using kqueue for monitoring a file

test_kqueue.c

/**
    Copyright: (c) SAEKI Yoshiyasu
    License  : MIT-style license
               <http://www.opensource.org/licenses/mit-license.php>
    last updated: 2011/05/07
**/

#include<stdio.h>
#include<stdlib.h>
#include <sys/event.h>

int main(int argc, char *argv[]) {
    FILE *fp = fopen("foo", "r");
    struct kevent kev, kev_r;
    int kq = kqueue();
    if(kq == -1) {
        printf("kqueue error\n");
        exit(0);
    }
    EV_SET(&kev, (*fp)._file, EVFILT_VNODE,
           EV_ADD | EV_ENABLE | EV_CLEAR,
           NOTE_DELETE | NOTE_WRITE, 0, NULL);
    if(kevent(kq, &kev, 1, NULL, 0, NULL) == -1) {
                printf("kevent error\n");
                exit(0);
    }
    while(1) {
        if(kevent(kq, NULL, 0, &kev_r, 1, NULL) == -1) {
            printf("kevent_r error\n");
            exit(0);
        }
        if(kev_r.fflags & NOTE_WRITE) {
            printf("file was updated!\n");
        } else if(kev_r.fflags & NOTE_DELETE) {
            printf("file was deleted!\n");
        }
    }
    fclose(fp);
    return 0;
}