#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <time.h>
#include <stdlib.h>
#include <syslog.h>

volatile sig_atomic_t get_info = 0;
volatile sig_atomic_t signal_counter = 0;

void handler(int s)
{
    signal(SIGUSR1, handler);
    signal(SIGALRM, handler);

    switch(s) {
    case SIGUSR1:
        get_info = 1;
        ++signal_counter;
        break;
    case SIGALRM:
        get_info = 1;
        alarm(300);
    }
}

int main()
{
    int fd, pid;
    char *path = "/tmp/ordinary_daemon.log";
    FILE *file;
    time_t start, end;
    double dif;

    signal(SIGUSR1, handler);
    signal(SIGALRM, handler);
    close(0);
    close(1);
    close(2);
    open("/dev/null", O_RDONLY);
    open("/dev/null", O_WRONLY);
    open("/dev/null", O_WRONLY);
    chdir("/");
    pid = fork();
    if(pid > 0)
        exit(0);
    setsid();
    pid = fork();
    if(pid > 0)
        exit(0);
    fd = open(path, O_CREAT | O_WRONLY | O_TRUNC, 0666);
    file = fdopen(fd, "w");
    if(fd == -1) {
        perror("can't open file");
        exit(1);
    }
    openlog("ordinary daemon", 0, LOG_USER);
    syslog(LOG_INFO, "daemon started");
    alarm(300);
    pid = getpid();
    time(&start);

    while(1) {
        pause();
        if(get_info) {
            time(&end);
            dif = difftime(end, start);
            fprintf(file, "time spent (in sec): %.2f pid: %u SIGUSR1: %u\n",
                    dif, pid, signal_counter);
            syslog(LOG_INFO, "time spent (in sec): %.2f pid: %u SIGUSR1: %u",
                    dif, pid, signal_counter);
            fflush(file);
            get_info = 0;
        }
    }
    closelog();
    close(fd);
    return 0;
}