signalfd_demo.c

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

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

int
main(int argc, char *argv[])
{
   sigset_t mask;
   int sfd;
   struct signalfd_siginfo fdsi;
   ssize_t s;

   sigemptyset(&mask);
   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");

   sfd = signalfd(-1, &mask, 0);
   if (sfd == -1)
       handle_error("signalfd");

   for (;;) {
       s = read(sfd, &fdsi, sizeof(struct signalfd_siginfo));
       if (s != sizeof(struct signalfd_siginfo))
           handle_error("read");

       if (fdsi.ssi_signo == SIGINT) {
           printf("Got SIGINT\n");
       } else if (fdsi.ssi_signo == SIGQUIT) {
           printf("Got SIGQUIT\n");
           exit(EXIT_SUCCESS);
       } else {
           printf("Read unexpected signal\n");
       }
   }
}