/*-
 * Copyright (c) 2014 Jakub Wojciech Klama <jceel@FreeBSD.org>
 * Copyright (c) 2015-2016 Vladimir Kondratyev <wulf@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.
 *
 * $FreeBSD$
 */

#include "opt_evdev.h"

#include <sys/types.h>
#include <sys/module.h>
#include <sys/devfs.h>

#include <sys/param.h>
#include <sys/caps.h>
#include <sys/conf.h>
#include <sys/filio.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/vnode.h> /* IO_NDELAY in read() */
#include <sys/uio.h>

#include <sys/errno.h>

#include <sys/device.h>
#include <sys/bus.h>

/* Use FreeBSD bitstring locally. */
#include "freebsd-bitstring.h"

#include <dev/misc/evdev/evdev.h>
#include <dev/misc/evdev/evdev_private.h>
#include <dev/misc/evdev/input.h>

#ifdef EVDEV_DEBUG
#define debugf(client, fmt, args...)    kprintf("evdev cdev: "fmt"\n", ##args)
#else
#define debugf(client, fmt, args...)
#endif

#define DEF_RING_REPORTS        8

static d_open_t         evdev_open;
static d_read_t         evdev_read;
static d_write_t        evdev_write;
static d_ioctl_t        evdev_ioctl;
static d_kqfilter_t     evdev_kqfilter;
static d_priv_dtor_t    evdev_dtor;

static int evdev_kqread(struct knote *kn, long hint);
static void evdev_kqdetach(struct knote *kn);
static int evdev_ioctl_eviocgbit(struct evdev_dev *, int, int, caddr_t);
static void evdev_client_filter_queue(struct evdev_client *, uint16_t);

static struct dev_ops evdev_cdevsw = {
        { "evdev", 0, 0 },
        .d_open = evdev_open,
        .d_read = evdev_read,
        .d_write = evdev_write,
        .d_ioctl = evdev_ioctl,
        .d_kqfilter = evdev_kqfilter,
};

static struct filterops evdev_cdev_filterops = {
        .f_flags = FILTEROP_ISFD,
        .f_attach = NULL,
        .f_detach = evdev_kqdetach,
        .f_event = evdev_kqread,
};

static int
evdev_open(struct dev_open_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        struct evdev_dev *evdev = dev->si_drv1;
        struct evdev_client *client;
        size_t buffer_size;
        int ret;

        /*
         * Disallow access to disk volumes if RESTRICTEDROOT
         */
        if (caps_priv_check_self(SYSCAP_RESTRICTEDROOT))
                return (EPERM);

        if (evdev == NULL)
                return (ENODEV);

        /* Initialize client structure */
        buffer_size = evdev->ev_report_size * DEF_RING_REPORTS;
        client = kmalloc(offsetof(struct evdev_client, ec_buffer) +
            sizeof(struct input_event) * buffer_size,
            M_EVDEV, M_WAITOK | M_ZERO);

        /* Initialize ring buffer */
        client->ec_buffer_size = buffer_size;
        client->ec_buffer_head = 0;
        client->ec_buffer_tail = 0;
        client->ec_buffer_ready = 0;

        client->ec_evdev = evdev;
        lockinit(&client->ec_buffer_mtx, "evclient", 0, LK_CANRECURSE);

        /* Avoid race with evdev_unregister */
        EVDEV_LOCK(evdev);
        if (dev->si_drv1 == NULL)
                ret = ENODEV;
        else
                ret = evdev_register_client(evdev, client);

        if (ret != 0)
                evdev_revoke_client(client);
        /*
         * Unlock evdev here because non-sleepable lock held
         * while calling devfs_set_cdevpriv upsets WITNESS
         */
        EVDEV_UNLOCK(evdev);

        if (ret == 0) {
                struct file *fp;

                fp = (ap->a_fpp) ? *ap->a_fpp : NULL;
                ret = devfs_set_cdevpriv(fp, client, &evdev_dtor);
        }

        if (ret != 0) {
                debugf(client, "cannot register evdev client");
        }

        return (ret);
}

static void
evdev_dtor(void *data)
{
        struct evdev_client *client = (struct evdev_client *)data;

