[apple/xnu.git] / bsd / kern / kern_event.c

/*
 * Copyright (c) 2000-2014 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 *
 */
/*-
 * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
 */
/*
 *      @(#)kern_event.c       1.0 (3/31/2000)
 */
#include <stdint.h>

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/malloc.h>
#include <sys/unistd.h>
#include <sys/file_internal.h>
#include <sys/fcntl.h>
#include <sys/select.h>
#include <sys/queue.h>
#include <sys/event.h>
#include <sys/eventvar.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/uio.h>
#include <sys/sysproto.h>
#include <sys/user.h>
#include <sys/vnode_internal.h>
#include <string.h>
#include <sys/proc_info.h>
#include <sys/codesign.h>

#include <kern/locks.h>
#include <kern/clock.h>
#include <kern/thread_call.h>
#include <kern/sched_prim.h>
#include <kern/zalloc.h>
#include <kern/assert.h>

#include <libkern/libkern.h>
#include "net/net_str_id.h"

#include <mach/task.h>

#if VM_PRESSURE_EVENTS
#include <kern/vm_pressure.h>
#endif

#if CONFIG_MEMORYSTATUS
#include <sys/kern_memorystatus.h>
#endif

MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system");

#define KQ_EVENT        NULL

static inline void kqlock(struct kqueue *kq);
static inline void kqunlock(struct kqueue *kq);

static int kqlock2knoteuse(struct kqueue *kq, struct knote *kn);
static int kqlock2knoteusewait(struct kqueue *kq, struct knote *kn);
static int kqlock2knotedrop(struct kqueue *kq, struct knote *kn);
static int knoteuse2kqlock(struct kqueue *kq, struct knote *kn);

static void kqueue_wakeup(struct kqueue *kq, int closed);
static int kqueue_read(struct fileproc *fp, struct uio *uio,
    int flags, vfs_context_t ctx);
static int kqueue_write(struct fileproc *fp, struct uio *uio,
    int flags, vfs_context_t ctx);
static int kqueue_ioctl(struct fileproc *fp, u_long com, caddr_t data,
    vfs_context_t ctx);
static int kqueue_select(struct fileproc *fp, int which, void *wql,
    vfs_context_t ctx);
static int kqueue_close(struct fileglob *fg, vfs_context_t ctx);
static int kqueue_kqfilter(struct fileproc *fp, struct knote *kn,
        vfs_context_t ctx);
static int kqueue_drain(struct fileproc *fp, vfs_context_t ctx);

static const struct fileops kqueueops = {
        .fo_type = DTYPE_KQUEUE,
        .fo_read = kqueue_read,
        .fo_write = kqueue_write,
        .fo_ioctl = kqueue_ioctl,
        .fo_select = kqueue_select,
        .fo_close = kqueue_close,
        .fo_kqfilter = kqueue_kqfilter,
        .fo_drain = kqueue_drain,
};

static int kevent_internal(struct proc *p, int iskev64, user_addr_t changelist,
    int nchanges, user_addr_t eventlist, int nevents, int fd,
    user_addr_t utimeout, unsigned int flags, int32_t *retval);
static int kevent_copyin(user_addr_t *addrp, struct kevent64_s *kevp,
    struct proc *p, int iskev64);
static int kevent_copyout(struct kevent64_s *kevp, user_addr_t *addrp,
    struct proc *p, int iskev64);
char * kevent_description(struct kevent64_s *kevp, char *s, size_t n);

static int kevent_callback(struct kqueue *kq, struct kevent64_s *kevp,
    void *data);
static void kevent_continue(struct kqueue *kq, void *data, int error);
static void kqueue_scan_continue(void *contp, wait_result_t wait_result);
static int kqueue_process(struct kqueue *kq, kevent_callback_t callback,
    void *data, int *countp, struct proc *p);
static int kqueue_begin_processing(struct kqueue *kq);
static void kqueue_end_processing(struct kqueue *kq);
static int knote_process(struct knote *kn, kevent_callback_t callback,
    void *data, struct kqtailq *inprocessp, struct proc *p);
static void knote_put(struct knote *kn);
static int knote_fdpattach(struct knote *kn, struct filedesc *fdp,
    struct proc *p);
static void knote_drop(struct knote *kn, struct proc *p);
static void knote_activate(struct knote *kn, int);
static void knote_deactivate(struct knote *kn);
static void knote_enqueue(struct knote *kn);
static void knote_dequeue(struct knote *kn);
static struct knote *knote_alloc(void);
static void knote_free(struct knote *kn);

static int filt_fileattach(struct knote *kn);
static struct filterops file_filtops = {
        .f_isfd = 1,
        .f_attach = filt_fileattach,
};

static void filt_kqdetach(struct knote *kn);
static int filt_kqueue(struct knote *kn, long hint);
static struct filterops kqread_filtops = {
        .f_isfd = 1,
        .f_detach = filt_kqdetach,
        .f_event = filt_kqueue,
};

/* placeholder for not-yet-implemented filters */
static int filt_badattach(struct knote *kn);
static struct filterops bad_filtops = {
        .f_attach = filt_badattach,
};

static int filt_procattach(struct knote *kn);
static void filt_procdetach(struct knote *kn);
static int filt_proc(struct knote *kn, long hint);
static struct filterops proc_filtops = {
        .f_attach = filt_procattach,
        .f_detach = filt_procdetach,
        .f_event = filt_proc,
};

#if VM_PRESSURE_EVENTS
static int filt_vmattach(struct knote *kn);
static void filt_vmdetach(struct knote *kn);
static int filt_vm(struct knote *kn, long hint);
static struct filterops vm_filtops = {
        .f_attach = filt_vmattach,
        .f_detach = filt_vmdetach,
        .f_event = filt_vm,
};
#endif /* VM_PRESSURE_EVENTS */

#if CONFIG_MEMORYSTATUS
extern struct filterops memorystatus_filtops;
#endif /* CONFIG_MEMORYSTATUS */

extern struct filterops fs_filtops;

extern struct filterops sig_filtops;

/* Timer filter */
static int filt_timerattach(struct knote *kn);
static void filt_timerdetach(struct knote *kn);
static int filt_timer(struct knote *kn, long hint);
static void filt_timertouch(struct knote *kn, struct kevent64_s *kev,
    long type);
static struct filterops timer_filtops = {
        .f_attach = filt_timerattach,
        .f_detach = filt_timerdetach,
        .f_event = filt_timer,
        .f_touch = filt_timertouch,
};

/* Helpers */
static void filt_timerexpire(void *knx, void *param1);
static int filt_timervalidate(struct knote *kn);
static void filt_timerupdate(struct knote *kn);
static void filt_timercancel(struct knote *kn);

#define TIMER_RUNNING           0x1
#define TIMER_CANCELWAIT        0x2

static lck_mtx_t _filt_timerlock;
static void filt_timerlock(void);
static void filt_timerunlock(void);

static zone_t knote_zone;

#define KN_HASH(val, mask)      (((val) ^ (val >> 8)) & (mask))

#if 0
extern struct filterops aio_filtops;
#endif

/* Mach portset filter */
extern struct filterops machport_filtops;

/* User filter */
static int filt_userattach(struct knote *kn);
static void filt_userdetach(struct knote *kn);
static int filt_user(struct knote *kn, long hint);
static void filt_usertouch(struct knote *kn, struct kevent64_s *kev,
    long type);
static struct filterops user_filtops = {
        .f_attach = filt_userattach,
        .f_detach = filt_userdetach,
        .f_event = filt_user,
        .f_touch = filt_usertouch,
};

/*
 * Table for all system-defined filters.
 */
static struct filterops *sysfilt_ops[] = {
        &file_filtops,                  /* EVFILT_READ */
        &file_filtops,                  /* EVFILT_WRITE */
#if 0
        &aio_filtops,                   /* EVFILT_AIO */
#else
        &bad_filtops,                   /* EVFILT_AIO */
#endif
        &file_filtops,                  /* EVFILT_VNODE */
        &proc_filtops,                  /* EVFILT_PROC */
        &sig_filtops,                   /* EVFILT_SIGNAL */
        &timer_filtops,                 /* EVFILT_TIMER */
        &machport_filtops,              /* EVFILT_MACHPORT */
        &fs_filtops,                    /* EVFILT_FS */
        &user_filtops,                  /* EVFILT_USER */
        &bad_filtops,                   /* unused */
#if VM_PRESSURE_EVENTS
        &vm_filtops,                    /* EVFILT_VM */
#else
        &bad_filtops,                   /* EVFILT_VM */
#endif
        &file_filtops,                  /* EVFILT_SOCK */
#if CONFIG_MEMORYSTATUS
        &memorystatus_filtops,  /* EVFILT_MEMORYSTATUS */
#else
        &bad_filtops,                   /* EVFILT_MEMORYSTATUS */
#endif
};

/*
 * kqueue/note lock attributes and implementations
 *
 *      kqueues have locks, while knotes have use counts
 *      Most of the knote state is guarded by the object lock.
 *      the knote "inuse" count and status use the kqueue lock.
 */
lck_grp_attr_t * kq_lck_grp_attr;
lck_grp_t * kq_lck_grp;
lck_attr_t * kq_lck_attr;

static inline void
kqlock(struct kqueue *kq)
{
        lck_spin_lock(&kq->kq_lock);
}

static inline void
kqunlock(struct kqueue *kq)
{
        lck_spin_unlock(&kq->kq_lock);
}

/*
 * Convert a kq lock to a knote use referece.
 *
 *      If the knote is being dropped, we can't get
 *      a use reference, so just return with it
 *      still locked.
 *      - kq locked at entry
 *      - unlock on exit if we get the use reference
 */
static int
kqlock2knoteuse(struct kqueue *kq, struct knote *kn)
{
        if (kn->kn_status & KN_DROPPING)
                return (0);
        kn->kn_inuse++;
        kqunlock(kq);
        return (1);
}

/*
 * Convert a kq lock to a knote use referece,
 * but wait for attach and drop events to complete.
 *
 *      If the knote is being dropped, we can't get
 *      a use reference, so just return with it
 *      still locked.
 *      - kq locked at entry
 *      - kq always unlocked on exit
 */
static int
kqlock2knoteusewait(struct kqueue *kq, struct knote *kn)
{
        if ((kn->kn_status & (KN_DROPPING | KN_ATTACHING)) != 0) {
                kn->kn_status |= KN_USEWAIT;
                wait_queue_assert_wait((wait_queue_t)kq->kq_wqs,
                    &kn->kn_status, THREAD_UNINT, 0);
                kqunlock(kq);
                thread_block(THREAD_CONTINUE_NULL);
                return (0);
        }
        kn->kn_inuse++;
        kqunlock(kq);
        return (1);
}

/*
 * Convert from a knote use reference back to kq lock.
 *
 *      Drop a use reference and wake any waiters if
 *      this is the last one.
 *
 *      The exit return indicates if the knote is
 *      still alive - but the kqueue lock is taken
 *      unconditionally.
 */
static int
knoteuse2kqlock(struct kqueue *kq, struct knote *kn)
{
        kqlock(kq);
        if (--kn->kn_inuse == 0) {
                if ((kn->kn_status & KN_ATTACHING) != 0) {
                        kn->kn_status &= ~KN_ATTACHING;
                }
                if ((kn->kn_status & KN_USEWAIT) != 0) {
                        kn->kn_status &= ~KN_USEWAIT;
                        wait_queue_wakeup_all((wait_queue_t)kq->kq_wqs,
                            &kn->kn_status, THREAD_AWAKENED);
                }
        }
        return ((kn->kn_status & KN_DROPPING) == 0);
}

/*
 * Convert a kq lock to a knote drop reference.
 *
 *      If the knote is in use, wait for the use count
 *      to subside.  We first mark our intention to drop
 *      it - keeping other users from "piling on."
 *      If we are too late, we have to wait for the
 *      other drop to complete.
 *
 *      - kq locked at entry
 *      - always unlocked on exit.
 *      - caller can't hold any locks that would prevent
 *        the other dropper from completing.
 */
static int
kqlock2knotedrop(struct kqueue *kq, struct knote *kn)
{
        int oktodrop;

        oktodrop = ((kn->kn_status & (KN_DROPPING | KN_ATTACHING)) == 0);
        kn->kn_status |= KN_DROPPING;
        if (oktodrop) {
                if (kn->kn_inuse == 0) {
                        kqunlock(kq);
                        return (oktodrop);
                }
        }
        kn->kn_status |= KN_USEWAIT;
        wait_queue_assert_wait((wait_queue_t)kq->kq_wqs, &kn->kn_status,
            THREAD_UNINT, 0);
        kqunlock(kq);
        thread_block(THREAD_CONTINUE_NULL);
        return (oktodrop);
}

/*
 * Release a knote use count reference.
 */
static void
knote_put(struct knote *kn)
{
        struct kqueue *kq = kn->kn_kq;

        kqlock(kq);
        if (--kn->kn_inuse == 0) {
                if ((kn->kn_status & KN_USEWAIT) != 0) {
                        kn->kn_status &= ~KN_USEWAIT;
                        wait_queue_wakeup_all((wait_queue_t)kq->kq_wqs,
                            &kn->kn_status, THREAD_AWAKENED);
                }
        }
        kqunlock(kq);
}

static int
filt_fileattach(struct knote *kn)
{
        return (fo_kqfilter(kn->kn_fp, kn, vfs_context_current()));
}

#define f_flag f_fglob->fg_flag
#define f_msgcount f_fglob->fg_msgcount
#define f_cred f_fglob->fg_cred
#define f_ops f_fglob->fg_ops
#define f_offset f_fglob->fg_offset
#define f_data f_fglob->fg_data

static void
filt_kqdetach(struct knote *kn)
{
        struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;

        kqlock(kq);
        KNOTE_DETACH(&kq->kq_sel.si_note, kn);
        kqunlock(kq);
}

