base64.py 文件源码

def urlsafe_b64decode(s):
    """Decode bytes using the URL- and filesystem-safe Base64 alphabet.

    Argument s is a bytes-like object or ASCII string to decode.  The result
    is returned as a bytes object.  A binascii.Error is raised if the input
    is incorrectly padded.  Characters that are not in the URL-safe base-64
    alphabet, and are not a plus '+' or slash '/', are discarded prior to the
    padding check.

    The alphabet uses '-' instead of '+' and '_' instead of '/'.
    """
    s = _bytes_from_decode_data(s)
    s = s.translate(_urlsafe_decode_translation)
    return b64decode(s)



# Base32 encoding/decoding must be done in Python