Function sidechannel_thread

backend/usb-libusb.c:1880–2017

 */

static void*
sidechannel_thread(void *reference)
{
  cups_sc_command_t	command;	/* Request command */
  cups_sc_status_t	status;		/* Request/response status */
  char			data[2048];	/* Request/response data */
  int			datalen;	/* Request/response data size */


  (void)reference;

  do
  {
    datalen = sizeof(data);

    if (cupsSideChannelRead(&command, &status, data, &datalen, 1.0))
    {
      if (status == CUPS_SC_STATUS_TIMEOUT)
	continue;
      else
	break;
    }

    switch (command)
    {
      case CUPS_SC_CMD_SOFT_RESET:	/* Do a soft reset */
	  fputs("DEBUG: CUPS_SC_CMD_SOFT_RESET received from driver...\n",
		stderr);

	  soft_reset();
	  cupsSideChannelWrite(command, CUPS_SC_STATUS_OK, NULL, 0, 1.0);
	  fputs("DEBUG: Returning status CUPS_STATUS_OK with no bytes...\n",
		stderr);
	  break;

      case CUPS_SC_CMD_DRAIN_OUTPUT:	/* Drain all pending output */
	  fputs("DEBUG: CUPS_SC_CMD_DRAIN_OUTPUT received from driver...\n",
		stderr);

	  g.drain_output = 1;
	  pthread_mutex_lock(&g.readwrite_lock_mutex);
	  if (!g.readwrite_lock)
	  {
	   /*
	    * If main thread is inside select(), assume it has infinite
	    * timeout and needs to be woken up.
	    */
	    if (write(g.wakeup_pipe[1], &data, 1) < 0)
	      fputs("DEBUG: Error writing to wakeup pipe\n", stderr);
	  }
	  pthread_mutex_unlock(&g.readwrite_lock_mutex);
	  break;

      case CUPS_SC_CMD_GET_BIDI:	/* Is the connection bidirectional? */
	  fputs("DEBUG: CUPS_SC_CMD_GET_BIDI received from driver...\n",
		stderr);

	  data[0] = (g.printer->protocol >= 2 ? 1 : 0);