nsh_altconsole.c

/****************************************************************************
 * apps/nshlib/nsh_altconsole.c
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <assert.h>
#include <debug.h>
#include <string.h>

#include "nsh.h"
#include "nsh_console.h"

#if defined(CONFIG_NSH_ALTCONDEV) && !defined(HAVE_USB_CONSOLE)

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: nsh_clone_console
 *
 * Description:
 *   Clone stdout and stderr to alternatives devices
 *
 ****************************************************************************/

static int nsh_clone_console(FAR struct console_stdio_s *pstate)
{
  int fd;

  /* Open the alternative standard error device */

  fd = open(CONFIG_NSH_ALTSTDERR, O_WRONLY);
  if (fd < 0)
    {
      return -ENODEV;
    }

  /* Associate the new opened file descriptor to stderr */

  dup2(fd, 2);

  /* Close the console device that we just opened */

  if (fd != 0)
    {
      close(fd);
    }

  /* Open the alternative standard output device */

  fd = open(CONFIG_NSH_ALTSTDOUT, O_WRONLY);
  if (fd < 0)
    {
      return -ENODEV;
    }

  /* Associate the new opened file descriptor to stdout */

  dup2(fd, 1);

  /* Close the console device that we just opened */

  if (fd != 0)
    {
      close(fd);
    }

  /* Setup the stderr */

  ERRFD(pstate) = 2;

  /* Setup the stdout */

  OUTFD(pstate) = 1;

  /* Setup stdin */

  INFD(pstate) = 0;

  return OK;
}

/****************************************************************************
 * Name: nsh_wait_inputdev
 *
 * Description:
 *   Wait for the input device to be ready
 *
 ****************************************************************************/

static int nsh_wait_inputdev(FAR struct console_stdio_s *pstate,
                             FAR const char *msg)
{
  int fd;

  /* Don't start the NSH console until the input device is ready.  Chances
   * are, we get here with no functional stdin. For example a USB keyboard
   * device will not be available until the device is connected to the host
   * and enumerated.
   */

  /* Open the USB keyboard device for read-only access */

  do
    {
      /* Try to open the alternative stdin device */

      fd = open(CONFIG_NSH_ALTSTDIN, O_RDWR);
      if (fd < 0)
        {
#ifdef CONFIG_DEBUG_FEATURES
          int errcode = errno;

          /* ENOENT means that the USB device is not yet connected and,
           * hence, has no entry under /dev.  If the USB driver still
           * exists under /dev (because other threads still have the driver
           * open), then we might also get ENODEV.  Anything else would
           * be really bad.
           */

          DEBUGASSERT(errcode == ENOENT || errcode == ENODEV);
#endif

          /* Let the user know that we are waiting */

          if (msg)
            {
              /* Show the waiting message only one time after the failure
               * to open the keyboard device.
               */

              write(STDOUT_FILENO, msg, strlen(msg));
              msg = NULL;
            }

          /* Sleep a bit and try again */

          sleep(2);
        }
    }
  while (fd < 0);

  /* Okay.. we have successfully opened the input device.  Did
   * we just re-open fd 0?
   */

  if (fd != 0)
    {
      /* No..  Dup the fd to create standard fd 0. stdin should not know. */

      dup2(fd, 0);

      /* Setup the input console */

      pstate->cn_confd = 0;

      /* Close the input device that we just opened */

      close(fd);
    }

  return OK;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: nsh_consolemain (USB console version)
 *
 * Description:
 *   This interfaces maybe to called or started with task_start to start a
 *   single an NSH instance that operates on stdin and stdout.  This
 *   function does not return.
 *
 *   This function handles generic /dev/console character devices for output
 *   but uses a special USB keyboard device for input.  The USB keyboard
 *   requires some special operations to handle the cases where the session
 *   input is lost when the USB keyboard is unplugged and restarted when the
 *   USB keyboard is plugged in again.
 *
 * Input Parameters:
 *   Standard task start-up arguments.  These are not used.  argc may be
 *   zero and argv may be NULL.
 *
 * Returned Values:
 *   This function does not return nor does it ever exit (unless the user
 *   executes the NSH exit command).
 *
 ****************************************************************************/

int nsh_consolemain(int argc, FAR char *argv[])
{
  FAR struct console_stdio_s *pstate = nsh_newconsole(true);
  FAR const char *msg;
  int ret;

  DEBUGASSERT(pstate);

  /* First map stderr and stdout to alternative devices */

  ret = nsh_clone_console(pstate);
  if (ret < 0)
    {
      return ret;
    }

  /* Now loop, executing creating a session for each USB connection */

  msg = "Waiting for a keyboard...\n";
  for (; ; )
    {
      /* Wait for the USB to be connected to the host and switch
       * standard I/O to the USB serial device.
       */

      ret = nsh_wait_inputdev(pstate, msg);

      DEBUGASSERT(ret == OK);
      UNUSED(ret);

      /* Execute the session */

      nsh_session(pstate, NSH_LOGIN_LOCAL, argc, argv);

      /* We lost the connection.  Wait for the keyboard to
       * be re-connected.
       */

      msg = "Please re-connect the keyboard...\n";
    }
}

#endif /* HAVE_USB_KEYBOARD && !HAVE_USB_CONSOLE */