hw_daemon_mssiraj.c

/*
COMPILATION COMMAND:
arm-linux-gnueabi-gcc -static -o hw_daemon_mssiraj hw_daemon_mssiraj.c
*/

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/times.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <unistd.h>
#include <syslog.h>
#include <errno.h>
#include <signal.h>
#include <inttypes.h>
#include <string.h>
#include <time.h>

#define OK 0
#define true 1
#define ERR_WTF 1
#define ERR_FORK 1
#define ERR_SETSID 1
#define ERR_CHDIR 1
#define ERR_TIME 1
#define ERROR_FORMAT "ERROR MESSAGE: %s"
#define DAEMON_NAME "sample_daemon_mssiraj"

static void _signal_handler(const int signal) {
    switch(signal) {
        case SIGHUP:
            break;

        case SIGTERM:
            syslog(LOG_INFO, "received SIGTERM, exiting.");
            closelog();
            exit(OK);
            break;
    default:
        syslog(LOG_INFO, "received unhandled signal");
    }
}

static int _do_work(void) {
    while(1) {
        time_t present_time = time(NULL);
        struct tm *ptm = localtime(&present_time);

        if (ptm == NULL) {
            return ERR_TIME;
            }

        syslog(LOG_INFO, "Present Time: %d:%d:%d", ptm->tm_hour, ptm->tm_min, ptm->tm_sec);
        sleep(1);
        }
}

int main(void) {
    openlog(DAEMON_NAME, LOG_PID | LOG_NDELAY | LOG_NOWAIT, LOG_DAEMON);
    syslog(LOG_INFO, "Starting hw_daemon_mssiraj");

    pid_t pid = fork();

    if (pid < 0) {
        syslog(LOG_ERR, ERROR_FORMAT, strerror(errno));
        return ERR_FORK;
    }

    if (pid > 0) {
        return OK;
    }

    if (setsid() < -1){
        syslog(LOG_ERR, ERROR_FORMAT, strerror(errno));
        return ERR_SETSID;
    }

    close(STDIN_FILENO);
    close(STDOUT_FILENO);
    close(STDERR_FILENO);

    umask(S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);

    if (chdir("/") < 0) {
        syslog(LOG_ERR, ERROR_FORMAT, strerror(errno));
        return ERR_CHDIR;
    }

    signal(SIGTERM, _signal_handler);
    signal(SIGHUP, _signal_handler);

    _do_work();

    return ERR_WTF;
}