Microsoft.Tools.WindowsInstaller.RegistryView.MapKeyPath C# (CSharp) Method

        internal string MapKeyPath(string keyPath)
        {
            // Callers should not have to handle exceptions for control flow.
            if (string.IsNullOrEmpty(keyPath) || 4 > keyPath.Length)
            {
                return null;
            }

            var root = keyPath.Substring(0, 2);
            var path = keyPath.Substring(3);
            var is64Bit = '2' == root[0];
            var hive = root[1];

            if (!this.Is64Bit)
            {
                // Simply return 32-bit paths as-is and null for 64-bit paths.
                if (!is64Bit)
                {
                    root = this.MapRoot(path, false, hive);
                    if (null != root)
                    {
                        return root + path;
                    }
                }
            }
            else
            {
                // Return 64-bit paths as-is but map 32-bit paths to WOW64 node only if redirected.
                if (is64Bit || !tree.Under(keyPath))
                {
                    root = this.MapRoot(path, true, hive);
                }
                else
                {
                    root = this.MapRoot(path, false, hive);

                    if ('3' == hive)
                    {
                        // Strip user SID from registry key.
                        var i = path.IndexOf(Path.DirectorySeparatorChar, 1);
                        path = path.Substring(i);
                    }

                    // The redirected root will be replaced.
                    if (0 == path.IndexOf(SOFTWARE, StringComparison.OrdinalIgnoreCase))
                    {
                        path = path.Substring(SOFTWARE.Length);
                    }

                    // Make sure the path doesn't reference the WOW64 node twice.
                    // Windows Installer seems to handle this correctly during installation.
                    if (0 == path.IndexOf(WOW64, StringComparison.OrdinalIgnoreCase))
                    {
                        path = path.Substring(WOW64.Length);
                    }
                }

                if (null != root)
                {
                    return root + path;
                }
            }

            return null;
        }

        public void MapKeyPathsIn64BitProcess()
        {
            var view = new RegistryView(true);
            Assert.IsTrue(view.Is64Bit);

            // Invalid paths.
            Assert.IsNull(view.MapKeyPath(null));
            Assert.IsNull(view.MapKeyPath("TRE"));
            Assert.IsNull(view.MapKeyPath("TEST"));

            // 32-bit paths.
            Assert.AreEqual(@"HKEY_CLASSES_ROOT\Wow6432Node\CLSID\", view.MapKeyPath(@"00:\CLSID\"), true);
            Assert.AreEqual(@"HKEY_CURRENT_USER\Software\Wow6432Node\Classes\CLSID\", view.MapKeyPath(@"01:\Software\Classes\CLSID\"), true);
            Assert.AreEqual(@"HKEY_LOCAL_MACHINE\Software\Wow6432Node\TEST\", view.MapKeyPath(@"02:\Software\TEST\"), true);
            Assert.AreEqual(@"HKEY_LOCAL_MACHINE\Software\Wow6432Node\Microsoft\", view.MapKeyPath(@"02:\Software\Microsoft\"), true);
            Assert.AreEqual(@"HKEY_LOCAL_MACHINE\Software\Microsoft\EventSystem\", view.MapKeyPath(@"02:\Software\Microsoft\EventSystem\"), true);
            Assert.AreEqual(@"HKEY_LOCAL_MACHINE\Software\Wow6432Node\TEST\", view.MapKeyPath(@"02:\Software\Wow6432Node\TEST\"), true);
            Assert.AreEqual(@"HKEY_USERS\S-1-5-18\Software\Wow6432Node\Classes\CLSID\", view.MapKeyPath(@"03:\S-1-5-18\Software\Classes\CLSID\"), true);

            // 64-bit paths.
            Assert.AreEqual(@"HKEY_CLASSES_ROOT\CLSID\", view.MapKeyPath(@"20:\CLSID\"), true);
            Assert.AreEqual(@"HKEY_CURRENT_USER\Software\Classes\CLSID\", view.MapKeyPath(@"21:\Software\Classes\CLSID\"), true);
            Assert.AreEqual(@"HKEY_LOCAL_MACHINE\Software\TEST\", view.MapKeyPath(@"22:\Software\TEST\"), true);
            Assert.AreEqual(@"HKEY_LOCAL_MACHINE\Software\Microsoft\", view.MapKeyPath(@"22:\Software\Microsoft\"), true);
            Assert.AreEqual(@"HKEY_LOCAL_MACHINE\Software\Microsoft\EventSystem\", view.MapKeyPath(@"22:\Software\Microsoft\EventSystem\"), true);
            Assert.AreEqual(@"HKEY_LOCAL_MACHINE\Software\Wow6432Node\TEST\", view.MapKeyPath(@"22:\Software\Wow6432Node\TEST\"), true);
            Assert.AreEqual(@"HKEY_USERS\S-1-5-18\Software\Classes\CLSID\", view.MapKeyPath(@"23:\S-1-5-18\Software\Classes\CLSID\"), true);
        }