services/inputflinger/EventHub.cpp

/*
 * Copyright (C) 2005 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <memory.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/limits.h>
#include <sys/inotify.h>
#include <sys/ioctl.h>
#include <sys/utsname.h>
#include <unistd.h>

#define LOG_TAG "EventHub"

// #define LOG_NDEBUG 0

#include "EventHub.h"

#include <hardware_legacy/power.h>

#include <android-base/stringprintf.h>
#include <cutils/properties.h>
#include <openssl/sha.h>
#include <utils/Log.h>
#include <utils/Timers.h>
#include <utils/threads.h>
#include <utils/Errors.h>

#include <input/KeyLayoutMap.h>
#include <input/KeyCharacterMap.h>
#include <input/VirtualKeyMap.h>

/* this macro is used to tell if "bit" is set in "array"
 * it selects a byte from the array, and does a boolean AND
 * operation with a byte that only has the relevant bit set.
 * eg. to check for the 12th bit, we do (array[1] & 1<<4)
 */
#define test_bit(bit, array)    ((array)[(bit)/8] & (1<<((bit)%8)))

/* this macro computes the number of bytes needed to represent a bit array of the specified size */
#define sizeof_bit_array(bits)  (((bits) + 7) / 8)

#define INDENT "  "
#define INDENT2 "    "
#define INDENT3 "      "

using android::base::StringPrintf;

namespace android {

static constexpr bool DEBUG = false;

static const char *WAKE_LOCK_ID = "KeyEvents";
static const char *DEVICE_PATH = "/dev/input";
// v4l2 devices go directly into /dev
static const char *VIDEO_DEVICE_PATH = "/dev";

static inline const char* toString(bool value) {
    return value ? "true" : "false";
}

static std::string sha1(const std::string& in) {
    SHA_CTX ctx;
    SHA1_Init(&ctx);
    SHA1_Update(&ctx, reinterpret_cast<const u_char*>(in.c_str()), in.size());
    u_char digest[SHA_DIGEST_LENGTH];
    SHA1_Final(digest, &ctx);

    std::string out;
    for (size_t i = 0; i < SHA_DIGEST_LENGTH; i++) {
        out += StringPrintf("%02x", digest[i]);
    }
    return out;
}

static void getLinuxRelease(int* major, int* minor) {
    struct utsname info;
    if (uname(&info) || sscanf(info.release, "%d.%d", major, minor) <= 0) {
        *major = 0, *minor = 0;
        ALOGE("Could not get linux version: %s", strerror(errno));
    }
}

/**
 * Return true if name matches "v4l-touch*"
 */
static bool isV4lTouchNode(const char* name) {
    return strstr(name, "v4l-touch") == name;
}

/**
 * Returns true if V4L devices should be scanned.
 *
 * The system property ro.input.video_enabled can be used to control whether
 * EventHub scans and opens V4L devices. As V4L does not support multiple
 * clients, EventHub effectively blocks access to these devices when it opens
 * them.
 *
 * Setting this to "false" would prevent any video devices from being discovered and
 * associated with input devices.
 *
 * This property can be used as follows:
 * 1. To turn off features that are dependent on video device presence.
 * 2. During testing and development, to allow other clients to read video devices
 * directly from /dev.
 */
static bool isV4lScanningEnabled() {
  return property_get_bool("ro.input.video_enabled", true /* default_value */);
}

static nsecs_t processEventTimestamp(const struct input_event& event) {
    // Use the time specified in the event instead of the current time
    // so that downstream code can get more accurate estimates of
    // event dispatch latency from the time the event is enqueued onto
    // the evdev client buffer.
    //
    // The event's timestamp fortuitously uses the same monotonic clock
    // time base as the rest of Android. The kernel event device driver
    // (drivers/input/evdev.c) obtains timestamps using ktime_get_ts().
    // The systemTime(SYSTEM_TIME_MONOTONIC) function we use everywhere
    // calls clock_gettime(CLOCK_MONOTONIC) which is implemented as a
    // system call that also queries ktime_get_ts().

    const nsecs_t inputEventTime = seconds_to_nanoseconds(event.time.tv_sec) +
            microseconds_to_nanoseconds(event.time.tv_usec);
    return inputEventTime;
}

// --- Global Functions ---

uint32_t getAbsAxisUsage(int32_t axis, uint32_t deviceClasses) {
    // Touch devices get dibs on touch-related axes.
    if (deviceClasses & INPUT_DEVICE_CLASS_TOUCH) {
        switch (axis) {
        case ABS_X:
        case ABS_Y:
        case ABS_PRESSURE:
        case ABS_TOOL_WIDTH:
        case ABS_DISTANCE:
        case ABS_TILT_X:
        case ABS_TILT_Y:
        case ABS_MT_SLOT:
        case ABS_MT_TOUCH_MAJOR:
        case ABS_MT_TOUCH_MINOR:
        case ABS_MT_WIDTH_MAJOR:
        case ABS_MT_WIDTH_MINOR:
        case ABS_MT_ORIENTATION:
        case ABS_MT_POSITION_X:
        case ABS_MT_POSITION_Y:
        case ABS_MT_TOOL_TYPE:
        case ABS_MT_BLOB_ID:
        case ABS_MT_TRACKING_ID:
        case ABS_MT_PRESSURE:
        case ABS_MT_DISTANCE:
            return INPUT_DEVICE_CLASS_TOUCH;
        }
    }

    // External stylus gets the pressure axis
    if (deviceClasses & INPUT_DEVICE_CLASS_EXTERNAL_STYLUS) {
        if (axis == ABS_PRESSURE) {
            return INPUT_DEVICE_CLASS_EXTERNAL_STYLUS;
        }
    }

    // Joystick devices get the rest.
    return deviceClasses & INPUT_DEVICE_CLASS_JOYSTICK;
}

// --- EventHub::Device ---

EventHub::Device::Device(int fd, int32_t id, const std::string& path,
        const InputDeviceIdentifier& identifier) :
        next(nullptr),
        fd(fd), id(id), path(path), identifier(identifier),
        classes(0), configuration(nullptr), virtualKeyMap(nullptr),
        ffEffectPlaying(false), ffEffectId(-1), controllerNumber(0),
        enabled(true), isVirtual(fd < 0) {
    memset(keyBitmask, 0, sizeof(keyBitmask));
    memset(absBitmask, 0, sizeof(absBitmask));
    memset(relBitmask, 0, sizeof(relBitmask));
    memset(swBitmask, 0, sizeof(swBitmask));
    memset(ledBitmask, 0, sizeof(ledBitmask));
    memset(ffBitmask, 0, sizeof(ffBitmask));
    memset(propBitmask, 0, sizeof(propBitmask));
}

EventHub::Device::~Device() {
    close();
    delete configuration;
}

void EventHub::Device::close() {
    if (fd >= 0) {
        ::close(fd);
        fd = -1;
    }
}

status_t EventHub::Device::enable() {
    fd = open(path.c_str(), O_RDWR | O_CLOEXEC | O_NONBLOCK);
    if(fd < 0) {
        ALOGE("could not open %s, %s\n", path.c_str(), strerror(errno));
        return -errno;
    }
    enabled = true;
    return OK;
}

status_t EventHub::Device::disable() {
    close();
    enabled = false;
    return OK;
}

bool EventHub::Device::hasValidFd() {
    return !isVirtual && enabled;
}

// --- EventHub ---

const int EventHub::EPOLL_MAX_EVENTS;

EventHub::EventHub(void) :
        mBuiltInKeyboardId(NO_BUILT_IN_KEYBOARD), mNextDeviceId(1), mControllerNumbers(),
        mOpeningDevices(nullptr), mClosingDevices(nullptr),
        mNeedToSendFinishedDeviceScan(false),
        mNeedToReopenDevices(false), mNeedToScanDevices(true),
        mPendingEventCount(0), mPendingEventIndex(0), mPendingINotify(false) {
    acquire_wake_lock(PARTIAL_WAKE_LOCK, WAKE_LOCK_ID);

    mEpollFd = epoll_create1(EPOLL_CLOEXEC);
    LOG_ALWAYS_FATAL_IF(mEpollFd < 0, "Could not create epoll instance: %s", strerror(errno));

    mINotifyFd = inotify_init();
    mInputWd = inotify_add_watch(mINotifyFd, DEVICE_PATH, IN_DELETE | IN_CREATE);
    LOG_ALWAYS_FATAL_IF(mInputWd < 0, "Could not register INotify for %s: %s",
            DEVICE_PATH, strerror(errno));
    if (isV4lScanningEnabled()) {
        mVideoWd = inotify_add_watch(mINotifyFd, VIDEO_DEVICE_PATH, IN_DELETE | IN_CREATE);
        LOG_ALWAYS_FATAL_IF(mVideoWd < 0, "Could not register INotify for %s: %s",
                VIDEO_DEVICE_PATH, strerror(errno));
    } else {
        mVideoWd = -1;
        ALOGI("Video device scanning disabled");
    }