        EVDEV_LOCK(client->ec_evdev);
        if (!client->ec_revoked)
                evdev_dispose_client(client->ec_evdev, client);
        EVDEV_UNLOCK(client->ec_evdev);

        funsetown(&client->ec_sigio);
        lockuninit(&client->ec_buffer_mtx);
        kfree(client, M_EVDEV);
}

static int
evdev_read(struct dev_read_args *ap)
{
        struct uio *uio = ap->a_uio;
        int ioflag = ap->a_ioflag;
        struct evdev_client *client;
        struct input_event event;
        int ret = 0;
        int remaining;

        ret = devfs_get_cdevpriv(ap->a_fp, (void **)&client);
        if (ret != 0)
                return (ret);

        debugf(client, "read %zd bytes by thread %d", uio->uio_resid, 0);

        if (client->ec_revoked)
                return (ENODEV);

        /* Zero-sized reads are allowed for error checking */
        if (uio->uio_resid != 0 && uio->uio_resid < sizeof(struct input_event))
                return (EINVAL);

        remaining = uio->uio_resid / sizeof(struct input_event);

        EVDEV_CLIENT_LOCKQ(client);

        if (EVDEV_CLIENT_EMPTYQ(client)) {
                if (ioflag & IO_NDELAY) {
                        ret = EWOULDBLOCK;
                } else {
                        if (remaining != 0) {
                                client->ec_blocked = true;
                                ret = lksleep(client, &client->ec_buffer_mtx,
                                    PCATCH, "evread", 0);
                                if (ret == 0 && client->ec_revoked)
                                        ret = ENODEV;
                        }
                }
        }

        while (ret == 0 && !EVDEV_CLIENT_EMPTYQ(client) && remaining > 0) {
                memcpy(&event, &client->ec_buffer[client->ec_buffer_head],
                    sizeof(struct input_event));
                client->ec_buffer_head =
                    (client->ec_buffer_head + 1) % client->ec_buffer_size;
                remaining--;

                EVDEV_CLIENT_UNLOCKQ(client);
                ret = uiomove((void *)&event, sizeof(struct input_event), uio);
                EVDEV_CLIENT_LOCKQ(client);
        }

        EVDEV_CLIENT_UNLOCKQ(client);

        return (ret);
}

static int
evdev_write(struct dev_write_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        struct uio *uio = ap->a_uio;
        struct evdev_dev *evdev = dev->si_drv1;
        struct evdev_client *client;
        struct input_event event;
        int ret = 0;

        ret = devfs_get_cdevpriv(ap->a_fp, (void **)&client);
        if (ret != 0)
                return (ret);

        debugf(client, "write %zd bytes by thread %d", uio->uio_resid, 0);

        if (client->ec_revoked || evdev == NULL)
                return (ENODEV);

        if (uio->uio_resid % sizeof(struct input_event) != 0) {
                debugf(client, "write size not multiple of input_event size");
                return (EINVAL);
        }

        while (uio->uio_resid > 0 && ret == 0) {
                ret = uiomove((void *)&event, sizeof(struct input_event), uio);
                if (ret == 0)
                        ret = evdev_inject_event(evdev, event.type, event.code,
                            event.value);
        }

        return (ret);
}

static int
evdev_kqfilter(struct dev_kqfilter_args *ap)
{
        struct knote *kn = ap->a_kn;
        struct klist *klist;
        struct evdev_client *client;
        int ret;

        ret = devfs_get_cdevpriv(ap->a_fp, (void **)&client);
        if (ret != 0)
                return (ret);

        if (client->ec_revoked)
                return (ENODEV);

        switch(kn->kn_filter) {
        case EVFILT_READ:
                kn->kn_fop = &evdev_cdev_filterops;
                break;
        default:
                return(EINVAL);
        }
        kn->kn_hook = (caddr_t)client;

        klist = &client->kqinfo.ki_note;
        knote_insert(klist, kn);
        return (0);
}

static int
evdev_kqread(struct knote *kn, long hint)
{
        struct evdev_client *client;
        int ret;
        int locked = 0;

        client = (struct evdev_client *)kn->kn_hook;

        /* NOTE on DragonFly v FreeBSD.
         * FreeBSD locks the klist when calling f_event, i.e. evdev_kqread().
         * That's why the plain assertion EVDEV_CLIENT_LOCKQ_ASSERT(client)
         * fails on DragonFly: DragonFly does not ensure the lock associated
         * with the klist is locked.
         * To mimic FreeBSD's behavior, we will lock ec_buffer_mtx if
         * it was not locked, and unlock when leaving.
         */
        locked = lockowned(&(client)->ec_buffer_mtx);
        if (!locked)
                EVDEV_CLIENT_LOCKQ(client);