/*ARGSUSED*/
static int
filt_kqueue(struct knote *kn, __unused long hint)
{
        struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;

        kn->kn_data = kq->kq_count;
        return (kn->kn_data > 0);
}

static int
filt_procattach(struct knote *kn)
{
        struct proc *p;

        assert(PID_MAX < NOTE_PDATAMASK);

        if ((kn->kn_sfflags & (NOTE_TRACK | NOTE_TRACKERR | NOTE_CHILD)) != 0)
                return (ENOTSUP);

        p = proc_find(kn->kn_id);
        if (p == NULL) {
                return (ESRCH);
        }

        const int NoteExitStatusBits = NOTE_EXIT | NOTE_EXITSTATUS;

        if ((kn->kn_sfflags & NoteExitStatusBits) == NoteExitStatusBits)
                do {
                        pid_t selfpid = proc_selfpid();

                        if (p->p_ppid == selfpid)
                                break;  /* parent => ok */

                        if ((p->p_lflag & P_LTRACED) != 0 &&
                            (p->p_oppid == selfpid))
                                break;  /* parent-in-waiting => ok */

                        proc_rele(p);
                        return (EACCES);
                } while (0);

        proc_klist_lock();

        kn->kn_flags |= EV_CLEAR;       /* automatically set */
        kn->kn_ptr.p_proc = p;          /* store the proc handle */

        KNOTE_ATTACH(&p->p_klist, kn);

        proc_klist_unlock();

        proc_rele(p);

        return (0);
}

/*
 * The knote may be attached to a different process, which may exit,
 * leaving nothing for the knote to be attached to.  In that case,
 * the pointer to the process will have already been nulled out.
 */
static void
filt_procdetach(struct knote *kn)
{
        struct proc *p;

        proc_klist_lock();

        p = kn->kn_ptr.p_proc;
        if (p != PROC_NULL) {
                kn->kn_ptr.p_proc = PROC_NULL;
                KNOTE_DETACH(&p->p_klist, kn);
        }

        proc_klist_unlock();
}

static int
filt_proc(struct knote *kn, long hint)
{
        /*
         * Note: a lot of bits in hint may be obtained from the knote
         * To free some of those bits, see <rdar://problem/12592988> Freeing up
         * bits in hint for filt_proc
         */
        /* hint is 0 when called from above */
        if (hint != 0) {
                u_int event;

                /* ALWAYS CALLED WITH proc_klist_lock when (hint != 0) */

                /*
                 * mask off extra data
                 */
                event = (u_int)hint & NOTE_PCTRLMASK;

                /*
                 * termination lifecycle events can happen while a debugger
                 * has reparented a process, in which case notifications
                 * should be quashed except to the tracing parent. When
                 * the debugger reaps the child (either via wait4(2) or
                 * process exit), the child will be reparented to the original
                 * parent and these knotes re-fired.
                 */
                if (event & NOTE_EXIT) {
                        if ((kn->kn_ptr.p_proc->p_oppid != 0)
                                && (kn->kn_kq->kq_p->p_pid != kn->kn_ptr.p_proc->p_ppid)) {
                                /*
                                 * This knote is not for the current ptrace(2) parent, ignore.
                                 */
                                return 0;
                        }
                }                                       

                /*
                 * if the user is interested in this event, record it.
                 */
                if (kn->kn_sfflags & event)
                        kn->kn_fflags |= event;

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
                if ((event == NOTE_REAP) || ((event == NOTE_EXIT) && !(kn->kn_sfflags & NOTE_REAP))) {
                        kn->kn_flags |= (EV_EOF | EV_ONESHOT);
                }
#pragma clang diagnostic pop


                /*
                 * The kernel has a wrapper in place that returns the same data
                 * as is collected here, in kn_data.  Any changes to how 
                 * NOTE_EXITSTATUS and NOTE_EXIT_DETAIL are collected
                 * should also be reflected in the proc_pidnoteexit() wrapper.
                 */
                if (event == NOTE_EXIT) {
                        kn->kn_data = 0;
                        if ((kn->kn_sfflags & NOTE_EXITSTATUS) != 0) {
                                kn->kn_fflags |= NOTE_EXITSTATUS;
                                kn->kn_data |= (hint & NOTE_PDATAMASK);
                        }
                        if ((kn->kn_sfflags & NOTE_EXIT_DETAIL) != 0) {
                                kn->kn_fflags |= NOTE_EXIT_DETAIL;
                                if ((kn->kn_ptr.p_proc->p_lflag &
                                    P_LTERM_DECRYPTFAIL) != 0) {
                                        kn->kn_data |= NOTE_EXIT_DECRYPTFAIL; 
                                }
                                if ((kn->kn_ptr.p_proc->p_lflag &
                                    P_LTERM_JETSAM) != 0) {
                                        kn->kn_data |= NOTE_EXIT_MEMORY;
                                        switch (kn->kn_ptr.p_proc->p_lflag &
                                            P_JETSAM_MASK) {
                                                case P_JETSAM_VMPAGESHORTAGE:
                                                        kn->kn_data |= NOTE_EXIT_MEMORY_VMPAGESHORTAGE;
                                                        break;
                                                case P_JETSAM_VMTHRASHING:
                                                        kn->kn_data |= NOTE_EXIT_MEMORY_VMTHRASHING;
                                                        break;
                                                case P_JETSAM_FCTHRASHING:
                                                        kn->kn_data |= NOTE_EXIT_MEMORY_FCTHRASHING;
                                                        break;
                                                case P_JETSAM_VNODE:
                                                        kn->kn_data |= NOTE_EXIT_MEMORY_VNODE;
                                                        break;
                                                case P_JETSAM_HIWAT:
                                                        kn->kn_data |= NOTE_EXIT_MEMORY_HIWAT;
                                                        break;
                                                case P_JETSAM_PID:
                                                        kn->kn_data |= NOTE_EXIT_MEMORY_PID;
                                                        break;
                                                case P_JETSAM_IDLEEXIT:
                                                        kn->kn_data |= NOTE_EXIT_MEMORY_IDLE;
                                                        break;
                                        }
                                }
                                if ((kn->kn_ptr.p_proc->p_csflags &
                                    CS_KILLED) != 0) {
                                        kn->kn_data |= NOTE_EXIT_CSERROR;
                                }
                        }
                }
        }

        /* atomic check, no locking need when called from above */
        return (kn->kn_fflags != 0);
}

#if VM_PRESSURE_EVENTS
/*
 * Virtual memory kevents
 *
 * author: Matt Jacobson [matthew_jacobson@apple.com]
 */

static int
filt_vmattach(struct knote *kn)
{
        /*
         * The note will be cleared once the information has been flushed to
         * the client. If there is still pressure, we will be re-alerted.
         */
        kn->kn_flags |= EV_CLEAR;
        return (vm_knote_register(kn));
}

static void
filt_vmdetach(struct knote *kn)
{
        vm_knote_unregister(kn);
}

static int
filt_vm(struct knote *kn, long hint)
{
        /* hint == 0 means this is just an alive? check (always true) */
        if (hint != 0) {
                const pid_t pid = (pid_t)hint;
                if ((kn->kn_sfflags & NOTE_VM_PRESSURE) &&
                    (kn->kn_kq->kq_p->p_pid == pid)) {
                        kn->kn_fflags |= NOTE_VM_PRESSURE;
                }
        }

        return (kn->kn_fflags != 0);
}
#endif /* VM_PRESSURE_EVENTS */

/*
 * filt_timervalidate - process data from user
 *
 *      Converts to either interval or deadline format.
 *
 *      The saved-data field in the knote contains the
 *      time value.  The saved filter-flags indicates
 *      the unit of measurement.
 *
 *      After validation, either the saved-data field
 *      contains the interval in absolute time, or ext[0]
 *      contains the expected deadline. If that deadline
 *      is in the past, ext[0] is 0.
 *
 *      Returns EINVAL for unrecognized units of time.
 *
 *      Timer filter lock is held.
 *
 */
static int
filt_timervalidate(struct knote *kn)
{
        uint64_t multiplier;
        uint64_t raw = 0;

        switch (kn->kn_sfflags & (NOTE_SECONDS|NOTE_USECONDS|NOTE_NSECONDS)) {
        case NOTE_SECONDS:
                multiplier = NSEC_PER_SEC;
                break;
        case NOTE_USECONDS:
                multiplier = NSEC_PER_USEC;
                break;
        case NOTE_NSECONDS:
                multiplier = 1;
                break;
        case 0: /* milliseconds (default) */
                multiplier = NSEC_PER_SEC / 1000;
                break;
        default:
                return (EINVAL);
        }

        /* transform the slop delta(leeway) in kn_ext[1] if passed to same time scale */
        if(kn->kn_sfflags & NOTE_LEEWAY){
                nanoseconds_to_absolutetime((uint64_t)kn->kn_ext[1] * multiplier, &raw);
                kn->kn_ext[1] = raw;
        }

        nanoseconds_to_absolutetime((uint64_t)kn->kn_sdata * multiplier, &raw);

        kn->kn_ext[0] = 0;
        kn->kn_sdata = 0;

        if (kn->kn_sfflags & NOTE_ABSOLUTE) {
                clock_sec_t seconds;
                clock_nsec_t nanoseconds;
                uint64_t now;

                clock_get_calendar_nanotime(&seconds, &nanoseconds);
                nanoseconds_to_absolutetime((uint64_t)seconds * NSEC_PER_SEC +
                    nanoseconds, &now);

                if (raw < now) {
                        /* time has already passed */
                        kn->kn_ext[0] = 0;
                } else {
                        raw -= now;
                        clock_absolutetime_interval_to_deadline(raw,
                            &kn->kn_ext[0]);
                }
        } else {
                kn->kn_sdata = raw;
        }

        return (0);
}

/*
 * filt_timerupdate - compute the next deadline
 *
 *      Repeating timers store their interval in kn_sdata. Absolute
 *      timers have already calculated the deadline, stored in ext[0].
 *
 *      On return, the next deadline (or zero if no deadline is needed)
 *      is stored in kn_ext[0].
 *
 *      Timer filter lock is held.
 */
static void
filt_timerupdate(struct knote *kn)
{
        /* if there's no interval, deadline is just in kn_ext[0] */
        if (kn->kn_sdata == 0)
                return;

        /* if timer hasn't fired before, fire in interval nsecs */
        if (kn->kn_ext[0] == 0) {
                clock_absolutetime_interval_to_deadline(kn->kn_sdata,
                    &kn->kn_ext[0]);
        } else {
                /*
                 * If timer has fired before, schedule the next pop
                 * relative to the last intended deadline.
                 *
                 * We could check for whether the deadline has expired,
                 * but the thread call layer can handle that.
                 */
                kn->kn_ext[0] += kn->kn_sdata;
        }
}

/*
 * filt_timerexpire - the timer callout routine
 *
 * Just propagate the timer event into the knote
 * filter routine (by going through the knote
 * synchronization point).  Pass a hint to
 * indicate this is a real event, not just a
 * query from above.
 */
static void
filt_timerexpire(void *knx, __unused void *spare)
{
        struct klist timer_list;
        struct knote *kn = knx;

        filt_timerlock();

        kn->kn_hookid &= ~TIMER_RUNNING;

        /* no "object" for timers, so fake a list */
        SLIST_INIT(&timer_list);
        SLIST_INSERT_HEAD(&timer_list, kn, kn_selnext);
        KNOTE(&timer_list, 1);

        /* if someone is waiting for timer to pop */
        if (kn->kn_hookid & TIMER_CANCELWAIT) {
                struct kqueue *kq = kn->kn_kq;
                wait_queue_wakeup_all((wait_queue_t)kq->kq_wqs, &kn->kn_hook,
                    THREAD_AWAKENED);
        }

        filt_timerunlock();
}

/*
 * Cancel a running timer (or wait for the pop).
 * Timer filter lock is held.
 */
static void
filt_timercancel(struct knote *kn)
{
        struct kqueue *kq = kn->kn_kq;
        thread_call_t callout = kn->kn_hook;
        boolean_t cancelled;

        if (kn->kn_hookid & TIMER_RUNNING) {
                /* cancel the callout if we can */
                cancelled = thread_call_cancel(callout);
                if (cancelled) {
                        kn->kn_hookid &= ~TIMER_RUNNING;
                } else {
                        /* we have to wait for the expire routine.  */
                        kn->kn_hookid |= TIMER_CANCELWAIT;
                        wait_queue_assert_wait((wait_queue_t)kq->kq_wqs,
                            &kn->kn_hook, THREAD_UNINT, 0);
                        filt_timerunlock();
                        thread_block(THREAD_CONTINUE_NULL);
                        filt_timerlock();
                        assert((kn->kn_hookid & TIMER_RUNNING) == 0);
                }
        }
}

/*
 * Allocate a thread call for the knote's lifetime, and kick off the timer.
 */
static int
filt_timerattach(struct knote *kn)
{
        thread_call_t callout;
        int error;

        callout = thread_call_allocate(filt_timerexpire, kn);
        if (NULL == callout)
                return (ENOMEM);

        filt_timerlock();
        error = filt_timervalidate(kn);
        if (error != 0) {
                filt_timerunlock();
                return (error);
        }

        kn->kn_hook = (void*)callout;
        kn->kn_hookid = 0;