    struct epoll_event eventItem;
    memset(&eventItem, 0, sizeof(eventItem));
    eventItem.events = EPOLLIN;
    eventItem.data.fd = mINotifyFd;
    int result = epoll_ctl(mEpollFd, EPOLL_CTL_ADD, mINotifyFd, &eventItem);
    LOG_ALWAYS_FATAL_IF(result != 0, "Could not add INotify to epoll instance.  errno=%d", errno);

    int wakeFds[2];
    result = pipe(wakeFds);
    LOG_ALWAYS_FATAL_IF(result != 0, "Could not create wake pipe.  errno=%d", errno);

    mWakeReadPipeFd = wakeFds[0];
    mWakeWritePipeFd = wakeFds[1];

    result = fcntl(mWakeReadPipeFd, F_SETFL, O_NONBLOCK);
    LOG_ALWAYS_FATAL_IF(result != 0, "Could not make wake read pipe non-blocking.  errno=%d",
            errno);

    result = fcntl(mWakeWritePipeFd, F_SETFL, O_NONBLOCK);
    LOG_ALWAYS_FATAL_IF(result != 0, "Could not make wake write pipe non-blocking.  errno=%d",
            errno);

    eventItem.data.fd = mWakeReadPipeFd;
    result = epoll_ctl(mEpollFd, EPOLL_CTL_ADD, mWakeReadPipeFd, &eventItem);
    LOG_ALWAYS_FATAL_IF(result != 0, "Could not add wake read pipe to epoll instance.  errno=%d",
            errno);

    int major, minor;
    getLinuxRelease(&major, &minor);
    // EPOLLWAKEUP was introduced in kernel 3.5
    mUsingEpollWakeup = major > 3 || (major == 3 && minor >= 5);
}

EventHub::~EventHub(void) {
    closeAllDevicesLocked();

    while (mClosingDevices) {
        Device* device = mClosingDevices;
        mClosingDevices = device->next;
        delete device;
    }

    ::close(mEpollFd);
    ::close(mINotifyFd);
    ::close(mWakeReadPipeFd);
    ::close(mWakeWritePipeFd);

    release_wake_lock(WAKE_LOCK_ID);
}

InputDeviceIdentifier EventHub::getDeviceIdentifier(int32_t deviceId) const {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device == nullptr) return InputDeviceIdentifier();
    return device->identifier;
}

uint32_t EventHub::getDeviceClasses(int32_t deviceId) const {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device == nullptr) return 0;
    return device->classes;
}

int32_t EventHub::getDeviceControllerNumber(int32_t deviceId) const {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device == nullptr) return 0;
    return device->controllerNumber;
}

void EventHub::getConfiguration(int32_t deviceId, PropertyMap* outConfiguration) const {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device && device->configuration) {
        *outConfiguration = *device->configuration;
    } else {
        outConfiguration->clear();
    }
}

status_t EventHub::getAbsoluteAxisInfo(int32_t deviceId, int axis,
        RawAbsoluteAxisInfo* outAxisInfo) const {
    outAxisInfo->clear();

    if (axis >= 0 && axis <= ABS_MAX) {
        AutoMutex _l(mLock);

        Device* device = getDeviceLocked(deviceId);
        if (device && device->hasValidFd() && test_bit(axis, device->absBitmask)) {
            struct input_absinfo info;
            if(ioctl(device->fd, EVIOCGABS(axis), &info)) {
                ALOGW("Error reading absolute controller %d for device %s fd %d, errno=%d",
                     axis, device->identifier.name.c_str(), device->fd, errno);
                return -errno;
            }

            if (info.minimum != info.maximum) {
                outAxisInfo->valid = true;
                outAxisInfo->minValue = info.minimum;
                outAxisInfo->maxValue = info.maximum;
                outAxisInfo->flat = info.flat;
                outAxisInfo->fuzz = info.fuzz;
                outAxisInfo->resolution = info.resolution;
            }
            return OK;
        }
    }
    return -1;
}

bool EventHub::hasRelativeAxis(int32_t deviceId, int axis) const {
    if (axis >= 0 && axis <= REL_MAX) {
        AutoMutex _l(mLock);

        Device* device = getDeviceLocked(deviceId);
        if (device) {
            return test_bit(axis, device->relBitmask);
        }
    }
    return false;
}

bool EventHub::hasInputProperty(int32_t deviceId, int property) const {
    if (property >= 0 && property <= INPUT_PROP_MAX) {
        AutoMutex _l(mLock);

        Device* device = getDeviceLocked(deviceId);
        if (device) {
            return test_bit(property, device->propBitmask);
        }
    }
    return false;
}

int32_t EventHub::getScanCodeState(int32_t deviceId, int32_t scanCode) const {
    if (scanCode >= 0 && scanCode <= KEY_MAX) {
        AutoMutex _l(mLock);

        Device* device = getDeviceLocked(deviceId);
        if (device && device->hasValidFd() && test_bit(scanCode, device->keyBitmask)) {
            uint8_t keyState[sizeof_bit_array(KEY_MAX + 1)];
            memset(keyState, 0, sizeof(keyState));
            if (ioctl(device->fd, EVIOCGKEY(sizeof(keyState)), keyState) >= 0) {
                return test_bit(scanCode, keyState) ? AKEY_STATE_DOWN : AKEY_STATE_UP;
            }
        }
    }
    return AKEY_STATE_UNKNOWN;
}

int32_t EventHub::getKeyCodeState(int32_t deviceId, int32_t keyCode) const {
    AutoMutex _l(mLock);

    Device* device = getDeviceLocked(deviceId);
    if (device && device->hasValidFd() && device->keyMap.haveKeyLayout()) {
        std::vector<int32_t> scanCodes;
        device->keyMap.keyLayoutMap->findScanCodesForKey(keyCode, &scanCodes);
        if (scanCodes.size() != 0) {
            uint8_t keyState[sizeof_bit_array(KEY_MAX + 1)];
            memset(keyState, 0, sizeof(keyState));
            if (ioctl(device->fd, EVIOCGKEY(sizeof(keyState)), keyState) >= 0) {
                for (size_t i = 0; i < scanCodes.size(); i++) {
                    int32_t sc = scanCodes[i];
                    if (sc >= 0 && sc <= KEY_MAX && test_bit(sc, keyState)) {
                        return AKEY_STATE_DOWN;
                    }
                }
                return AKEY_STATE_UP;
            }
        }
    }
    return AKEY_STATE_UNKNOWN;
}

int32_t EventHub::getSwitchState(int32_t deviceId, int32_t sw) const {
    if (sw >= 0 && sw <= SW_MAX) {
        AutoMutex _l(mLock);

        Device* device = getDeviceLocked(deviceId);
        if (device && device->hasValidFd() && test_bit(sw, device->swBitmask)) {
            uint8_t swState[sizeof_bit_array(SW_MAX + 1)];
            memset(swState, 0, sizeof(swState));
            if (ioctl(device->fd, EVIOCGSW(sizeof(swState)), swState) >= 0) {
                return test_bit(sw, swState) ? AKEY_STATE_DOWN : AKEY_STATE_UP;
            }
        }
    }
    return AKEY_STATE_UNKNOWN;
}

status_t EventHub::getAbsoluteAxisValue(int32_t deviceId, int32_t axis, int32_t* outValue) const {
    *outValue = 0;

    if (axis >= 0 && axis <= ABS_MAX) {
        AutoMutex _l(mLock);

        Device* device = getDeviceLocked(deviceId);
        if (device && device->hasValidFd() && test_bit(axis, device->absBitmask)) {
            struct input_absinfo info;
            if(ioctl(device->fd, EVIOCGABS(axis), &info)) {
                ALOGW("Error reading absolute controller %d for device %s fd %d, errno=%d",
                     axis, device->identifier.name.c_str(), device->fd, errno);
                return -errno;
            }

            *outValue = info.value;
            return OK;
        }
    }
    return -1;
}

bool EventHub::markSupportedKeyCodes(int32_t deviceId, size_t numCodes,
        const int32_t* keyCodes, uint8_t* outFlags) const {
    AutoMutex _l(mLock);

    Device* device = getDeviceLocked(deviceId);
    if (device && device->keyMap.haveKeyLayout()) {
        std::vector<int32_t> scanCodes;
        for (size_t codeIndex = 0; codeIndex < numCodes; codeIndex++) {
            scanCodes.clear();

            status_t err = device->keyMap.keyLayoutMap->findScanCodesForKey(
                    keyCodes[codeIndex], &scanCodes);
            if (! err) {
                // check the possible scan codes identified by the layout map against the
                // map of codes actually emitted by the driver
                for (size_t sc = 0; sc < scanCodes.size(); sc++) {
                    if (test_bit(scanCodes[sc], device->keyBitmask)) {
                        outFlags[codeIndex] = 1;
                        break;
                    }
                }
            }
        }
        return true;
    }
    return false;
}

status_t EventHub::mapKey(int32_t deviceId,
        int32_t scanCode, int32_t usageCode, int32_t metaState,
        int32_t* outKeycode, int32_t* outMetaState, uint32_t* outFlags) const {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    status_t status = NAME_NOT_FOUND;

    if (device) {
        // Check the key character map first.
        sp<KeyCharacterMap> kcm = device->getKeyCharacterMap();
        if (kcm != nullptr) {
            if (!kcm->mapKey(scanCode, usageCode, outKeycode)) {
                *outFlags = 0;
                status = NO_ERROR;
            }
        }

