scd_command_handler (ctrl_t ctrl, int fd)
{
  int rc;
  assuan_context_t ctx = NULL;
  int stopme;

  rc = assuan_new (&ctx);
  if (rc)
    {
      log_error ("failed to allocate assuan context: %s\n",
                 gpg_strerror (rc));
      scd_exit (2);
    }

  if (fd == -1)
    {
      assuan_fd_t filedes[2];

      filedes[0] = assuan_fdopen (0);
      filedes[1] = assuan_fdopen (1);
      rc = assuan_init_pipe_server (ctx, filedes);
    }
  else
    {
      rc = assuan_init_socket_server (ctx, INT2FD(fd),
				      ASSUAN_SOCKET_SERVER_ACCEPTED);
    }
  if (rc)
    {
      log_error ("failed to initialize the server: %s\n",
                 gpg_strerror(rc));
      scd_exit (2);
    }
  rc = register_commands (ctx);
  if (rc)
    {
      log_error ("failed to register commands with Assuan: %s\n",
                 gpg_strerror(rc));
      scd_exit (2);
    }
  assuan_set_pointer (ctx, ctrl);

  /* Allocate and initialize the server object.  Put it into the list
     of active sessions. */
  ctrl->server_local = xcalloc (1, sizeof *ctrl->server_local);
  ctrl->server_local->next_session = session_list;
  session_list = ctrl->server_local;
  ctrl->server_local->ctrl_backlink = ctrl;
  ctrl->server_local->assuan_ctx = ctx;
  ctrl->server_local->vreader_idx = -1;

  /* We open the reader right at startup so that the ticker is able to
     update the status file. */
  if (ctrl->server_local->vreader_idx == -1)
    {
      ctrl->server_local->vreader_idx = get_current_reader ();
    }

  /* Command processing loop. */
  for (;;)
    {
      rc = assuan_accept (ctx);
      if (rc == -1)
        {
          break;
        }
      else if (rc)
        {
          log_info ("Assuan accept problem: %s\n", gpg_strerror (rc));
          break;
        }

      rc = assuan_process (ctx);
      if (rc)
        {
          log_info ("Assuan processing failed: %s\n", gpg_strerror (rc));
          continue;
        }
    }

  /* Cleanup.  We don't send an explicit reset to the card.  */
  do_reset (ctrl, 0);

  /* Release the server object.  */
  if (session_list == ctrl->server_local)
    session_list = ctrl->server_local->next_session;
  else
    {
      struct server_local_s *sl;

      for (sl=session_list; sl->next_session; sl = sl->next_session)
        if (sl->next_session == ctrl->server_local)
          break;
      if (!sl->next_session)
          BUG ();
      sl->next_session = ctrl->server_local->next_session;
    }
  stopme = ctrl->server_local->stopme;
  xfree (ctrl->server_local);
  ctrl->server_local = NULL;

  /* Release the Assuan context.  */
  assuan_release (ctx);

  if (stopme)
    scd_exit (0);

  /* If there are no more sessions return true.  */
  return !session_list;
}