uinput keyboard sample

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/input.h>
#include <linux/uinput.h>


void usage(void)
{
    printf("  Usage : keyboard  [key number...]\n");
    printf("          keyboard 29 56 32  /* CTRL + ALT +D */\n");
    printf("          keyboard 125 32  /* WIN +D */\n");
    printf("/* Types of key number are defined in /usr/include/linux/input.h */\n");

    return;
}

/* Setup the uinput device */
int setup_uinput_device(int fd)
{
    struct uinput_user_dev uidev;    // uInput device structure

    memset(&uidev, 0, sizeof(struct uinput_user_dev));    // Intialize the uInput device to NULL
    snprintf(uidev.name, UINPUT_MAX_NAME_SIZE, "uinput-keyboard");
    uidev.id.bustype = BUS_USB;
    uidev.id.vendor = 0x1;
    uidev.id.product = 0x1;
    uidev.id.version = 1;
    // Setup the driver I/O channels
    ioctl(fd, UI_SET_EVBIT, EV_KEY);
    ioctl(fd, UI_SET_KEYBIT, BTN_LEFT);
    for (int i = 0; i < 256; i++) {
        ioctl(fd, UI_SET_KEYBIT, i);
    }
    ioctl(fd, UI_SET_EVBIT, EV_REL);
    ioctl(fd, UI_SET_RELBIT, REL_X);
    ioctl(fd, UI_SET_RELBIT, REL_Y);

    /* Create input device into input sub-system */
    write(fd, &uidev, sizeof(struct uinput_user_dev));
    if (ioctl(fd, UI_DEV_CREATE) < 0) {
        printf("error: create uinput device\n");
        return -1;
    }

    return 0;
}

void uinput_key(int fd, int keycode, int keyvalue)
{
    struct input_event ev;            // Input device structure

    memset(&ev, 0, sizeof(struct input_event));
    gettimeofday(&ev.time, NULL);
    ev.type = EV_KEY;
    ev.code = keycode;
    ev.value = keyvalue;
    if (write(fd, &ev, sizeof(struct input_event)) < 0) {
        printf("uinput key error\n");
        return;
    } else {
        printf("uinput key %d, %d\n", keycode, keyvalue);
    }

    return;
}

void uinput_key_end(int fd)
{
    struct input_event ev;            // Input device structure

    memset(&ev, 0, sizeof(struct input_event));
    ev.type = EV_SYN;
    ev.code = 0;
    ev.value = 0;
    write(fd, &ev, sizeof(struct input_event));

    return;
}

//check the key is control key
int check_valid_control_key(int key)
{
    int ret = 0;
    int control_key[] = {29, 42, 54, 56, 97, 100, 125, 126};
    int len = sizeof(control_key) / sizeof(control_key[0]);

    for (int i = 0; i < len; i++) {
        if (control_key[i] == key) {
            ret = 1;
            break;
        }
    }

    return ret;
}

int main(int argc, char *argv[])
{
    int fd = -1;
    int key;
    int i;

    if (argc <= 1) {
        usage();
        return -1;
    }

    fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);    // Open the input device
    if (fd < 0) {
        printf("error: open /dev/uinput\n");
        return -1;
    }

    setup_uinput_device(fd);

    sleep(1);

    for (i = 1; i < argc; i++) {
        key = atoi(argv[i]);
        uinput_key(fd, key, 1);
        if (check_valid_control_key(key) == 0) {
            uinput_key(fd,key, 0);
        }
    }

    for (i = 1; i < argc; i++) {
        key = atoi(argv[i]);
        if (check_valid_control_key(key) == 1) {
            uinput_key(fd,key, 0);
        }
    }

    uinput_key_end(fd);
    if (ioctl(fd, UI_DEV_DESTROY) < 0) {
        printf("error: ioctl");
        return -1;
    }

    close(fd);
    fd = -1;

    return 0;
}