        // Check the key layout next.
        if (status != NO_ERROR && device->keyMap.haveKeyLayout()) {
            if (!device->keyMap.keyLayoutMap->mapKey(scanCode, usageCode, outKeycode, outFlags)) {
                status = NO_ERROR;
            }
        }

        if (status == NO_ERROR) {
            if (kcm != nullptr) {
                kcm->tryRemapKey(*outKeycode, metaState, outKeycode, outMetaState);
            } else {
                *outMetaState = metaState;
            }
        }
    }

    if (status != NO_ERROR) {
        *outKeycode = 0;
        *outFlags = 0;
        *outMetaState = metaState;
    }

    return status;
}

status_t EventHub::mapAxis(int32_t deviceId, int32_t scanCode, AxisInfo* outAxisInfo) const {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);

    if (device && device->keyMap.haveKeyLayout()) {
        status_t err = device->keyMap.keyLayoutMap->mapAxis(scanCode, outAxisInfo);
        if (err == NO_ERROR) {
            return NO_ERROR;
        }
    }

    return NAME_NOT_FOUND;
}

void EventHub::setExcludedDevices(const std::vector<std::string>& devices) {
    AutoMutex _l(mLock);

    mExcludedDevices = devices;
}

bool EventHub::hasScanCode(int32_t deviceId, int32_t scanCode) const {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device && scanCode >= 0 && scanCode <= KEY_MAX) {
        if (test_bit(scanCode, device->keyBitmask)) {
            return true;
        }
    }
    return false;
}

bool EventHub::hasLed(int32_t deviceId, int32_t led) const {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    int32_t sc;
    if (device && mapLed(device, led, &sc) == NO_ERROR) {
        if (test_bit(sc, device->ledBitmask)) {
            return true;
        }
    }
    return false;
}

void EventHub::setLedState(int32_t deviceId, int32_t led, bool on) {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    setLedStateLocked(device, led, on);
}

void EventHub::setLedStateLocked(Device* device, int32_t led, bool on) {
    int32_t sc;
    if (device && device->hasValidFd() && mapLed(device, led, &sc) != NAME_NOT_FOUND) {
        struct input_event ev;
        ev.time.tv_sec = 0;
        ev.time.tv_usec = 0;
        ev.type = EV_LED;
        ev.code = sc;
        ev.value = on ? 1 : 0;

        ssize_t nWrite;
        do {
            nWrite = write(device->fd, &ev, sizeof(struct input_event));
        } while (nWrite == -1 && errno == EINTR);
    }
}

void EventHub::getVirtualKeyDefinitions(int32_t deviceId,
        std::vector<VirtualKeyDefinition>& outVirtualKeys) const {
    outVirtualKeys.clear();

    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device && device->virtualKeyMap) {
        const std::vector<VirtualKeyDefinition> virtualKeys =
                device->virtualKeyMap->getVirtualKeys();
        outVirtualKeys.insert(outVirtualKeys.end(), virtualKeys.begin(), virtualKeys.end());
    }
}

sp<KeyCharacterMap> EventHub::getKeyCharacterMap(int32_t deviceId) const {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device) {
        return device->getKeyCharacterMap();
    }
    return nullptr;
}

bool EventHub::setKeyboardLayoutOverlay(int32_t deviceId,
        const sp<KeyCharacterMap>& map) {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device) {
        if (map != device->overlayKeyMap) {
            device->overlayKeyMap = map;
            device->combinedKeyMap = KeyCharacterMap::combine(
                    device->keyMap.keyCharacterMap, map);
            return true;
        }
    }
    return false;
}

static std::string generateDescriptor(InputDeviceIdentifier& identifier) {
    std::string rawDescriptor;
    rawDescriptor += StringPrintf(":%04x:%04x:", identifier.vendor,
            identifier.product);
    // TODO add handling for USB devices to not uniqueify kbs that show up twice
    if (!identifier.uniqueId.empty()) {
        rawDescriptor += "uniqueId:";
        rawDescriptor += identifier.uniqueId;
    } else if (identifier.nonce != 0) {
        rawDescriptor += StringPrintf("nonce:%04x", identifier.nonce);
    }

    if (identifier.vendor == 0 && identifier.product == 0) {
        // If we don't know the vendor and product id, then the device is probably
        // built-in so we need to rely on other information to uniquely identify
        // the input device.  Usually we try to avoid relying on the device name or
        // location but for built-in input device, they are unlikely to ever change.
        if (!identifier.name.empty()) {
            rawDescriptor += "name:";
            rawDescriptor += identifier.name;
        } else if (!identifier.location.empty()) {
            rawDescriptor += "location:";
            rawDescriptor += identifier.location;
        }
    }
    identifier.descriptor = sha1(rawDescriptor);
    return rawDescriptor;
}

void EventHub::assignDescriptorLocked(InputDeviceIdentifier& identifier) {
    // Compute a device descriptor that uniquely identifies the device.
    // The descriptor is assumed to be a stable identifier.  Its value should not
    // change between reboots, reconnections, firmware updates or new releases
    // of Android. In practice we sometimes get devices that cannot be uniquely
    // identified. In this case we enforce uniqueness between connected devices.
    // Ideally, we also want the descriptor to be short and relatively opaque.

    identifier.nonce = 0;
    std::string rawDescriptor = generateDescriptor(identifier);
    if (identifier.uniqueId.empty()) {
        // If it didn't have a unique id check for conflicts and enforce
        // uniqueness if necessary.
        while(getDeviceByDescriptorLocked(identifier.descriptor) != nullptr) {
            identifier.nonce++;
            rawDescriptor = generateDescriptor(identifier);
        }
    }
    ALOGV("Created descriptor: raw=%s, cooked=%s", rawDescriptor.c_str(),
            identifier.descriptor.c_str());
}

void EventHub::vibrate(int32_t deviceId, nsecs_t duration) {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device && device->hasValidFd()) {
        ff_effect effect;
        memset(&effect, 0, sizeof(effect));
        effect.type = FF_RUMBLE;
        effect.id = device->ffEffectId;
        effect.u.rumble.strong_magnitude = 0xc000;
        effect.u.rumble.weak_magnitude = 0xc000;
        effect.replay.length = (duration + 999999LL) / 1000000LL;
        effect.replay.delay = 0;
        if (ioctl(device->fd, EVIOCSFF, &effect)) {
            ALOGW("Could not upload force feedback effect to device %s due to error %d.",
                    device->identifier.name.c_str(), errno);
            return;
        }
        device->ffEffectId = effect.id;

        struct input_event ev;
        ev.time.tv_sec = 0;
        ev.time.tv_usec = 0;
        ev.type = EV_FF;
        ev.code = device->ffEffectId;
        ev.value = 1;
        if (write(device->fd, &ev, sizeof(ev)) != sizeof(ev)) {
            ALOGW("Could not start force feedback effect on device %s due to error %d.",
                    device->identifier.name.c_str(), errno);
            return;
        }
        device->ffEffectPlaying = true;
    }
}

void EventHub::cancelVibrate(int32_t deviceId) {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device && device->hasValidFd()) {
        if (device->ffEffectPlaying) {
            device->ffEffectPlaying = false;

            struct input_event ev;
            ev.time.tv_sec = 0;
            ev.time.tv_usec = 0;
            ev.type = EV_FF;
            ev.code = device->ffEffectId;
            ev.value = 0;
            if (write(device->fd, &ev, sizeof(ev)) != sizeof(ev)) {
                ALOGW("Could not stop force feedback effect on device %s due to error %d.",
                        device->identifier.name.c_str(), errno);
                return;
            }
        }
    }
}

EventHub::Device* EventHub::getDeviceByDescriptorLocked(const std::string& descriptor) const {
    size_t size = mDevices.size();
    for (size_t i = 0; i < size; i++) {
        Device* device = mDevices.valueAt(i);
        if (descriptor == device->identifier.descriptor) {
            return device;
        }
    }
    return nullptr;
}

EventHub::Device* EventHub::getDeviceLocked(int32_t deviceId) const {
    if (deviceId == ReservedInputDeviceId::BUILT_IN_KEYBOARD_ID) {
        deviceId = mBuiltInKeyboardId;
    }
    ssize_t index = mDevices.indexOfKey(deviceId);
    return index >= 0 ? mDevices.valueAt(index) : NULL;
}

EventHub::Device* EventHub::getDeviceByPathLocked(const char* devicePath) const {
    for (size_t i = 0; i < mDevices.size(); i++) {
        Device* device = mDevices.valueAt(i);
        if (device->path == devicePath) {
            return device;
        }
    }
    return nullptr;
}

