#include <pthread.h>
       #include <stdio.h>
       #include <errno.h>
       #include <stdlib.h>
       #include <unistd.h>

       #define handle_error_en(en, msg) \
               do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)

       static void *
       thread_func(void *ignored_argument)
       {
           int s;

           /* Disable cancellation for a while, so that we don't
              immediately react to a cancellation request */

           s = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
           if (s != 0)
               handle_error_en(s, "pthread_setcancelstate");

           printf("thread_func(): started; cancellation disabled\n");
           sleep(5);
           printf("thread_func(): about to enable cancellation\n");

           s = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
           if (s != 0)
               handle_error_en(s, "pthread_setcancelstate");

           /* sleep() is a cancellation point */

           sleep(1000);        /* Should get canceled while we sleep */

           /* Should never get here */

           printf("thread_func(): not canceled!\n");
           return NULL;
       }

       int
       main(void)
       {
           pthread_t thr;
           void *res;
           int s;

           /* Start a thread and then send it a cancellation request */

           s = pthread_create(&thr, NULL, &thread_func, NULL);
           if (s != 0)
               handle_error_en(s, "pthread_create");

           sleep(2);           /* Give thread a chance to get started */

           printf("main(): sending cancellation request\n");
           s = pthread_cancel(thr);
           if (s != 0)
               handle_error_en(s, "pthread_cancel");

           /* Join with thread to see what its exit status was */

           s = pthread_join(thr, &res);
           if (s != 0)
               handle_error_en(s, "pthread_join");

           if (res == PTHREAD_CANCELED)
               printf("main(): thread was canceled\n");
           else
               printf("main(): thread wasn't canceled (shouldn't happen!)\n");
           exit(EXIT_SUCCESS);
       }