/***
    This file is part of snapcast
    Copyright (C) 2014-2016  Johannes Pohl

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
***/

#ifndef DAEMONIZE_H
#define DAEMONIZE_H

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <syslog.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

int pidFilehandle;

void daemonize(const char *pidfile)
{
	/* Our process ID and Session ID */
	pid_t pid, sid;

	/* Fork off the parent process */
	pid = fork();
	if (pid < 0)
		exit(EXIT_FAILURE);

	/* If we got a good PID, then
	   we can exit the parent process. */
	if (pid > 0)
		exit(EXIT_SUCCESS);

	/* Change the file mode mask */
	umask(0);

	/* Open any logs here */

	/* Create a new SID for the child process */
	sid = setsid();
	if (sid < 0)
	{
		/* Log the failure */
		exit(EXIT_FAILURE);
	}

	/* Change the current working directory */
	if ((chdir("/")) < 0)
	{
		/* Log the failure */
		exit(EXIT_FAILURE);
	}

	/* Ensure only one copy */
	pidFilehandle = open(pidfile, O_RDWR|O_CREAT, 0600);

	if (pidFilehandle == -1 )
	{
		/* Couldn't open lock file */
		syslog(LOG_INFO, "Could not open PID lock file %s, exiting", pidfile);
		exit(EXIT_FAILURE);
	}

	/* Try to lock file */
	if (lockf(pidFilehandle,F_TLOCK,0) == -1)
	{
		/* Couldn't get lock on lock file */
		syslog(LOG_INFO, "Could not lock PID lock file %s, exiting", pidfile);
		exit(EXIT_FAILURE);
	}

	char str[10];
	/* Get and format PID */
	sprintf(str, "%d\n", getpid());

	/* write pid to lockfile */
	if (write(pidFilehandle, str, strlen(str)) != (int)strlen(str))
	{
		/* Couldn't get lock on lock file */
		syslog(LOG_INFO, "Could write PID to lock file %s, exiting", pidfile);
		exit(EXIT_FAILURE);
	}

	/* Close out the standard file descriptors */
	close(STDIN_FILENO);
	close(STDOUT_FILENO);
	close(STDERR_FILENO);
}


void daemonShutdown()
{
	close(pidFilehandle);
}


#endif