        /* absolute=EV_ONESHOT */
        if (kn->kn_sfflags & NOTE_ABSOLUTE)
                kn->kn_flags |= EV_ONESHOT;

        filt_timerupdate(kn);
        if (kn->kn_ext[0]) {
                kn->kn_flags |= EV_CLEAR;
                unsigned int timer_flags = 0;
                if (kn->kn_sfflags & NOTE_CRITICAL)
                        timer_flags |= THREAD_CALL_DELAY_USER_CRITICAL;
                else if (kn->kn_sfflags & NOTE_BACKGROUND)
                        timer_flags |= THREAD_CALL_DELAY_USER_BACKGROUND;
                else
                        timer_flags |= THREAD_CALL_DELAY_USER_NORMAL;

                if (kn->kn_sfflags & NOTE_LEEWAY)
                        timer_flags |= THREAD_CALL_DELAY_LEEWAY;

                thread_call_enter_delayed_with_leeway(callout, NULL,
                                kn->kn_ext[0], kn->kn_ext[1], timer_flags);

                kn->kn_hookid |= TIMER_RUNNING;
        } else {
                /* fake immediate */
                kn->kn_data = 1;
        }

        filt_timerunlock();
        return (0);
}

/*
 * Shut down the timer if it's running, and free the callout.
 */
static void
filt_timerdetach(struct knote *kn)
{
        thread_call_t callout;

        filt_timerlock();

        callout = (thread_call_t)kn->kn_hook;
        filt_timercancel(kn);

        filt_timerunlock();

        thread_call_free(callout);
}



static int
filt_timer(struct knote *kn, long hint)
{
        int result;

        if (hint) {
                /* real timer pop -- timer lock held by filt_timerexpire */
                kn->kn_data++;

                if (((kn->kn_hookid & TIMER_CANCELWAIT) == 0) &&
                                ((kn->kn_flags & EV_ONESHOT) == 0)) {

                        /* evaluate next time to fire */
                        filt_timerupdate(kn);

                        if (kn->kn_ext[0]) {
                                unsigned int timer_flags = 0;

                                /* keep the callout and re-arm */
                                if (kn->kn_sfflags & NOTE_CRITICAL)
                                        timer_flags |= THREAD_CALL_DELAY_USER_CRITICAL;
                                else if (kn->kn_sfflags & NOTE_BACKGROUND)
                                        timer_flags |= THREAD_CALL_DELAY_USER_BACKGROUND;
                                else
                                        timer_flags |= THREAD_CALL_DELAY_USER_NORMAL;

                                if (kn->kn_sfflags & NOTE_LEEWAY)
                                        timer_flags |= THREAD_CALL_DELAY_LEEWAY;

                                thread_call_enter_delayed_with_leeway(kn->kn_hook, NULL,
                                                kn->kn_ext[0], kn->kn_ext[1], timer_flags);

                                kn->kn_hookid |= TIMER_RUNNING;
                        }
                }

                return (1);
        }

        /* user-query */
        filt_timerlock();

        result = (kn->kn_data != 0);

        filt_timerunlock();

        return (result);
}


/*
 * filt_timertouch - update knote with new user input
 *
 * Cancel and restart the timer based on new user data. When
 * the user picks up a knote, clear the count of how many timer
 * pops have gone off (in kn_data).
 */
static void
filt_timertouch(struct knote *kn, struct kevent64_s *kev, long type)
{
        int error;
        filt_timerlock();

        switch (type) {
        case EVENT_REGISTER:
                /* cancel current call */
                filt_timercancel(kn);

                /* recalculate deadline */
                kn->kn_sdata = kev->data;
                kn->kn_sfflags = kev->fflags;
                kn->kn_ext[0] = kev->ext[0];
                kn->kn_ext[1] = kev->ext[1];

                error = filt_timervalidate(kn);
                if (error) {
                        /* no way to report error, so mark it in the knote */
                        kn->kn_flags |= EV_ERROR;
                        kn->kn_data = error;
                        break;
                }

                /* start timer if necessary */
                filt_timerupdate(kn);

                if (kn->kn_ext[0]) {
                        unsigned int timer_flags = 0;
                        if (kn->kn_sfflags & NOTE_CRITICAL)
                                timer_flags |= THREAD_CALL_DELAY_USER_CRITICAL;
                        else if (kn->kn_sfflags & NOTE_BACKGROUND)
                                timer_flags |= THREAD_CALL_DELAY_USER_BACKGROUND;
                        else
                                timer_flags |= THREAD_CALL_DELAY_USER_NORMAL;

                        if (kn->kn_sfflags & NOTE_LEEWAY)
                                timer_flags |= THREAD_CALL_DELAY_LEEWAY;

                        thread_call_enter_delayed_with_leeway(kn->kn_hook, NULL,
                                        kn->kn_ext[0], kn->kn_ext[1], timer_flags);

                        kn->kn_hookid |= TIMER_RUNNING;
                } else {
                        /* pretend the timer has fired */
                        kn->kn_data = 1;
                }

                break;

        case EVENT_PROCESS:
                /* reset the timer pop count in kn_data */
                *kev = kn->kn_kevent;
                kev->ext[0] = 0;
                kn->kn_data = 0;
                if (kn->kn_flags & EV_CLEAR)
                        kn->kn_fflags = 0;
                break;
        default:
                panic("%s: - invalid type (%ld)", __func__, type);
                break;
        }

        filt_timerunlock();
}

static void
filt_timerlock(void)
{
        lck_mtx_lock(&_filt_timerlock);
}

static void
filt_timerunlock(void)
{
        lck_mtx_unlock(&_filt_timerlock);
}

static int
filt_userattach(struct knote *kn)
{
        /* EVFILT_USER knotes are not attached to anything in the kernel */
        kn->kn_hook = NULL;
        if (kn->kn_fflags & NOTE_TRIGGER) {
                kn->kn_hookid = 1;
        } else {
                kn->kn_hookid = 0;
        }
        return (0);
}

static void
filt_userdetach(__unused struct knote *kn)
{
        /* EVFILT_USER knotes are not attached to anything in the kernel */
}

static int
filt_user(struct knote *kn, __unused long hint)
{
        return (kn->kn_hookid);
}

static void
filt_usertouch(struct knote *kn, struct kevent64_s *kev, long type)
{
        uint32_t ffctrl;
        switch (type) {
        case EVENT_REGISTER:
                if (kev->fflags & NOTE_TRIGGER) {
                        kn->kn_hookid = 1;
                }

                ffctrl = kev->fflags & NOTE_FFCTRLMASK;
                kev->fflags &= NOTE_FFLAGSMASK;
                switch (ffctrl) {
                case NOTE_FFNOP:
                        break;
                case NOTE_FFAND:
                        OSBitAndAtomic(kev->fflags, &kn->kn_sfflags);
                        break;
                case NOTE_FFOR:
                        OSBitOrAtomic(kev->fflags, &kn->kn_sfflags);
                        break;
                case NOTE_FFCOPY:
                        kn->kn_sfflags = kev->fflags;
                        break;
                }
                kn->kn_sdata = kev->data;
                break;
        case EVENT_PROCESS:
                *kev = kn->kn_kevent;
                kev->fflags = (volatile UInt32)kn->kn_sfflags;
                kev->data = kn->kn_sdata;
                if (kn->kn_flags & EV_CLEAR) {
                        kn->kn_hookid = 0;
                        kn->kn_data = 0;
                        kn->kn_fflags = 0;
                }
                break;
        default:
                panic("%s: - invalid type (%ld)", __func__, type);
                break;
        }
}

/*
 * JMM - placeholder for not-yet-implemented filters
 */
static int
filt_badattach(__unused struct knote *kn)
{
        return (ENOTSUP);
}

struct kqueue *
kqueue_alloc(struct proc *p)
{
        struct filedesc *fdp = p->p_fd;
        struct kqueue *kq;

        MALLOC_ZONE(kq, struct kqueue *, sizeof (struct kqueue), M_KQUEUE,
            M_WAITOK);
        if (kq != NULL) {
                wait_queue_set_t wqs;

                wqs = wait_queue_set_alloc(SYNC_POLICY_FIFO |
                    SYNC_POLICY_PREPOST);
                if (wqs != NULL) {
                        bzero(kq, sizeof (struct kqueue));
                        lck_spin_init(&kq->kq_lock, kq_lck_grp, kq_lck_attr);
                        TAILQ_INIT(&kq->kq_head);
                        kq->kq_wqs = wqs;
                        kq->kq_p = p;
                } else {
                        FREE_ZONE(kq, sizeof (struct kqueue), M_KQUEUE);
                }
        }

        if (fdp->fd_knlistsize < 0) {
                proc_fdlock(p);
                if (fdp->fd_knlistsize < 0)
                        fdp->fd_knlistsize = 0; /* this process has had a kq */
                proc_fdunlock(p);
        }

        return (kq);
}

/*
 * kqueue_dealloc - detach all knotes from a kqueue and free it
 *
 *      We walk each list looking for knotes referencing this
 *      this kqueue.  If we find one, we try to drop it.  But
 *      if we fail to get a drop reference, that will wait
 *      until it is dropped.  So, we can just restart again
 *      safe in the assumption that the list will eventually
 *      not contain any more references to this kqueue (either
 *      we dropped them all, or someone else did).
 *
 *      Assumes no new events are being added to the kqueue.
 *      Nothing locked on entry or exit.
 */
void
kqueue_dealloc(struct kqueue *kq)
{
        struct proc *p = kq->kq_p;
        struct filedesc *fdp = p->p_fd;
        struct knote *kn;
        int i;

        proc_fdlock(p);
        for (i = 0; i < fdp->fd_knlistsize; i++) {
                kn = SLIST_FIRST(&fdp->fd_knlist[i]);
                while (kn != NULL) {
                        if (kq == kn->kn_kq) {
                                kqlock(kq);
                                proc_fdunlock(p);
                                /* drop it ourselves or wait */
                                if (kqlock2knotedrop(kq, kn)) {
                                        kn->kn_fop->f_detach(kn);
                                        knote_drop(kn, p);
                                }
                                proc_fdlock(p);
                                /* start over at beginning of list */
                                kn = SLIST_FIRST(&fdp->fd_knlist[i]);
                                continue;
                        }
                        kn = SLIST_NEXT(kn, kn_link);
                }
        }
        if (fdp->fd_knhashmask != 0) {
                for (i = 0; i < (int)fdp->fd_knhashmask + 1; i++) {
                        kn = SLIST_FIRST(&fdp->fd_knhash[i]);
                        while (kn != NULL) {
                                if (kq == kn->kn_kq) {
                                        kqlock(kq);
                                        proc_fdunlock(p);
                                        /* drop it ourselves or wait */
                                        if (kqlock2knotedrop(kq, kn)) {
                                                kn->kn_fop->f_detach(kn);
                                                knote_drop(kn, p);
                                        }
                                        proc_fdlock(p);
                                        /* start over at beginning of list */
                                        kn = SLIST_FIRST(&fdp->fd_knhash[i]);
                                        continue;
                                }
                                kn = SLIST_NEXT(kn, kn_link);
                        }
                }
        }
        proc_fdunlock(p);

        /*
         * before freeing the wait queue set for this kqueue,
         * make sure it is unlinked from all its containing (select) sets.
         */
        wait_queue_unlink_all((wait_queue_t)kq->kq_wqs);
        wait_queue_set_free(kq->kq_wqs);
        lck_spin_destroy(&kq->kq_lock, kq_lck_grp);
        FREE_ZONE(kq, sizeof (struct kqueue), M_KQUEUE);
}

int
kqueue_body(struct proc *p, fp_allocfn_t fp_zalloc, void *cra, int32_t *retval)
{
        struct kqueue *kq;
        struct fileproc *fp;
        int fd, error;

        error = falloc_withalloc(p,
            &fp, &fd, vfs_context_current(), fp_zalloc, cra);
        if (error) {
                return (error);
        }

        kq = kqueue_alloc(p);
        if (kq == NULL) {
                fp_free(p, fd, fp);
                return (ENOMEM);
        }

        fp->f_flag = FREAD | FWRITE;
        fp->f_ops = &kqueueops;
        fp->f_data = kq;

        proc_fdlock(p);
        *fdflags(p, fd) |= UF_EXCLOSE;
        procfdtbl_releasefd(p, fd, NULL);
        fp_drop(p, fd, fp, 1);
        proc_fdunlock(p);

        *retval = fd;
        return (error);
}

int
kqueue(struct proc *p, __unused struct kqueue_args *uap, int32_t *retval)
{
        return (kqueue_body(p, fileproc_alloc_init, NULL, retval));
}

static int
kevent_copyin(user_addr_t *addrp, struct kevent64_s *kevp, struct proc *p,
    int iskev64)
{
        int advance;
        int error;

        if (iskev64) {
                advance = sizeof (struct kevent64_s);
                error = copyin(*addrp, (caddr_t)kevp, advance);
        } else if (IS_64BIT_PROCESS(p)) {
                struct user64_kevent kev64;
                bzero(kevp, sizeof (struct kevent64_s));

                advance = sizeof (kev64);
                error = copyin(*addrp, (caddr_t)&kev64, advance);
                if (error)
                        return (error);
                kevp->ident = kev64.ident;
                kevp->filter = kev64.filter;
                kevp->flags = kev64.flags;
                kevp->fflags = kev64.fflags;
                kevp->data = kev64.data;
                kevp->udata = kev64.udata;
        } else {
                struct user32_kevent kev32;
                bzero(kevp, sizeof (struct kevent64_s));

                advance = sizeof (kev32);
                error = copyin(*addrp, (caddr_t)&kev32, advance);
                if (error)
                        return (error);
                kevp->ident = (uintptr_t)kev32.ident;
                kevp->filter = kev32.filter;
                kevp->flags = kev32.flags;
                kevp->fflags = kev32.fflags;
                kevp->data = (intptr_t)kev32.data;
                kevp->udata = CAST_USER_ADDR_T(kev32.udata);
        }
        if (!error)
                *addrp += advance;
        return (error);
}

static int
kevent_copyout(struct kevent64_s *kevp, user_addr_t *addrp, struct proc *p,
    int iskev64)
{
        int advance;
        int error;

        if (iskev64) {
                advance = sizeof (struct kevent64_s);
                error = copyout((caddr_t)kevp, *addrp, advance);
        } else if (IS_64BIT_PROCESS(p)) {
                struct user64_kevent kev64;

