// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  User level driver support for input subsystem
 *
 * Heavily based on evdev.c by Vojtech Pavlik
 *
 * Author: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
 *
 * Changes/Revisions:
 *      0.4     01/09/2014 (Benjamin Tissoires <benjamin.tissoires@redhat.com>)
 *              - add UI_GET_SYSNAME ioctl
 *      0.3     09/04/2006 (Anssi Hannula <anssi.hannula@gmail.com>)
 *              - updated ff support for the changes in kernel interface
 *              - added MODULE_VERSION
 *      0.2     16/10/2004 (Micah Dowty <micah@navi.cx>)
 *              - added force feedback support
 *              - added UI_SET_PHYS
 *      0.1     20/06/2002
 *              - first public version
 */
#include <uapi/linux/uinput.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/lockdep.h>
#include <linux/miscdevice.h>
#include <linux/overflow.h>
#include <linux/spinlock.h>
#include <linux/input/mt.h>
#include "../input-compat.h"

#define UINPUT_NAME             "uinput"
#define UINPUT_BUFFER_SIZE      16
#define UINPUT_NUM_REQUESTS     16
#define UINPUT_TIMESTAMP_ALLOWED_OFFSET_SECS 10

enum uinput_state { UIST_NEW_DEVICE, UIST_SETUP_COMPLETE, UIST_CREATED };

struct uinput_request {
        unsigned int            id;
        unsigned int            code;   /* UI_FF_UPLOAD, UI_FF_ERASE */

        int                     retval;
        struct completion       done;

        union {
                unsigned int    effect_id;
                struct {
                        struct ff_effect *effect;
                        struct ff_effect *old;
                } upload;
        } u;
};

struct uinput_device {
        struct input_dev        *dev;
        struct mutex            mutex;
        enum uinput_state       state;
        spinlock_t              state_lock;
        wait_queue_head_t       waitq;
        unsigned char           ready;
        unsigned char           head;
        unsigned char           tail;
        struct input_event      buff[UINPUT_BUFFER_SIZE];
        unsigned int            ff_effects_max;

        struct uinput_request   *requests[UINPUT_NUM_REQUESTS];
        wait_queue_head_t       requests_waitq;
        spinlock_t              requests_lock;
};

static int uinput_dev_event(struct input_dev *dev,
                            unsigned int type, unsigned int code, int value)
{
        struct uinput_device    *udev = input_get_drvdata(dev);
        struct timespec64       ts;

        lockdep_assert_held(&dev->event_lock);

        ktime_get_ts64(&ts);

        udev->buff[udev->head] = (struct input_event) {
                .input_event_sec = ts.tv_sec,
                .input_event_usec = ts.tv_nsec / NSEC_PER_USEC,
                .type = type,
                .code = code,
                .value = value,
        };

        udev->head = (udev->head + 1) % UINPUT_BUFFER_SIZE;

        wake_up_interruptible(&udev->waitq);

        return 0;
}

/* Atomically allocate an ID for the given request. Returns 0 on success. */
static bool uinput_request_alloc_id(struct uinput_device *udev,
                                    struct uinput_request *request)
{
        unsigned int id;
        bool reserved = false;

        spin_lock(&udev->requests_lock);

        for (id = 0; id < UINPUT_NUM_REQUESTS; id++) {
                if (!udev->requests[id]) {
                        request->id = id;
                        udev->requests[id] = request;
                        reserved = true;
                        break;
                }
        }

        spin_unlock(&udev->requests_lock);
        return reserved;
}

static struct uinput_request *uinput_request_find(struct uinput_device *udev,
                                                  unsigned int id)
{
        /* Find an input request, by ID. Returns NULL if the ID isn't valid. */
        if (id >= UINPUT_NUM_REQUESTS)
                return NULL;

        return udev->requests[id];
}

static int uinput_request_reserve_slot(struct uinput_device *udev,
                                       struct uinput_request *request)
{
        /* Allocate slot. If none are available right away, wait. */
        return wait_event_interruptible(udev->requests_waitq,
                                        uinput_request_alloc_id(udev, request));
}

static void uinput_request_release_slot(struct uinput_device *udev,
                                        unsigned int id)
{
        /* Mark slot as available */
        spin_lock(&udev->requests_lock);
        udev->requests[id] = NULL;
        spin_unlock(&udev->requests_lock);

        wake_up(&udev->requests_waitq);
}

static int uinput_request_send(struct uinput_device *udev,
                               struct uinput_request *request)
{
        unsigned long flags;
        int retval = 0;

        spin_lock(&udev->state_lock);

        if (udev->state != UIST_CREATED) {
                retval = -ENODEV;
                goto out;
        }

