/* Example of use of a Linux-specific call - signalfd() to handle signals using
* a file descriptor.
*/
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sys/signalfd.h>
#include <string.h>
int main (int argc, char *argv[])
{
int sfd;
sigset_t mask;
/* We will handle SIGTERM and SIGINT. */
sigemptyset (&mask);
sigaddset (&mask, SIGTERM);
sigaddset (&mask, SIGINT);
/* Block the signals thet we handle using signalfd(), so they don't
* cause signal handlers or default signal actions to execute. */
if (sigprocmask(SIG_BLOCK, &mask, NULL) < 0) {
perror ("sigprocmask");
return 1;
}
/* Create a file descriptor from which we will read the signals. */
sfd = signalfd (-1, &mask, 0);
if (sfd < 0) {
perror ("signalfd");
return 1;
}
while (1) {
/** The buffor for read(), this structure contains information
* about the signal we've read. */
struct signalfd_siginfo si;
ssize_t res;
res = read (sfd, &si, sizeof(si));
if (res < 0) {
perror ("read");
return 1;
}
if (res != sizeof(si)) {
fprintf (stderr, "Something wrong\n");
return 1;
}
if (si.ssi_signo == SIGTERM)
printf ("Got SIGTERM\n");
else if (si.ssi_signo == SIGINT) {
printf ("Bye!\n");
break;
}
else {
fprintf (stderr, "Got some unhandled signal\n");
return 1;
}
}
/* Close the file descriptor if we no longer need it. */
close (sfd);
return 0;
}
