如何从任意字符串生成有效的Windows文件名？

import re

def generate_valid_windows_filename(input_string):
    # 删除非法字符
    cleaned_string = re.sub(r'[\\/*?:"<>|]', '', input_string)
    
    # 将空格替换为下划线
    cleaned_string = cleaned_string.replace(' ', '_')
    
    # 检查字符串长度
    if len(cleaned_string) > 255:
        cleaned_string = cleaned_string[:255]
    
    # 确保第一个字符不是点
    if cleaned_string[0] == '.':
        cleaned_string = '_' + cleaned_string[1:]
    
    # 检查是否与保留名称冲突
    reserved_names = ['CON', 'PRN', 'AUX', 'NUL', 'COM1', 'COM2', 'COM3', 'COM4', 'COM5', 'COM6', 'COM7', 'COM8', 'COM9', 'LPT1', 'LPT2', 'LPT3', 'LPT4', 'LPT5', 'LPT6', 'LPT7', 'LPT8', 'LPT9']
    if cleaned_string.upper() in reserved_names:
        cleaned_string = '_' + cleaned_string
    
    return cleaned_string