        EVDEV_CLIENT_LOCKQ_ASSERT(client);

        if (client->ec_revoked) {
                kn->kn_flags |= EV_EOF;
                ret = 1;
        } else {
                kn->kn_data = EVDEV_CLIENT_SIZEQ(client) *
                    sizeof(struct input_event);
                ret = !EVDEV_CLIENT_EMPTYQ(client);
        }

        /* Unlock if ec_buffer_mtx was not locked. */
        if (!locked) {
                EVDEV_CLIENT_UNLOCKQ(client);
        }

        return (ret);
}

static void
evdev_kqdetach(struct knote *kn)
{
        struct evdev_client *client;

        client = (struct evdev_client *)kn->kn_hook;
        knote_remove(&client->kqinfo.ki_note, kn);
}

static int
evdev_ioctl(struct dev_ioctl_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        u_long cmd = ap->a_cmd;
        caddr_t data = ap->a_data;
        struct evdev_dev *evdev = dev->si_drv1;
        struct evdev_client *client;
        struct input_keymap_entry *ke;
        int ret, len, limit, type_num;
        uint32_t code;
        size_t nvalues;

        ret = devfs_get_cdevpriv(ap->a_fp, (void **)&client);
        if (ret != 0)
                return (ret);

        if (client->ec_revoked || evdev == NULL)
                return (ENODEV);

        /* file I/O ioctl handling */
        switch (cmd) {
        case FIOSETOWN:
                return (fsetown(*(int *)data, &client->ec_sigio));

        case FIOGETOWN:
                *(int *)data = fgetown(&client->ec_sigio);
                return (0);

        case FIONBIO:
                return (0);

        case FIOASYNC:
                if (*(int *)data)
                        client->ec_async = true;
                else
                        client->ec_async = false;

                return (0);

        case FIONREAD:
                EVDEV_CLIENT_LOCKQ(client);
                *(int *)data =
                    EVDEV_CLIENT_SIZEQ(client) * sizeof(struct input_event);
                EVDEV_CLIENT_UNLOCKQ(client);
                return (0);
        }

        len = IOCPARM_LEN(cmd);
        debugf(client, "ioctl called: cmd=0x%08lx, data=%p", cmd, data);

        /* evdev fixed-length ioctls handling */
        switch (cmd) {
        case EVIOCGVERSION:
                *(int *)data = EV_VERSION;
                return (0);

        case EVIOCGID:
                debugf(client, "EVIOCGID: bus=%d vendor=0x%04x product=0x%04x",
                    evdev->ev_id.bustype, evdev->ev_id.vendor,
                    evdev->ev_id.product);
                memcpy(data, &evdev->ev_id, sizeof(struct input_id));
                return (0);

        case EVIOCGREP:
                if (!evdev_event_supported(evdev, EV_REP))
                        return (ENOTSUP);

                memcpy(data, evdev->ev_rep, sizeof(evdev->ev_rep));
                return (0);

        case EVIOCSREP:
                if (!evdev_event_supported(evdev, EV_REP))
                        return (ENOTSUP);

                evdev_inject_event(evdev, EV_REP, REP_DELAY, ((int *)data)[0]);
                evdev_inject_event(evdev, EV_REP, REP_PERIOD,
                    ((int *)data)[1]);
                return (0);

        case EVIOCGKEYCODE:
                /* Fake unsupported ioctl */
                return (0);

        case EVIOCGKEYCODE_V2:
                if (evdev->ev_methods == NULL ||
                    evdev->ev_methods->ev_get_keycode == NULL)
                        return (ENOTSUP);

                ke = (struct input_keymap_entry *)data;
                evdev->ev_methods->ev_get_keycode(evdev, ke);
                return (0);

        case EVIOCSKEYCODE:
                /* Fake unsupported ioctl */
                return (0);

        case EVIOCSKEYCODE_V2:
                if (evdev->ev_methods == NULL ||
                    evdev->ev_methods->ev_set_keycode == NULL)
                        return (ENOTSUP);

                ke = (struct input_keymap_entry *)data;
                evdev->ev_methods->ev_set_keycode(evdev, ke);
                return (0);

        case EVIOCGABS(0) ... EVIOCGABS(ABS_MAX):
                if (evdev->ev_absinfo == NULL)
                        return (EINVAL);

                memcpy(data, &evdev->ev_absinfo[cmd - EVIOCGABS(0)],
                    sizeof(struct input_absinfo));
                return (0);

        case EVIOCSABS(0) ... EVIOCSABS(ABS_MAX):
                if (evdev->ev_absinfo == NULL)
                        return (EINVAL);

                code = cmd - EVIOCSABS(0);
                /* mt-slot number can not be changed */
                if (code == ABS_MT_SLOT)
                        return (EINVAL);