/**
 * The file descriptor could be either input device, or a video device (associated with a
 * specific input device). Check both cases here, and return the device that this event
 * belongs to. Caller can compare the fd's once more to determine event type.
 * Looks through all input devices, and only attached video devices. Unattached video
 * devices are ignored.
 */
EventHub::Device* EventHub::getDeviceByFdLocked(int fd) const {
    for (size_t i = 0; i < mDevices.size(); i++) {
        Device* device = mDevices.valueAt(i);
        if (device->fd == fd) {
            // This is an input device event
            return device;
        }
        if (device->videoDevice && device->videoDevice->getFd() == fd) {
            // This is a video device event
            return device;
        }
    }
    // We do not check mUnattachedVideoDevices here because they should not participate in epoll,
    // and therefore should never be looked up by fd.
    return nullptr;
}

size_t EventHub::getEvents(int timeoutMillis, RawEvent* buffer, size_t bufferSize) {
    ALOG_ASSERT(bufferSize >= 1);

    AutoMutex _l(mLock);

    struct input_event readBuffer[bufferSize];

    RawEvent* event = buffer;
    size_t capacity = bufferSize;
    bool awoken = false;
    for (;;) {
        nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);

        // Reopen input devices if needed.
        if (mNeedToReopenDevices) {
            mNeedToReopenDevices = false;

            ALOGI("Reopening all input devices due to a configuration change.");

            closeAllDevicesLocked();
            mNeedToScanDevices = true;
            break; // return to the caller before we actually rescan
        }

        // Report any devices that had last been added/removed.
        while (mClosingDevices) {
            Device* device = mClosingDevices;
            ALOGV("Reporting device closed: id=%d, name=%s\n",
                 device->id, device->path.c_str());
            mClosingDevices = device->next;
            event->when = now;
            event->deviceId = (device->id == mBuiltInKeyboardId) ?
                    ReservedInputDeviceId::BUILT_IN_KEYBOARD_ID : device->id;
            event->type = DEVICE_REMOVED;
            event += 1;
            delete device;
            mNeedToSendFinishedDeviceScan = true;
            if (--capacity == 0) {
                break;
            }
        }

        if (mNeedToScanDevices) {
            mNeedToScanDevices = false;
            scanDevicesLocked();
            mNeedToSendFinishedDeviceScan = true;
        }

        while (mOpeningDevices != nullptr) {
            Device* device = mOpeningDevices;
            ALOGV("Reporting device opened: id=%d, name=%s\n",
                 device->id, device->path.c_str());
            mOpeningDevices = device->next;
            event->when = now;
            event->deviceId = device->id == mBuiltInKeyboardId ? 0 : device->id;
            event->type = DEVICE_ADDED;
            event += 1;
            mNeedToSendFinishedDeviceScan = true;
            if (--capacity == 0) {
                break;
            }
        }

        if (mNeedToSendFinishedDeviceScan) {
            mNeedToSendFinishedDeviceScan = false;
            event->when = now;
            event->type = FINISHED_DEVICE_SCAN;
            event += 1;
            if (--capacity == 0) {
                break;
            }
        }

        // Grab the next input event.
        bool deviceChanged = false;
        while (mPendingEventIndex < mPendingEventCount) {
            const struct epoll_event& eventItem = mPendingEventItems[mPendingEventIndex++];
            if (eventItem.data.fd == mINotifyFd) {
                if (eventItem.events & EPOLLIN) {
                    mPendingINotify = true;
                } else {
                    ALOGW("Received unexpected epoll event 0x%08x for INotify.", eventItem.events);
                }
                continue;
            }

            if (eventItem.data.fd == mWakeReadPipeFd) {
                if (eventItem.events & EPOLLIN) {
                    ALOGV("awoken after wake()");
                    awoken = true;
                    char buffer[16];
                    ssize_t nRead;
                    do {
                        nRead = read(mWakeReadPipeFd, buffer, sizeof(buffer));
                    } while ((nRead == -1 && errno == EINTR) || nRead == sizeof(buffer));
                } else {
                    ALOGW("Received unexpected epoll event 0x%08x for wake read pipe.",
                            eventItem.events);
                }
                continue;
            }

            Device* device = getDeviceByFdLocked(eventItem.data.fd);
            if (!device) {
                ALOGE("Received unexpected epoll event 0x%08x for unknown fd %d.",
                        eventItem.events, eventItem.data.fd);
                ALOG_ASSERT(!DEBUG);
                continue;
            }
            if (device->videoDevice && eventItem.data.fd == device->videoDevice->getFd()) {
                if (eventItem.events & EPOLLIN) {
                    size_t numFrames = device->videoDevice->readAndQueueFrames();
                    if (numFrames == 0) {
                        ALOGE("Received epoll event for video device %s, but could not read frame",
                                device->videoDevice->getName().c_str());
                    }
                } else if (eventItem.events & EPOLLHUP) {
                    // TODO(b/121395353) - consider adding EPOLLRDHUP
                    ALOGI("Removing video device %s due to epoll hang-up event.",
                            device->videoDevice->getName().c_str());
                    unregisterVideoDeviceFromEpollLocked(*device->videoDevice);
                    device->videoDevice = nullptr;
                } else {
                    ALOGW("Received unexpected epoll event 0x%08x for device %s.",
                            eventItem.events, device->videoDevice->getName().c_str());
                    ALOG_ASSERT(!DEBUG);
                }
                continue;
            }
            // This must be an input event
            if (eventItem.events & EPOLLIN) {
                int32_t readSize = read(device->fd, readBuffer,
                        sizeof(struct input_event) * capacity);
                if (readSize == 0 || (readSize < 0 && errno == ENODEV)) {
                    // Device was removed before INotify noticed.
                    ALOGW("could not get event, removed? (fd: %d size: %" PRId32
                            " bufferSize: %zu capacity: %zu errno: %d)\n",
                            device->fd, readSize, bufferSize, capacity, errno);
                    deviceChanged = true;
                    closeDeviceLocked(device);
                } else if (readSize < 0) {
                    if (errno != EAGAIN && errno != EINTR) {
                        ALOGW("could not get event (errno=%d)", errno);
                    }
                } else if ((readSize % sizeof(struct input_event)) != 0) {
                    ALOGE("could not get event (wrong size: %d)", readSize);
                } else {
                    int32_t deviceId = device->id == mBuiltInKeyboardId ? 0 : device->id;

                    size_t count = size_t(readSize) / sizeof(struct input_event);
                    for (size_t i = 0; i < count; i++) {
                        struct input_event& iev = readBuffer[i];
                        event->when = processEventTimestamp(iev);
                        event->deviceId = deviceId;
                        event->type = iev.type;
                        event->code = iev.code;
                        event->value = iev.value;
                        event += 1;
                        capacity -= 1;
                    }
                    if (capacity == 0) {
                        // The result buffer is full.  Reset the pending event index
                        // so we will try to read the device again on the next iteration.
                        mPendingEventIndex -= 1;
                        break;
                    }
                }
            } else if (eventItem.events & EPOLLHUP) {
                ALOGI("Removing device %s due to epoll hang-up event.",
                        device->identifier.name.c_str());
                deviceChanged = true;
                closeDeviceLocked(device);
            } else {
                ALOGW("Received unexpected epoll event 0x%08x for device %s.",
                        eventItem.events, device->identifier.name.c_str());
            }
        }

        // readNotify() will modify the list of devices so this must be done after
        // processing all other events to ensure that we read all remaining events
        // before closing the devices.
        if (mPendingINotify && mPendingEventIndex >= mPendingEventCount) {
            mPendingINotify = false;
            readNotifyLocked();
            deviceChanged = true;
        }

        // Report added or removed devices immediately.
        if (deviceChanged) {
            continue;
        }

        // Return now if we have collected any events or if we were explicitly awoken.
        if (event != buffer || awoken) {
            break;
        }

        // Poll for events.  Mind the wake lock dance!
        // We hold a wake lock at all times except during epoll_wait().  This works due to some
        // subtle choreography.  When a device driver has pending (unread) events, it acquires
        // a kernel wake lock.  However, once the last pending event has been read, the device
        // driver will release the kernel wake lock.  To prevent the system from going to sleep
        // when this happens, the EventHub holds onto its own user wake lock while the client
        // is processing events.  Thus the system can only sleep if there are no events
        // pending or currently being processed.
        //
        // The timeout is advisory only.  If the device is asleep, it will not wake just to
        // service the timeout.
        mPendingEventIndex = 0;

        mLock.unlock(); // release lock before poll, must be before release_wake_lock
        release_wake_lock(WAKE_LOCK_ID);

        int pollResult = epoll_wait(mEpollFd, mPendingEventItems, EPOLL_MAX_EVENTS, timeoutMillis);

        acquire_wake_lock(PARTIAL_WAKE_LOCK, WAKE_LOCK_ID);
        mLock.lock(); // reacquire lock after poll, must be after acquire_wake_lock

        if (pollResult == 0) {
            // Timed out.
            mPendingEventCount = 0;
            break;
        }

        if (pollResult < 0) {
            // An error occurred.
            mPendingEventCount = 0;

            // Sleep after errors to avoid locking up the system.
            // Hopefully the error is transient.
            if (errno != EINTR) {
                ALOGW("poll failed (errno=%d)\n", errno);
                usleep(100000);
            }
        } else {
            // Some events occurred.
            mPendingEventCount = size_t(pollResult);
        }
    }

