c# 无法从 Windows 服务达到注册表值

Question

I have a problem to read value from registry on my service application. I'm new on this service application part of .NET but I was using this code on my form application. There must be something different because it's not working in Service application. Anyway this is my code that I was reading normally:

 public string GetValue(string Name, string Path = "")
    {
        try
        {
            RegKey = Registry.CurrentUser.OpenSubKey(DefaultFolder + @Path + @"\");
            if (RegKey != null)
            {
                object TempObj = RegKey.GetValue(Name);
                if (TempObj == null) return "-13003";
                Type T = TempObj.GetType();
                if (T.IsArray)
                {
                    string[] TempArray = (string[])TempObj;
                    string output = "";
                    for (int i = 0; i < TempArray.Length; i++)
                    {
                        output += TempArray[i].Substring(0, TempArray[i].Length - 1);
                        if (i != TempArray.Length) output += "\n";
                    }

                    return output;
                }
                else
                {
                    return RegKey.GetValue(Name).ToString();
                }
            }
            else
            {
                return "-13001";
            }
        }
        catch (Exception ex)
        {
            return "-13002";
        }
    }

Once I change my program.cs to call my class like console application it's working again then I put this back:

ServiceBase[] ServicesToRun;
            ServicesToRun = new ServiceBase[]
            {

                new TestAppService()
            };
            ServiceBase.Run(ServicesToRun);

and it's not working.

So far I know that RegKey variable remains null after

RegKey = Registry.CurrentUser.OpenSubKey(DefaultFolder + @Path + @"\");

this line but I don't know why.

I've googled a bit and found something like this

RegistryKey rb = RegistryKey.OpenBaseKey(RegistryHive.CurrentUser, RegistryView.Default);
RegKey = rb.OpenSubKey(DefaultFolder + @"\" + Name, false);

But the result is same, my RegKey variable is still null.

All I want is reading a value under a path like this: Computer\HKEY_CURRENT_USER\Software\ServiceReadLocation\Values

Answer 1

The code Registry.CurrentUser and RegistryHive.CurrentUser when executed in a Windows Service LocalSystem won't work as you are expecting and is most likely the cause of null you are encountering.

MSDN:

The registry key HKEY_CURRENT_USER is associated with the default user, not the current user . To access another user's profile, impersonate the user, then access HKEY_CURRENT_USER

So I can see too options.

1. Arguably the easiest is to run the service as that user
2. Run the service as LocalSystem and impersonate the user and then access the registry when needed. After reading, you can stop impersonating.