Check device path is a valid keyboard

is_keyboard.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/input.h>
#include <string.h>

// Function to check if the input device is a keyboard
int is_keyboard(const char *device_path) {
    int fd = open(device_path, O_RDONLY);
    if (fd == -1) {
        perror("Failed to open device");
        return 0;  // Failed to open device, return false
    }

    // Get the device name
    char name[256];
    if (ioctl(fd, EVIOCGNAME(sizeof(name)), name) < 0) {
        perror("Failed to get device name");
        close(fd);
        return 0;  // Error reading device name, return false
    }

    // Output the device name for debugging (optional)
    printf("Device name: %s\n", name);

    // Check if the device supports key events (EV_KEY)
    unsigned long evbit[2];  // 2 bits to store capability info
    if (ioctl(fd, EVIOCGBIT(0, sizeof(evbit)), evbit) < 0) {
      perror("Failed to get device capabilities");
        close(fd);
        return 0;  // Error getting capabilities, return false
    }

    // Check if EV_KEY is set in the capabilities (indicates a keyboard)
    if (evbit[0] & (1 << EV_KEY)) {
        close(fd);
        return 1;  // It's a keyboard
    }

    close(fd);
    return 0;  // Not a keyboard
}

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/input.h>

void process_keyboard_events(const char *device_path) {
    int fd = open(device_path, O_RDONLY);
    if (fd == -1) {
        perror("Failed to open device");
        return;
    }

    struct input_event ev;
    while (1) {
        // Read an input event from the device
        ssize_t n = read(fd, &ev, sizeof(struct input_event));
        if (n == -1) {
            perror("Error reading input event");
            break;
        }
// Filter for key events (EV_KEY)
        if (ev.type == EV_KEY) {
            printf("Scan Code: %d\n", ev.code);  // Print scan code
            if (ev.value == 0) {
                printf("Key Released: Scan Code %d\n", ev.code);
            } else if (ev.value == 1) {
                printf("Key Pressed: Scan Code %d\n", ev.code);
            } else if (ev.value == 2) {
                printf("Key Held: Scan Code %d\n", ev.code);
            }
        }
    }

    close(fd);
}

char scanCodeToKey(int scanCode) {
    switch (scanCode) {
        case 0x1E: return 'A';
        case 0x30: return 'B';
        case 0x2E: return 'C';
        case 0x20: return 'D';
        case 0x12: return 'E';
        case 0x21: return 'F';
        case 0x22: return 'G';
        case 0x23: return 'H';
        case 0x17: return 'I';
        case 0x24: return 'J';
        case 0x25: return 'K';
        case 0x26: return 'L';
        case 0x32: return 'M';
        case 0x31: return 'N';
        case 0x18: return 'O';
        case 0x19: return 'P';
        case 0x10: return 'Q';
        case 0x13: return 'R';
        case 0x1F: return 'S';
        case 0x14: return 'T';
        case 0x16: return 'U';
        case 0x2F: return 'V';
        case 0x11: return 'W';
        case 0x2D: return 'X';
        case 0x15: return 'Y';
        case 0x2C: return 'Z';
        case 0x39: return ' '; // Space
        case 0x0E: return '\b'; // Backspace
        case 0x1C: return '\n'; // Enter
        default: return '\0';   // Undefined scan code
    }
}

int main() {
    const char *device_path = "/dev/input/event0";  // Change this to your device path

    if (is_keyboard(device_path)) {
        printf("The device is a keyboard.\n");
    } else {
        printf("The device is not a keyboard.\n");
    }

    return 0;
}