sighup_EINTR_example

#include <stdio.h>
#include <signal.h>
#include <pthread.h>
#include <stdatomic.h>
#include <unistd.h>
#include <sys/wait.h>
#include <stdlib.h>

/*
 * Set this variable if any signal is received
 */
volatile sig_atomic_t sig_set_flag = 0;

pthread_mutex_t cleanup_mutex;

/*
 * Resource cleanup function.
 */
int cleaup_resources() {

    pthread_mutex_lock(&cleanup_mutex);
    /*
     * Send notification to all the clients.
     * Delete all the temp files
     */
    printf("Notified to clients.Exiting process\n");
    pthread_mutex_unlock(&cleanup_mutex);

    return 0;
}

/*
 * Signal handler thread
 */
void sig_term_handler(int sig_num) {
  sig_set_flag = sig_num;
}


int main()
{
    int loop_count,status;
    pthread_t tid;
    pid_t pid;
    int ret;
    struct sigaction sig;
    sig.sa_handler = &sig_term_handler;
    sig.sa_flags = 0;
    sigaction(SIGHUP, &sig, NULL);

    /*
     * Spawn a thread to monitor signals.
     * If signal received, Exit the process.
     */
    while(1) {
     printf("Some time consuming task in progress... PID = %d\n",getpid());
     pid = fork();
     if(pid == 0) {

         sleep(100);
         return 0;
     } else {
     ret = waitpid(pid, &status, 0);
     if( (ret == -1) && (errno == EINTR) ) {
         printf("System call interrpted\n");
     }
     loop_count++;
     if( loop_count>=10)
        break;
     }
    }
    cleaup_resources();
    exit(0);

}