        /*
         * Tell our userspace application about this new request
         * by queueing an input event.
         */
        spin_lock_irqsave(&udev->dev->event_lock, flags);
        uinput_dev_event(udev->dev, EV_UINPUT, request->code, request->id);
        spin_unlock_irqrestore(&udev->dev->event_lock, flags);

 out:
        spin_unlock(&udev->state_lock);
        return retval;
}

static int uinput_request_submit(struct uinput_device *udev,
                                 struct uinput_request *request)
{
        int retval;

        /*
         * Initialize completion before allocating the request slot.
         * Once the slot is allocated, uinput_flush_requests() may
         * complete it at any time, so it must be initialized first.
         */
        init_completion(&request->done);

        retval = uinput_request_reserve_slot(udev, request);
        if (retval)
                return retval;

        retval = uinput_request_send(udev, request);
        if (retval)
                goto out;

        if (!wait_for_completion_timeout(&request->done, 30 * HZ)) {
                retval = -ETIMEDOUT;
                goto out;
        }

        retval = request->retval;

 out:
        uinput_request_release_slot(udev, request->id);
        return retval;
}

/*
 * Fail all outstanding requests so handlers don't wait for the userspace
 * to finish processing them.
 */
static void uinput_flush_requests(struct uinput_device *udev)
{
        struct uinput_request *request;
        int i;

        spin_lock(&udev->requests_lock);

        for (i = 0; i < UINPUT_NUM_REQUESTS; i++) {
                request = udev->requests[i];
                if (request) {
                        request->retval = -ENODEV;
                        complete(&request->done);
                }
        }

        spin_unlock(&udev->requests_lock);
}

static void uinput_dev_set_gain(struct input_dev *dev, u16 gain)
{
        uinput_dev_event(dev, EV_FF, FF_GAIN, gain);
}

static void uinput_dev_set_autocenter(struct input_dev *dev, u16 magnitude)
{
        uinput_dev_event(dev, EV_FF, FF_AUTOCENTER, magnitude);
}

static int uinput_dev_playback(struct input_dev *dev, int effect_id, int value)
{
        return uinput_dev_event(dev, EV_FF, effect_id, value);
}

static int uinput_dev_upload_effect(struct input_dev *dev,
                                    struct ff_effect *effect,
                                    struct ff_effect *old)
{
        struct uinput_device *udev = input_get_drvdata(dev);
        struct uinput_request request;

        /*
         * uinput driver does not currently support periodic effects with
         * custom waveform since it does not have a way to pass buffer of
         * samples (custom_data) to userspace. If ever there is a device
         * supporting custom waveforms we would need to define an additional
         * ioctl (UI_UPLOAD_SAMPLES) but for now we just bail out.
         */
        if (effect->type == FF_PERIODIC &&
                        effect->u.periodic.waveform == FF_CUSTOM)
                return -EINVAL;

        request.code = UI_FF_UPLOAD;
        request.u.upload.effect = effect;
        request.u.upload.old = old;

        return uinput_request_submit(udev, &request);
}

static int uinput_dev_erase_effect(struct input_dev *dev, int effect_id)
{
        struct uinput_device *udev = input_get_drvdata(dev);
        struct uinput_request request;

        if (!test_bit(EV_FF, dev->evbit))
                return -ENOSYS;

        request.code = UI_FF_ERASE;
        request.u.effect_id = effect_id;

        return uinput_request_submit(udev, &request);
}

static int uinput_dev_flush(struct input_dev *dev, struct file *file)
{
        /*
         * If we are called with file == NULL that means we are tearing
         * down the device, and therefore we can not handle FF erase
         * requests: either we are handling UI_DEV_DESTROY (and holding
         * the udev->mutex), or the file descriptor is closed and there is
         * nobody on the other side anymore.
         */
        return file ? input_ff_flush(dev, file) : 0;
}

static void uinput_destroy_device(struct uinput_device *udev)
{
        const char *name, *phys;
        struct input_dev *dev = udev->dev;
        enum uinput_state old_state = udev->state;

