input之上层（二）

　　在上篇blog中以InputReaderThread为入口，主要了解了一下getEvents这个函数，接下来还有很多函数在等着我们去探索，下面继续：

　status_t EventHub::readNotifyLocked() {
   ...........

    ALOGV("EventHub::readNotify nfd: %d\n", mINotifyFd);
    res = read(mINotifyFd, event_buf, sizeof(event_buf));　　　//读取设备新增删除事件的具体信息
    if(res < (int)sizeof(*event)) {
        if(errno == EINTR)
            return 0;
        ALOGW("could not get event, %s\n", strerror(errno));
        return -1;
    }
    //printf("got %d bytes of event information\n", res);

    strcpy(devname, DEVICE_PATH);　　　//路径：/dev/input
    filename = devname + strlen(devname);
    *filename++ = '/';

    while(res >= (int)sizeof(*event)) {　　　　//遍历所有事件信息
        event = (struct inotify_event *)(event_buf + event_pos);
        //printf("%d: %08x \"%s\"\n", event->wd, event->mask, event->len ? event->name : "");
        if(event->len) {
            strcpy(filename, event->name);
            if(event->mask & IN_CREATE) {　　　　//创建新的输入设备
                openDeviceLocked(devname);
            } else {
                ALOGI("Removing device '%s' due to inotify event\n", devname);　　　//删除事件
                closeDeviceByPathLocked(devname);
            }
        }
        event_size = sizeof(*event) + event->len;
        res -= event_size;
        event_pos += event_size;
    }
    return 0;
}

看一下上面调用的新增设备openDeviceLocked

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

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

    InputDeviceIdentifier identifier;

    //获取设备名称
    if(ioctl(fd, EVIOCGNAME(sizeof(buffer) - 1), &buffer) < 1) {
        //fprintf(stderr, "could not get device name for %s, %s\n", devicePath, strerror(errno));
    } else {
        buffer[sizeof(buffer) - 1] = '\0';
        identifier.name.setTo(buffer);
    }

    // 查看这个设备是否在拒绝的里表里面
    for (size_t i = 0; i < mExcludedDevices.size(); i++) {
        const String8& item = mExcludedDevices.itemAt(i);
        if (identifier.name == item) {
            ALOGI("ignoring event id %s driver %s\n", devicePath, item.string());
            close(fd);
            return -1;
        }
    }

    // 获取设备驱动版本
    int driverVersion;
    if(ioctl(fd, EVIOCGVERSION, &driverVersion)) {
        ALOGE("could not get driver version for %s, %s\n", devicePath, strerror(errno));
        close(fd);
        return -1;
    }

    // 获取设备标识符
    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;

    // 获取设备物理位置
    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.setTo(buffer);
    }

    // 获取设备唯一的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.setTo(buffer);
    }

    // 填充描述信息
    assignDescriptorLocked(identifier);

    //使文件描述器无阻塞的用于轮询
    if (fcntl(fd, F_SETFL, O_NONBLOCK)) {
        ALOGE("Error %d making device file descriptor non-blocking.", errno);
        close(fd);
        return -1;
    }

    // 分配设备，此时设备对象获得fd的所有权
    int32_t deviceId = mNextDeviceId++;
    Device* device = new Device(fd, deviceId, String8(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.string());
    ALOGV("  location:   \"%s\"\n", identifier.location.string());
    ALOGV("  unique id:  \"%s\"\n", identifier.uniqueId.string());
    ALOGV("  descriptor: \"%s\"\n", identifier.descriptor.string());
    ALOGV("  driver:     v%d.%d.%d\n",
        driverVersion >> 16, (driverVersion >> 8) & 0xff, driverVersion & 0xff);

    //加载设备配置
    loadConfigurationLocked(device);

    // 指出设备上报事件的种类
    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);