import os
import random
import string


def listdir(dir_path):
    file_names = []
    for filename in os.listdir(dir_path):
        if os.path.isfile(os.path.join(dir_path, filename)):
            if ".crdownload" not in filename:
                file_names.append(filename)
    return file_names


def generate_random_string(length):
    letters = string.ascii_letters + string.digits
    return ''.join(random.choice(letters) for _ in range(length))