diff --git a/kqueue.c b/kqueue.c
new file mode 100644
index 0000000..51984a4
--- /dev/null
+++ b/kqueue.c
@@ -0,0 +1,475 @@
+/*	$OpenBSD: kqueue.c,v 1.5 2002/07/10 14:41:31 art Exp $	*/
+
+/*
+ * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
+ * Copyright 2007-2012 Niels Provos and Nick Mathewson
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "event2/event-config.h"
+
+#define _GNU_SOURCE
+
+#include <sys/types.h>
+#ifdef _EVENT_HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+#include <sys/queue.h>
+#include <sys/event.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#ifdef _EVENT_HAVE_INTTYPES_H
+#include <inttypes.h>
+#endif
+
+/* Some platforms apparently define the udata field of struct kevent as
+ * intptr_t, whereas others define it as void*.  There doesn't seem to be an
+ * easy way to tell them apart via autoconf, so we need to use OS macros. */
+#if defined(_EVENT_HAVE_INTTYPES_H) && !defined(__OpenBSD__) && !defined(__FreeBSD__) && !defined(__darwin__) && !defined(__APPLE__)
+#define PTR_TO_UDATA(x)	((intptr_t)(x))
+#define INT_TO_UDATA(x) ((intptr_t)(x))
+#else
+#define PTR_TO_UDATA(x)	(x)
+#define INT_TO_UDATA(x) ((void*)(x))
+#endif
+
+#include "event-internal.h"
+#include "log-internal.h"
+#include "evmap-internal.h"
+#include "event2/thread.h"
+#include "evthread-internal.h"
+#include "changelist-internal.h"
+
+#define NEVENT		64
+
+struct kqop {
+	struct kevent *changes;
+	int changes_size;
+
+	struct kevent *events;
+	int events_size;
+	int kq;
+	pid_t pid;
+};
+
+static void kqop_free(struct kqop *kqop);
+
+static void *kq_init(struct event_base *);
+static int kq_sig_add(struct event_base *, int, short, short, void *);
+static int kq_sig_del(struct event_base *, int, short, short, void *);
+static int kq_dispatch(struct event_base *, struct timeval *);
+static void kq_dealloc(struct event_base *);
+
+const struct eventop kqops = {
+	"kqueue",
+	kq_init,
+	event_changelist_add,
+	event_changelist_del,
+	kq_dispatch,
+	kq_dealloc,
+	1 /* need reinit */,
+    EV_FEATURE_ET|EV_FEATURE_O1|EV_FEATURE_FDS,
+	EVENT_CHANGELIST_FDINFO_SIZE
+};
+
+static const struct eventop kqsigops = {
+	"kqueue_signal",
+	NULL,
+	kq_sig_add,
+	kq_sig_del,
+	NULL,
+	NULL,
+	1 /* need reinit */,
+	0,
+	0
+};
+
+static void *
+kq_init(struct event_base *base)
+{
+	int kq = -1;
+	struct kqop *kqueueop = NULL;
+
+	if (!(kqueueop = mm_calloc(1, sizeof(struct kqop))))
+		return (NULL);
+
+/* Initialize the kernel queue */
+
+	if ((kq = kqueue()) == -1) {
+		event_warn("kqueue");
+		goto err;
+	}
+
+	kqueueop->kq = kq;
+
+	kqueueop->pid = getpid();
+
+	/* Initialize fields */
+	kqueueop->changes = mm_calloc(NEVENT, sizeof(struct kevent));
+	if (kqueueop->changes == NULL)
+		goto err;
+	kqueueop->events = mm_calloc(NEVENT, sizeof(struct kevent));
+	if (kqueueop->events == NULL)
+		goto err;
+	kqueueop->events_size = kqueueop->changes_size = NEVENT;
+
+	/* Check for Mac OS X kqueue bug. */
+	memset(&kqueueop->changes[0], 0, sizeof kqueueop->changes[0]);
+	kqueueop->changes[0].ident = -1;
+	kqueueop->changes[0].filter = EVFILT_READ;
+	kqueueop->changes[0].flags = EV_ADD;
+	/*
+	 * If kqueue works, then kevent will succeed, and it will
+	 * stick an error in events[0].  If kqueue is broken, then
+	 * kevent will fail.
