/*	$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);

}