C Function Reading Cursor Position

void get_cursor_position(int *col, int *rows)
{
    int a = 0;
    int i = 0;
    char buf[4]

    write(1, "\033[6n", 4); // string asking for the cursor position
    read(1, buf, 4);

    while (buf[i])
    {
        if (buf[i] >= 48 && buf[i] <= 57)
        {
            if (a == 0)
                *rows = atoi(&buf[i]) - 1;
            else
                *col = atoi(&(buf[i]) - 1;
            a++;
        }
        i++;
    }
}