        /*
         * Update state under state_lock so that concurrent
         * uinput_request_send() sees the state change before we
         * flush pending requests and tear down the device.
         */
        spin_lock(&udev->state_lock);
        udev->state = UIST_NEW_DEVICE;
        spin_unlock(&udev->state_lock);

        if (dev) {
                name = dev->name;
                phys = dev->phys;
                if (old_state == UIST_CREATED) {
                        uinput_flush_requests(udev);
                        input_unregister_device(dev);
                } else {
                        input_free_device(dev);
                }
                kfree(name);
                kfree(phys);
                udev->dev = NULL;
        }
}

static int uinput_create_device(struct uinput_device *udev)
{
        struct input_dev *dev = udev->dev;
        int error, nslot;

        if (udev->state != UIST_SETUP_COMPLETE) {
                printk(KERN_DEBUG "%s: write device info first\n", UINPUT_NAME);
                return -EINVAL;
        }

        if (test_bit(EV_ABS, dev->evbit)) {
                input_alloc_absinfo(dev);
                if (!dev->absinfo) {
                        error = -EINVAL;
                        goto fail1;
                }

                if (test_bit(ABS_MT_SLOT, dev->absbit)) {
                        nslot = input_abs_get_max(dev, ABS_MT_SLOT) + 1;
                        error = input_mt_init_slots(dev, nslot, 0);
                        if (error)
                                goto fail1;
                } else if (test_bit(ABS_MT_POSITION_X, dev->absbit)) {
                        input_set_events_per_packet(dev, 60);
                }
        }

        if (test_bit(EV_FF, dev->evbit) && !udev->ff_effects_max) {
                printk(KERN_DEBUG "%s: ff_effects_max should be non-zero when FF_BIT is set\n",
                        UINPUT_NAME);
                error = -EINVAL;
                goto fail1;
        }

        if (udev->ff_effects_max) {
                error = input_ff_create(dev, udev->ff_effects_max);
                if (error)
                        goto fail1;

                dev->ff->upload = uinput_dev_upload_effect;
                dev->ff->erase = uinput_dev_erase_effect;
                dev->ff->playback = uinput_dev_playback;
                dev->ff->set_gain = uinput_dev_set_gain;
                dev->ff->set_autocenter = uinput_dev_set_autocenter;
                /*
                 * The standard input_ff_flush() implementation does
                 * not quite work for uinput as we can't reasonably
                 * handle FF requests during device teardown.
                 */
                dev->flush = uinput_dev_flush;
        }

        dev->event = uinput_dev_event;

        input_set_drvdata(udev->dev, udev);

        error = input_register_device(udev->dev);
        if (error)
                goto fail2;

        spin_lock(&udev->state_lock);
        udev->state = UIST_CREATED;
        spin_unlock(&udev->state_lock);

        return 0;

 fail2: input_ff_destroy(dev);
 fail1: uinput_destroy_device(udev);
        return error;
}

static int uinput_open(struct inode *inode, struct file *file)
{
        struct uinput_device *newdev;

        newdev = kzalloc_obj(*newdev);
        if (!newdev)
                return -ENOMEM;

        mutex_init(&newdev->mutex);
        spin_lock_init(&newdev->state_lock);
        spin_lock_init(&newdev->requests_lock);
        init_waitqueue_head(&newdev->requests_waitq);
        init_waitqueue_head(&newdev->waitq);
        newdev->state = UIST_NEW_DEVICE;

        file->private_data = newdev;
        stream_open(inode, file);

        return 0;
}

static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
                                   const struct input_absinfo *abs)
{
        int min, max, range;

        min = abs->minimum;
        max = abs->maximum;

        if ((min != 0 || max != 0) && max < min) {
                printk(KERN_DEBUG
                       "%s: invalid abs[%02x] min:%d max:%d\n",
                       UINPUT_NAME, code, min, max);
                return -EINVAL;
        }

        if (!check_sub_overflow(max, min, &range) && abs->flat > range) {
                printk(KERN_DEBUG
                       "%s: abs_flat #%02x out of range: %d (min:%d/max:%d)\n",
                       UINPUT_NAME, code, abs->flat, min, max);
                return -EINVAL;
        }