                EVDEV_LOCK(evdev);
                evdev_set_absinfo(evdev, code, (struct input_absinfo *)data);
                EVDEV_UNLOCK(evdev);
                return (0);

        case EVIOCSFF:
        case EVIOCRMFF:
        case EVIOCGEFFECTS:
                /* Fake unsupported ioctls */
                return (0);

        case EVIOCGRAB:
                EVDEV_LOCK(evdev);
                if (*(int *)data)
                        ret = evdev_grab_client(evdev, client);
                else
                        ret = evdev_release_client(evdev, client);
                EVDEV_UNLOCK(evdev);
                return (ret);

        case EVIOCREVOKE:
                if (*(int *)data != 0)
                        return (EINVAL);

                EVDEV_LOCK(evdev);
                if (dev->si_drv1 != NULL && !client->ec_revoked) {
                        evdev_dispose_client(evdev, client);
                        evdev_revoke_client(client);
                }
                EVDEV_UNLOCK(evdev);
                return (0);

        case EVIOCSCLOCKID:
                switch (*(int *)data) {
                case CLOCK_REALTIME:
                        client->ec_clock_id = EV_CLOCK_REALTIME;
                        return (0);
                case CLOCK_MONOTONIC:
                        client->ec_clock_id = EV_CLOCK_MONOTONIC;
                        return (0);
                default:
                        return (EINVAL);
                }
        }

        /* evdev variable-length ioctls handling */
        switch (IOCBASECMD(cmd)) {
        case EVIOCGNAME(0):
                strlcpy(data, evdev->ev_name, len);
                return (0);

        case EVIOCGPHYS(0):
                if (evdev->ev_shortname[0] == 0)
                        return (ENOENT);

                strlcpy(data, evdev->ev_shortname, len);
                return (0);

        case EVIOCGUNIQ(0):
                if (evdev->ev_serial[0] == 0)
                        return (ENOENT);

                strlcpy(data, evdev->ev_serial, len);
                return (0);

        case EVIOCGPROP(0):
                limit = MIN(len, bitstr_size(INPUT_PROP_CNT));
                memcpy(data, evdev->ev_prop_flags, limit);
                return (0);

        case EVIOCGMTSLOTS(0):
                if (evdev->ev_mt == NULL)
                        return (EINVAL);
                if (len < sizeof(uint32_t))
                        return (EINVAL);
                code = *(uint32_t *)data;
                if (!ABS_IS_MT(code))
                        return (EINVAL);

                nvalues =
                    MIN(len / sizeof(int32_t) - 1, MAXIMAL_MT_SLOT(evdev) + 1);
                for (int i = 0; i < nvalues; i++)
                        ((int32_t *)data)[i + 1] =
                            evdev_mt_get_value(evdev, i, code);
                return (0);

        case EVIOCGKEY(0):
                limit = MIN(len, bitstr_size(KEY_CNT));
                EVDEV_LOCK(evdev);
                evdev_client_filter_queue(client, EV_KEY);
                memcpy(data, evdev->ev_key_states, limit);
                EVDEV_UNLOCK(evdev);
                return (0);

        case EVIOCGLED(0):
                limit = MIN(len, bitstr_size(LED_CNT));
                EVDEV_LOCK(evdev);
                evdev_client_filter_queue(client, EV_LED);
                memcpy(data, evdev->ev_led_states, limit);
                EVDEV_UNLOCK(evdev);
                return (0);

        case EVIOCGSND(0):
                limit = MIN(len, bitstr_size(SND_CNT));
                EVDEV_LOCK(evdev);
                evdev_client_filter_queue(client, EV_SND);
                memcpy(data, evdev->ev_snd_states, limit);
                EVDEV_UNLOCK(evdev);
                return (0);

        case EVIOCGSW(0):
                limit = MIN(len, bitstr_size(SW_CNT));
                EVDEV_LOCK(evdev);
                evdev_client_filter_queue(client, EV_SW);
                memcpy(data, evdev->ev_sw_states, limit);
                EVDEV_UNLOCK(evdev);
                return (0);

