Signal handling in Linux with signalfd #c #Linux #Signals

signal_handling.c

/* Signal handling with signalfd()
 * Original Source : http://741mhz.com/signal-handler/ 
 */

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/signalfd.h>
#include <unistd.h>

#define handle_error(msg)	\
	do { perror(msg); exit(EXIT_FAILURE); } while(0)

int main(int argc, char *argv[])
{
	// Mask to specify what signals are affected.
	sigset_t mask;

	int sfd;
	struct signalfd_siginfo fdsi;
	ssize_t s;

	// Initializes the signal set given by set to empty,
	// with all the signals excluded from the set.
	sigemptyset(&mask);

	// add signals to the set
	sigaddset(&mask, SIGINT);
	sigaddset(&mask, SIGQUIT);

	// Block signals so that they aren't handled
	// according to their default dispositions 

	if(sigprocmask(SIG_BLOCK, &mask, NULL) == -1)
		handle_error("sigprocmask");

	// Create a file descriptor for accepting signals
	sfd = signalfd(-1, &mask, 0);
	if(sfd == -1)
		handle_error("signalfd");

	for(;;){
		
		// Read from file descriptor
		s = read(sfd, &fdsi, sizeof(struct signalfd_siginfo));

		if(s != sizeof(struct signalfd_siginfo))
			handle_error("read");

		switch(fdsi.ssi_signo){
			case SIGINT:
				printf("Got SIGINT \n");
				break;
			case SIGQUIT:
				printf("Got SIGQUIT \n");
				break;
			default:
				printf("Oops...!\n");

		}
	}
}