        /*
         * Limit number of contacts to a reasonable value (100). This
         * ensures that we need less than 2 pages for struct input_mt
         * (we are not using in-kernel slot assignment so not going to
         * allocate memory for the "red" table), and we should have no
         * trouble getting this much memory.
         */
        if (code == ABS_MT_SLOT && max > 99) {
                printk(KERN_DEBUG
                       "%s: unreasonably large number of slots requested: %d\n",
                       UINPUT_NAME, max);
                return -EINVAL;
        }

        return 0;
}

static int uinput_validate_absbits(struct input_dev *dev)
{
        unsigned int cnt;
        int error;

        if (!test_bit(EV_ABS, dev->evbit))
                return 0;

        /*
         * Check if absmin/absmax/absfuzz/absflat are sane.
         */

        for_each_set_bit(cnt, dev->absbit, ABS_CNT) {
                if (!dev->absinfo)
                        return -EINVAL;

                error = uinput_validate_absinfo(dev, cnt, &dev->absinfo[cnt]);
                if (error)
                        return error;
        }

        return 0;
}

static int uinput_dev_setup(struct uinput_device *udev,
                            struct uinput_setup __user *arg)
{
        struct uinput_setup setup;
        struct input_dev *dev;

        if (udev->state == UIST_CREATED)
                return -EINVAL;

        if (copy_from_user(&setup, arg, sizeof(setup)))
                return -EFAULT;

        if (!setup.name[0])
                return -EINVAL;

        dev = udev->dev;
        dev->id = setup.id;
        udev->ff_effects_max = setup.ff_effects_max;

        kfree(dev->name);
        dev->name = kstrndup(setup.name, UINPUT_MAX_NAME_SIZE, GFP_KERNEL);
        if (!dev->name)
                return -ENOMEM;

        udev->state = UIST_SETUP_COMPLETE;
        return 0;
}

static int uinput_abs_setup(struct uinput_device *udev,
                            struct uinput_setup __user *arg, size_t size)
{
        struct uinput_abs_setup setup = {};
        struct input_dev *dev;
        int error;

        if (size > sizeof(setup))
                return -E2BIG;

        if (udev->state == UIST_CREATED)
                return -EINVAL;

        if (copy_from_user(&setup, arg, size))
                return -EFAULT;

        if (setup.code > ABS_MAX)
                return -ERANGE;

        dev = udev->dev;

        error = uinput_validate_absinfo(dev, setup.code, &setup.absinfo);
        if (error)
                return error;

        input_alloc_absinfo(dev);
        if (!dev->absinfo)
                return -ENOMEM;

        set_bit(setup.code, dev->absbit);
        dev->absinfo[setup.code] = setup.absinfo;
        return 0;
}

/* legacy setup via write() */
static int uinput_setup_device_legacy(struct uinput_device *udev,
                                      const char __user *buffer, size_t count)
{
        struct uinput_user_dev  *user_dev;
        struct input_dev        *dev;
        int                     i;
        int                     retval;

        if (count != sizeof(struct uinput_user_dev))
                return -EINVAL;

        if (!udev->dev) {
                udev->dev = input_allocate_device();
                if (!udev->dev)
                        return -ENOMEM;
        }

        dev = udev->dev;

        user_dev = memdup_user(buffer, sizeof(struct uinput_user_dev));
        if (IS_ERR(user_dev))
                return PTR_ERR(user_dev);

        udev->ff_effects_max = user_dev->ff_effects_max;

        /* Ensure name is filled in */
        if (!user_dev->name[0]) {
                retval = -EINVAL;
                goto exit;
        }

        kfree(dev->name);
        dev->name = kstrndup(user_dev->name, UINPUT_MAX_NAME_SIZE,
                             GFP_KERNEL);
        if (!dev->name) {
                retval = -ENOMEM;
                goto exit;
        }

        dev->id.bustype = user_dev->id.bustype;
        dev->id.vendor  = user_dev->id.vendor;
        dev->id.product = user_dev->id.product;
        dev->id.version = user_dev->id.version;