        case EVIOCGBIT(0, 0) ... EVIOCGBIT(EV_MAX, 0):
                type_num = IOCBASECMD(cmd) - EVIOCGBIT(0, 0);
                debugf(client, "EVIOCGBIT(%d): data=%p, len=%d", type_num,
                    data, len);
                return (evdev_ioctl_eviocgbit(evdev, type_num, len, data));
        }

        return (EINVAL);
}

static int
evdev_ioctl_eviocgbit(struct evdev_dev *evdev, int type, int len, caddr_t data)
{
        /*
         * We will use freebsd-bitstring.h locally. This ensures bitmap
         * is of type (unsigned long *). DragonFly's original bitmap
         * is (unsigned char *).
         */
        unsigned long *bitmap;
        int limit;

        switch (type) {
        case 0:
                bitmap = evdev->ev_type_flags;
                limit = EV_CNT;
                break;
        case EV_KEY:
                bitmap = evdev->ev_key_flags;
                limit = KEY_CNT;
                break;
        case EV_REL:
                bitmap = evdev->ev_rel_flags;
                limit = REL_CNT;
                break;
        case EV_ABS:
                bitmap = evdev->ev_abs_flags;
                limit = ABS_CNT;
                break;
        case EV_MSC:
                bitmap = evdev->ev_msc_flags;
                limit = MSC_CNT;
                break;
        case EV_LED:
                bitmap = evdev->ev_led_flags;
                limit = LED_CNT;
                break;
        case EV_SND:
                bitmap = evdev->ev_snd_flags;
                limit = SND_CNT;
                break;
        case EV_SW:
                bitmap = evdev->ev_sw_flags;
                limit = SW_CNT;
                break;
        case EV_FF:
                /*
                 * We don't support EV_FF now, so let's
                 * just fake it returning only zeros.
                 */
                bzero(data, len);
                return (0);
        default:
                return (ENOTTY);
        }

        /*
         * Clear ioctl data buffer in case it's bigger than
         * bitmap size
         */
        bzero(data, len);

        limit = bitstr_size(limit);
        len = MIN(limit, len);
        memcpy(data, bitmap, len);
        return (0);
}

void
evdev_revoke_client(struct evdev_client *client)
{

        EVDEV_LOCK_ASSERT(client->ec_evdev);

        client->ec_revoked = true;
}

void
evdev_notify_event(struct evdev_client *client)
{

        EVDEV_CLIENT_LOCKQ_ASSERT(client);

        if (client->ec_blocked) {
                client->ec_blocked = false;
                wakeup(client);
        }
        if (client->ec_selected) {
                client->ec_selected = false;
                wakeup(&client->kqinfo);
        }

        KNOTE(&client->kqinfo.ki_note, 0);

        if (client->ec_async && client->ec_sigio != NULL)
                pgsigio(client->ec_sigio, SIGIO, 0);
}

int
evdev_cdev_create(struct evdev_dev *evdev)
{
        cdev_t dev;
        int ret, unit;

        /*
         * Iterate over devices input/eventX until we find a non-existing
         * one and record its number in unit.
         */
        unit = 0;
        while (devfs_find_device_by_name("input/event%d", unit) != NULL) {
            unit++;
        }

        /*
         * Put unit as minor. Minor and major will determine st_rdev of
         * eventX. Ensuring that all eventX have different major and minor
         * will make st_rdev unique. This is needed by libinput, which
         * determines eventX from st_rdev.
         */
        dev = make_dev(&evdev_cdevsw, unit, UID_ROOT, GID_WHEEL, 0600,
            "input/event%d", unit);

        if (dev != NULL) {
                dev->si_drv1 = evdev;
                evdev->ev_cdev = dev;
                evdev->ev_unit = unit;
                ret = 0;
        } else {
                ret = ENODEV;
                goto err;
        }

        reference_dev(evdev->ev_cdev);

err:
        return (ret);
}

int
evdev_cdev_destroy(struct evdev_dev *evdev)
{

        if (evdev->ev_cdev) {
                dev_ops_remove_minor(&evdev_cdevsw, evdev->ev_unit);
        }

        return (0);
}

static void
evdev_client_gettime(struct evdev_client *client, struct timeval *tv)
{

        switch (client->ec_clock_id) {
        case EV_CLOCK_BOOTTIME:
                /*
                 * XXX: FreeBSD does not support true POSIX monotonic clock.
                 *      So aliase EV_CLOCK_BOOTTIME to EV_CLOCK_MONOTONIC.
                 */
        case EV_CLOCK_MONOTONIC:
                microuptime(tv);
                break;

        case EV_CLOCK_REALTIME:
        default:
                microtime(tv);
                break;
        }
}

void
evdev_client_push(struct evdev_client *client, uint16_t type, uint16_t code,
    int32_t value)
{
        struct timeval time;
        size_t count, head, tail, ready;

