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.NET - Diving into System Programming - Part 2

, 9 Mar 2004 CPOL
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Device configuration using C# (Part 2) . How to enumerate devices.

Introduction

In Part 1, I have demonstrated how to enumerate device classes. Now let us see how to enumerate devices of the class.

Device enumeration

First of all, let us look again at the picture with Device Manager information. It is easy - Device Manager enumerate devices when we expand the tree for device class.

The idea of device enumeration is not difficult for understanding:

  • Get class Guid using device class name (SetupDiClassGuidsFromNameA function)
  • Get device info set for device class (SetupDiGetClassDevsA function)
  • Get device info data for every device (SetupDiGetClassDevsA function, second parameters for this function is sequential device index in the device class, so call this function in circle with device index = 0, 1, etc.).
  • Get device name from Registry via SetupDiGetDeviceRegistryPropertyA function.

Below you see code in C# that will enumerate devices for selected device class for PC.

using System;
using System.Text;
using System.Runtime.InteropServices;

namespace DevInfo
{

    class DeviceInfo
    {

        public const int DIGCF_PRESENT    = (0x00000002);
        public const int MAX_DEV_LEN = 1000;
        public const int SPDRP_FRIENDLYNAME = (0x0000000C);  
          // FriendlyName (R/W)
        public const int SPDRP_DEVICEDESC = (0x00000000);    
          // DeviceDesc (R/W)

        [StructLayout(LayoutKind.Sequential)]
            public class SP_DEVINFO_DATA
                {
                 public int cbSize;
                 public Guid  ClassGuid;
                 public int DevInst;    // DEVINST handle
                 public ulong Reserved;
                };

        [DllImport("setupapi.dll")]//
        public static extern Boolean
          SetupDiClassGuidsFromNameA(string ClassN, ref Guid guids, 
            UInt32 ClassNameSize, ref UInt32 ReqSize);

        [DllImport("setupapi.dll")]
        public static extern IntPtr                //result HDEVINFO
          SetupDiGetClassDevsA(ref Guid ClassGuid, UInt32 Enumerator,
            IntPtr     hwndParent,  UInt32 Flags);

        [DllImport("setupapi.dll")]
        public static extern Boolean
          SetupDiEnumDeviceInfo(IntPtr DeviceInfoSet, UInt32 MemberIndex,
            SP_DEVINFO_DATA     DeviceInfoData);

        [DllImport("setupapi.dll")]
        public static extern Boolean
          SetupDiDestroyDeviceInfoList(IntPtr DeviceInfoSet);

        [DllImport("setupapi.dll")]
        public static extern Boolean
          SetupDiGetDeviceRegistryPropertyA(IntPtr DeviceInfoSet,
          SP_DEVINFO_DATA     DeviceInfoData, UInt32 Property,
          UInt32   PropertyRegDataType, StringBuilder  PropertyBuffer,
          UInt32 PropertyBufferSize, IntPtr RequiredSize);



        public static int EnumerateDevices(UInt32 DeviceIndex, 
                string ClassName,
                StringBuilder DeviceName)
        {
         UInt32 RequiredSize = 0;
         Guid guid=Guid.Empty;
         Guid[] guids=new Guid[1];
         IntPtr NewDeviceInfoSet;
         SP_DEVINFO_DATA DeviceInfoData= new SP_DEVINFO_DATA();


         bool res=SetupDiClassGuidsFromNameA(ClassName,
                    ref guids[0],RequiredSize,
                    ref RequiredSize);

         if(RequiredSize==0)
               {
                //incorrect class name:
                DeviceName=new StringBuilder("");
                return -2;
               }

         if(!res)
          {
           guids=new Guid[RequiredSize];
           res=SetupDiClassGuidsFromNameA(ClassName,ref guids[0],RequiredSize,
                ref RequiredSize);

           if(!res || RequiredSize==0)
               {
           //incorrect class name:
                DeviceName=new StringBuilder("");
                return -2;
               }
          }

         //get device info set for our device class
         NewDeviceInfoSet=SetupDiGetClassDevsA(ref guids[0],0,IntPtr.Zero,
                     DIGCF_PRESENT);
         if( NewDeviceInfoSet.ToInt32() == -1 )
         if(!res)
               {
          //device information is unavailable:
                DeviceName=new StringBuilder("");
                return -3;
               }

            DeviceInfoData.cbSize = 28;
            //is devices exist for class
            DeviceInfoData.DevInst=0;
            DeviceInfoData.ClassGuid=System.Guid.Empty;
            DeviceInfoData.Reserved=0;

            res=SetupDiEnumDeviceInfo(NewDeviceInfoSet,
                   DeviceIndex,DeviceInfoData);
            if(!res) {
         //no such device:
                SetupDiDestroyDeviceInfoList(NewDeviceInfoSet);
                DeviceName=new StringBuilder("");
                return -1;
            }