        for (i = 0; i < ABS_CNT; i++) {
                input_abs_set_max(dev, i, user_dev->absmax[i]);
                input_abs_set_min(dev, i, user_dev->absmin[i]);
                input_abs_set_fuzz(dev, i, user_dev->absfuzz[i]);
                input_abs_set_flat(dev, i, user_dev->absflat[i]);
        }

        retval = uinput_validate_absbits(dev);
        if (retval < 0)
                goto exit;

        udev->state = UIST_SETUP_COMPLETE;
        retval = count;

 exit:
        kfree(user_dev);
        return retval;
}

/*
 * Returns true if the given timestamp is valid (i.e., if all the following
 * conditions are satisfied), false otherwise.
 * 1) given timestamp is positive
 * 2) it's within the allowed offset before the current time
 * 3) it's not in the future
 */
static bool is_valid_timestamp(const ktime_t timestamp)
{
        ktime_t zero_time;
        ktime_t current_time;
        ktime_t min_time;
        ktime_t offset;

        zero_time = ktime_set(0, 0);
        if (ktime_compare(zero_time, timestamp) >= 0)
                return false;

        current_time = ktime_get();
        offset = ktime_set(UINPUT_TIMESTAMP_ALLOWED_OFFSET_SECS, 0);
        min_time = ktime_sub(current_time, offset);

        if (ktime_after(min_time, timestamp) || ktime_after(timestamp, current_time))
                return false;

        return true;
}

static ssize_t uinput_inject_events(struct uinput_device *udev,
                                    const char __user *buffer, size_t count)
{
        struct input_event ev;
        size_t bytes = 0;
        ktime_t timestamp;

        if (count != 0 && count < input_event_size())
                return -EINVAL;

        while (bytes + input_event_size() <= count) {
                /*
                 * Note that even if some events were fetched successfully
                 * we are still going to return EFAULT instead of partial
                 * count to let userspace know that it got it's buffers
                 * all wrong.
                 */
                if (input_event_from_user(buffer + bytes, &ev))
                        return -EFAULT;

                timestamp = ktime_set(ev.input_event_sec, ev.input_event_usec * NSEC_PER_USEC);
                if (is_valid_timestamp(timestamp))
                        input_set_timestamp(udev->dev, timestamp);

                input_event(udev->dev, ev.type, ev.code, ev.value);
                bytes += input_event_size();
                cond_resched();
        }

        return bytes;
}

static ssize_t uinput_write(struct file *file, const char __user *buffer,
                            size_t count, loff_t *ppos)
{
        struct uinput_device *udev = file->private_data;
        int retval;

        if (count == 0)
                return 0;

        retval = mutex_lock_interruptible(&udev->mutex);
        if (retval)
                return retval;

        retval = udev->state == UIST_CREATED ?
                        uinput_inject_events(udev, buffer, count) :
                        uinput_setup_device_legacy(udev, buffer, count);

        mutex_unlock(&udev->mutex);

        return retval;
}

static bool uinput_fetch_next_event(struct uinput_device *udev,
                                    struct input_event *event)
{
        bool have_event;

        spin_lock_irq(&udev->dev->event_lock);

        have_event = udev->head != udev->tail;
        if (have_event) {
                *event = udev->buff[udev->tail];
                udev->tail = (udev->tail + 1) % UINPUT_BUFFER_SIZE;
        }

        spin_unlock_irq(&udev->dev->event_lock);

        return have_event;
}

static ssize_t uinput_events_to_user(struct uinput_device *udev,
                                     char __user *buffer, size_t count)
{
        struct input_event event;
        size_t read = 0;

        while (read + input_event_size() <= count &&
               uinput_fetch_next_event(udev, &event)) {

                if (input_event_to_user(buffer + read, &event))
                        return -EFAULT;

                read += input_event_size();
        }

        return read;
}

static ssize_t uinput_read(struct file *file, char __user *buffer,
                           size_t count, loff_t *ppos)
{
        struct uinput_device *udev = file->private_data;
        ssize_t retval;

        if (count != 0 && count < input_event_size())
                return -EINVAL;

        do {
                retval = mutex_lock_interruptible(&udev->mutex);
                if (retval)
                        return retval;

                if (udev->state != UIST_CREATED)
                        retval = -ENODEV;
                else if (udev->head == udev->tail &&
                         (file->f_flags & O_NONBLOCK))
                        retval = -EAGAIN;
                else
                        retval = uinput_events_to_user(udev, buffer, count);

