#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <pthread.h>

int doshutdown = 0;

static void set_shutdown(int sig);
static void *threadfn(void *vd);

static void
set_shutdown(int sig) {
  printf("Got TERM signal\n");
  fflush(stdout);
  doshutdown = 1;
  signal(SIGTERM, set_shutdown);
  return;
}

static void *
threadfn(void *vd) {
  pid_t mypid = getpid();

  printf("Starting thread (pid: %d) and sleeping 3 seconds\n", mypid);
  sleep(3);
  printf("Terminating thread\n");
  return NULL;
}

int main(int argc, char *argv[]) {
    int rc;
    pthread_t mythread;
    pthread_attr_t mythread_attr;
    sigset_t proc_mask;
    int resetmask;
    pid_t mypid = getpid();

    if (argc != 2) {
      fprintf(stderr, "usage: %s <0|1>\n", argv[0]);
      exit(1);
    }

    resetmask = atoi(argv[1]);
    if (resetmask) {
      printf("Clearing procmask\n");
      (void)sigemptyset(&proc_mask);
      rc = sigprocmask(SIG_SETMASK, &proc_mask, NULL);
      if (rc != 0) {
	fprintf(stderr, "Failed to set sigprocmask\n");
	exit(1);
      }
    }

    signal(SIGTERM, set_shutdown);

    printf("Created thread\n");
    printf("Please, send TERM signal to pid %d\n", mypid);
    pthread_attr_init(&mythread_attr);
    pthread_attr_setdetachstate(&mythread_attr, PTHREAD_CREATE_DETACHED);
    pthread_attr_setscope(&mythread_attr, PTHREAD_SCOPE_SYSTEM);
    pthread_create(&mythread,
		   &mythread_attr,
		   threadfn,
		   NULL);

    while (!doshutdown);
    exit(0); 
}