    // All done, return the number of events we read.
    return event - buffer;
}

std::vector<TouchVideoFrame> EventHub::getVideoFrames(int32_t deviceId) {
    AutoMutex _l(mLock);

    Device* device = getDeviceLocked(deviceId);
    if (!device || !device->videoDevice) {
        return {};
    }
    return device->videoDevice->consumeFrames();
}

void EventHub::wake() {
    ALOGV("wake() called");

    ssize_t nWrite;
    do {
        nWrite = write(mWakeWritePipeFd, "W", 1);
    } while (nWrite == -1 && errno == EINTR);

    if (nWrite != 1 && errno != EAGAIN) {
        ALOGW("Could not write wake signal: %s", strerror(errno));
    }
}

void EventHub::scanDevicesLocked() {
    status_t result = scanDirLocked(DEVICE_PATH);
    if(result < 0) {
        ALOGE("scan dir failed for %s", DEVICE_PATH);
    }
    if (isV4lScanningEnabled()) {
        result = scanVideoDirLocked(VIDEO_DEVICE_PATH);
        if (result != OK) {
            ALOGE("scan video dir failed for %s", VIDEO_DEVICE_PATH);
        }
    }
    if (mDevices.indexOfKey(ReservedInputDeviceId::VIRTUAL_KEYBOARD_ID) < 0) {
        createVirtualKeyboardLocked();
    }
}

// ----------------------------------------------------------------------------

static bool containsNonZeroByte(const uint8_t* array, uint32_t startIndex, uint32_t endIndex) {
    const uint8_t* end = array + endIndex;
    array += startIndex;
    while (array != end) {
        if (*(array++) != 0) {
            return true;
        }
    }
    return false;
}

static const int32_t GAMEPAD_KEYCODES[] = {
        AKEYCODE_BUTTON_A, AKEYCODE_BUTTON_B, AKEYCODE_BUTTON_C,
        AKEYCODE_BUTTON_X, AKEYCODE_BUTTON_Y, AKEYCODE_BUTTON_Z,
        AKEYCODE_BUTTON_L1, AKEYCODE_BUTTON_R1,
        AKEYCODE_BUTTON_L2, AKEYCODE_BUTTON_R2,
        AKEYCODE_BUTTON_THUMBL, AKEYCODE_BUTTON_THUMBR,
        AKEYCODE_BUTTON_START, AKEYCODE_BUTTON_SELECT, AKEYCODE_BUTTON_MODE,
};

status_t EventHub::registerFdForEpoll(int fd) {
    // TODO(b/121395353) - consider adding EPOLLRDHUP
    struct epoll_event eventItem = {};
    eventItem.events = EPOLLIN | EPOLLWAKEUP;
    eventItem.data.fd = fd;
    if (epoll_ctl(mEpollFd, EPOLL_CTL_ADD, fd, &eventItem)) {
        ALOGE("Could not add fd to epoll instance: %s", strerror(errno));
        return -errno;
    }
    return OK;
}

status_t EventHub::unregisterFdFromEpoll(int fd) {
    if (epoll_ctl(mEpollFd, EPOLL_CTL_DEL, fd, nullptr)) {
        ALOGW("Could not remove fd from epoll instance: %s", strerror(errno));
        return -errno;
    }
    return OK;
}

status_t EventHub::registerDeviceForEpollLocked(Device* device) {
    if (device == nullptr) {
        if (DEBUG) {
            LOG_ALWAYS_FATAL("Cannot call registerDeviceForEpollLocked with null Device");
        }
        return BAD_VALUE;
    }
    status_t result = registerFdForEpoll(device->fd);
    if (result != OK) {
        ALOGE("Could not add input device fd to epoll for device %" PRId32, device->id);
        return result;
    }
    if (device->videoDevice) {
        registerVideoDeviceForEpollLocked(*device->videoDevice);
    }
    return result;
}

void EventHub::registerVideoDeviceForEpollLocked(const TouchVideoDevice& videoDevice) {
    status_t result = registerFdForEpoll(videoDevice.getFd());
    if (result != OK) {
        ALOGE("Could not add video device %s to epoll", videoDevice.getName().c_str());
    }
}

status_t EventHub::unregisterDeviceFromEpollLocked(Device* device) {
    if (device->hasValidFd()) {
        status_t result = unregisterFdFromEpoll(device->fd);
        if (result != OK) {
            ALOGW("Could not remove input device fd from epoll for device %" PRId32, device->id);
            return result;
        }
    }
    if (device->videoDevice) {
        unregisterVideoDeviceFromEpollLocked(*device->videoDevice);
    }
    return OK;
}

void EventHub::unregisterVideoDeviceFromEpollLocked(const TouchVideoDevice& videoDevice) {
    if (videoDevice.hasValidFd()) {
        status_t result = unregisterFdFromEpoll(videoDevice.getFd());
        if (result != OK) {
            ALOGW("Could not remove video device fd from epoll for device: %s",
                    videoDevice.getName().c_str());
        }
    }
}

status_t EventHub::openDeviceLocked(const char* devicePath) {
    char buffer[80];

    ALOGV("Opening device: %s", devicePath);

    int fd = open(devicePath, O_RDWR | O_CLOEXEC | O_NONBLOCK);
    if(fd < 0) {
        ALOGE("could not open %s, %s\n", devicePath, strerror(errno));
        return -1;
    }

    InputDeviceIdentifier identifier;

    // Get device name.
    if(ioctl(fd, EVIOCGNAME(sizeof(buffer) - 1), &buffer) < 1) {
        ALOGE("Could not get device name for %s: %s", devicePath, strerror(errno));
    } else {
        buffer[sizeof(buffer) - 1] = '\0';
        identifier.name = buffer;
    }

    // Check to see if the device is on our excluded list
    for (size_t i = 0; i < mExcludedDevices.size(); i++) {
        const std::string& item = mExcludedDevices[i];
        if (identifier.name == item) {
            ALOGI("ignoring event id %s driver %s\n", devicePath, item.c_str());
            close(fd);
            return -1;
        }
    }

    // Get device driver version.
    int driverVersion;
    if(ioctl(fd, EVIOCGVERSION, &driverVersion)) {
        ALOGE("could not get driver version for %s, %s\n", devicePath, strerror(errno));
        close(fd);
        return -1;
    }

    // Get device identifier.
    struct input_id inputId;
    if(ioctl(fd, EVIOCGID, &inputId)) {
        ALOGE("could not get device input id for %s, %s\n", devicePath, strerror(errno));
        close(fd);
        return -1;
    }
    identifier.bus = inputId.bustype;
    identifier.product = inputId.product;
    identifier.vendor = inputId.vendor;
    identifier.version = inputId.version;

    // Get device physical location.
    if(ioctl(fd, EVIOCGPHYS(sizeof(buffer) - 1), &buffer) < 1) {
        //fprintf(stderr, "could not get location for %s, %s\n", devicePath, strerror(errno));
    } else {
        buffer[sizeof(buffer) - 1] = '\0';
        identifier.location = buffer;
    }

    // Get device unique id.
    if(ioctl(fd, EVIOCGUNIQ(sizeof(buffer) - 1), &buffer) < 1) {
        //fprintf(stderr, "could not get idstring for %s, %s\n", devicePath, strerror(errno));
    } else {
        buffer[sizeof(buffer) - 1] = '\0';
        identifier.uniqueId = buffer;
    }

    // Fill in the descriptor.
    assignDescriptorLocked(identifier);

    // Allocate device.  (The device object takes ownership of the fd at this point.)
    int32_t deviceId = mNextDeviceId++;
    Device* device = new Device(fd, deviceId, devicePath, identifier);

    ALOGV("add device %d: %s\n", deviceId, devicePath);
    ALOGV("  bus:        %04x\n"
         "  vendor      %04x\n"
         "  product     %04x\n"
         "  version     %04x\n",
        identifier.bus, identifier.vendor, identifier.product, identifier.version);
    ALOGV("  name:       \"%s\"\n", identifier.name.c_str());
    ALOGV("  location:   \"%s\"\n", identifier.location.c_str());
    ALOGV("  unique id:  \"%s\"\n", identifier.uniqueId.c_str());
    ALOGV("  descriptor: \"%s\"\n", identifier.descriptor.c_str());
    ALOGV("  driver:     v%d.%d.%d\n",
        driverVersion >> 16, (driverVersion >> 8) & 0xff, driverVersion & 0xff);

    // Load the configuration file for the device.
    loadConfigurationLocked(device);

    // Figure out the kinds of events the device reports.
    ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(device->keyBitmask)), device->keyBitmask);
    ioctl(fd, EVIOCGBIT(EV_ABS, sizeof(device->absBitmask)), device->absBitmask);
    ioctl(fd, EVIOCGBIT(EV_REL, sizeof(device->relBitmask)), device->relBitmask);
    ioctl(fd, EVIOCGBIT(EV_SW, sizeof(device->swBitmask)), device->swBitmask);
    ioctl(fd, EVIOCGBIT(EV_LED, sizeof(device->ledBitmask)), device->ledBitmask);
    ioctl(fd, EVIOCGBIT(EV_FF, sizeof(device->ffBitmask)), device->ffBitmask);
    ioctl(fd, EVIOCGPROP(sizeof(device->propBitmask)), device->propBitmask);