                mutex_unlock(&udev->mutex);

                if (retval || count == 0)
                        break;

                if (!(file->f_flags & O_NONBLOCK))
                        retval = wait_event_interruptible(udev->waitq,
                                                  udev->head != udev->tail ||
                                                  udev->state != UIST_CREATED);
        } while (retval == 0);

        return retval;
}

static __poll_t uinput_poll(struct file *file, poll_table *wait)
{
        struct uinput_device *udev = file->private_data;
        __poll_t mask = EPOLLOUT | EPOLLWRNORM; /* uinput is always writable */

        poll_wait(file, &udev->waitq, wait);

        if (udev->head != udev->tail)
                mask |= EPOLLIN | EPOLLRDNORM;

        return mask;
}

static int uinput_release(struct inode *inode, struct file *file)
{
        struct uinput_device *udev = file->private_data;

        uinput_destroy_device(udev);
        kfree(udev);

        return 0;
}

#ifdef CONFIG_COMPAT
struct uinput_ff_upload_compat {
        __u32                   request_id;
        __s32                   retval;
        struct ff_effect_compat effect;
        struct ff_effect_compat old;
};

static int uinput_ff_upload_to_user(char __user *buffer,
                                    const struct uinput_ff_upload *ff_up)
{
        if (in_compat_syscall()) {
                struct uinput_ff_upload_compat ff_up_compat;

                memset(&ff_up_compat, 0, sizeof(ff_up_compat));
                ff_up_compat.request_id = ff_up->request_id;
                ff_up_compat.retval = ff_up->retval;
                /*
                 * It so happens that the pointer that gives us the trouble
                 * is the last field in the structure. Since we don't support
                 * custom waveforms in uinput anyway we can just copy the whole
                 * thing (to the compat size) and ignore the pointer.
                 */
                memcpy(&ff_up_compat.effect, &ff_up->effect,
                        sizeof(struct ff_effect_compat));
                memcpy(&ff_up_compat.old, &ff_up->old,
                        sizeof(struct ff_effect_compat));

                if (copy_to_user(buffer, &ff_up_compat,
                                 sizeof(struct uinput_ff_upload_compat)))
                        return -EFAULT;
        } else {
                if (copy_to_user(buffer, ff_up,
                                 sizeof(struct uinput_ff_upload)))
                        return -EFAULT;
        }

        return 0;
}

static int uinput_ff_upload_from_user(const char __user *buffer,
                                      struct uinput_ff_upload *ff_up)
{
        if (in_compat_syscall()) {
                struct uinput_ff_upload_compat ff_up_compat;

                if (copy_from_user(&ff_up_compat, buffer,
                                   sizeof(struct uinput_ff_upload_compat)))
                        return -EFAULT;

                ff_up->request_id = ff_up_compat.request_id;
                ff_up->retval = ff_up_compat.retval;
                memcpy(&ff_up->effect, &ff_up_compat.effect,
                        sizeof(struct ff_effect_compat));
                memcpy(&ff_up->old, &ff_up_compat.old,
                        sizeof(struct ff_effect_compat));

        } else {
                if (copy_from_user(ff_up, buffer,
                                   sizeof(struct uinput_ff_upload)))
                        return -EFAULT;
        }

        return 0;
}

#else

static int uinput_ff_upload_to_user(char __user *buffer,
                                    const struct uinput_ff_upload *ff_up)
{
        if (copy_to_user(buffer, ff_up, sizeof(struct uinput_ff_upload)))
                return -EFAULT;

        return 0;
}

static int uinput_ff_upload_from_user(const char __user *buffer,
                                      struct uinput_ff_upload *ff_up)
{
        if (copy_from_user(ff_up, buffer, sizeof(struct uinput_ff_upload)))
                return -EFAULT;

        return 0;
}

#endif

#define uinput_set_bit(_arg, _bit, _max)                \
({                                                      \
        int __ret = 0;                                  \
        if (udev->state == UIST_CREATED)                \
                __ret =  -EINVAL;                       \
        else if ((_arg) > (_max))                       \
                __ret = -EINVAL;                        \
        else set_bit((_arg), udev->dev->_bit);          \
        __ret;                                          \
})

static int uinput_str_to_user(void __user *dest, const char *str,
                              unsigned int maxlen)
{
        char __user *p = dest;
        int len, ret;

        if (!str)
                return -ENOENT;

        if (maxlen == 0)
                return -EINVAL;

        len = strlen(str) + 1;
        if (len > maxlen)
                len = maxlen;

        ret = copy_to_user(p, str, len);
        if (ret)
                return -EFAULT;

