kqueue/kqtimer.c

   1 #include <sys/event.h>
   2 #include <sys/time.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>   /* for strerror() */
   6 #include <unistd.h>
   7
   8 /* function prototypes */
   9 void diep(const char *s);
  10
  11 int main(void)
  12 {
  13     struct kevent change;    /* event we want to monitor */
  14     struct kevent event;     /* event that was triggered */
  15     pid_t pid;
  16     int kq, nev;
  17
  18     /* create a new kernel event queue */
  19     if ((kq = kqueue()) == -1)
  20         diep("kqueue()");
  21
  22     /* initalise kevent structure */
  23     EV_SET(&change, 1, EVFILT_TIMER, EV_ADD | EV_ENABLE, 0, 5000, 0);
  24
  25     /* loop forever */
  26     for (;;) {
  27         nev = kevent(kq, &change, 1, &event, 1, NULL);
  28
  29         if (nev < 0)
  30             diep("kevent()");
  31
  32         else if (nev > 0) {
  33             if (event.flags & EV_ERROR) {   /* report any error */
  34                 fprintf(stderr, "EV_ERROR: %s\n", strerror(event.data));
  35                 exit(EXIT_FAILURE);
  36             }
  37
  38             if ((pid = fork()) < 0)         /* fork error */
  39                 diep("fork()");
  40
  41             else if (pid == 0)              /* child */
  42                 if (execlp("date", "date", (char *)0) < 0)
  43                     diep("execlp()");
  44         }
  45     }
  46
  47     close(kq);
  48     return EXIT_SUCCESS;
  49 }
  50
  51 void diep(const char *s)
  52 {
  53     perror(s);
  54     exit(EXIT_FAILURE);
  55 }