        EVDEV_CLIENT_LOCKQ_ASSERT(client);
        head = client->ec_buffer_head;
        tail = client->ec_buffer_tail;
        ready = client->ec_buffer_ready;
        count = client->ec_buffer_size;

        /* If queue is full drop its content and place SYN_DROPPED event */
        if ((tail + 1) % count == head) {
                debugf(client, "client %p: buffer overflow", client);

                head = (tail + count - 1) % count;
                client->ec_buffer[head] = (struct input_event) {
                        .type = EV_SYN,
                        .code = SYN_DROPPED,
                        .value = 0
                };
                /*
                 * XXX: Here is a small race window from now till the end of
                 *      report. The queue is empty but client has been already
                 *      notified of data readyness. Can be fixed in two ways:
                 * 1. Implement bulk insert so queue lock would not be dropped
                 *    till the SYN_REPORT event.
                 * 2. Insert SYN_REPORT just now and skip remaining events
                 */
                client->ec_buffer_head = head;
                client->ec_buffer_ready = head;
        }

        client->ec_buffer[tail].type = type;
        client->ec_buffer[tail].code = code;
        client->ec_buffer[tail].value = value;
        client->ec_buffer_tail = (tail + 1) % count;

        /* Allow users to read events only after report has been completed */
        if (type == EV_SYN && code == SYN_REPORT) {
                evdev_client_gettime(client, &time);
                for (; ready != client->ec_buffer_tail;
                    ready = (ready + 1) % count)
                        client->ec_buffer[ready].time = time;
                client->ec_buffer_ready = client->ec_buffer_tail;
        }
}

void
evdev_client_dumpqueue(struct evdev_client *client)
{
        struct input_event *event;
        size_t i, head, tail, ready, size;

        head = client->ec_buffer_head;
        tail = client->ec_buffer_tail;
        ready = client->ec_buffer_ready;
        size = client->ec_buffer_size;

        kprintf("evdev client: %p\n", client);
        kprintf("event queue: head=%zu ready=%zu tail=%zu size=%zu\n",
            head, ready, tail, size);

        kprintf("queue contents:\n");

        for (i = 0; i < size; i++) {
                event = &client->ec_buffer[i];
                kprintf("%zu: ", i);

                if (i < head || i > tail)
                        kprintf("unused\n");
                else
                        kprintf("type=%d code=%d value=%d ", event->type,
                            event->code, event->value);

                if (i == head)
                        kprintf("<- head\n");
                else if (i == tail)
                        kprintf("<- tail\n");
                else if (i == ready)
                        kprintf("<- ready\n");
                else
                        kprintf("\n");
        }
}

static void
evdev_client_filter_queue(struct evdev_client *client, uint16_t type)
{
        struct input_event *event;
        size_t head, tail, count, i;
        bool last_was_syn = false;

        EVDEV_CLIENT_LOCKQ(client);

        i = head = client->ec_buffer_head;
        tail = client->ec_buffer_tail;
        count = client->ec_buffer_size;
        client->ec_buffer_ready = client->ec_buffer_tail;

        while (i != client->ec_buffer_tail) {
                event = &client->ec_buffer[i];
                i = (i + 1) % count;

                /* Skip event of given type */
                if (event->type == type)
                        continue;

                /* Remove empty SYN_REPORT events */
                if (event->type == EV_SYN && event->code == SYN_REPORT) {
                        if (last_was_syn)
                                continue;
                        else
                                client->ec_buffer_ready = (tail + 1) % count;
                }

                /* Rewrite entry */
                memcpy(&client->ec_buffer[tail], event,
                    sizeof(struct input_event));

                last_was_syn = (event->type == EV_SYN &&
                    event->code == SYN_REPORT);

                tail = (tail + 1) % count;
        }

        client->ec_buffer_head = i;
        client->ec_buffer_tail = tail;

        EVDEV_CLIENT_UNLOCKQ(client);
}