android 使用uinput模拟输入设备的方法

在google remote中，android接收端接收socket发来的ir code，然后将ir code模拟出来发给系统处理，这就是google remote接收端的原理。

系统端怎样模拟input event呢？
方法一：通过instrumentation.sendkeydownupsync 实现，简单使用但是问题在于sendkeydownupsync发出的event，无法运行到
interceptkeybeforedispatching，也就无法正常作用 home，vol...
方法二：通过uinput桥接；原理是利用内核现有的uinput驱动，通过内核驱动uinput来发送input event，而且还容易使用kl,kcm 客制化；

  经过比较方法二较优，下面就就给出方法二的测试代码...
  1、main函数，setup_uinput_device 完成设备的注册，然后创建一个线程 virtualinputdev_eventthread，该线程重复发出keycode；

  int main()
{

 printf("enter process !!!! \n");

    stvirtualinputdevdata *pkpddata = (stvirtualinputdevdata*) malloc(sizeof(stvirtualinputdevdata));
   pkpddata->min_keycode = umin_keycode;
   pkpddata->max_keycode = umax_keycode;
    if (setup_uinput_device(pkpddata) < 0) {
        printf("unable to find uinput device\n");
        free(pkpddata);
        return -1;
    }

    pthread_attr_t attr;
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, pthread_create_detached);
    if (0 != pthread_create(&keypad_eventthreadid, &attr, virtualinputdev_eventthread, (void *)0)) {
        printf("create keypadeventthread failed!!\n");
        exit(1);
    }

    // coverity server need set to ignore this.
    while (1) {
        usleep(1000000);  // sleep 1 second
    }

    free(pkpddata);
    pkpddata = 0;

    // destroy the device
    ioctl(uinp_fd, ui_dev_destroy);

    close(uinp_fd);
    return 0;
}

2、setup_uinput_device函数，完成设备注册；可以看到是直接打开uinput节点，设置了虚拟设备的name，verdor，product，bustype，
   最后通过ioctl(uinp_fd, ui_dev_create)注册设备

   int setup_uinput_device(stvirtualinputdevdata* mstvirtualinputdevdata)
{
    struct uinput_user_dev uinp; // uinput device structure
    int i;

    // open the input device
    uinp_fd = open("/dev/uinput", o_wronly | o_ndelay);
    if (uinp_fd == 0) {
        printf("unable to open /dev/uinput\n");
        return -1;
    }

    // intialize the uinput device to null
    memset(&uinp, 0x00, sizeof(uinp));
    strncpy(uinp.name, "virtualinputdev", sizeof(uinp.name)-1);
    uinp.id.vendor = 0x1341;
    uinp.id.product = 0x0001;
    uinp.id.bustype = bus_virtual;

    // keyboard
    ioctl(uinp_fd, ui_set_evbit, ev_key);
    for (i = mstvirtualinputdevdata->min_keycode; i < mstvirtualinputdevdata->max_keycode; i++) {
        ioctl(uinp_fd, ui_set_keybit, i);
    }

    // create input device into input sub-system
    if (write(uinp_fd, &uinp, sizeof(uinp)) != sizeof(uinp)) {
        printf("first write returned fail.\n");
        return -1;
    }

    if (ioctl(uinp_fd, ui_dev_create)) {
        printf("ioctl ui_dev_create returned fail.\n");
        return -1;
    }

    return 1;
}

3、线程 virtualinputdev_eventthread，只是重复发key，发key是通过write_event_to_device来完成的

   static void* virtualinputdev_eventthread(void *driver_data)
{

    unsigned char u8keycode,i=umin_keycode;

    while (1) {
        u8keycode = 0xff;

        /* sleep an interval time */
        usleep(2000000);//sleep 5 s
        /* fill event to uinput device. */
        write_event_to_device(i++, 0);
  if(i==4){
  i = 0;
  }
  printf ("virtualinputdev thread ...\n");
  //i %= umax_keycode;
    }

    printf ("virtualinputdev thread died\n");
    pthread_exit(0);
    return 0;
}

4、write_event_to_device 写event到uinput节点

  void write_event_to_device(unsigned char u8keycode, unsigned char u8repeat)
{
    struct input_event event; // input device structure
    struct timespec s;
    s.tv_nsec = 5000000l;
    s.tv_sec = 0;

    memset(&event, 0x00, sizeof(event));
    gettimeofday(&event.time, 0);
    event.type = ev_key;
    event.code = u8keycode;
    event.value = 1;
    write(uinp_fd, &event, sizeof(event));

    memset(&event, 0x00, sizeof(event));
    gettimeofday(&event.time, 0);
    event.type = ev_key;
    event.code = u8keycode;
    event.value = 0;
    write(uinp_fd, &event, sizeof(event));

    memset(&event, 0x00, sizeof(event));
    gettimeofday(&event.time, 0);
    event.type = ev_syn;
    event.code = syn_report;
    event.value = 0;
    write(uinp_fd, &event, sizeof(event));
}