                /*
                 * deal with the special case of a user-supplied
                 * value of (uintptr_t)-1.
                 */
                kev64.ident = (kevp->ident == (uintptr_t)-1) ?
                    (uint64_t)-1LL : (uint64_t)kevp->ident;

                kev64.filter = kevp->filter;
                kev64.flags = kevp->flags;
                kev64.fflags = kevp->fflags;
                kev64.data = (int64_t) kevp->data;
                kev64.udata = kevp->udata;
                advance = sizeof (kev64);
                error = copyout((caddr_t)&kev64, *addrp, advance);
        } else {
                struct user32_kevent kev32;

                kev32.ident = (uint32_t)kevp->ident;
                kev32.filter = kevp->filter;
                kev32.flags = kevp->flags;
                kev32.fflags = kevp->fflags;
                kev32.data = (int32_t)kevp->data;
                kev32.udata = kevp->udata;
                advance = sizeof (kev32);
                error = copyout((caddr_t)&kev32, *addrp, advance);
        }
        if (!error)
                *addrp += advance;
        return (error);
}

/*
 * kevent_continue - continue a kevent syscall after blocking
 *
 *      assume we inherit a use count on the kq fileglob.
 */

static void
kevent_continue(__unused struct kqueue *kq, void *data, int error)
{
        struct _kevent *cont_args;
        struct fileproc *fp;
        int32_t *retval;
        int noutputs;
        int fd;
        struct proc *p = current_proc();

        cont_args = (struct _kevent *)data;
        noutputs = cont_args->eventout;
        retval = cont_args->retval;
        fd = cont_args->fd;
        fp = cont_args->fp;

        fp_drop(p, fd, fp, 0);

        /* don't restart after signals... */
        if (error == ERESTART)
                error = EINTR;
        else if (error == EWOULDBLOCK)
                error = 0;
        if (error == 0)
                *retval = noutputs;
        unix_syscall_return(error);
}

/*
 * kevent - [syscall] register and wait for kernel events
 *
 */
int
kevent(struct proc *p, struct kevent_args *uap, int32_t *retval)
{
        return (kevent_internal(p,
            0,
            uap->changelist,
            uap->nchanges,
            uap->eventlist,
            uap->nevents,
            uap->fd,
            uap->timeout,
            0, /* no flags from old kevent() call */
            retval));
}

int
kevent64(struct proc *p, struct kevent64_args *uap, int32_t *retval)
{
        return (kevent_internal(p,
            1,
            uap->changelist,
            uap->nchanges,
            uap->eventlist,
            uap->nevents,
            uap->fd,
            uap->timeout,
            uap->flags,
            retval));
}

static int
kevent_internal(struct proc *p, int iskev64, user_addr_t changelist,
    int nchanges, user_addr_t ueventlist, int nevents, int fd,
    user_addr_t utimeout, __unused unsigned int flags,
    int32_t *retval)
{
        struct _kevent *cont_args;
        uthread_t ut;
        struct kqueue *kq;
        struct fileproc *fp;
        struct kevent64_s kev;
        int error, noutputs;
        struct timeval atv;

        /* convert timeout to absolute - if we have one */
        if (utimeout != USER_ADDR_NULL) {
                struct timeval rtv;
                if (IS_64BIT_PROCESS(p)) {
                        struct user64_timespec ts;
                        error = copyin(utimeout, &ts, sizeof(ts));
                        if ((ts.tv_sec & 0xFFFFFFFF00000000ull) != 0)
                                error = EINVAL;
                        else
                                TIMESPEC_TO_TIMEVAL(&rtv, &ts);
                } else {
                        struct user32_timespec ts;
                        error = copyin(utimeout, &ts, sizeof(ts));
                        TIMESPEC_TO_TIMEVAL(&rtv, &ts);
                }
                if (error)
                        return (error);
                if (itimerfix(&rtv))
                        return (EINVAL);
                getmicrouptime(&atv);
                timevaladd(&atv, &rtv);
        } else {
                atv.tv_sec = 0;
                atv.tv_usec = 0;
        }

        /* get a usecount for the kq itself */
        if ((error = fp_getfkq(p, fd, &fp, &kq)) != 0)
                return (error);

        /* each kq should only be used for events of one type */
        kqlock(kq);
        if (kq->kq_state & (KQ_KEV32 | KQ_KEV64)) {
                if (((iskev64 && (kq->kq_state & KQ_KEV32)) ||
                        (!iskev64 && (kq->kq_state & KQ_KEV64)))) {
                        error = EINVAL;
                        kqunlock(kq);
                        goto errorout;
                }
        } else {
                kq->kq_state |= (iskev64 ? KQ_KEV64 : KQ_KEV32);
        }
        kqunlock(kq);

        /* register all the change requests the user provided... */
        noutputs = 0;
        while (nchanges > 0 && error == 0) {
                error = kevent_copyin(&changelist, &kev, p, iskev64);
                if (error)
                        break;

                kev.flags &= ~EV_SYSFLAGS;
                error = kevent_register(kq, &kev, p);
                if ((error || (kev.flags & EV_RECEIPT)) && nevents > 0) {
                        kev.flags = EV_ERROR;
                        kev.data = error;
                        error = kevent_copyout(&kev, &ueventlist, p, iskev64);
                        if (error == 0) {
                                nevents--;
                                noutputs++;
                        }
                }
                nchanges--;
        }

        /* store the continuation/completion data in the uthread */
        ut = (uthread_t)get_bsdthread_info(current_thread());
        cont_args = &ut->uu_kevent.ss_kevent;
        cont_args->fp = fp;
        cont_args->fd = fd;
        cont_args->retval = retval;
        cont_args->eventlist = ueventlist;
        cont_args->eventcount = nevents;
        cont_args->eventout = noutputs;
        cont_args->eventsize = iskev64;

        if (nevents > 0 && noutputs == 0 && error == 0)
                error = kqueue_scan(kq, kevent_callback,
                    kevent_continue, cont_args,
                    &atv, p);
        kevent_continue(kq, cont_args, error);

errorout:
        fp_drop(p, fd, fp, 0);
        return (error);
}


/*
 * kevent_callback - callback for each individual event
 *
 * called with nothing locked
 * caller holds a reference on the kqueue
 */
static int
kevent_callback(__unused struct kqueue *kq, struct kevent64_s *kevp,
    void *data)
{
        struct _kevent *cont_args;
        int error;
        int iskev64;

        cont_args = (struct _kevent *)data;
        assert(cont_args->eventout < cont_args->eventcount);

        iskev64 = cont_args->eventsize;

        /*
         * Copy out the appropriate amount of event data for this user.
         */
        error = kevent_copyout(kevp, &cont_args->eventlist, current_proc(),
            iskev64);

        /*
         * If there isn't space for additional events, return
         * a harmless error to stop the processing here
         */
        if (error == 0 && ++cont_args->eventout == cont_args->eventcount)
                error = EWOULDBLOCK;
        return (error);
}

/*
 * kevent_description - format a description of a kevent for diagnostic output
 *
 * called with a 128-byte string buffer
 */

char *
kevent_description(struct kevent64_s *kevp, char *s, size_t n)
{
        snprintf(s, n,
            "kevent="
            "{.ident=%#llx, .filter=%d, .flags=%#x, .fflags=%#x, .data=%#llx, .udata=%#llx, .ext[0]=%#llx, .ext[1]=%#llx}",
            kevp->ident,
            kevp->filter,
            kevp->flags,
            kevp->fflags,
            kevp->data,
            kevp->udata,
            kevp->ext[0],
            kevp->ext[1]);

        return (s);
}

/*
 * kevent_register - add a new event to a kqueue
 *
 *      Creates a mapping between the event source and
 *      the kqueue via a knote data structure.
 *
 *      Because many/most the event sources are file
 *      descriptor related, the knote is linked off
 *      the filedescriptor table for quick access.
 *
 *      called with nothing locked
 *      caller holds a reference on the kqueue
 */

int
kevent_register(struct kqueue *kq, struct kevent64_s *kev,
    __unused struct proc *ctxp)
{
        struct proc *p = kq->kq_p;
        struct filedesc *fdp = p->p_fd;
        struct filterops *fops;
        struct fileproc *fp = NULL;
        struct knote *kn = NULL;
        int error = 0;

        if (kev->filter < 0) {
                if (kev->filter + EVFILT_SYSCOUNT < 0)
                        return (EINVAL);
                fops = sysfilt_ops[~kev->filter];       /* to 0-base index */
        } else {
                /*
                 * XXX
                 * filter attach routine is responsible for insuring that
                 * the identifier can be attached to it.
                 */
                printf("unknown filter: %d\n", kev->filter);
                return (EINVAL);
        }

restart:
        /* this iocount needs to be dropped if it is not registered */
        proc_fdlock(p);
        if (fops->f_isfd && (error = fp_lookup(p, kev->ident, &fp, 1)) != 0) {
                proc_fdunlock(p);
                return (error);
        }

        if (fops->f_isfd) {
                /* fd-based knotes are linked off the fd table */
                if (kev->ident < (u_int)fdp->fd_knlistsize) {
                        SLIST_FOREACH(kn, &fdp->fd_knlist[kev->ident], kn_link)
                                if (kq == kn->kn_kq &&
                                    kev->filter == kn->kn_filter)
                                        break;
                }
        } else {
                /* hash non-fd knotes here too */
                if (fdp->fd_knhashmask != 0) {
                        struct klist *list;

                        list = &fdp->fd_knhash[
                            KN_HASH((u_long)kev->ident, fdp->fd_knhashmask)];
                        SLIST_FOREACH(kn, list, kn_link)
                                if (kev->ident == kn->kn_id &&
                                    kq == kn->kn_kq &&
                                    kev->filter == kn->kn_filter)
                                        break;
                }
        }

        /*
         * kn now contains the matching knote, or NULL if no match
         */
        if (kn == NULL) {
                if ((kev->flags & (EV_ADD|EV_DELETE)) == EV_ADD) {
                        kn = knote_alloc();
                        if (kn == NULL) {
                                proc_fdunlock(p);
                                error = ENOMEM;
                                goto done;
                        }
                        kn->kn_fp = fp;
                        kn->kn_kq = kq;
                        kn->kn_tq = &kq->kq_head;
                        kn->kn_fop = fops;
                        kn->kn_sfflags = kev->fflags;
                        kn->kn_sdata = kev->data;
                        kev->fflags = 0;
                        kev->data = 0;
                        kn->kn_kevent = *kev;
                        kn->kn_inuse = 1;  /* for f_attach() */
                        kn->kn_status = KN_ATTACHING;

                        /* before anyone can find it */
                        if (kev->flags & EV_DISABLE)
                                kn->kn_status |= KN_DISABLED;

                        error = knote_fdpattach(kn, fdp, p);
                        proc_fdunlock(p);

                        if (error) {
                                knote_free(kn);
                                goto done;
                        }

                        /*
                         * apply reference count to knote structure, and
                         * do not release it at the end of this routine.
                         */
                        fp = NULL;

                        error = fops->f_attach(kn);

                        kqlock(kq);

                        if (error != 0) {
                                /*
                                 * Failed to attach correctly, so drop.
                                 * All other possible users/droppers
                                 * have deferred to us.
                                 */
                                kn->kn_status |= KN_DROPPING;
                                kqunlock(kq);
                                knote_drop(kn, p);
                                goto done;
                        } else if (kn->kn_status & KN_DROPPING) {
                                /*
                                 * Attach succeeded, but someone else
                                 * deferred their drop - now we have
                                 * to do it for them (after detaching).
                                 */
                                kqunlock(kq);
                                kn->kn_fop->f_detach(kn);
                                knote_drop(kn, p);
                                goto done;
                        }
                        kn->kn_status &= ~KN_ATTACHING;
                        kqunlock(kq);
                } else {
                        proc_fdunlock(p);
                        error = ENOENT;
                        goto done;
                }
        } else {
                /* existing knote - get kqueue lock */
                kqlock(kq);
                proc_fdunlock(p);

                if (kev->flags & EV_DELETE) {
                        knote_dequeue(kn);
                        kn->kn_status |= KN_DISABLED;
                        if (kqlock2knotedrop(kq, kn)) {
                                kn->kn_fop->f_detach(kn);
                                knote_drop(kn, p);
                        }
                        goto done;
                }

                /* update status flags for existing knote */
                if (kev->flags & EV_DISABLE) {
                        knote_dequeue(kn);
                        kn->kn_status |= KN_DISABLED;
                } else if (kev->flags & EV_ENABLE) {
                        kn->kn_status &= ~KN_DISABLED;
                        if (kn->kn_status & KN_ACTIVE)
                                knote_enqueue(kn);
                }

                /*
                 * The user may change some filter values after the
                 * initial EV_ADD, but doing so will not reset any
                 * filter which have already been triggered.
                 */
                kn->kn_kevent.udata = kev->udata;
                if (fops->f_isfd || fops->f_touch == NULL) {
                        kn->kn_sfflags = kev->fflags;
                        kn->kn_sdata = kev->data;
                }

                /*
                 * If somebody is in the middle of dropping this
                 * knote - go find/insert a new one.  But we have
                 * wait for this one to go away first. Attaches
                 * running in parallel may also drop/modify the
                 * knote.  Wait for those to complete as well and
                 * then start over if we encounter one.
                 */
                if (!kqlock2knoteusewait(kq, kn)) {
                        /* kqueue, proc_fdlock both unlocked */
                        goto restart;
                }

