/*-
 * Copyright (c)2010 Takehiko NOZAKI,
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>


static int running;
static pthread_t thread;
static pthread_mutex_t mutex;
static pthread_cond_t cond;

static void *timer(void *);
static void init_timer(void);
static void start_timer(void);
static void stop_timer(void);

static void *
timer(void *arg)
{
	struct timeval now;
	struct timespec timeout;

	pthread_mutex_lock(&mutex);
	pthread_cond_signal(&cond);
	do {
		printf("zzz...\n");
		gettimeofday(&now, NULL);
		timeout.tv_sec  = now.tv_sec + 1;
		timeout.tv_nsec = now.tv_usec * 1000;
		pthread_cond_timedwait(&cond, &mutex, &timeout);
	} while (running);
	pthread_mutex_unlock(&mutex);
	return NULL;
}

static void
init_timer(void)
{
	running = 0;
	pthread_mutex_init(&mutex, NULL);
	pthread_cond_init(&cond, NULL);
}

static void
start_timer(void)
{
	pthread_mutex_lock(&mutex);
	running = 1;
	if (pthread_create(&thread, NULL, &timer, NULL) == 0)
		pthread_cond_wait(&cond, &mutex);
	pthread_mutex_unlock(&mutex);
}

void
stop_timer()
{
	pthread_mutex_lock(&mutex);
	running = 0;
	pthread_cond_signal(&cond);
	pthread_mutex_unlock(&mutex);
	pthread_join(thread, NULL);
}

int
main(void)
{
	int pid;

	pthread_atfork(&stop_timer, &start_timer, &init_timer);
	init_timer();
	start_timer();

	pid = fork();
	if (pid < 0)
		abort();
	if (pid == 0) {
		/* child process */
	} else {
		/* parent process */
	}
}