    // See if this is a keyboard.  Ignore everything in the button range except for
    // joystick and gamepad buttons which are handled like keyboards for the most part.
    bool haveKeyboardKeys = containsNonZeroByte(device->keyBitmask, 0, sizeof_bit_array(BTN_MISC))
            || containsNonZeroByte(device->keyBitmask, sizeof_bit_array(KEY_OK),
                    sizeof_bit_array(KEY_MAX + 1));
    bool haveGamepadButtons = containsNonZeroByte(device->keyBitmask, sizeof_bit_array(BTN_MISC),
                    sizeof_bit_array(BTN_MOUSE))
            || containsNonZeroByte(device->keyBitmask, sizeof_bit_array(BTN_JOYSTICK),
                    sizeof_bit_array(BTN_DIGI));
    if (haveKeyboardKeys || haveGamepadButtons) {
        device->classes |= INPUT_DEVICE_CLASS_KEYBOARD;
    }

    // See if this is a cursor device such as a trackball or mouse.
    if (test_bit(BTN_MOUSE, device->keyBitmask)
            && test_bit(REL_X, device->relBitmask)
            && test_bit(REL_Y, device->relBitmask)) {
        device->classes |= INPUT_DEVICE_CLASS_CURSOR;
    }

    // See if this is a rotary encoder type device.
    String8 deviceType = String8();
    if (device->configuration &&
        device->configuration->tryGetProperty(String8("device.type"), deviceType)) {
            if (!deviceType.compare(String8("rotaryEncoder"))) {
                device->classes |= INPUT_DEVICE_CLASS_ROTARY_ENCODER;
            }
    }

    // See if this is a touch pad.
    // Is this a new modern multi-touch driver?
    if (test_bit(ABS_MT_POSITION_X, device->absBitmask)
            && test_bit(ABS_MT_POSITION_Y, device->absBitmask)) {
        // Some joysticks such as the PS3 controller report axes that conflict
        // with the ABS_MT range.  Try to confirm that the device really is
        // a touch screen.
        if (test_bit(BTN_TOUCH, device->keyBitmask) || !haveGamepadButtons) {
            device->classes |= INPUT_DEVICE_CLASS_TOUCH | INPUT_DEVICE_CLASS_TOUCH_MT;
        }
    // Is this an old style single-touch driver?
    } else if (test_bit(BTN_TOUCH, device->keyBitmask)
            && test_bit(ABS_X, device->absBitmask)
            && test_bit(ABS_Y, device->absBitmask)) {
        device->classes |= INPUT_DEVICE_CLASS_TOUCH;
    // Is this a BT stylus?
    } else if ((test_bit(ABS_PRESSURE, device->absBitmask) ||
                test_bit(BTN_TOUCH, device->keyBitmask))
            && !test_bit(ABS_X, device->absBitmask)
            && !test_bit(ABS_Y, device->absBitmask)) {
        device->classes |= INPUT_DEVICE_CLASS_EXTERNAL_STYLUS;
        // Keyboard will try to claim some of the buttons but we really want to reserve those so we
        // can fuse it with the touch screen data, so just take them back. Note this means an
        // external stylus cannot also be a keyboard device.
        device->classes &= ~INPUT_DEVICE_CLASS_KEYBOARD;
    }

    // See if this device is a joystick.
    // Assumes that joysticks always have gamepad buttons in order to distinguish them
    // from other devices such as accelerometers that also have absolute axes.
    if (haveGamepadButtons) {
        uint32_t assumedClasses = device->classes | INPUT_DEVICE_CLASS_JOYSTICK;
        for (int i = 0; i <= ABS_MAX; i++) {
            if (test_bit(i, device->absBitmask)
                    && (getAbsAxisUsage(i, assumedClasses) & INPUT_DEVICE_CLASS_JOYSTICK)) {
                device->classes = assumedClasses;
                break;
            }
        }
    }

    // Check whether this device has switches.
    for (int i = 0; i <= SW_MAX; i++) {
        if (test_bit(i, device->swBitmask)) {
            device->classes |= INPUT_DEVICE_CLASS_SWITCH;
            break;
        }
    }

    // Check whether this device supports the vibrator.
    if (test_bit(FF_RUMBLE, device->ffBitmask)) {
        device->classes |= INPUT_DEVICE_CLASS_VIBRATOR;
    }

    // Configure virtual keys.
    if ((device->classes & INPUT_DEVICE_CLASS_TOUCH)) {
        // Load the virtual keys for the touch screen, if any.
        // We do this now so that we can make sure to load the keymap if necessary.
        bool success = loadVirtualKeyMapLocked(device);
        if (success) {
            device->classes |= INPUT_DEVICE_CLASS_KEYBOARD;
        }
    }

    // Load the key map.
    // We need to do this for joysticks too because the key layout may specify axes.
    status_t keyMapStatus = NAME_NOT_FOUND;
    if (device->classes & (INPUT_DEVICE_CLASS_KEYBOARD | INPUT_DEVICE_CLASS_JOYSTICK)) {
        // Load the keymap for the device.
        keyMapStatus = loadKeyMapLocked(device);
    }

    // Configure the keyboard, gamepad or virtual keyboard.
    if (device->classes & INPUT_DEVICE_CLASS_KEYBOARD) {
        // Register the keyboard as a built-in keyboard if it is eligible.
        if (!keyMapStatus
                && mBuiltInKeyboardId == NO_BUILT_IN_KEYBOARD
                && isEligibleBuiltInKeyboard(device->identifier,
                        device->configuration, &device->keyMap)) {
            mBuiltInKeyboardId = device->id;
        }

        // 'Q' key support = cheap test of whether this is an alpha-capable kbd
        if (hasKeycodeLocked(device, AKEYCODE_Q)) {
            device->classes |= INPUT_DEVICE_CLASS_ALPHAKEY;
        }

        // See if this device has a DPAD.
        if (hasKeycodeLocked(device, AKEYCODE_DPAD_UP) &&
                hasKeycodeLocked(device, AKEYCODE_DPAD_DOWN) &&
                hasKeycodeLocked(device, AKEYCODE_DPAD_LEFT) &&
                hasKeycodeLocked(device, AKEYCODE_DPAD_RIGHT) &&
                hasKeycodeLocked(device, AKEYCODE_DPAD_CENTER)) {
            device->classes |= INPUT_DEVICE_CLASS_DPAD;
        }

        // See if this device has a gamepad.
        for (size_t i = 0; i < sizeof(GAMEPAD_KEYCODES)/sizeof(GAMEPAD_KEYCODES[0]); i++) {
            if (hasKeycodeLocked(device, GAMEPAD_KEYCODES[i])) {
                device->classes |= INPUT_DEVICE_CLASS_GAMEPAD;
                break;
            }
        }
    }

    // If the device isn't recognized as something we handle, don't monitor it.
    if (device->classes == 0) {
        ALOGV("Dropping device: id=%d, path='%s', name='%s'",
                deviceId, devicePath, device->identifier.name.c_str());
        delete device;
        return -1;
    }

    // Determine whether the device has a mic.
    if (deviceHasMicLocked(device)) {
        device->classes |= INPUT_DEVICE_CLASS_MIC;
    }

    // Determine whether the device is external or internal.
    if (isExternalDeviceLocked(device)) {
        device->classes |= INPUT_DEVICE_CLASS_EXTERNAL;
    }

    if (device->classes & (INPUT_DEVICE_CLASS_JOYSTICK | INPUT_DEVICE_CLASS_DPAD)
            && device->classes & INPUT_DEVICE_CLASS_GAMEPAD) {
        device->controllerNumber = getNextControllerNumberLocked(device);
        setLedForControllerLocked(device);
    }

    // Find a matching video device by comparing device names
    // This should be done before registerDeviceForEpollLocked, so that both fds are added to epoll
    for (std::unique_ptr<TouchVideoDevice>& videoDevice : mUnattachedVideoDevices) {
        if (device->identifier.name == videoDevice->getName()) {
            device->videoDevice = std::move(videoDevice);
            break;
        }
    }
    mUnattachedVideoDevices.erase(std::remove_if(mUnattachedVideoDevices.begin(),
            mUnattachedVideoDevices.end(),
            [](const std::unique_ptr<TouchVideoDevice>& videoDevice){
            return videoDevice == nullptr; }), mUnattachedVideoDevices.end());

    if (registerDeviceForEpollLocked(device) != OK) {
        delete device;
        return -1;
    }

    configureFd(device);