                /*
                 * Call touch routine to notify filter of changes
                 * in filter values.
                 */
                if (!fops->f_isfd && fops->f_touch != NULL)
                        fops->f_touch(kn, kev, EVENT_REGISTER);
        }
        /* still have use ref on knote */

        /*
         * If the knote is not marked to always stay enqueued,
         * invoke the filter routine to see if it should be
         * enqueued now.
         */
        if ((kn->kn_status & KN_STAYQUEUED) == 0 && kn->kn_fop->f_event(kn, 0)) {
                if (knoteuse2kqlock(kq, kn))
                        knote_activate(kn, 1);
                kqunlock(kq);
        } else {
                knote_put(kn);
        }

done:
        if (fp != NULL)
                fp_drop(p, kev->ident, fp, 0);
        return (error);
}


/*
 * knote_process - process a triggered event
 *
 *      Validate that it is really still a triggered event
 *      by calling the filter routines (if necessary).  Hold
 *      a use reference on the knote to avoid it being detached.
 *      If it is still considered triggered, invoke the callback
 *      routine provided and move it to the provided inprocess
 *      queue.
 *
 *      caller holds a reference on the kqueue.
 *      kqueue locked on entry and exit - but may be dropped
 */
static int
knote_process(struct knote *kn,
    kevent_callback_t callback,
    void *data,
    struct kqtailq *inprocessp,
    struct proc *p)
{
        struct kqueue *kq = kn->kn_kq;
        struct kevent64_s kev;
        int touch;
        int result;
        int error;

        /*
         * Determine the kevent state we want to return.
         *
         * Some event states need to be revalidated before returning
         * them, others we take the snapshot at the time the event
         * was enqueued.
         *
         * Events with non-NULL f_touch operations must be touched.
         * Triggered events must fill in kev for the callback.
         *
         * Convert our lock to a use-count and call the event's
         * filter routine(s) to update.
         */
        if ((kn->kn_status & KN_DISABLED) != 0) {
                result = 0;
                touch = 0;
        } else {
                int revalidate;

                result = 1;
                revalidate = ((kn->kn_status & KN_STAYQUEUED) != 0 ||
                    (kn->kn_flags & EV_ONESHOT) == 0);
                touch = (!kn->kn_fop->f_isfd && kn->kn_fop->f_touch != NULL);

                if (revalidate || touch) {
                        if (revalidate)
                                knote_deactivate(kn);

                        /* call the filter/touch routines with just a ref */
                        if (kqlock2knoteuse(kq, kn)) {
                                /* if we have to revalidate, call the filter */
                                if (revalidate) {
                                        result = kn->kn_fop->f_event(kn, 0);
                                }

                                /*
                                 * capture the kevent data - using touch if
                                 * specified
                                 */
                                if (result && touch) {
                                        kn->kn_fop->f_touch(kn, &kev,
                                            EVENT_PROCESS);
                                }

                                /*
                                 * convert back to a kqlock - bail if the knote
                                 * went away
                                 */
                                if (!knoteuse2kqlock(kq, kn)) {
                                        return (EJUSTRETURN);
                                } else if (result) {
                                        /*
                                         * if revalidated as alive, make sure
                                         * it's active
                                         */
                                        if (!(kn->kn_status & KN_ACTIVE)) {
                                                knote_activate(kn, 0);
                                        }

                                        /*
                                         * capture all events that occurred
                                         * during filter
                                         */
                                        if (!touch) {
                                                kev = kn->kn_kevent;
                                        }

                                } else if ((kn->kn_status & KN_STAYQUEUED) == 0) {
                                        /*
                                         * was already dequeued, so just bail on
                                         * this one
                                         */
                                        return (EJUSTRETURN);
                                }
                        } else {
                                return (EJUSTRETURN);
                        }
                } else {
                        kev = kn->kn_kevent;
                }
        }

        /* move knote onto inprocess queue */
        assert(kn->kn_tq == &kq->kq_head);
        TAILQ_REMOVE(&kq->kq_head, kn, kn_tqe);
        kn->kn_tq = inprocessp;
        TAILQ_INSERT_TAIL(inprocessp, kn, kn_tqe);

        /*
         * Determine how to dispatch the knote for future event handling.
         * not-fired: just return (do not callout).
         * One-shot: deactivate it.
         * Clear: deactivate and clear the state.
         * Dispatch: don't clear state, just deactivate it and mark it disabled.
         * All others: just leave where they are.
         */

        if (result == 0) {
                return (EJUSTRETURN);
        } else if ((kn->kn_flags & EV_ONESHOT) != 0) {
                knote_deactivate(kn);
                if (kqlock2knotedrop(kq, kn)) {
                        kn->kn_fop->f_detach(kn);
                        knote_drop(kn, p);
                }
        } else if ((kn->kn_flags & (EV_CLEAR | EV_DISPATCH)) != 0) {
                if ((kn->kn_flags & EV_DISPATCH) != 0) {
                        /* deactivate and disable all dispatch knotes */
                        knote_deactivate(kn);
                        kn->kn_status |= KN_DISABLED;
                } else if (!touch || kn->kn_fflags == 0) {
                        /* only deactivate if nothing since the touch */
                        knote_deactivate(kn);
                }
                if (!touch && (kn->kn_flags & EV_CLEAR) != 0) {
                        /* manually clear non-touch knotes */
                        kn->kn_data = 0;
                        kn->kn_fflags = 0;
                }
                kqunlock(kq);
        } else {
                /*
                 * leave on inprocess queue.  We'll
                 * move all the remaining ones back
                 * the kq queue and wakeup any
                 * waiters when we are done.
                 */
                kqunlock(kq);
        }

        /* callback to handle each event as we find it */
        error = (callback)(kq, &kev, data);

        kqlock(kq);
        return (error);
}

/*
 * Return 0 to indicate that processing should proceed,
 * -1 if there is nothing to process.
 *
 * Called with kqueue locked and returns the same way,
 * but may drop lock temporarily.
 */
static int
kqueue_begin_processing(struct kqueue *kq)
{
        for (;;) {
                if (kq->kq_count == 0) {
                        return (-1);
                }

                /* if someone else is processing the queue, wait */
                if (kq->kq_nprocess != 0) {
                        wait_queue_assert_wait((wait_queue_t)kq->kq_wqs,
                            &kq->kq_nprocess, THREAD_UNINT, 0);
                        kq->kq_state |= KQ_PROCWAIT;
                        kqunlock(kq);
                        thread_block(THREAD_CONTINUE_NULL);
                        kqlock(kq);
                } else {
                        kq->kq_nprocess = 1;
                        return (0);
                }
        }
}

/*
 * Called with kqueue lock held.
 */
static void
kqueue_end_processing(struct kqueue *kq)
{
        kq->kq_nprocess = 0;
        if (kq->kq_state & KQ_PROCWAIT) {
                kq->kq_state &= ~KQ_PROCWAIT;
                wait_queue_wakeup_all((wait_queue_t)kq->kq_wqs,
                    &kq->kq_nprocess, THREAD_AWAKENED);
        }
}

/*
 * kqueue_process - process the triggered events in a kqueue
 *
 *      Walk the queued knotes and validate that they are
 *      really still triggered events by calling the filter
 *      routines (if necessary).  Hold a use reference on
 *      the knote to avoid it being detached. For each event
 *      that is still considered triggered, invoke the
 *      callback routine provided.
 *
 *      caller holds a reference on the kqueue.
 *      kqueue locked on entry and exit - but may be dropped
 *      kqueue list locked (held for duration of call)
 */

static int
kqueue_process(struct kqueue *kq,
    kevent_callback_t callback,
    void *data,
    int *countp,
    struct proc *p)
{
        struct kqtailq inprocess;
        struct knote *kn;
        int nevents;
        int error;

        TAILQ_INIT(&inprocess);

        if (kqueue_begin_processing(kq) == -1) {
                *countp = 0;
                /* Nothing to process */
                return (0);
        }

        /*
         * Clear any pre-posted status from previous runs, so we
         * only detect events that occur during this run.
         */
        wait_queue_sub_clearrefs(kq->kq_wqs);

        /*
         * loop through the enqueued knotes, processing each one and
         * revalidating those that need it. As they are processed,
         * they get moved to the inprocess queue (so the loop can end).
         */
        error = 0;
        nevents = 0;

        while (error == 0 &&
            (kn = TAILQ_FIRST(&kq->kq_head)) != NULL) {
                error = knote_process(kn, callback, data, &inprocess, p);
                if (error == EJUSTRETURN)
                        error = 0;
                else
                        nevents++;
        }

        /*
         * With the kqueue still locked, move any knotes
         * remaining on the inprocess queue back to the
         * kq's queue and wake up any waiters.
         */
        while ((kn = TAILQ_FIRST(&inprocess)) != NULL) {
                assert(kn->kn_tq == &inprocess);
                TAILQ_REMOVE(&inprocess, kn, kn_tqe);
                kn->kn_tq = &kq->kq_head;
                TAILQ_INSERT_TAIL(&kq->kq_head, kn, kn_tqe);
        }

        kqueue_end_processing(kq);

        *countp = nevents;
        return (error);
}


static void
kqueue_scan_continue(void *data, wait_result_t wait_result)
{
        thread_t self = current_thread();
        uthread_t ut = (uthread_t)get_bsdthread_info(self);
        struct _kqueue_scan * cont_args = &ut->uu_kevent.ss_kqueue_scan;
        struct kqueue *kq = (struct kqueue *)data;
        int error;
        int count;

        /* convert the (previous) wait_result to a proper error */
        switch (wait_result) {
        case THREAD_AWAKENED:
                kqlock(kq);
                error = kqueue_process(kq, cont_args->call, cont_args, &count,
                    current_proc());
                if (error == 0 && count == 0) {
                        wait_queue_assert_wait((wait_queue_t)kq->kq_wqs,
                            KQ_EVENT, THREAD_ABORTSAFE, cont_args->deadline);
                        kq->kq_state |= KQ_SLEEP;
                        kqunlock(kq);
                        thread_block_parameter(kqueue_scan_continue, kq);
                        /* NOTREACHED */
                }
                kqunlock(kq);
                break;
        case THREAD_TIMED_OUT:
                error = EWOULDBLOCK;
                break;
        case THREAD_INTERRUPTED:
                error = EINTR;
                break;
        default:
                panic("%s: - invalid wait_result (%d)", __func__,
                    wait_result);
                error = 0;
        }

        /* call the continuation with the results */
        assert(cont_args->cont != NULL);
        (cont_args->cont)(kq, cont_args->data, error);
}


/*
 * kqueue_scan - scan and wait for events in a kqueue
 *
 *      Process the triggered events in a kqueue.
 *
 *      If there are no events triggered arrange to
 *      wait for them. If the caller provided a
 *      continuation routine, then kevent_scan will
 *      also.
 *
 *      The callback routine must be valid.
 *      The caller must hold a use-count reference on the kq.
 */

int
kqueue_scan(struct kqueue *kq,
            kevent_callback_t callback,
            kqueue_continue_t continuation,
            void *data,
            struct timeval *atvp,
            struct proc *p)
{
        thread_continue_t cont = THREAD_CONTINUE_NULL;
        uint64_t deadline;
        int error;
        int first;

        assert(callback != NULL);

        first = 1;
        for (;;) {
                wait_result_t wait_result;
                int count;

                /*
                 * Make a pass through the kq to find events already
                 * triggered.
                 */
                kqlock(kq);
                error = kqueue_process(kq, callback, data, &count, p);
                if (error || count)
                        break; /* lock still held */

                /* looks like we have to consider blocking */
                if (first) {
                        first = 0;
                        /* convert the timeout to a deadline once */
                        if (atvp->tv_sec || atvp->tv_usec) {
                                uint64_t now;

                                clock_get_uptime(&now);
                                nanoseconds_to_absolutetime((uint64_t)atvp->tv_sec * NSEC_PER_SEC +
                                                            atvp->tv_usec * (long)NSEC_PER_USEC,
                                                            &deadline);
                                if (now >= deadline) {
                                        /* non-blocking call */
                                        error = EWOULDBLOCK;
                                        break; /* lock still held */
                                }
                                deadline -= now;
                                clock_absolutetime_interval_to_deadline(deadline, &deadline);
                        } else {
                                deadline = 0;   /* block forever */
                        }

                        if (continuation) {
                                uthread_t ut = (uthread_t)get_bsdthread_info(current_thread());
                                struct _kqueue_scan *cont_args = &ut->uu_kevent.ss_kqueue_scan;

                                cont_args->call = callback;
                                cont_args->cont = continuation;
                                cont_args->deadline = deadline;
                                cont_args->data = data;
                                cont = kqueue_scan_continue;
                        }
                }

                /* go ahead and wait */
                wait_queue_assert_wait_with_leeway((wait_queue_t)kq->kq_wqs,
                    KQ_EVENT, THREAD_ABORTSAFE, TIMEOUT_URGENCY_USER_NORMAL,
                    deadline, 0);
                kq->kq_state |= KQ_SLEEP;
                kqunlock(kq);
                wait_result = thread_block_parameter(cont, kq);
                /* NOTREACHED if (continuation != NULL) */

                switch (wait_result) {
                case THREAD_AWAKENED:
                        continue;
                case THREAD_TIMED_OUT:
                        return (EWOULDBLOCK);
                case THREAD_INTERRUPTED:
                        return (EINTR);
                default:
                        panic("%s: - bad wait_result (%d)", __func__,
                            wait_result);
                        error = 0;
                }
        }
        kqunlock(kq);
        return (error);
}