        /* force terminating '\0' */
        ret = put_user(0, p + len - 1);
        return ret ? -EFAULT : len;
}

static long uinput_ioctl_handler(struct file *file, unsigned int cmd,
                                 unsigned long arg, void __user *p)
{
        int                     retval;
        struct uinput_device    *udev = file->private_data;
        struct uinput_ff_upload ff_up;
        struct uinput_ff_erase  ff_erase;
        struct uinput_request   *req;
        char                    *phys;
        const char              *name;
        unsigned int            size;

        retval = mutex_lock_interruptible(&udev->mutex);
        if (retval)
                return retval;

        if (!udev->dev) {
                udev->dev = input_allocate_device();
                if (!udev->dev) {
                        retval = -ENOMEM;
                        goto out;
                }
        }

        switch (cmd) {
        case UI_GET_VERSION:
                if (put_user(UINPUT_VERSION, (unsigned int __user *)p))
                        retval = -EFAULT;
                goto out;

        case UI_DEV_CREATE:
                retval = uinput_create_device(udev);
                goto out;

        case UI_DEV_DESTROY:
                uinput_destroy_device(udev);
                goto out;

        case UI_DEV_SETUP:
                retval = uinput_dev_setup(udev, p);
                goto out;

        /* UI_ABS_SETUP is handled in the variable size ioctls */

        case UI_SET_EVBIT:
                retval = uinput_set_bit(arg, evbit, EV_MAX);
                goto out;

        case UI_SET_KEYBIT:
                retval = uinput_set_bit(arg, keybit, KEY_MAX);
                goto out;

        case UI_SET_RELBIT:
                retval = uinput_set_bit(arg, relbit, REL_MAX);
                goto out;

        case UI_SET_ABSBIT:
                retval = uinput_set_bit(arg, absbit, ABS_MAX);
                goto out;

        case UI_SET_MSCBIT:
                retval = uinput_set_bit(arg, mscbit, MSC_MAX);
                goto out;

        case UI_SET_LEDBIT:
                retval = uinput_set_bit(arg, ledbit, LED_MAX);
                goto out;

        case UI_SET_SNDBIT:
                retval = uinput_set_bit(arg, sndbit, SND_MAX);
                goto out;

        case UI_SET_FFBIT:
                retval = uinput_set_bit(arg, ffbit, FF_MAX);
                goto out;

        case UI_SET_SWBIT:
                retval = uinput_set_bit(arg, swbit, SW_MAX);
                goto out;

        case UI_SET_PROPBIT:
                retval = uinput_set_bit(arg, propbit, INPUT_PROP_MAX);
                goto out;

        case UI_SET_PHYS:
                if (udev->state == UIST_CREATED) {
                        retval = -EINVAL;
                        goto out;
                }

                phys = strndup_user(p, 1024);
                if (IS_ERR(phys)) {
                        retval = PTR_ERR(phys);
                        goto out;
                }

                kfree(udev->dev->phys);
                udev->dev->phys = phys;
                goto out;

        case UI_BEGIN_FF_UPLOAD:
                retval = uinput_ff_upload_from_user(p, &ff_up);
                if (retval)
                        goto out;

                req = uinput_request_find(udev, ff_up.request_id);
                if (!req || req->code != UI_FF_UPLOAD ||
                    !req->u.upload.effect) {
                        retval = -EINVAL;
                        goto out;
                }

                ff_up.retval = 0;
                ff_up.effect = *req->u.upload.effect;
                if (req->u.upload.old)
                        ff_up.old = *req->u.upload.old;
                else
                        memset(&ff_up.old, 0, sizeof(struct ff_effect));

                retval = uinput_ff_upload_to_user(p, &ff_up);
                goto out;

        case UI_BEGIN_FF_ERASE:
                if (copy_from_user(&ff_erase, p, sizeof(ff_erase))) {
                        retval = -EFAULT;
                        goto out;
                }

