text: /****************************************************************************
   * libs/libc/termios/lib_tcsetattr.c
   *
   * 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 <sys/ioctl.h>
  
  #include <termios.h>
  #include <errno.h>
  
  #include <nuttx/serial/tioctl.h>
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: tcsetattr
   *
   * Description:
   *   The tcsetattr() function sets the parameters associated with the
   *   terminal referred to by the open file descriptor 'fd' from the termios
   *   structure referenced by 'termiop' as follows:
   *
   *   If 'options' is TCSANOW, the change will occur immediately.
   *
   *   If 'options' is TCSADRAIN, the change will occur after all output
   *   written to 'fd' is transmitted. This function should be used when
   *   changing parameters that affect output.
   *
   *   If 'options' is TCSAFLUSH, the change will occur after all
   *   output written to 'fd' is transmitted, and all input so far received but
   *   not read will be discarded before the change is made.
   *
   *   The tcsetattr() function will return successfully if it was able to
   *   perform any of the requested actions, even if some of the requested
   *   actions could not be performed. It will set all the attributes that
   *   implementation supports as requested and leave all the attributes not
   *   supported by the implementation unchanged. If no part of the request
   *   can be honoured, it will return -1 and set errno to EINVAL.
   *
   *   The effect of tcsetattr() is undefined if the value of the termios
   *   structure pointed to by 'termiop' was not derived from the result of
   *   a call to tcgetattr() on 'fd'; an application should modify only fields
   *   and flags defined by this specification between the call to tcgetattr()
   *   and tcsetattr(), leaving all other fields and flags unmodified.
   *
   * Returned Value:
   *
   *   Upon successful completion, 0 is returned. Otherwise, -1 is returned
   *   and errno is set to indicate the error.  The following errors may be
   *   reported:
   *
   *   - EBADF: The 'fd' argument is not a valid file descriptor.
   *   - EINTR:  A signal interrupted tcsetattr().
   *   - EINVAL: The 'options' argument is not a supported value, or
   *     an attempt was made to change an attribute represented in the
   *     termios structure to an unsupported value.
   *   - ENOTTY: The file associated with 'fd' is not a terminal.
   *
   ****************************************************************************/
  
  int tcsetattr(int fd, int options, FAR const struct termios *termiosp)
  {
    if (options != TCSANOW)
      {
        tcdrain(fd);
      }
  
    if (options == TCSAFLUSH)
      {
        tcflush(fd, TCIFLUSH);
      }
  
    return ioctl(fd, TCSETS, (unsigned long)termiosp);
  }
  