/*
 * XXX
 * This could be expanded to call kqueue_scan, if desired.
 */
/*ARGSUSED*/
static int
kqueue_read(__unused struct fileproc *fp,
    __unused struct uio *uio,
    __unused int flags,
    __unused vfs_context_t ctx)
{
        return (ENXIO);
}

/*ARGSUSED*/
static int
kqueue_write(__unused struct fileproc *fp,
    __unused struct uio *uio,
    __unused int flags,
    __unused vfs_context_t ctx)
{
        return (ENXIO);
}

/*ARGSUSED*/
static int
kqueue_ioctl(__unused struct fileproc *fp,
    __unused u_long com,
    __unused caddr_t data,
    __unused vfs_context_t ctx)
{
        return (ENOTTY);
}

/*ARGSUSED*/
static int
kqueue_select(struct fileproc *fp, int which, void *wql,
    __unused vfs_context_t ctx)
{
        struct kqueue *kq = (struct kqueue *)fp->f_data;
        struct knote *kn;
        struct kqtailq inprocessq;
        int retnum = 0;

        if (which != FREAD)
                return (0);

        TAILQ_INIT(&inprocessq);

        kqlock(kq);
        /*
         * If this is the first pass, link the wait queue associated with the
         * the kqueue onto the wait queue set for the select().  Normally we
         * use selrecord() for this, but it uses the wait queue within the
         * selinfo structure and we need to use the main one for the kqueue to
         * catch events from KN_STAYQUEUED sources. So we do the linkage manually.
         * (The select() call will unlink them when it ends).
         */
        if (wql != NULL) {
                thread_t cur_act = current_thread();
                struct uthread * ut = get_bsdthread_info(cur_act);

                kq->kq_state |= KQ_SEL;
                wait_queue_link_noalloc((wait_queue_t)kq->kq_wqs, ut->uu_wqset,
                    (wait_queue_link_t)wql);
        }

        if (kqueue_begin_processing(kq) == -1) {
                kqunlock(kq);
                return (0);
        }

        if (kq->kq_count != 0) {
                /*
                 * there is something queued - but it might be a
                 * KN_STAYQUEUED knote, which may or may not have
                 * any events pending.  So, we have to walk the
                 * list of knotes to see, and peek at the stay-
                 * queued ones to be really sure.
                 */
                while ((kn = (struct knote *)TAILQ_FIRST(&kq->kq_head)) != NULL) {
                        if ((kn->kn_status & KN_STAYQUEUED) == 0) {
                                retnum = 1;
                                goto out;
                        }

                        TAILQ_REMOVE(&kq->kq_head, kn, kn_tqe);
                        TAILQ_INSERT_TAIL(&inprocessq, kn, kn_tqe);

                        if (kqlock2knoteuse(kq, kn)) {
                                unsigned peek;

                                peek = kn->kn_fop->f_peek(kn);
                                if (knoteuse2kqlock(kq, kn)) {
                                        if (peek > 0) {
                                                retnum = 1;
                                                goto out;
                                        }
                                } else {
                                        retnum = 0;
                                }
                        }
                }
        }

out:
        /* Return knotes to active queue */
        while ((kn = TAILQ_FIRST(&inprocessq)) != NULL) {
                TAILQ_REMOVE(&inprocessq, kn, kn_tqe);
                kn->kn_tq = &kq->kq_head;
                TAILQ_INSERT_TAIL(&kq->kq_head, kn, kn_tqe);
        }

        kqueue_end_processing(kq);
        kqunlock(kq);
        return (retnum);
}

/*
 * kqueue_close -
 */
/*ARGSUSED*/
static int
kqueue_close(struct fileglob *fg, __unused vfs_context_t ctx)
{
        struct kqueue *kq = (struct kqueue *)fg->fg_data;

        kqueue_dealloc(kq);
        fg->fg_data = NULL;
        return (0);
}

/*ARGSUSED*/
/*
 * The callers has taken a use-count reference on this kqueue and will donate it
 * to the kqueue we are being added to.  This keeps the kqueue from closing until
 * that relationship is torn down.
 */
static int
kqueue_kqfilter(__unused struct fileproc *fp, struct knote *kn, __unused vfs_context_t ctx)
{
        struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
        struct kqueue *parentkq = kn->kn_kq;

        if (parentkq == kq ||
            kn->kn_filter != EVFILT_READ)
                return (1);

        /*
         * We have to avoid creating a cycle when nesting kqueues
         * inside another.  Rather than trying to walk the whole
         * potential DAG of nested kqueues, we just use a simple
         * ceiling protocol.  When a kqueue is inserted into another,
         * we check that the (future) parent is not already nested
         * into another kqueue at a lower level than the potenial
         * child (because it could indicate a cycle).  If that test
         * passes, we just mark the nesting levels accordingly.
         */

        kqlock(parentkq);
        if (parentkq->kq_level > 0 &&
            parentkq->kq_level < kq->kq_level)
        {
                kqunlock(parentkq);
                return (1);
        } else {
                /* set parent level appropriately */
                if (parentkq->kq_level == 0)
                        parentkq->kq_level = 2;
                if (parentkq->kq_level < kq->kq_level + 1)
                        parentkq->kq_level = kq->kq_level + 1;
                kqunlock(parentkq);

                kn->kn_fop = &kqread_filtops;
                kqlock(kq);
                KNOTE_ATTACH(&kq->kq_sel.si_note, kn);
                /* indicate nesting in child, if needed */
                if (kq->kq_level == 0)
                        kq->kq_level = 1;
                kqunlock(kq);
                return (0);
        }
}

/*
 * kqueue_drain - called when kq is closed
 */
/*ARGSUSED*/
static int
kqueue_drain(struct fileproc *fp, __unused vfs_context_t ctx)
{
        struct kqueue *kq = (struct kqueue *)fp->f_fglob->fg_data;
        kqlock(kq);
        kqueue_wakeup(kq, 1);
        kqunlock(kq);
        return (0);
}

/*ARGSUSED*/
int
kqueue_stat(struct kqueue *kq, void *ub, int isstat64, proc_t p)
{
        kqlock(kq);
        if (isstat64 != 0) {
                struct stat64 *sb64 = (struct stat64 *)ub;

                bzero((void *)sb64, sizeof(*sb64));
                sb64->st_size = kq->kq_count;
                if (kq->kq_state & KQ_KEV64)
                        sb64->st_blksize = sizeof(struct kevent64_s);
                else
                        sb64->st_blksize = IS_64BIT_PROCESS(p) ? sizeof(struct user64_kevent) : sizeof(struct user32_kevent);
                sb64->st_mode = S_IFIFO;
        } else {
                struct stat *sb = (struct stat *)ub;

                bzero((void *)sb, sizeof(*sb));
                sb->st_size = kq->kq_count;
                if (kq->kq_state & KQ_KEV64)
                        sb->st_blksize = sizeof(struct kevent64_s);
                else
                        sb->st_blksize = IS_64BIT_PROCESS(p) ? sizeof(struct user64_kevent) : sizeof(struct user32_kevent);
                sb->st_mode = S_IFIFO;
        }
        kqunlock(kq);
        return (0);
}

/*
 * Called with the kqueue locked
 */
static void
kqueue_wakeup(struct kqueue *kq, int closed)
{
        if ((kq->kq_state & (KQ_SLEEP | KQ_SEL)) != 0 || kq->kq_nprocess > 0) {
                kq->kq_state &= ~(KQ_SLEEP | KQ_SEL);
                wait_queue_wakeup_all((wait_queue_t)kq->kq_wqs, KQ_EVENT,
                    (closed) ? THREAD_INTERRUPTED : THREAD_AWAKENED);
        }
}

void
klist_init(struct klist *list)
{
        SLIST_INIT(list);
}


/*
 * Query/Post each knote in the object's list
 *
 *      The object lock protects the list. It is assumed
 *      that the filter/event routine for the object can
 *      determine that the object is already locked (via
 *      the hint) and not deadlock itself.
 *
 *      The object lock should also hold off pending
 *      detach/drop operations.  But we'll prevent it here
 *      too - just in case.
 */
void
knote(struct klist *list, long hint)
{
        struct knote *kn;

        SLIST_FOREACH(kn, list, kn_selnext) {
                struct kqueue *kq = kn->kn_kq;

                kqlock(kq);
                if (kqlock2knoteuse(kq, kn)) {
                        int result;

                        /* call the event with only a use count */
                        result = kn->kn_fop->f_event(kn, hint);

                        /* if its not going away and triggered */
                        if (knoteuse2kqlock(kq, kn) && result)
                                knote_activate(kn, 1);
                        /* lock held again */
                }
                kqunlock(kq);
        }
}

/*
 * attach a knote to the specified list.  Return true if this is the first entry.
 * The list is protected by whatever lock the object it is associated with uses.
 */
int
knote_attach(struct klist *list, struct knote *kn)
{
        int ret = SLIST_EMPTY(list);
        SLIST_INSERT_HEAD(list, kn, kn_selnext);
        return (ret);
}

/*
 * detach a knote from the specified list.  Return true if that was the last entry.
 * The list is protected by whatever lock the object it is associated with uses.
 */
int
knote_detach(struct klist *list, struct knote *kn)
{
        SLIST_REMOVE(list, kn, knote, kn_selnext);
        return (SLIST_EMPTY(list));
}

/*
 * For a given knote, link a provided wait queue directly with the kqueue.
 * Wakeups will happen via recursive wait queue support.  But nothing will move
 * the knote to the active list at wakeup (nothing calls knote()).  Instead,
 * we permanently enqueue them here.
 *
 * kqueue and knote references are held by caller.
 *
 * caller provides the wait queue link structure.
 */
int
knote_link_wait_queue(struct knote *kn, struct wait_queue *wq, wait_queue_link_t wql)
{
        struct kqueue *kq = kn->kn_kq;
        kern_return_t kr;

        kr = wait_queue_link_noalloc(wq, kq->kq_wqs, wql);
        if (kr == KERN_SUCCESS) {
                knote_markstayqueued(kn);
                return (0);
        } else {
                return (EINVAL);
        }
}

/*
 * Unlink the provided wait queue from the kqueue associated with a knote.
 * Also remove it from the magic list of directly attached knotes.
 *
 * Note that the unlink may have already happened from the other side, so
 * ignore any failures to unlink and just remove it from the kqueue list.
 *
 * On success, caller is responsible for the link structure
 */
int
knote_unlink_wait_queue(struct knote *kn, struct wait_queue *wq, wait_queue_link_t *wqlp)
{
        struct kqueue *kq = kn->kn_kq;
        kern_return_t kr;

        kr = wait_queue_unlink_nofree(wq, kq->kq_wqs, wqlp);
        kqlock(kq);
        kn->kn_status &= ~KN_STAYQUEUED;
        knote_dequeue(kn);
        kqunlock(kq);
        return ((kr != KERN_SUCCESS) ? EINVAL : 0);
}

/*
 * remove all knotes referencing a specified fd
 *
 * Essentially an inlined knote_remove & knote_drop
 * when we know for sure that the thing is a file
 *
 * Entered with the proc_fd lock already held.
 * It returns the same way, but may drop it temporarily.
 */
void
knote_fdclose(struct proc *p, int fd)
{
        struct filedesc *fdp = p->p_fd;
        struct klist *list;
        struct knote *kn;

        list = &fdp->fd_knlist[fd];
        while ((kn = SLIST_FIRST(list)) != NULL) {
                struct kqueue *kq = kn->kn_kq;

                if (kq->kq_p != p)
                        panic("%s: proc mismatch (kq->kq_p=%p != p=%p)",
                            __func__, kq->kq_p, p);

                kqlock(kq);
                proc_fdunlock(p);

                /*
                 * Convert the lock to a drop ref.
                 * If we get it, go ahead and drop it.
                 * Otherwise, we waited for it to
                 * be dropped by the other guy, so
                 * it is safe to move on in the list.
                 */
                if (kqlock2knotedrop(kq, kn)) {
                        kn->kn_fop->f_detach(kn);
                        knote_drop(kn, p);
                }

                proc_fdlock(p);

                /* the fd tables may have changed - start over */
                list = &fdp->fd_knlist[fd];
        }
}

/* proc_fdlock held on entry (and exit) */
static int
knote_fdpattach(struct knote *kn, struct filedesc *fdp, struct proc *p)
{
        struct klist *list = NULL;

        if (! kn->kn_fop->f_isfd) {
                if (fdp->fd_knhashmask == 0)
                        fdp->fd_knhash = hashinit(CONFIG_KN_HASHSIZE, M_KQUEUE,
                            &fdp->fd_knhashmask);
                list = &fdp->fd_knhash[KN_HASH(kn->kn_id, fdp->fd_knhashmask)];
        } else {
                if ((u_int)fdp->fd_knlistsize <= kn->kn_id) {
                        u_int size = 0;

                        if (kn->kn_id >= (uint64_t)p->p_rlimit[RLIMIT_NOFILE].rlim_cur
                            || kn->kn_id >= (uint64_t)maxfiles)
                                return (EINVAL);

                        /* have to grow the fd_knlist */
                        size = fdp->fd_knlistsize;
                        while (size <= kn->kn_id)
                                size += KQEXTENT;

                        if (size >= (UINT_MAX/sizeof(struct klist *)))
                                return (EINVAL);

                        MALLOC(list, struct klist *,
                            size * sizeof(struct klist *), M_KQUEUE, M_WAITOK);
                        if (list == NULL)
                                return (ENOMEM);

                        bcopy((caddr_t)fdp->fd_knlist, (caddr_t)list,
                            fdp->fd_knlistsize * sizeof(struct klist *));
                        bzero((caddr_t)list +
                            fdp->fd_knlistsize * sizeof(struct klist *),
                            (size - fdp->fd_knlistsize) * sizeof(struct klist *));
                        FREE(fdp->fd_knlist, M_KQUEUE);
                        fdp->fd_knlist = list;
                        fdp->fd_knlistsize = size;
                }
                list = &fdp->fd_knlist[kn->kn_id];
        }
        SLIST_INSERT_HEAD(list, kn, kn_link);
        return (0);
}



