http.py 文件源码

def urlsafe_base64_decode(s):
    """
    Decodes a base64 encoded string, adding back any trailing equal signs that
    might have been stripped.
    """
    s = force_bytes(s)
    try:
        return base64.urlsafe_b64decode(s.ljust(len(s) + len(s) % 4, b'='))
    except (LookupError, BinasciiError) as e:
        raise ValueError(e)