#include <stdlib.h>
#include <signal.h>
#include <stdio.h>

#define DAEMON_NAME "polld"
#define RUN_AS_USER "rps"
#define LOCK_FILE "/var/lock/polld"
#define WORKING_DIR "/tmp"
#define LOG_FILE "/var/log/polld"

#define INTERVAL 1

#define TRUE 1
#define FALSE 0




int running;

void daemonize();
void catch_SIGUSR1();
void catch_SIGTERM();
void catch_SIGALRM();
void execute();




int
main(int argc, char* argv[])
{
        daemonize();

        running = TRUE;

        signal(SIGTERM, catch_SIGTERM);
        signal(SIGALRM, catch_SIGALRM);

        while (running)
        {
                alarm(INTERVAL);
                pause();
        }

        signal(SIGTERM, SIG_DFL);
        signal(SIGALRM, SIG_DFL);

        exit(EXIT_SUCCESS);
}




void
daemonize()
{
        pid_t pid;
        pid_t sid;
        pid_t parrent;

        FILE* fp;

        if (getppid() == 1)
                return;
        if (fp = fopen(LOCK_FILE, "r"))
        {
                fclose(fp);
                fprintf(stderr, "Daemon is already running.\n\n");
                exit(EXIT_FAILURE);
        }
        else
        {
                fp = fopen(LOCK_FILE, "w");
        }

        signal(SIGUSR1, catch_SIGUSR1);

        pid = fork();
        if (pid < 0)
        {
                fprintf(stderr, "Starting daemon failed (unable to fork child process).\n\n");
                exit(EXIT_FAILURE);
        }
        else if (pid > 0)
        {
                alarm(10);
                pause();

                fprintf(stderr, "Starting daemon failed (child process did not kill parrent).\n\n");
                exit(EXIT_SUCCESS);
        }

        fprintf(fp, "%d\n", getpid());
        fclose(fp);

        parrent = getppid();

        signal(SIGCHLD, SIG_DFL);
        signal(SIGTSTP, SIG_IGN);
        signal(SIGTTOU, SIG_IGN);
        signal(SIGTTIN, SIG_IGN);
        signal(SIGHUP, SIG_IGN);
        signal(SIGTERM, SIG_DFL);

        umask(0);

        sid = setsid();
        if (sid < 0)
        {
                fprintf(stderr, "Starting daemon failed (unable to establish new session).\n\n");
                exit(EXIT_FAILURE);
        }

        if ((chdir(WORKING_DIR)) < 0)
        {
                fprintf(stderr, "Error: Unable to change to working directory.\n\n");
                exit(EXIT_FAILURE);
        }

        freopen("/dev/null", "r", stdin);

        freopen(LOG_FILE, "a+", stdout);
        freopen(LOG_FILE, "a+", stderr);

        kill(parrent, SIGUSR1);
}




void
catch_SIGUSR1()
{
        exit(EXIT_SUCCESS);
}




void
catch_SIGTERM()
{
        running = FALSE;
        unlink(LOCK_FILE);
}




void
catch_SIGALRM()
{
        pid_t pid;

        pid = fork();
        if (pid == 0)
        {
                execute();
                exit(EXIT_SUCCESS);
        }
        else {
                wait();
        }

}




void
execute()
{
        printf("Testing.\n");
}