+	 */
+	if (kevent(kq,
+		kqueueop->changes, 1, kqueueop->events, NEVENT, NULL) != 1 ||
+	    (int)kqueueop->events[0].ident != -1 ||
+	    kqueueop->events[0].flags != EV_ERROR) {
+		event_warn("%s: detected broken kqueue; not using.", __func__);
+		goto err;
+	}
+
+	base->evsigsel = &kqsigops;
+
+	return (kqueueop);
+err:
+	if (kqueueop)
+		kqop_free(kqueueop);
+
+	return (NULL);
+}
+
+static void
+kq_sighandler(int sig)
+{
+	/* Do nothing here */
+}
+
+#define ADD_UDATA 0x30303
+
+static void
+kq_setup_kevent(struct kevent *out, evutil_socket_t fd, int filter, short change)
+{
+	memset(out, 0, sizeof(struct kevent));
+	out->ident = fd;
+	out->filter = filter;
+
+	if (change & EV_CHANGE_ADD) {
+		out->flags = EV_ADD;
+		/* We set a magic number here so that we can tell 'add'
+		 * errors from 'del' errors. */
+		out->udata = INT_TO_UDATA(ADD_UDATA);
+		if (change & EV_ET)
+			out->flags |= EV_CLEAR;
+#ifdef NOTE_EOF
+		/* Make it behave like select() and poll() */
+		if (filter == EVFILT_READ)
+			out->fflags = NOTE_EOF;
+#endif
+	} else {
+		EVUTIL_ASSERT(change & EV_CHANGE_DEL);
+		out->flags = EV_DELETE;
+	}
+}
+
+static int
+kq_build_changes_list(const struct event_changelist *changelist,
+    struct kqop *kqop)
+{
+	int i;
+	int n_changes = 0;
+
+	for (i = 0; i < changelist->n_changes; ++i) {
+		struct event_change *in_ch = &changelist->changes[i];
+		struct kevent *out_ch;
+		if (n_changes >= kqop->changes_size - 1) {
+			int newsize = kqop->changes_size * 2;
+			struct kevent *newchanges;
+
+			newchanges = mm_realloc(kqop->changes,
+			    newsize * sizeof(struct kevent));
+			if (newchanges == NULL) {
+				event_warn("%s: realloc", __func__);
+				return (-1);
+			}
+			kqop->changes = newchanges;
+			kqop->changes_size = newsize;
+		}
+		if (in_ch->read_change) {
+			out_ch = &kqop->changes[n_changes++];
+			kq_setup_kevent(out_ch, in_ch->fd, EVFILT_READ,
+			    in_ch->read_change);
+		}
+		if (in_ch->write_change) {
+			out_ch = &kqop->changes[n_changes++];
+			kq_setup_kevent(out_ch, in_ch->fd, EVFILT_WRITE,
+			    in_ch->write_change);
+		}
+	}
+	return n_changes;
+}
+
+static int
+kq_grow_events(struct kqop *kqop, size_t new_size)
+{
+	struct kevent *newresult;
+
+	newresult = mm_realloc(kqop->events,
+	    new_size * sizeof(struct kevent));
+
+	if (newresult) {
+		kqop->events = newresult;
+		kqop->events_size = new_size;
+		return 0;
+	} else {
+		return -1;
+	}
+}
+
+static int
+kq_dispatch(struct event_base *base, struct timeval *tv)
+{
+	struct kqop *kqop = base->evbase;
+	struct kevent *events = kqop->events;
+	struct kevent *changes;
+	struct timespec ts, *ts_p = NULL;
+	int i, n_changes, res;
+
+	if (tv != NULL) {
+		TIMEVAL_TO_TIMESPEC(tv, &ts);
+		ts_p = &ts;
+	}
+
+	/* Build "changes" from "base->changes" */
+	EVUTIL_ASSERT(kqop->changes);
+	n_changes = kq_build_changes_list(&base->changelist, kqop);
+	if (n_changes < 0)
+		return -1;
+
+	event_changelist_remove_all(&base->changelist, base);
+
+	/* steal the changes array in case some broken code tries to call
+	 * dispatch twice at once. */
+	changes = kqop->changes;
+	kqop->changes = NULL;
+
+	/* Make sure that 'events' is at least as long as the list of changes:
+	 * otherwise errors in the changes can get reported as a -1 return
+	 * value from kevent() rather than as EV_ERROR events in the events
+	 * array.
+	 *
+	 * (We could instead handle -1 return values from kevent() by
+	 * retrying with a smaller changes array or a larger events array,
+	 * but this approach seems less risky for now.)
