sig.c

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>
#include <pthread.h>

#define NUM_THREADS 4

void* signal_watcher(void* arg) {
  int kq;
  int numevents;
  struct kevent event;

  kq = kqueue();

  EV_SET(&event, SIGINT, EVFILT_SIGNAL, EV_ADD | EV_ENABLE, 0, 0, 0);
  numevents = kevent(kq, &event, 1, NULL, 0, NULL);
  assert(numevents == 0);

  for (;;) {
    numevents = kevent(kq, NULL, 0, &event, 1, NULL);
    if (numevents < 0) {
      if (errno == EINTR) continue;
      fprintf(stderr, "Unexpected error: %d\n", errno);
      abort();
    }

    fprintf(stdout, "received signal\n");
    break;
  }
}

int main() {
  int i;
  int r;
  pthread_t threads[NUM_THREADS];
  struct sigaction sigact;

  /* Ignore SIGINT */
  memset(&sigact, 0, sizeof(sigact));
  sigact.sa_handler = SIG_IGN;
  sigaction(SIGINT, &sigact, NULL);

  for (i = 0; i < NUM_THREADS; i++) {
    r = pthread_create(&threads[i], NULL, signal_watcher, NULL);
    assert(r == 0);
  }

  for (i = 0; i < NUM_THREADS; i++) {
    pthread_join(threads[i], NULL);
  }

  return 0;
}