/* Built-in watchdog daemon
 *
 * Copyright (c) 2016  Joachim Nilsson <troglobit@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <signal.h>
#include <sys/ioctl.h>
#include <linux/watchdog.h>

#include "finit.h"
#include "log.h"
#include "watchdog.h"

int running  = 1;
int handover = 0;

static void sighandler(int signo)
{
	if (signo == SIGTERM)
		handover = 1;
	running = 0;
}

static int init(char *progname, char *devnode, int timeout)
{
	int fd;

	sprintf(progname, "@finit-watchdog");
	signal(SIGTERM, sighandler);
	signal(SIGPWR,  sighandler);

	fd = open(devnode, O_WRONLY);
	if (fd == -1)
		return -1;

	ioctl(fd, WDIOC_SETTIMEOUT, &timeout);

	return fd;
}

static int loop(int fd, int period)
{
	int dummy = 0;

	while (running) {
		ioctl(fd, WDIOC_KEEPALIVE, &dummy);
		sleep(period);
	}

	if (handover) {
		ioctl(fd, WDIOC_KEEPALIVE, &dummy);
		return !write(fd, "V", 1);
	}

	return 0;
}

int watchdog(char *progname)
{
	int pid;

	pid = fork();
	if (pid == 0) {
		int fd, ret;

		fd = init(progname, WDT_DEVNODE, WDT_TIMEOUT);
		if (fd == -1) {
			_pe("Failed connecting to watchdog %s", WDT_DEVNODE);
			_exit(1);
		}

		ret = loop(fd, WDT_TIMEOUT / 2);
		close(fd);

		_exit(ret);
	}

	return pid;
}

/**
 * Local Variables:
 *  indent-tabs-mode: t
 *  c-file-style: "linux"
 * End:
 */