Installing Sitecore update package from code

gistfile1.cs

      var files = Directory.GetFiles(Server.MapPath("/sitecore/admin/Packages"), "*.update", SearchOption.AllDirectories);
      Sitecore.Context.SetActiveSite("shell");
      using (new SecurityDisabler())
      {
        using (new ProxyDisabler())
        {
          using (new SyncOperationContext())
          {
            foreach (var file in files)
            {
              Install(file);
              Response.Write("Installed Package: " + file + "<br>");
            }
          }
        }
      }

    protected static string Install(string package)
    {
      var log = LogManager.GetLogger("LogFileAppender");
      string result;
      using (new ShutdownGuard())
      {
        var installationInfo = new PackageInstallationInfo
        {
          Action = UpgradeAction.Upgrade,
          Mode = InstallMode.Install,
          Path = package
        };
        string text = null;
        List<ContingencyEntry> entries = null;
        try
        {
          entries = UpdateHelper.Install(installationInfo, log, out text);
        }
        catch (PostStepInstallerException ex)
        {
          entries = ex.Entries;
          text = ex.HistoryPath;
          throw;
        }
        finally
        {
          UpdateHelper.SaveInstallationMessages(entries, text);
        }

        result = text;
      }

      return result;
    }