/*
 * should be called at spl == 0, since we don't want to hold spl
 * while calling fdrop and free.
 */
static void
knote_drop(struct knote *kn, __unused struct proc *ctxp)
{
        struct kqueue *kq = kn->kn_kq;
        struct proc *p = kq->kq_p;
        struct filedesc *fdp = p->p_fd;
        struct klist *list;
        int needswakeup;

        proc_fdlock(p);
        if (kn->kn_fop->f_isfd)
                list = &fdp->fd_knlist[kn->kn_id];
        else
                list = &fdp->fd_knhash[KN_HASH(kn->kn_id, fdp->fd_knhashmask)];

        SLIST_REMOVE(list, kn, knote, kn_link);
        kqlock(kq);
        knote_dequeue(kn);
        needswakeup = (kn->kn_status & KN_USEWAIT);
        kqunlock(kq);
        proc_fdunlock(p);

        if (needswakeup)
                wait_queue_wakeup_all((wait_queue_t)kq->kq_wqs, &kn->kn_status,
                    THREAD_AWAKENED);

        if (kn->kn_fop->f_isfd)
                fp_drop(p, kn->kn_id, kn->kn_fp, 0);

        knote_free(kn);
}

/* called with kqueue lock held */
static void
knote_activate(struct knote *kn, int propagate)
{
        struct kqueue *kq = kn->kn_kq;

        kn->kn_status |= KN_ACTIVE;
        knote_enqueue(kn);
        kqueue_wakeup(kq, 0);

        /* this is a real event: wake up the parent kq, too */
        if (propagate)
                KNOTE(&kq->kq_sel.si_note, 0);
}

/* called with kqueue lock held */
static void
knote_deactivate(struct knote *kn)
{
        kn->kn_status &= ~KN_ACTIVE;
        knote_dequeue(kn);
}

/* called with kqueue lock held */
static void
knote_enqueue(struct knote *kn)
{
        if ((kn->kn_status & (KN_QUEUED | KN_STAYQUEUED)) == KN_STAYQUEUED ||
            (kn->kn_status & (KN_QUEUED | KN_STAYQUEUED | KN_DISABLED)) == 0) {
                struct kqtailq *tq = kn->kn_tq;
                struct kqueue *kq = kn->kn_kq;

                TAILQ_INSERT_TAIL(tq, kn, kn_tqe);
                kn->kn_status |= KN_QUEUED;
                kq->kq_count++;
        }
}

/* called with kqueue lock held */
static void
knote_dequeue(struct knote *kn)
{
        struct kqueue *kq = kn->kn_kq;

        if ((kn->kn_status & (KN_QUEUED | KN_STAYQUEUED)) == KN_QUEUED) {
                struct kqtailq *tq = kn->kn_tq;

                TAILQ_REMOVE(tq, kn, kn_tqe);
                kn->kn_tq = &kq->kq_head;
                kn->kn_status &= ~KN_QUEUED;
                kq->kq_count--;
        }
}

void
knote_init(void)
{
        knote_zone = zinit(sizeof(struct knote), 8192*sizeof(struct knote),
            8192, "knote zone");

        /* allocate kq lock group attribute and group */
        kq_lck_grp_attr = lck_grp_attr_alloc_init();

        kq_lck_grp = lck_grp_alloc_init("kqueue",  kq_lck_grp_attr);

        /* Allocate kq lock attribute */
        kq_lck_attr = lck_attr_alloc_init();

        /* Initialize the timer filter lock */
        lck_mtx_init(&_filt_timerlock, kq_lck_grp, kq_lck_attr);

#if VM_PRESSURE_EVENTS
        /* Initialize the vm pressure list lock */
        vm_pressure_init(kq_lck_grp, kq_lck_attr);
#endif

#if CONFIG_MEMORYSTATUS
        /* Initialize the memorystatus list lock */
        memorystatus_kevent_init(kq_lck_grp, kq_lck_attr);
#endif
}
SYSINIT(knote, SI_SUB_PSEUDO, SI_ORDER_ANY, knote_init, NULL)

static struct knote *
knote_alloc(void)
{
        return ((struct knote *)zalloc(knote_zone));
}

static void
knote_free(struct knote *kn)
{
        zfree(knote_zone, kn);
}

#if SOCKETS
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/domain.h>
#include <sys/mbuf.h>
#include <sys/kern_event.h>
#include <sys/malloc.h>
#include <sys/sys_domain.h>
#include <sys/syslog.h>

#ifndef ROUNDUP64
#define ROUNDUP64(x) P2ROUNDUP((x), sizeof (u_int64_t))
#endif

#ifndef ADVANCE64
#define ADVANCE64(p, n) (void*)((char *)(p) + ROUNDUP64(n))
#endif

static lck_grp_attr_t *kev_lck_grp_attr;
static lck_attr_t *kev_lck_attr;
static lck_grp_t *kev_lck_grp;
static decl_lck_rw_data(,kev_lck_data);
static lck_rw_t *kev_rwlock = &kev_lck_data;

static int kev_attach(struct socket *so, int proto, struct proc *p);
static int kev_detach(struct socket *so);
static int kev_control(struct socket *so, u_long cmd, caddr_t data,
    struct ifnet *ifp, struct proc *p);
static lck_mtx_t * event_getlock(struct socket *, int);
static int event_lock(struct socket *, int, void *);
static int event_unlock(struct socket *, int, void *);

static int event_sofreelastref(struct socket *);
static void kev_delete(struct kern_event_pcb *);

static struct pr_usrreqs event_usrreqs = {
        .pru_attach =           kev_attach,
        .pru_control =          kev_control,
        .pru_detach =           kev_detach,
        .pru_soreceive =        soreceive,
};

static struct protosw eventsw[] = {
{
        .pr_type =              SOCK_RAW,
        .pr_protocol =          SYSPROTO_EVENT,
        .pr_flags =             PR_ATOMIC,
        .pr_usrreqs =           &event_usrreqs,
        .pr_lock =              event_lock,
        .pr_unlock =            event_unlock,
        .pr_getlock =           event_getlock,
}
};

__private_extern__ int kevt_getstat SYSCTL_HANDLER_ARGS;
__private_extern__ int kevt_pcblist SYSCTL_HANDLER_ARGS;

SYSCTL_NODE(_net_systm, OID_AUTO, kevt,
        CTLFLAG_RW|CTLFLAG_LOCKED, 0, "Kernel event family");

struct kevtstat kevtstat;
SYSCTL_PROC(_net_systm_kevt, OID_AUTO, stats,
    CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
    kevt_getstat, "S,kevtstat", "");

SYSCTL_PROC(_net_systm_kevt, OID_AUTO, pcblist,
        CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
        kevt_pcblist, "S,xkevtpcb", "");

static lck_mtx_t *
event_getlock(struct socket *so, int locktype)
{
#pragma unused(locktype)
        struct kern_event_pcb *ev_pcb = (struct kern_event_pcb *)so->so_pcb;

        if (so->so_pcb != NULL)  {
                if (so->so_usecount < 0)
                        panic("%s: so=%p usecount=%d lrh= %s\n", __func__,
                            so, so->so_usecount, solockhistory_nr(so));
                        /* NOTREACHED */
        } else {
                panic("%s: so=%p NULL NO so_pcb %s\n", __func__,
                    so, solockhistory_nr(so));
                /* NOTREACHED */
        }
        return (&ev_pcb->evp_mtx);
}

static int
event_lock(struct socket *so, int refcount, void *lr)
{
        void *lr_saved;

        if (lr == NULL)
                lr_saved = __builtin_return_address(0);
        else
                lr_saved = lr;

        if (so->so_pcb != NULL) {
                lck_mtx_lock(&((struct kern_event_pcb *)so->so_pcb)->evp_mtx);
        } else  {
                panic("%s: so=%p NO PCB! lr=%p lrh= %s\n", __func__,
                    so, lr_saved, solockhistory_nr(so));
                /* NOTREACHED */
        }

        if (so->so_usecount < 0) {
                panic("%s: so=%p so_pcb=%p lr=%p ref=%d lrh= %s\n", __func__,
                    so, so->so_pcb, lr_saved, so->so_usecount,
                    solockhistory_nr(so));
                /* NOTREACHED */
        }

        if (refcount)
                so->so_usecount++;

        so->lock_lr[so->next_lock_lr] = lr_saved;
        so->next_lock_lr = (so->next_lock_lr+1) % SO_LCKDBG_MAX;
        return (0);
}

static int
event_unlock(struct socket *so, int refcount, void *lr)
{
        void *lr_saved;
        lck_mtx_t *mutex_held;

        if (lr == NULL)
                lr_saved = __builtin_return_address(0);
        else
                lr_saved = lr;

        if (refcount)
                so->so_usecount--;

        if (so->so_usecount < 0) {
                panic("%s: so=%p usecount=%d lrh= %s\n", __func__,
                    so, so->so_usecount, solockhistory_nr(so));
                /* NOTREACHED */
        }
        if (so->so_pcb == NULL) {
                panic("%s: so=%p NO PCB usecount=%d lr=%p lrh= %s\n", __func__,
                    so, so->so_usecount, (void *)lr_saved,
                    solockhistory_nr(so));
                /* NOTREACHED */
        }
        mutex_held = (&((struct kern_event_pcb *)so->so_pcb)->evp_mtx);

        lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);
        so->unlock_lr[so->next_unlock_lr] = lr_saved;
        so->next_unlock_lr = (so->next_unlock_lr+1) % SO_LCKDBG_MAX;

        if (so->so_usecount == 0) {
                VERIFY(so->so_flags & SOF_PCBCLEARING);
                event_sofreelastref(so);
        } else {
                lck_mtx_unlock(mutex_held);
        }

        return (0);
}

static int
event_sofreelastref(struct socket *so)
{
        struct kern_event_pcb *ev_pcb = (struct kern_event_pcb *)so->so_pcb;

        lck_mtx_assert(&(ev_pcb->evp_mtx), LCK_MTX_ASSERT_OWNED);

        so->so_pcb = NULL;

        /*
         * Disable upcall in the event another thread is in kev_post_msg()
         * appending record to the receive socket buffer, since sbwakeup()
         * may release the socket lock otherwise.
         */
        so->so_rcv.sb_flags &= ~SB_UPCALL;
        so->so_snd.sb_flags &= ~SB_UPCALL;
        so->so_event = sonullevent;
        lck_mtx_unlock(&(ev_pcb->evp_mtx));

        lck_mtx_assert(&(ev_pcb->evp_mtx), LCK_MTX_ASSERT_NOTOWNED);
        lck_rw_lock_exclusive(kev_rwlock);
        LIST_REMOVE(ev_pcb, evp_link);
        kevtstat.kes_pcbcount--;
        kevtstat.kes_gencnt++;
        lck_rw_done(kev_rwlock);
        kev_delete(ev_pcb);

        sofreelastref(so, 1);
        return (0);
}

static int event_proto_count = (sizeof (eventsw) / sizeof (struct protosw));

static
struct kern_event_head kern_event_head;

static u_int32_t static_event_id = 0;

#define EVPCB_ZONE_MAX          65536
#define EVPCB_ZONE_NAME         "kerneventpcb"
static struct zone *ev_pcb_zone;

/*
 * Install the protosw's for the NKE manager.  Invoked at extension load time
 */
void
kern_event_init(struct domain *dp)
{
        struct protosw *pr;
        int i;

        VERIFY(!(dp->dom_flags & DOM_INITIALIZED));
        VERIFY(dp == systemdomain);

        kev_lck_grp_attr = lck_grp_attr_alloc_init();
        if (kev_lck_grp_attr == NULL) {
                panic("%s: lck_grp_attr_alloc_init failed\n", __func__);
                /* NOTREACHED */
        }

        kev_lck_grp = lck_grp_alloc_init("Kernel Event Protocol",
            kev_lck_grp_attr);
        if (kev_lck_grp == NULL) {
                panic("%s: lck_grp_alloc_init failed\n", __func__);
                /* NOTREACHED */
        }

        kev_lck_attr = lck_attr_alloc_init();
        if (kev_lck_attr == NULL) {
                panic("%s: lck_attr_alloc_init failed\n", __func__);
                /* NOTREACHED */
        }

        lck_rw_init(kev_rwlock, kev_lck_grp, kev_lck_attr);
        if (kev_rwlock == NULL) {
                panic("%s: lck_mtx_alloc_init failed\n", __func__);
                /* NOTREACHED */
        }

        for (i = 0, pr = &eventsw[0]; i < event_proto_count; i++, pr++)
                net_add_proto(pr, dp, 1);

        ev_pcb_zone = zinit(sizeof(struct kern_event_pcb),
            EVPCB_ZONE_MAX * sizeof(struct kern_event_pcb), 0, EVPCB_ZONE_NAME);
        if (ev_pcb_zone == NULL) {
                panic("%s: failed allocating ev_pcb_zone", __func__);
                /* NOTREACHED */
        }
        zone_change(ev_pcb_zone, Z_EXPAND, TRUE);
        zone_change(ev_pcb_zone, Z_CALLERACCT, TRUE);
}

static int
kev_attach(struct socket *so, __unused int proto, __unused struct proc *p)
{
        int error = 0;
        struct kern_event_pcb *ev_pcb;

        error = soreserve(so, KEV_SNDSPACE, KEV_RECVSPACE);
        if (error != 0)
                return (error);

        if ((ev_pcb = (struct kern_event_pcb *)zalloc(ev_pcb_zone)) == NULL) {
                return (ENOBUFS);
        }
        bzero(ev_pcb, sizeof(struct kern_event_pcb));
        lck_mtx_init(&ev_pcb->evp_mtx, kev_lck_grp, kev_lck_attr);

        ev_pcb->evp_socket = so;
        ev_pcb->evp_vendor_code_filter = 0xffffffff;

        so->so_pcb = (caddr_t) ev_pcb;
        lck_rw_lock_exclusive(kev_rwlock);
        LIST_INSERT_HEAD(&kern_event_head, ev_pcb, evp_link);
        kevtstat.kes_pcbcount++;
        kevtstat.kes_gencnt++;
        lck_rw_done(kev_rwlock);

        return (error);
}

static void
kev_delete(struct kern_event_pcb *ev_pcb)
{
        VERIFY(ev_pcb != NULL);
        lck_mtx_destroy(&ev_pcb->evp_mtx, kev_lck_grp);
        zfree(ev_pcb_zone, ev_pcb);
}

static int
kev_detach(struct socket *so)
{
        struct kern_event_pcb *ev_pcb = (struct kern_event_pcb *) so->so_pcb;

        if (ev_pcb != NULL) {
                soisdisconnected(so);
                so->so_flags |= SOF_PCBCLEARING;
        }

        return (0);
}

/*
 * For now, kev_vendor_code and mbuf_tags use the same
 * mechanism.
 */
errno_t kev_vendor_code_find(
        const char      *string,
        u_int32_t       *out_vendor_code)
{
        if (strlen(string) >= KEV_VENDOR_CODE_MAX_STR_LEN) {
                return (EINVAL);
        }
        return (net_str_id_find_internal(string, out_vendor_code,
            NSI_VENDOR_CODE, 1));
}

errno_t
kev_msg_post(struct kev_msg *event_msg)
{
        mbuf_tag_id_t min_vendor, max_vendor;

        net_str_id_first_last(&min_vendor, &max_vendor, NSI_VENDOR_CODE);

        if (event_msg == NULL)
                return (EINVAL);