                req = uinput_request_find(udev, ff_erase.request_id);
                if (!req || req->code != UI_FF_ERASE) {
                        retval = -EINVAL;
                        goto out;
                }

                ff_erase.retval = 0;
                ff_erase.effect_id = req->u.effect_id;
                if (copy_to_user(p, &ff_erase, sizeof(ff_erase))) {
                        retval = -EFAULT;
                        goto out;
                }

                goto out;

        case UI_END_FF_UPLOAD:
                retval = uinput_ff_upload_from_user(p, &ff_up);
                if (retval)
                        goto out;

                req = uinput_request_find(udev, ff_up.request_id);
                if (!req || req->code != UI_FF_UPLOAD ||
                    !req->u.upload.effect) {
                        retval = -EINVAL;
                        goto out;
                }

                req->retval = ff_up.retval;
                complete(&req->done);
                goto out;

        case UI_END_FF_ERASE:
                if (copy_from_user(&ff_erase, p, sizeof(ff_erase))) {
                        retval = -EFAULT;
                        goto out;
                }

                req = uinput_request_find(udev, ff_erase.request_id);
                if (!req || req->code != UI_FF_ERASE) {
                        retval = -EINVAL;
                        goto out;
                }

                req->retval = ff_erase.retval;
                complete(&req->done);
                goto out;
        }

        size = _IOC_SIZE(cmd);

        /* Now check variable-length commands */
        switch (cmd & ~IOCSIZE_MASK) {
        case UI_GET_SYSNAME(0):
                if (udev->state != UIST_CREATED) {
                        retval = -ENOENT;
                        goto out;
                }
                name = dev_name(&udev->dev->dev);
                retval = uinput_str_to_user(p, name, size);
                goto out;

        case UI_ABS_SETUP & ~IOCSIZE_MASK:
                retval = uinput_abs_setup(udev, p, size);
                goto out;
        }

        retval = -EINVAL;
 out:
        mutex_unlock(&udev->mutex);
        return retval;
}

static long uinput_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        return uinput_ioctl_handler(file, cmd, arg, (void __user *)arg);
}

#ifdef CONFIG_COMPAT

/*
 * These IOCTLs change their size and thus their numbers between
 * 32 and 64 bits.
 */
#define UI_SET_PHYS_COMPAT              \
        _IOW(UINPUT_IOCTL_BASE, 108, compat_uptr_t)
#define UI_BEGIN_FF_UPLOAD_COMPAT       \
        _IOWR(UINPUT_IOCTL_BASE, 200, struct uinput_ff_upload_compat)
#define UI_END_FF_UPLOAD_COMPAT         \
        _IOW(UINPUT_IOCTL_BASE, 201, struct uinput_ff_upload_compat)

static long uinput_compat_ioctl(struct file *file,
                                unsigned int cmd, unsigned long arg)
{
        switch (cmd) {
        case UI_SET_PHYS_COMPAT:
                cmd = UI_SET_PHYS;
                break;
        case UI_BEGIN_FF_UPLOAD_COMPAT:
                cmd = UI_BEGIN_FF_UPLOAD;
                break;
        case UI_END_FF_UPLOAD_COMPAT:
                cmd = UI_END_FF_UPLOAD;
                break;
        }

        return uinput_ioctl_handler(file, cmd, arg, compat_ptr(arg));
}
#endif

static const struct file_operations uinput_fops = {
        .owner          = THIS_MODULE,
        .open           = uinput_open,
        .release        = uinput_release,
        .read           = uinput_read,
        .write          = uinput_write,
        .poll           = uinput_poll,
        .unlocked_ioctl = uinput_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = uinput_compat_ioctl,
#endif
};

static struct miscdevice uinput_misc = {
        .fops           = &uinput_fops,
        .minor          = UINPUT_MINOR,
        .name           = UINPUT_NAME,
};
module_misc_device(uinput_misc);

MODULE_ALIAS_MISCDEV(UINPUT_MINOR);
MODULE_ALIAS("devname:" UINPUT_NAME);

MODULE_AUTHOR("Aristeu Sergio Rozanski Filho");
MODULE_DESCRIPTION("User level driver support for input subsystem");
MODULE_LICENSE("GPL");