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

/* signal handlers declarations */
void proces_event(int sig);
void process_sigterm(int sig);
void process_sigint(int sig);

int run = 1;

int main()
{
	struct sigaction act;

	/* 1. masking signal SIGUSR1 */

	/* signal handler function */
	act.sa_handler = proces_event;

	/* additionally block SIGTERM in handler function */
	sigemptyset(&act.sa_mask);
	sigaddset(&act.sa_mask, SIGTERM);

	act.sa_flags = 0; /* advanced features not used */

	/* mask the signal SIGUSR1 as described above */
	sigaction(SIGUSR1, &act, NULL);

	/* 2. masking signal SIGTERM */
	act.sa_handler = process_sigterm;
	sigemptyset(&act.sa_mask);
	sigaction(SIGTERM, &act, NULL);

	/* 3. masking signal SIGINT */
	act.sa_handler = process_sigint;
	sigaction(SIGINT, &act, NULL);

	printf("Process with PID=%ld started\n", (long) getpid());

	/* processing simulation */
	int i = 1;
	while(run) {
		printf("Process: iteration %d\n", i++);
		sleep(1);
	}

	printf("Process with PID=%ld finished\n", (long) getpid());

	return 0;
}

void proces_event(int sig)
{
	int i;
	printf("Event processing started for signal %d (SIGINT)\n", sig);
	for (i = 1; i <= 5; i++) {
		printf("Processing signal %d: %d/5\n", sig, i);
		sleep(1);
	}
	printf("Event processing completed for signal %d (SIGINT)\n", sig);
}

void process_sigterm(int sig)
{
	printf("Received SIGTERM, saving data before exit\n");
	run = 0;
}

void process_sigint(int sig)
{
	printf("Received SIGINT, canceling process\n");
	exit(1);
}