incubator-nuttx/libs/libc/unistd/lib_alarm.c

/****************************************************************************
 * libs/libc/unistd/lib_alarm.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 <unistd.h>
#include <sys/time.h>

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

/****************************************************************************
 * Name: alarm
 *
 * Description:
 *   The alarm() function will arranges for a SIGALRM signal to be delivered
 *   to the calling process in seconds seconds.
 *
 *   Interactions between alarm() and any of setitimer() are unspecified.
 *
 * Input Parameters:
 *   seconds - The number of seconds to alarm
 *
 * Returned Value:
 *   alarm() returns the number of seconds remaining until any previously
 *   scheduled alarm was due to be delivered, or zero if there was no
 *   previously scheduled alarm.
 *
 * Assumptions:
 *
 ****************************************************************************/

unsigned int alarm(unsigned int seconds)
{
  struct itimerval value =
  {
    {0, 0},
    {0, 0}
  };

  struct itimerval ovalue =
  {
    {0, 0},
    {0, 0}
  };

  value.it_value.tv_sec = seconds;
  setitimer(ITIMER_REAL, &value, &ovalue);

  return ovalue.it_value.tv_sec;
}