nuttx/drivers/serial/tcdrain.c

/****************************************************************************
 * drivers/serial/tcdrain.c
 *
 *   Copyright (C) 2017 Gregory Nutt. All rights reserved.
 *   Copyright (C) 2017 Sebastien Lorquet. All rights reserved.
 *   Author: Sebastien Lorquet <sebastien@lorquet.fr>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

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

#include <nuttx/config.h>

#include <sys/ioctl.h>

#include <termios.h>
#include <errno.h>

#include <nuttx/cancelpt.h>
#include <nuttx/serial/tioctl.h>

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

/****************************************************************************
 * Name: tcdrain
 *
 * Description:
 *   Function for draining the output buffer of a terminal/serial device
 *
 * Input Parameters:
 *   fd  - The 'fd' argument is an open file descriptor associated with a terminal.
 *
 * Returned Value:
 *   Upon successful completion, 0 is returned. Otherwise, -1 is returned and
 *   errno is set to indicate the error.
 *
 ****************************************************************************/

int tcdrain(int fd)
{
  int ret;

  /* tcdrain is a cancellation point */

  if (enter_cancellation_point())
    {
#ifdef CONFIG_CANCELLATION_POINTS
      /* If there is a pending cancellation, then do not perform
       * the wait.  Exit now with ECANCELED.
       */

      set_errno(ECANCELED);
      leave_cancellation_point();
      return ERROR;
#endif
    }

  /* Perform the TCDRM IOCTL command.  It is safe to use the file descriptor
   * in this context because we are executing on the calling application's
   * thread.
   *
   * NOTE: ioctl() will set the errno variable and return ERROR is any error
   * occurs.
   */

  ret = ioctl(fd, TCDRN, (unsigned long)0);

  leave_cancellation_point();
  return ret;
}