python 本地文件操作（modify|append|combos|MD5）

def sum_file_md5(file_path, offset=0, end=None):

　　"""
　　获取文件md5
　　:param file_path: 文件路径
　　:param offset: 　 
　　:param end: 
　　:return: 
　　"""

    md5 = hashlib.md5()
    with open(file_path, "rb") as f:
        f.seek(offset, 0)
        if end is None:
            md5.update(f.read())
        else:
            md5.update(f.read(end - offset + 1))
    return md5.hexdigest()


def del_file(file_path):
    system = platform.system()
    if system == "Windows":
        os.system("DEL %s" % (file_path))
    elif system == "Linux":
        os.system("rm %s" % (file_path))


def random_write_file(save_file, target_file, position, src_file):
    """
    save_file: 随机写后新保存的文件
    target_file： 被随机写的文件
    postion: 开始写的起始位置，从0开始
    src_file: 需要写的内容
    单位按byte
    """
    if os.path.getsize(src_file) + position > os.path.getsize(target_file):
        return "随机写越界"

    with open(save_file, "wb") as save_file_io:
        with open(target_file, "rb") as target_file_io:
            save_file_io.write(target_file_io.read(position))
            with open(src_file, "rb") as src_file_io:
                save_file_io.write(src_file_io.read())
                target_file_io.seek(position + os.path.getsize(src_file))
                save_file_io.write(target_file_io.read())


def combos_files(des_file, file_arg):
    """
    des_file: 合并后的文件路径
    file_arg: [(file_path_1, offset, length), (file_path_1, offset, length)]
    """
    with open(des_file, "wb") as f:
        for file, offset, length in file_arg:
            with open(file, "rb") as tmp_f:
                tmp_f.seek(offset, 0)
                f.write(tmp_f.read(length))


def append_write_file(des_file, src_file):
    """
    des_file: 被追加写的文件
    src_file:需要追加写的内容
    """
    with open(des_file, "ab") as des_file_io:
        with open(src_file, "rb") as src_file_io:
            des_file_io.write(src_file_io.read())