reactos操作系统实现(119)

前介绍了初始化函数ScsiClassInitialize，那么在这个函数里使用下面的语句来查找SCSI的磁盘，如下：

if (InitializationData->ClassFindDevices(DriverObject,Argument2,InitializationData,portDeviceObject,portNumber))

其实这里的函数InitializationData->ClassFindDevices就是函数FindScsiDisks的调用，要了解这个函数的作用，一定要仔细地分析它的代码，才可以理解它，看看它是怎么样实现查找SCSI硬盘的，实现代码如下：

#001 BOOLEAN

#002 NTAPI

#003 FindScsiDisks(

#004 IN PDRIVER_OBJECT DriverObject,

#005 IN PUNICODE_STRING RegistryPath,

#006 IN PCLASS_INIT_DATA InitializationData,

#007 IN PDEVICE_OBJECT PortDeviceObject,

#008 IN ULONG PortNumber

#009 )

#010

#011 /*++

#012

#013 Routine Description:

#014

#015 This routine gets a port drivers capabilities,obtains the

#016 inquiry data,searches the SCSI bus for the port driver and creates

#017 the device objects for the disks found.

#018

#019 Arguments:

#020

#021 DriverObject - Pointer to driver object created by system.

#022

#023 PortDeviceObject - Device object use to send requests to port driver.

#024

#025 PortNumber - Number for port driver. Used to pass on to

#026 CreateDiskDeviceObjects() and create device objects.

#027

#028 Return Value:

#029

#030 True is returned if one disk was found and successfully created.

#031

#032 --*/

#033

#034 {

#035 PIO_SCSI_CAPABILITIES portCapabilities;

#036 PULONG diskCount;

#037 PCONFIGURATION_INFORMATION configurationInformation;

#038 PCHAR buffer;

#039 PSCSI_INQUIRY_DATA lunInfo;

#040 PSCSI_ADAPTER_BUS_INFO adapterInfo;

#041 PINQUIRYDATA inquiryData;

#042 ULONG scsiBus;

#043 ULONG adapterDisk;

#044 NTSTATUS status;

#045 BOOLEAN foundOne = FALSE;

#046

#047 PAGED_CODE();

#048

#049 //

#050 // Call port driver to get adapter capabilities.

#051 //

#052

获取底层端口驱动程序的属性。

#053 status = ScsiClassGetCapabilities(PortDeviceObject,&portCapabilities);

#054

#055 if (!NT_SUCCESS(status)) {

#056 DebugPrint((1,"FindScsiDevices: ScsiClassGetCapabilities failed/n"));

#057 return(FALSE);

#058 }

#059

#060 //

#061 // Call port driver to get inquiry information to find disks.

#062 //

#063

获取端口驱动程序的配置信息。

#064 status = ScsiClassGetInquiryData(PortDeviceObject,(PSCSI_ADAPTER_BUS_INFO *) &buffer);

#065

#066 if (!NT_SUCCESS(status)) {

#067 DebugPrint((1,"FindScsiDevices: ScsiClassGetInquiryData failed/n"));

#068 return(FALSE);

#069 }

#070

#071 //

#072 // Do a quick scan of the devices on this adapter to determine how many

#073 // disks are on this adapter. This is used to determine the number of

#074 // SRB zone elements to allocate.

#075 //

#076

#077 adapterDisk = 0;

#078 adapterInfo = (PVOID) buffer;

#079

从端口驱动程序里返回的信息分析有几个磁盘。

#080 adapterDisk = ScsiClassFindUnclaimedDevices(InitializationData,adapterInfo);

#081

#082 //

#083 // Allocate a zone of SRB for disks on this adapter.

#084 //

#085

如果没有找到磁盘就返回。

#086 if (adapterDisk == 0) {

#087

#088 //

#089 // No free disks were found.

#090 //

#091

#092 return(FALSE);

#093 }

#094

#095 //

#096 // Get the number of disks already initialized.

#097 //

#098

获取配置信息。

#099 configurationInformation = IoGetConfigurationInformation();

配置信息里的磁盘个数。

#100 diskCount = &configurationInformation->DiskCount;

#101

#102 //

#103 // For each SCSI bus this adapter supports ...

#104 //

#105

找适配器里所有总线磁盘。

#106 for (scsiBus=0; scsiBus < (ULONG)adapterInfo->NumberOfBuses; scsiBus++) {

#107

#108 //

#109 // Get the SCSI bus scan data for this bus.

#110 //

#111

#112 lunInfo = (PVOID) (buffer + adapterInfo->BusData[scsiBus].InquiryDataOffset);

#113

#114 //

#115 // Search list for unclaimed disk devices.

#116 //

#117

搜索一个磁盘总线上所有设备。

#118 while (adapterInfo->BusData[scsiBus].InquiryDataOffset) {

#119

#120 inquiryData = (PVOID)lunInfo->InquiryData;

#121

#122 if (((inquiryData->DeviceType == DIRECT_ACCESS_DEVICE) ||

#123 (inquiryData->DeviceType == OPTICAL_DEVICE)) &&

#124 inquiryData->DeviceTypeQualifier == 0 &&

#125 (!lunInfo->DeviceClaimed)) {

#126

#127 DebugPrint((1,

#128 "FindScsiDevices: Vendor string is %.24s/n",

#129 inquiryData->VendorId));

#130

#131 //

#132 // Create device objects for disk

#133 //

#134

每找到一个磁盘设备，就创建一个磁盘对象。

#135 status = CreateDiskDeviceObject(DriverObject,

#136 RegistryPath,

#137 PortDeviceObject,

#138 PortNumber,

#139 diskCount,

#140 portCapabilities,

#141 lunInfo,

#142 InitializationData);

#143

#144 if (NT_SUCCESS(status)) {

#145

#146 //

#147 // Increment system disk device count.

#148 //

#149

增加系统磁盘设备个数。

#150 (*diskCount)++;

#151 foundOne = TRUE;

#152

#153 }

#154 }

#155

#156 //

#157 // Get next LunInfo.

#158 //

#159

获取一下磁盘设备。

#160 if (lunInfo->NextInquiryDataOffset == 0) {

#161 break;

#162 }

#163

#164 lunInfo = (PVOID) (buffer + lunInfo->NextInquiryDataOffset);

#165

#166 }

#167 }

#168

#169 //

#170 // Buffer is allocated by ScsiClassGetInquiryData and must be free returning.

#171 //

#172

#173 ExFreePool(buffer);

#174

#175 return(foundOne);

#176

#177} // end FindScsiDisks()

（编辑：李大同）

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