+	 */
+	if (kqop->events_size < n_changes) {
+		int new_size = kqop->events_size;
+		do {
+			new_size *= 2;
+		} while (new_size < n_changes);
+
+		kq_grow_events(kqop, new_size);
+		events = kqop->events;
+	}
+
+	EVBASE_RELEASE_LOCK(base, th_base_lock);
+
+	res = kevent(kqop->kq, changes, n_changes,
+	    events, kqop->events_size, ts_p);
+
+	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
+
+	EVUTIL_ASSERT(kqop->changes == NULL);
+	kqop->changes = changes;
+
+	if (res == -1) {
+		if (errno != EINTR) {
+			event_warn("kevent");
+			return (-1);
+		}
+
+		return (0);
+	}
+
+	event_debug(("%s: kevent reports %d", __func__, res));
+
+	for (i = 0; i < res; i++) {
+		int which = 0;
+
+		if (events[i].flags & EV_ERROR) {
+			switch (events[i].data) {
+
+			/* Can occur on delete if we are not currently
+			 * watching any events on this fd.  That can
+			 * happen when the fd was closed and another
+			 * file was opened with that fd. */
+			case ENOENT:
+			/* Can occur for reasons not fully understood
+			 * on FreeBSD. */
+			case EINVAL:
+				continue;
+
+			/* Can occur on a delete if the fd is closed. */
+			case EBADF:
+				/* XXXX On NetBSD, we can also get EBADF if we
+				 * try to add the write side of a pipe, but
+				 * the read side has already been closed.
+				 * Other BSDs call this situation 'EPIPE'. It
+				 * would be good if we had a way to report
+				 * this situation. */
+				continue;
+			/* These two can occur on an add if the fd was one side
+			 * of a pipe, and the other side was closed. */
+			case EPERM:
+			case EPIPE:
+				/* Report read events, if we're listening for
+				 * them, so that the user can learn about any
+				 * add errors.  (If the operation was a
+				 * delete, then udata should be cleared.) */
+				if (events[i].udata) {
+					/* The operation was an add:
+					 * report the error as a read. */
+					which |= EV_READ;
+					break;
+				} else {
+					/* The operation was a del:
+					 * report nothing. */
+					continue;
+				}
+
+			/* Other errors shouldn't occur. */
+			default:
+				errno = events[i].data;
+				return (-1);
+			}
+		} else if (events[i].filter == EVFILT_READ) {
+			which |= EV_READ;
+		} else if (events[i].filter == EVFILT_WRITE) {
+			which |= EV_WRITE;
+		} else if (events[i].filter == EVFILT_SIGNAL) {
+			which |= EV_SIGNAL;
+		}
+
+		if (!which)
+			continue;
+
+		if (events[i].filter == EVFILT_SIGNAL) {
+			evmap_signal_active(base, events[i].ident, 1);
+		} else {
+			evmap_io_active(base, events[i].ident, which | EV_ET);
+		}
+	}
+
+	if (res == kqop->events_size) {
+		/* We used all the events space that we have. Maybe we should
+		   make it bigger. */
+		kq_grow_events(kqop, kqop->events_size * 2);
+	}
+
+	return (0);
+}
+
+static void
+kqop_free(struct kqop *kqop)
+{
+	if (kqop->changes)
+		mm_free(kqop->changes);
+	if (kqop->events)
+		mm_free(kqop->events);
+	if (kqop->kq >= 0 && kqop->pid == getpid())
+		close(kqop->kq);
+	memset(kqop, 0, sizeof(struct kqop));
+	mm_free(kqop);
+}
+
+static void
+kq_dealloc(struct event_base *base)
+{
+	struct kqop *kqop = base->evbase;
+	evsig_dealloc(base);
+	kqop_free(kqop);
+}
+
+/* signal handling */
+static int
+kq_sig_add(struct event_base *base, int nsignal, short old, short events, void *p)
+{
+	struct kqop *kqop = base->evbase;
+	struct kevent kev;
+	struct timespec timeout = { 0, 0 };
+	(void)p;
+
+	EVUTIL_ASSERT(nsignal >= 0 && nsignal < NSIG);
+
+	memset(&kev, 0, sizeof(kev));
+	kev.ident = nsignal;
+	kev.filter = EVFILT_SIGNAL;
+	kev.flags = EV_ADD;
+
+	/* Be ready for the signal if it is sent any
+	 * time between now and the next call to
+	 * kq_dispatch. */
+	if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
+		return (-1);
+
+	/* XXXX The manpage suggest we could use SIG_IGN instead of a
+	 * do-nothing handler */
+	if (_evsig_set_handler(base, nsignal, kq_sighandler) == -1)
+		return (-1);
+
+	return (0);
+}
+
+static int
+kq_sig_del(struct event_base *base, int nsignal, short old, short events, void *p)
+{
+	struct kqop *kqop = base->evbase;
+	struct kevent kev;
+
+	struct timespec timeout = { 0, 0 };
+	(void)p;
+
+	EVUTIL_ASSERT(nsignal >= 0 && nsignal < NSIG);
+
+	memset(&kev, 0, sizeof(kev));
+	kev.ident = nsignal;
+	kev.filter = EVFILT_SIGNAL;
+	kev.flags = EV_DELETE;
+
+	/* Because we insert signal events
+	 * immediately, we need to delete them
+	 * immediately, too */
+	if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
+		return (-1);
+
+	if (_evsig_restore_handler(base, nsignal) == -1)
+		return (-1);
+
+	return (0);
+}