nuttx/libs/libc/unistd/lib_alarm.c

84 lines
3.0 KiB
C

/****************************************************************************
* lib/lib_alarm.c
*
* Copyright (C) 2019 Xiaomi Inc. All rights reserved.
*
* 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 <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 =
{
};
struct itimerval ovalue =
{
};
value.it_value.tv_sec = seconds;
setitimer(ITIMER_REAL, &value, &ovalue);
return ovalue.it_value.tv_sec;
}