    ALOGI("New device: id=%d, fd=%d, path='%s', name='%s', classes=0x%x, "
            "configuration='%s', keyLayout='%s', keyCharacterMap='%s', builtinKeyboard=%s, ",
         deviceId, fd, devicePath, device->identifier.name.c_str(),
         device->classes,
         device->configurationFile.c_str(),
         device->keyMap.keyLayoutFile.c_str(),
         device->keyMap.keyCharacterMapFile.c_str(),
         toString(mBuiltInKeyboardId == deviceId));

    addDeviceLocked(device);
    return OK;
}

void EventHub::configureFd(Device* device) {
    // Set fd parameters with ioctl, such as key repeat, suspend block, and clock type
    if (device->classes & INPUT_DEVICE_CLASS_KEYBOARD) {
        // Disable kernel key repeat since we handle it ourselves
        unsigned int repeatRate[] = {0, 0};
        if (ioctl(device->fd, EVIOCSREP, repeatRate)) {
            ALOGW("Unable to disable kernel key repeat for %s: %s",
                  device->path.c_str(), strerror(errno));
        }
    }

    std::string wakeMechanism = "EPOLLWAKEUP";
    if (!mUsingEpollWakeup) {
#ifndef EVIOCSSUSPENDBLOCK
        // uapi headers don't include EVIOCSSUSPENDBLOCK, and future kernels
        // will use an epoll flag instead, so as long as we want to support
        // this feature, we need to be prepared to define the ioctl ourselves.
#define EVIOCSSUSPENDBLOCK _IOW('E', 0x91, int)
#endif
        if (ioctl(device->fd, EVIOCSSUSPENDBLOCK, 1)) {
            wakeMechanism = "<none>";
        } else {
            wakeMechanism = "EVIOCSSUSPENDBLOCK";
        }
    }
    // Tell the kernel that we want to use the monotonic clock for reporting timestamps
    // associated with input events.  This is important because the input system
    // uses the timestamps extensively and assumes they were recorded using the monotonic
    // clock.
    int clockId = CLOCK_MONOTONIC;
    bool usingClockIoctl = !ioctl(device->fd, EVIOCSCLOCKID, &clockId);
    ALOGI("wakeMechanism=%s, usingClockIoctl=%s", wakeMechanism.c_str(),
          toString(usingClockIoctl));
}

void EventHub::openVideoDeviceLocked(const std::string& devicePath) {
    std::unique_ptr<TouchVideoDevice> videoDevice = TouchVideoDevice::create(devicePath);
    if (!videoDevice) {
        ALOGE("Could not create touch video device for %s. Ignoring", devicePath.c_str());
        return;
    }
    // Transfer ownership of this video device to a matching input device
    for (size_t i = 0; i < mDevices.size(); i++) {
        Device* device = mDevices.valueAt(i);
        if (videoDevice->getName() == device->identifier.name) {
            device->videoDevice = std::move(videoDevice);
            if (device->enabled) {
                registerVideoDeviceForEpollLocked(*device->videoDevice);
            }
            return;
        }
    }

    // Couldn't find a matching input device, so just add it to a temporary holding queue.
    // A matching input device may appear later.
    ALOGI("Adding video device %s to list of unattached video devices",
            videoDevice->getName().c_str());
    mUnattachedVideoDevices.push_back(std::move(videoDevice));
}

bool EventHub::isDeviceEnabled(int32_t deviceId) {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device == nullptr) {
        ALOGE("Invalid device id=%" PRId32 " provided to %s", deviceId, __func__);
        return false;
    }
    return device->enabled;
}

status_t EventHub::enableDevice(int32_t deviceId) {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device == nullptr) {
        ALOGE("Invalid device id=%" PRId32 " provided to %s", deviceId, __func__);
        return BAD_VALUE;
    }
    if (device->enabled) {
        ALOGW("Duplicate call to %s, input device %" PRId32 " already enabled", __func__, deviceId);
        return OK;
    }
    status_t result = device->enable();
    if (result != OK) {
        ALOGE("Failed to enable device %" PRId32, deviceId);
        return result;
    }

    configureFd(device);

    return registerDeviceForEpollLocked(device);
}

status_t EventHub::disableDevice(int32_t deviceId) {
    AutoMutex _l(mLock);
    Device* device = getDeviceLocked(deviceId);
    if (device == nullptr) {
        ALOGE("Invalid device id=%" PRId32 " provided to %s", deviceId, __func__);
        return BAD_VALUE;
    }
    if (!device->enabled) {
        ALOGW("Duplicate call to %s, input device already disabled", __func__);
        return OK;
    }
    unregisterDeviceFromEpollLocked(device);
    return device->disable();
}

void EventHub::createVirtualKeyboardLocked() {
    InputDeviceIdentifier identifier;
    identifier.name = "Virtual";
    identifier.uniqueId = "<virtual>";
    assignDescriptorLocked(identifier);

    Device* device = new Device(-1, ReservedInputDeviceId::VIRTUAL_KEYBOARD_ID, "<virtual>",
            identifier);
    device->classes = INPUT_DEVICE_CLASS_KEYBOARD
            | INPUT_DEVICE_CLASS_ALPHAKEY
            | INPUT_DEVICE_CLASS_DPAD
            | INPUT_DEVICE_CLASS_VIRTUAL;
    loadKeyMapLocked(device);
    addDeviceLocked(device);
}

void EventHub::addDeviceLocked(Device* device) {
    mDevices.add(device->id, device);
    device->next = mOpeningDevices;
    mOpeningDevices = device;
}

void EventHub::loadConfigurationLocked(Device* device) {
    device->configurationFile = getInputDeviceConfigurationFilePathByDeviceIdentifier(
            device->identifier, INPUT_DEVICE_CONFIGURATION_FILE_TYPE_CONFIGURATION);
    if (device->configurationFile.empty()) {
        ALOGD("No input device configuration file found for device '%s'.",
                device->identifier.name.c_str());
    } else {
        status_t status = PropertyMap::load(String8(device->configurationFile.c_str()),
                &device->configuration);
        if (status) {
            ALOGE("Error loading input device configuration file for device '%s'.  "
                    "Using default configuration.",
                    device->identifier.name.c_str());
        }
    }
}

bool EventHub::loadVirtualKeyMapLocked(Device* device) {
    // The virtual key map is supplied by the kernel as a system board property file.
    std::string path;
    path += "/sys/board_properties/virtualkeys.";
    path += device->identifier.getCanonicalName();
    if (access(path.c_str(), R_OK)) {
        return false;
    }
    device->virtualKeyMap = VirtualKeyMap::load(path);
    return device->virtualKeyMap != nullptr;
}

status_t EventHub::loadKeyMapLocked(Device* device) {
    return device->keyMap.load(device->identifier, device->configuration);
}

bool EventHub::isExternalDeviceLocked(Device* device) {
    if (device->configuration) {
        bool value;
        if (device->configuration->tryGetProperty(String8("device.internal"), value)) {
            return !value;
        }
    }
    return device->identifier.bus == BUS_USB || device->identifier.bus == BUS_BLUETOOTH;
}

bool EventHub::deviceHasMicLocked(Device* device) {
    if (device->configuration) {
        bool value;
        if (device->configuration->tryGetProperty(String8("audio.mic"), value)) {
            return value;
        }
    }
    return false;
}

int32_t EventHub::getNextControllerNumberLocked(Device* device) {
    if (mControllerNumbers.isFull()) {
        ALOGI("Maximum number of controllers reached, assigning controller number 0 to device %s",
                device->identifier.name.c_str());
        return 0;
    }
    // Since the controller number 0 is reserved for non-controllers, translate all numbers up by
    // one
    return static_cast<int32_t>(mControllerNumbers.markFirstUnmarkedBit() + 1);
}

void EventHub::releaseControllerNumberLocked(Device* device) {
    int32_t num = device->controllerNumber;
    device->controllerNumber= 0;
    if (num == 0) {
        return;
    }
    mControllerNumbers.clearBit(static_cast<uint32_t>(num - 1));
}

void EventHub::setLedForControllerLocked(Device* device) {
    for (int i = 0; i < MAX_CONTROLLER_LEDS; i++) {
        setLedStateLocked(device, ALED_CONTROLLER_1 + i, device->controllerNumber == i + 1);
    }
}

bool EventHub::hasKeycodeLocked(Device* device, int keycode) const {
    if (!device->keyMap.haveKeyLayout()) {
        return false;
    }

    std::vector<int32_t> scanCodes;
    device->keyMap.keyLayoutMap->findScanCodesForKey(keycode, &scanCodes);
    const size_t N = scanCodes.size();
    for (size_t i=0; i<N && i<=KEY_MAX; i++) {
        int32_t sc = scanCodes[i];
        if (sc >= 0 && sc <= KEY_MAX && test_bit(sc, device->keyBitmask)) {
            return true;
        }
    }

    return false;
}

status_t EventHub::mapLed(Device* device, int32_t led, int32_t* outScanCode) const {
    if (!device->keyMap.haveKeyLayout()) {
        return NAME_NOT_FOUND;
    }

    int32_t scanCode;
    if(device->keyMap.keyLayoutMap->findScanCodeForLed(led, &scanCode) != NAME_NOT_FOUND) {
        if(scanCode >= 0 && scanCode <= LED_MAX && test_bit(scanCode, device->ledBitmask)) {
            *outScanCode = scanCode;
            return NO_ERROR;
        }
    }
    return NAME_NOT_FOUND;
}

void EventHub::closeDeviceByPathLocked(const char *devicePath) {
    Device* device = getDeviceByPathLocked(devicePath);
    if (device) {
        closeDeviceLocked(device);
        return;
    }
    ALOGV("Remove device: %s not found, device may already have been removed.", devicePath);
}

