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/* kqueue interface, C mini-library
*
* Copyright 2012 Joey Hess <id@joeyh.name>
*
* License: BSD-2-clause
*/
#include <stdio.h>
#include <dirent.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.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.
*
* Returns the fd that changed, or -1 on error.
*/
signed int helper(const int kq, const int fdcnt, const int *fdlist, int nodelay) {
int i, nev;
struct kevent evlist[1];
struct kevent chlist[fdcnt];
struct timespec avoiddelay = {0, 0};
struct timespec *timeout = nodelay ? &avoiddelay : NULL;
for (i = 0; i < fdcnt; i++) {
EV_SET(&chlist[i], fdlist[i], EVFILT_VNODE,
EV_ADD | EV_ENABLE | EV_CLEAR,
NOTE_WRITE,
0, 0);
}
nev = kevent(kq, chlist, fdcnt, evlist, 1, timeout);
if (nev == 1)
return evlist[0].ident;
else
return -1;
}
/* Initializes a new, empty kqueue. */
int init_kqueue() {
int kq;
if ((kq = kqueue()) == -1) {
perror("kqueue");
exit(1);
}
return kq;
}
/* Adds fds to the set that should be watched. */
void addfds_kqueue(const int kq, const int fdcnt, const int *fdlist) {
helper(kq, fdcnt, fdlist, 1);
}
/* Waits for a change event on a kqueue. */
signed int waitchange_kqueue(const int kq) {
return helper(kq, 0, NULL, 0);
}
/*
main () {
int list[1];
int kq;
list[0]=open(".", O_RDONLY);
kq = init_kqueue();
addfds_kqueue(kq, 1, list)
printf("change: %i\n", waitchange_kqueue(kq));
}
*/
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