Manipulate app compatibility flags

gistfile1.cs

using System;
using System.Configuration.Abstractions;
using System.IO;
using log4net;
using Microsoft.Win32;

namespace Doco.Conversion
{
    public class BackwardsCompatabilityPatchForWindowsServer : IBackwardsCompatabilityPatchForWindowsServer
    {
        private static readonly ILog Log = LogManager.GetLogger(typeof(BackwardsCompatabilityPatchForWindowsServer));

        private readonly IConfigurationManager _config;
        private readonly Paths _paths;

        public BackwardsCompatabilityPatchForWindowsServer(IConfigurationManager config, Paths paths)
        {
            _config = config;
            _paths = paths;
        }

        public bool PatchIsRequired()
        {
            return _config.AppSettings.AppSetting("Wordconv.EmulateWindowsXp", () => true);
        }

        public void ForceApplicationCompatabilityMode(string filePath, bool forAllSystemUsers = false)
        {
            var wordConvPath = Path.Combine(_paths.CurrentApplicationPath, filePath);
            
            Log.Debug("Backwards compatibility patch is required, setting registry key...");
            Log.Debug("Codebase: " + _paths.CurrentApplicationPath);
            Log.Debug("WordConv.exe path: " + wordConvPath);

            var rootKey = forAllSystemUsers ? Registry.LocalMachine : Registry.CurrentUser;
            using (var appCompatFlags = OpenOrCreate(rootKey, "Software\\Microsoft\\Windows NT\\CurrentVersion\\AppCompatFlags"))
            using (var layers = OpenOrCreate(appCompatFlags, "Layers"))
            {
                layers.SetValue(wordConvPath, "~ WINXPSP3", RegistryValueKind.String);

                Log.Debug("Set Software\\Microsoft\\Windows NT\\CurrentVersion\\AppCompatFlags\\Layers\\" + wordConvPath + " to ~ WINXPSP3");
            }
        }
        
        private static RegistryKey OpenOrCreate(RegistryKey parent, string path)
        {
            var key = parent.OpenSubKey(path, true) ?? parent.CreateSubKey(path);
            if (key == null)
            {
                throw NotSupported();
            }

            return key;
        }

        private static NotSupportedException NotSupported()
        {
            return new NotSupportedException("Attempted to set compatability mode for but registry unavailable on platform.");
        }
    }
}