/**
 * Find the video device by filename, and close it.
 * The video device is closed by path during an inotify event, where we don't have the
 * additional context about the video device fd, or the associated input device.
 */
void EventHub::closeVideoDeviceByPathLocked(const std::string& devicePath) {
    // A video device may be owned by an existing input device, or it may be stored in
    // the mUnattachedVideoDevices queue. Check both locations.
    for (size_t i = 0; i < mDevices.size(); i++) {
        Device* device = mDevices.valueAt(i);
        if (device->videoDevice && device->videoDevice->getPath() == devicePath) {
            unregisterVideoDeviceFromEpollLocked(*device->videoDevice);
            device->videoDevice = nullptr;
            return;
        }
    }
    mUnattachedVideoDevices.erase(std::remove_if(mUnattachedVideoDevices.begin(),
            mUnattachedVideoDevices.end(), [&devicePath](
            const std::unique_ptr<TouchVideoDevice>& videoDevice) {
            return videoDevice->getPath() == devicePath; }), mUnattachedVideoDevices.end());
}

void EventHub::closeAllDevicesLocked() {
    mUnattachedVideoDevices.clear();
    while (mDevices.size() > 0) {
        closeDeviceLocked(mDevices.valueAt(mDevices.size() - 1));
    }
}

void EventHub::closeDeviceLocked(Device* device) {
    ALOGI("Removed device: path=%s name=%s id=%d fd=%d classes=0x%x",
         device->path.c_str(), device->identifier.name.c_str(), device->id,
         device->fd, device->classes);

    if (device->id == mBuiltInKeyboardId) {
        ALOGW("built-in keyboard device %s (id=%d) is closing! the apps will not like this",
                device->path.c_str(), mBuiltInKeyboardId);
        mBuiltInKeyboardId = NO_BUILT_IN_KEYBOARD;
    }

    unregisterDeviceFromEpollLocked(device);
    if (device->videoDevice) {
        // This must be done after the video device is removed from epoll
        mUnattachedVideoDevices.push_back(std::move(device->videoDevice));
    }

    releaseControllerNumberLocked(device);

    mDevices.removeItem(device->id);
    device->close();

    // Unlink for opening devices list if it is present.
    Device* pred = nullptr;
    bool found = false;
    for (Device* entry = mOpeningDevices; entry != nullptr; ) {
        if (entry == device) {
            found = true;
            break;
        }
        pred = entry;
        entry = entry->next;
    }
    if (found) {
        // Unlink the device from the opening devices list then delete it.
        // We don't need to tell the client that the device was closed because
        // it does not even know it was opened in the first place.
        ALOGI("Device %s was immediately closed after opening.", device->path.c_str());
        if (pred) {
            pred->next = device->next;
        } else {
            mOpeningDevices = device->next;
        }
        delete device;
    } else {
        // Link into closing devices list.
        // The device will be deleted later after we have informed the client.
        device->next = mClosingDevices;
        mClosingDevices = device;
    }
}

status_t EventHub::readNotifyLocked() {
    int res;
    char event_buf[512];
    int event_size;
    int event_pos = 0;
    struct inotify_event *event;

    ALOGV("EventHub::readNotify nfd: %d\n", mINotifyFd);
    res = read(mINotifyFd, event_buf, sizeof(event_buf));
    if(res < (int)sizeof(*event)) {
        if(errno == EINTR)
            return 0;
        ALOGW("could not get event, %s\n", strerror(errno));
        return -1;
    }

    while(res >= (int)sizeof(*event)) {
        event = (struct inotify_event *)(event_buf + event_pos);
        if(event->len) {
            if (event->wd == mInputWd) {
                std::string filename = StringPrintf("%s/%s", DEVICE_PATH, event->name);
                if(event->mask & IN_CREATE) {
                    openDeviceLocked(filename.c_str());
                } else {
                    ALOGI("Removing device '%s' due to inotify event\n", filename.c_str());
                    closeDeviceByPathLocked(filename.c_str());
                }
            }
            else if (event->wd == mVideoWd) {
                if (isV4lTouchNode(event->name)) {
                    std::string filename = StringPrintf("%s/%s", VIDEO_DEVICE_PATH, event->name);
                    if (event->mask & IN_CREATE) {
                        openVideoDeviceLocked(filename);
                    } else {
                        ALOGI("Removing video device '%s' due to inotify event", filename.c_str());
                        closeVideoDeviceByPathLocked(filename);
                    }
                }
            }
            else {
                LOG_ALWAYS_FATAL("Unexpected inotify event, wd = %i", event->wd);
            }
        }
        event_size = sizeof(*event) + event->len;
        res -= event_size;
        event_pos += event_size;
    }
    return 0;
}

status_t EventHub::scanDirLocked(const char *dirname)
{
    char devname[PATH_MAX];
    char *filename;
    DIR *dir;
    struct dirent *de;
    dir = opendir(dirname);
    if(dir == nullptr)
        return -1;
    strcpy(devname, dirname);
    filename = devname + strlen(devname);
    *filename++ = '/';
    while((de = readdir(dir))) {
        if(de->d_name[0] == '.' &&
           (de->d_name[1] == '\0' ||
            (de->d_name[1] == '.' && de->d_name[2] == '\0')))
            continue;
        strcpy(filename, de->d_name);
        openDeviceLocked(devname);
    }
    closedir(dir);
    return 0;
}

/**
 * Look for all dirname/v4l-touch* devices, and open them.
 */
status_t EventHub::scanVideoDirLocked(const std::string& dirname)
{
    DIR* dir;
    struct dirent* de;
    dir = opendir(dirname.c_str());
    if(!dir) {
        ALOGE("Could not open video directory %s", dirname.c_str());
        return BAD_VALUE;
    }

    while((de = readdir(dir))) {
        const char* name = de->d_name;
        if (isV4lTouchNode(name)) {
            ALOGI("Found touch video device %s", name);
            openVideoDeviceLocked(dirname + "/" + name);
        }
    }
    closedir(dir);
    return OK;
}

void EventHub::requestReopenDevices() {
    ALOGV("requestReopenDevices() called");

    AutoMutex _l(mLock);
    mNeedToReopenDevices = true;
}

void EventHub::dump(std::string& dump) {
    dump += "Event Hub State:\n";

    { // acquire lock
        AutoMutex _l(mLock);

        dump += StringPrintf(INDENT "BuiltInKeyboardId: %d\n", mBuiltInKeyboardId);

        dump += INDENT "Devices:\n";

        for (size_t i = 0; i < mDevices.size(); i++) {
            const Device* device = mDevices.valueAt(i);
            if (mBuiltInKeyboardId == device->id) {
                dump += StringPrintf(INDENT2 "%d: %s (aka device 0 - built-in keyboard)\n",
                        device->id, device->identifier.name.c_str());
            } else {
                dump += StringPrintf(INDENT2 "%d: %s\n", device->id,
                        device->identifier.name.c_str());
            }
            dump += StringPrintf(INDENT3 "Classes: 0x%08x\n", device->classes);
            dump += StringPrintf(INDENT3 "Path: %s\n", device->path.c_str());
            dump += StringPrintf(INDENT3 "Enabled: %s\n", toString(device->enabled));
            dump += StringPrintf(INDENT3 "Descriptor: %s\n", device->identifier.descriptor.c_str());
            dump += StringPrintf(INDENT3 "Location: %s\n", device->identifier.location.c_str());
            dump += StringPrintf(INDENT3 "ControllerNumber: %d\n", device->controllerNumber);
            dump += StringPrintf(INDENT3 "UniqueId: %s\n", device->identifier.uniqueId.c_str());
            dump += StringPrintf(INDENT3 "Identifier: bus=0x%04x, vendor=0x%04x, "
                    "product=0x%04x, version=0x%04x\n",
                    device->identifier.bus, device->identifier.vendor,
                    device->identifier.product, device->identifier.version);
            dump += StringPrintf(INDENT3 "KeyLayoutFile: %s\n",
                    device->keyMap.keyLayoutFile.c_str());
            dump += StringPrintf(INDENT3 "KeyCharacterMapFile: %s\n",
                    device->keyMap.keyCharacterMapFile.c_str());
            dump += StringPrintf(INDENT3 "ConfigurationFile: %s\n",
                    device->configurationFile.c_str());
            dump += StringPrintf(INDENT3 "HaveKeyboardLayoutOverlay: %s\n",
                    toString(device->overlayKeyMap != nullptr));
            dump += INDENT3 "VideoDevice: ";
            if (device->videoDevice) {
                dump += device->videoDevice->dump() + "\n";
            } else {
                dump += "<none>\n";
            }
        }

        dump += INDENT "Unattached video devices:\n";
        for (const std::unique_ptr<TouchVideoDevice>& videoDevice : mUnattachedVideoDevices) {
            dump += INDENT2 + videoDevice->dump() + "\n";
        }
        if (mUnattachedVideoDevices.empty()) {
            dump += INDENT2 "<none>\n";
        }
    } // release lock
}

void EventHub::monitor() {
    // Acquire and release the lock to ensure that the event hub has not deadlocked.
    mLock.lock();
    mLock.unlock();
}


}; // namespace android