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/* kqueue interface, C mini-library
*
* Copyright 2012 Joey Hess <joey@kitenet.net>
*
* Licensed under the GNU GPL version 3 or higher.
*/
#include <stdio.h>
#include <dirent.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/event.h>
#include <sys/time.h>
#include <errno.h>
/* The specified fds are added to the set of fds being watched for changes.
* Fds passed to prior calls still take effect, so it's most efficient to
* not pass the same fds repeatedly.
*/
signed int helper(const int kq, const int fdcnt, const int *fdlist,
struct timespec *timeout) {
int i, nev;
struct kevent evlist[1];
struct kevent chlist[fdcnt];
for (i = 0; i < fdcnt; i++) {
EV_SET(&chlist[i], fdlist[i], EVFILT_VNODE,
EV_ADD | EV_ENABLE | EV_CLEAR,
NOTE_WRITE,
0, 0);
}
while ((nev = kevent(kq, chlist, fdcnt, evlist, 1, timeout))) {
if (!(nev == -1 && errno == EINTR)) {
break;
}
}
if (nev == 1)
return evlist[0].ident;
else
return -1;
}
/* Initializes a kqueue, with a list of fds to watch for changes.
* Returns the kqueue's handle. */
int init_kqueue(const int fdcnt, const int *fdlist) {
struct timespec nodelay = {0, 0};
int kq;
if ((kq = kqueue()) == -1) {
perror("kqueue");
exit(1);
}
/* Prime the pump with the list of fds, but don't wait for any
* change events. */
helper(kq, fdcnt, fdlist, &nodelay);
return kq;
}
/* Waits for a change event on a kqueue.
*
* Returns the fd that changed, or -1 on error.
*/
signed int waitchange_kqueue(const int kq) {
return helper(kq, 0, NULL, NULL);
}
/*
main () {
int list[1];
int kq;
list[0]=open(".", O_RDONLY);
kq = init_kqueue(1, list);
printf("change: %i\n", waitchange_kqueue(kq));
}
*/
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