Initialize services for discovered children.

#123 */

#124 Status = IopInitializePnpServices(DeviceNode);

#125 if (!NT_SUCCESS(Status))

#126 {

#127 DPRINT("IopInitializePnpServices() failed with status 0x%08lx/n",Status);

#128 return Status;

#129 }

#130

#131 DPRINT("IopEnumerateDevice() finished/n");

#132 return STATUS_SUCCESS;

#133 }

#134

（编辑：李大同）

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