        /* 
         * Limit third parties to posting events for registered vendor codes
         * only
         */
        if (event_msg->vendor_code < min_vendor ||
            event_msg->vendor_code > max_vendor) {
                OSIncrementAtomic64((SInt64 *)&kevtstat.kes_badvendor);
                return (EINVAL);
        }
        return (kev_post_msg(event_msg));
}

int
kev_post_msg(struct kev_msg *event_msg)
{
        struct mbuf *m, *m2;
        struct kern_event_pcb *ev_pcb;
        struct kern_event_msg *ev;
        char *tmp;
        u_int32_t total_size;
        int i;

        /* Verify the message is small enough to fit in one mbuf w/o cluster */
        total_size = KEV_MSG_HEADER_SIZE;

        for (i = 0; i < 5; i++) {
                if (event_msg->dv[i].data_length == 0)
                        break;
                total_size += event_msg->dv[i].data_length;
        }

        if (total_size > MLEN) {
                OSIncrementAtomic64((SInt64 *)&kevtstat.kes_toobig);
                return (EMSGSIZE);
        }

        m = m_get(M_DONTWAIT, MT_DATA);
        if (m == 0) {
                OSIncrementAtomic64((SInt64 *)&kevtstat.kes_nomem);
                return (ENOMEM);
        }
        ev = mtod(m, struct kern_event_msg *);
        total_size = KEV_MSG_HEADER_SIZE;

        tmp = (char *) &ev->event_data[0];
        for (i = 0; i < 5; i++) {
                if (event_msg->dv[i].data_length == 0)
                        break;

                total_size += event_msg->dv[i].data_length;
                bcopy(event_msg->dv[i].data_ptr, tmp,
                    event_msg->dv[i].data_length);
                tmp += event_msg->dv[i].data_length;
        }

        ev->id = ++static_event_id;
        ev->total_size   = total_size;
        ev->vendor_code  = event_msg->vendor_code;
        ev->kev_class    = event_msg->kev_class;
        ev->kev_subclass = event_msg->kev_subclass;
        ev->event_code   = event_msg->event_code;

        m->m_len = total_size;
        lck_rw_lock_shared(kev_rwlock);
        for (ev_pcb = LIST_FIRST(&kern_event_head);
            ev_pcb;
            ev_pcb = LIST_NEXT(ev_pcb, evp_link)) {
                lck_mtx_lock(&ev_pcb->evp_mtx);
                if (ev_pcb->evp_socket->so_pcb == NULL) {
                        lck_mtx_unlock(&ev_pcb->evp_mtx);
                        continue;
                }
                if (ev_pcb->evp_vendor_code_filter != KEV_ANY_VENDOR) {
                        if (ev_pcb->evp_vendor_code_filter != ev->vendor_code) {
                                lck_mtx_unlock(&ev_pcb->evp_mtx);
                                continue;
                        }

                        if (ev_pcb->evp_class_filter != KEV_ANY_CLASS) {
                                if (ev_pcb->evp_class_filter != ev->kev_class) {
                                        lck_mtx_unlock(&ev_pcb->evp_mtx);
                                        continue;
                                }

                                if ((ev_pcb->evp_subclass_filter !=
                                    KEV_ANY_SUBCLASS) &&
                                    (ev_pcb->evp_subclass_filter !=
                                    ev->kev_subclass)) {
                                        lck_mtx_unlock(&ev_pcb->evp_mtx);
                                        continue;
                                }
                        }
                }

                m2 = m_copym(m, 0, m->m_len, M_NOWAIT);
                if (m2 == 0) {
                        OSIncrementAtomic64((SInt64 *)&kevtstat.kes_nomem);
                        m_free(m);
                        lck_mtx_unlock(&ev_pcb->evp_mtx);
                        lck_rw_done(kev_rwlock);
                        return (ENOMEM);
                }
                if (sbappendrecord(&ev_pcb->evp_socket->so_rcv, m2)) {
                        /*
                         * We use "m" for the socket stats as it would be
                         * unsafe to use "m2"
                         */
                        so_inc_recv_data_stat(ev_pcb->evp_socket,
                            1, m->m_len, SO_TC_BE);

                        sorwakeup(ev_pcb->evp_socket);
                        OSIncrementAtomic64((SInt64 *)&kevtstat.kes_posted);
                } else {
                        OSIncrementAtomic64((SInt64 *)&kevtstat.kes_fullsock);
                }
                lck_mtx_unlock(&ev_pcb->evp_mtx);
        }
        m_free(m);
        lck_rw_done(kev_rwlock);

        return (0);
}

static int
kev_control(struct socket *so,
    u_long cmd,
    caddr_t data,
    __unused struct ifnet *ifp,
    __unused struct proc *p)
{
        struct kev_request *kev_req = (struct kev_request *) data;
        struct kern_event_pcb  *ev_pcb;
        struct kev_vendor_code *kev_vendor;
        u_int32_t  *id_value = (u_int32_t *) data;

        switch (cmd) {
                case SIOCGKEVID:
                        *id_value = static_event_id;
                        break;
                case SIOCSKEVFILT:
                        ev_pcb = (struct kern_event_pcb *) so->so_pcb;
                        ev_pcb->evp_vendor_code_filter = kev_req->vendor_code;
                        ev_pcb->evp_class_filter = kev_req->kev_class;
                        ev_pcb->evp_subclass_filter  = kev_req->kev_subclass;
                        break;
                case SIOCGKEVFILT:
                        ev_pcb = (struct kern_event_pcb *) so->so_pcb;
                        kev_req->vendor_code = ev_pcb->evp_vendor_code_filter;
                        kev_req->kev_class   = ev_pcb->evp_class_filter;
                        kev_req->kev_subclass = ev_pcb->evp_subclass_filter;
                        break;
                case SIOCGKEVVENDOR:
                        kev_vendor = (struct kev_vendor_code *)data;
                        /* Make sure string is NULL terminated */
                        kev_vendor->vendor_string[KEV_VENDOR_CODE_MAX_STR_LEN-1] = 0;
                        return (net_str_id_find_internal(kev_vendor->vendor_string,
                            &kev_vendor->vendor_code, NSI_VENDOR_CODE, 0));
                default:
                        return (ENOTSUP);
        }

        return (0);
}

int
kevt_getstat SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
        int error = 0;

        lck_rw_lock_shared(kev_rwlock);

        if (req->newptr != USER_ADDR_NULL) {
                error = EPERM;
                goto done;
        }
        if (req->oldptr == USER_ADDR_NULL) {
                req->oldidx = sizeof(struct kevtstat);
                goto done;
        }

        error = SYSCTL_OUT(req, &kevtstat,
            MIN(sizeof(struct kevtstat), req->oldlen));
done:
        lck_rw_done(kev_rwlock);

        return (error);
}

__private_extern__ int
kevt_pcblist SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
        int error = 0;
        int n, i;
        struct xsystmgen xsg;
        void *buf = NULL;
        size_t item_size = ROUNDUP64(sizeof (struct xkevtpcb)) +
                ROUNDUP64(sizeof (struct xsocket_n)) +
                2 * ROUNDUP64(sizeof (struct xsockbuf_n)) +
                ROUNDUP64(sizeof (struct xsockstat_n));
        struct kern_event_pcb  *ev_pcb;

        buf = _MALLOC(item_size, M_TEMP, M_WAITOK | M_ZERO);
        if (buf == NULL)
                return (ENOMEM);

        lck_rw_lock_shared(kev_rwlock);

        n = kevtstat.kes_pcbcount;

        if (req->oldptr == USER_ADDR_NULL) {
                req->oldidx = (n + n/8) * item_size;
                goto done;
        }
        if (req->newptr != USER_ADDR_NULL) {
                error = EPERM;
                goto done;
        }
        bzero(&xsg, sizeof (xsg));
        xsg.xg_len = sizeof (xsg);
        xsg.xg_count = n;
        xsg.xg_gen = kevtstat.kes_gencnt;
        xsg.xg_sogen = so_gencnt;
        error = SYSCTL_OUT(req, &xsg, sizeof (xsg));
        if (error) {
                goto done;
        }
        /*
         * We are done if there is no pcb
         */
        if (n == 0) {
                goto done;
        }

        i = 0;
        for (i = 0, ev_pcb = LIST_FIRST(&kern_event_head);
            i < n && ev_pcb != NULL;
            i++, ev_pcb = LIST_NEXT(ev_pcb, evp_link)) {
                struct xkevtpcb *xk = (struct xkevtpcb *)buf;
                struct xsocket_n *xso = (struct xsocket_n *)
                        ADVANCE64(xk, sizeof (*xk));
                struct xsockbuf_n *xsbrcv = (struct xsockbuf_n *)
                        ADVANCE64(xso, sizeof (*xso));
                struct xsockbuf_n *xsbsnd = (struct xsockbuf_n *)
                        ADVANCE64(xsbrcv, sizeof (*xsbrcv));
                struct xsockstat_n *xsostats = (struct xsockstat_n *)
                        ADVANCE64(xsbsnd, sizeof (*xsbsnd));

                bzero(buf, item_size);

                lck_mtx_lock(&ev_pcb->evp_mtx);

                xk->kep_len = sizeof(struct xkevtpcb);
                xk->kep_kind = XSO_EVT;
                xk->kep_evtpcb = (uint64_t)VM_KERNEL_ADDRPERM(ev_pcb);
                xk->kep_vendor_code_filter = ev_pcb->evp_vendor_code_filter;
                xk->kep_class_filter = ev_pcb->evp_class_filter;
                xk->kep_subclass_filter = ev_pcb->evp_subclass_filter;

                sotoxsocket_n(ev_pcb->evp_socket, xso);
                sbtoxsockbuf_n(ev_pcb->evp_socket ?
                        &ev_pcb->evp_socket->so_rcv : NULL, xsbrcv);
                sbtoxsockbuf_n(ev_pcb->evp_socket ?
                        &ev_pcb->evp_socket->so_snd : NULL, xsbsnd);
                sbtoxsockstat_n(ev_pcb->evp_socket, xsostats);

                lck_mtx_unlock(&ev_pcb->evp_mtx);

                error = SYSCTL_OUT(req, buf, item_size);
        }

        if (error == 0) {
                /*
                 * Give the user an updated idea of our state.
                 * If the generation differs from what we told
                 * her before, she knows that something happened
                 * while we were processing this request, and it
                 * might be necessary to retry.
                 */
                bzero(&xsg, sizeof (xsg));
                xsg.xg_len = sizeof (xsg);
                xsg.xg_count = n;
                xsg.xg_gen = kevtstat.kes_gencnt;
                xsg.xg_sogen = so_gencnt;
                error = SYSCTL_OUT(req, &xsg, sizeof (xsg));
                if (error) {
                        goto done;
                }
        }

done:
        lck_rw_done(kev_rwlock);

        return (error);
}

#endif /* SOCKETS */


int
fill_kqueueinfo(struct kqueue *kq, struct kqueue_info * kinfo)
{
        struct vinfo_stat * st;

        st = &kinfo->kq_stat;

        st->vst_size = kq->kq_count;
        if (kq->kq_state & KQ_KEV64)
                st->vst_blksize = sizeof(struct kevent64_s);
        else
                st->vst_blksize = sizeof(struct kevent);
        st->vst_mode = S_IFIFO;
        if (kq->kq_state & KQ_SEL)
                kinfo->kq_state |=  PROC_KQUEUE_SELECT;
        if (kq->kq_state & KQ_SLEEP)
                kinfo->kq_state |= PROC_KQUEUE_SLEEP;

        return (0);
}


void
knote_markstayqueued(struct knote *kn)
{
        kqlock(kn->kn_kq);
        kn->kn_status |= KN_STAYQUEUED;
        knote_enqueue(kn);
        kqunlock(kn->kn_kq);
}