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#include <sys/event.h>
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
int
main(int argc, char **argv)
{
struct kevent event; /* Event we want to monitor */
struct kevent tevent; /* Event triggered */
int kq, fd, ret;
if (argc != 2)
err(EXIT_FAILURE, "Usage: %s path\n", argv[0]);
fd = open(argv[1], O_RDONLY);
if (fd == -1)
err(EXIT_FAILURE, "Failed to open '%s'", argv[1]);
/* Create kqueue. */
kq = kqueuex(KQUEUE_CLOEXEC);
if (kq == -1)
err(EXIT_FAILURE, "kqueuex(KQUEUE_CLOEXEC) failed");
/* Initialize kevent structure. */
EV_SET(&event, fd, EVFILT_VNODE, EV_ADD | EV_CLEAR, NOTE_WRITE,
0, NULL);
/* Attach event to the kqueue. */
ret = kevent(kq, &event, 1, NULL, 0, NULL);
if (ret == -1)
err(EXIT_FAILURE, "kevent register");
for (;;) {
/* Sleep until something happens. */
ret = kevent(kq, NULL, 0, &tevent, 1, NULL);
if (ret == -1) {
err(EXIT_FAILURE, "kevent wait");
} else if (ret > 0) {
if (tevent.flags & EV_ERROR)
errx(EXIT_FAILURE, "Event error: %s", strerror(event.data));
else {
printf("Something was written in '%s'\n", argv[1]);
exit(0);
}
}
}
/* kqueues are destroyed upon close() */
(void)close(kq);
(void)close(fd);
}
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