        DeviceName.Capacity=MAX_DEV_LEN;
        if(!SetupDiGetDeviceRegistryPropertyA(NewDeviceInfoSet,
          DeviceInfoData,
        SPDRP_FRIENDLYNAME,0,DeviceName,MAX_DEV_LEN,IntPtr.Zero) )
        {
         res = SetupDiGetDeviceRegistryPropertyA(NewDeviceInfoSet,
          DeviceInfoData,SPDRP_DEVICEDESC,0,DeviceName,MAX_DEV_LEN, 
            IntPtr.Zero);
         if(!res){
         //incorrect device name:
                SetupDiDestroyDeviceInfoList(NewDeviceInfoSet);
                DeviceName=new StringBuilder("");
                return -4;
            }
        }
         return 0;
        }

        [STAThread]
        static void Main(string[] args)
        {
         StringBuilder devices=new StringBuilder("");
         UInt32 Index=0;
         int result=0;

         if(args.Length != 1)
          {
            Console.WriteLine("command line format:");
            Console.WriteLine("DevInfo <CLASSNAME>");
            return;
          }

         while(true)
          {
            result=EnumerateDevices(Index, args[0], devices);
            Index++;
            if(result == -2)
                    {
                     Console.WriteLine("Incorrect name of Class = {0}",
                       args[0]);
                     break;
                    }
            if(result == -1)break;
            if(result == 0)Console.WriteLine("Device{0} is {1}", 
              Index, devices);
        }

        }
    }
}

The command line for this console application - DevInfo classname

classname - the name of device class. You can use application from previous article to find correct device class name. After running application you can see devices for any device class on your PC.

Summary

Now we can join code from the first article and this article, add information about devices (for example, resources like IRQs, ports, etc) and put it in the Windows Forms application. But it is a subject for Part 3.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Vladimir Afanasyev
Web Developer
Ukraine Ukraine
I am C++ Builder developer.
I am interesting in WMI, Shell, some deep
COM interface. Beside these I am Brainbench
Win32 API Master.
Now I very like Microsoft .NET and C#. I made some firsts OPOS drivers for Ukrainian fiscal printers.

Comments and Discussions

 
GeneralI'm getting a negative return at line 108 PinmemberThe-Great-Kazoo14-Apr-11 6:37 
AnswerRe: I'm getting a negative return at line 108 PinmemberSelwyn Leeke14-Oct-12 10:01 
I had this same issue and solved it by setting the DeviceInfoData.cbSize to the correct value for the DeviceInfoData. To fix the issue, change line 101 onwards to this:
 
//is devices exist for class
DeviceInfoData.DevInst = 0;
DeviceInfoData.ClassGuid = System.Guid.Empty;
DeviceInfoData.Reserved = 0;
DeviceInfoData.cbSize = System.Runtime.InteropServices.Marshal.SizeOf(DeviceInfoData)
 
From http://msdn.microsoft.com/en-us/library/windows/hardware/ff551010(v=vs.85).aspx[^]):
 
DeviceInfoData [out]
A pointer to an SP_DEVINFO_DATA structure to receive information about an enumerated device information element. The caller must set DeviceInfoData.cbSize to sizeof(SP_DEVINFO_DATA).
 

Hopefully this might save someone a little time...
QuestionCommercial License PinmemberZemien23-Jun-08 20:37 
AnswerRe: Commercial License PinmemberVladimir Afanasyev30-Jan-09 1:45 
QuestionList devices by connection PinmemberRaul Bachmann6-Jun-07 23:23 
AnswerRe: List devices by connection PinmemberVladimir Afanasyev3-Oct-07 23:21 
QuestionEnumeration in .NET 20 ???? Pinmembermandrei130-Mar-07 23:17 
AnswerRe: Enumeration in .NET 20 ???? PinmemberVladimir Afanasyev3-Oct-07 23:26 
GeneralAuthorization request PinmemberFabio Zanetta19-Jan-07 3:34 
GeneralRe: Authorization request PinmemberVladimir Afanasyev23-Feb-07 3:51 
QuestionVC# to VC++ Help Pinmemberchanbx5-Nov-06 14:50 
QuestionVC# to VC++ Pinmemberchanbx5-Nov-06 14:50 
QuestionVC# to VC++ Help Pinmemberchanbx5-Nov-06 14:49 
Questiondevice state Pinmembergumigyuri7-Mar-06 9:51 
AnswerRe: device state PinmemberVladimir Afanasyev8-Mar-06 21:29 
QuestionRe: device state Pinmembergumigyuri9-Mar-06 8:09 
AnswerRe: device state PinmemberVladimir Afanasyev9-Mar-06 20:59 
QuestionListing device driver files with WMI Pinmembermohcin26-Jan-06 2:17 
AnswerRe: Listing device driver files with WMI PinmemberVladimir Afanasyev26-Jan-06 3:30 
General'{' missing (possibly '}' too) Pinmemberhobyrne5-Dec-05 4:12 
GeneralRe: '{' missing (possibly '}' too) PinmemberVladimir Afanasyev5-Dec-05 6:27 
GeneralRe: '{' missing (possibly '}' too) PinmemberVladimir Afanasyev5-Dec-05 6:32 
GeneralIssues with WIN32 calls PinmemberRLyon9-May-04 23:43 
GeneralRe: Issues with WIN32 calls PinmemberVladimir Afanasyev10-May-04 22:29 
QuestionWhat about WMI? Pinmemberzucchini11-Mar-04 4:26 
AnswerRe: What about WMI? PinmemberVladimir Afanasyev11-Mar-04 6:00 

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