C# UnauthorizedAccessException on RegistryKey CreateSubKey

Question

I get an UnauthorizedAccessException any time I try to call CreateSubKey in my code.

const string regKeyPath = @"Software\Apps\jp2code.net\FTMaint";

private void BuildRegistry() {
  string[] split = regKeyPath.Split('\\');
  keyMaker(Registry.LocalMachine, split, 0);
}

private static void keyMaker(RegistryKey key, string[] path, int index) {
  string keyValue = path[index++];
  RegistryKey key2;
  if (!String.IsNullOrEmpty(keyValue)) {
    string subKey = null;
    string[] subKeyNames = key.GetSubKeyNames();
    foreach (var item in subKeyNames) {
      if (keyValue == item) {
        subKey = item;
      }
    }
    if (String.IsNullOrEmpty(subKey)) {
      key2 = key.CreateSubKey(keyValue);
    } else {
      key2 = key.OpenSubKey(subKey);
    }
    //key2 = key.OpenSubKey(keyValue, String.IsNullOrEmpty(subKey));
  } else {
    key2 = key;
  }
  if (index < path.Length) {
    try {
      keyMaker(key2, path, index + 1);
    } finally {
      key2.Close();
    }
  }
}

I found a post where someone was having a similar problem >> HERE << on MSDN Social, but the solution there (to use the overloaded OpenSubKey method) only returned a NULL RegistryKey for me.

This is for a Windows Mobile 5 device emulator.

Can anyone see what I'm doing wrong?

The error is thrown the first time the code reaches a key that does not exist and tries to create it.

Thanks!

Answer 1

All three of these work fine for me on the WinMo 6 Emulator.

Create a root key:

using (var swKey = Registry.LocalMachine.CreateSubKey("foo"))
{
    using (var subkey = swKey.CreateSubKey("OpenNETCF"))
    {
    }
}

Create a subkey via path

using (var swKey = Registry.LocalMachine.CreateSubKey("software\\foo"))
{
    using (var subkey = swKey.CreateSubKey("OpenNETCF"))
    {
    }
}

Create a subkey directly:

using (var swKey = Registry.LocalMachine.OpenSubKey("software", true))
{
    using (var subkey = swKey.CreateSubKey("OpenNETCF"))
    {
    }
}

Answer 2

I found when creating a RegistryKey instance via Registry.CurrentUser.OpenSubKey that it was read-only. So I could call GetValue but when I came to try to call SetValue I got the UnauthorizedAccessException . The trick is to call Registry.CurrentUser.OpenSubKey setting the writable parameter to true, then calls to SetValue were successful.

So instead of:

key2 = key.OpenSubKey(subKey);

use:

key2 = key.OpenSubKey(subKey, writable: true);

the same probably applies to the call to CreateSubKey .

The original question was asked in the context of Windows Mobile. I've not used Windows Mobile (not sure anyone does these days), but I expect the writeable parameter will be there.

Answer 3

To create a key in LocalMachine during installation do something like this:

[RunInstaller(true)]
public class InstallRegistry : Installer
{
    public override void Install(System.Collections.IDictionary stateSaver)
    {
        base.Install(stateSaver);

        using (RegistryKey key = Registry.LocalMachine.CreateSubKey(@"software\..."))
        {
            RegistrySecurity rs = new RegistrySecurity();
            rs.AddAccessRule(new RegistryAccessRule(new SecurityIdentifier(WellKnownSidType.BuiltinUsersSid, null), RegistryRights.FullControl, InheritanceFlags.None, PropagationFlags.NoPropagateInherit, AccessControlType.Allow));
            key.SetAccessControl(rs);
        }
    }
    public override void Rollback(System.Collections.IDictionary savedState)
    {
        base.Rollback(savedState);
    }
}

Hope this will help you.