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#1466065: add validate option to base64.b64decode

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Patch by Neil Tallim.  This provides a mechanism for module
users to achieve RFC 3548 compliance in the cases where ignoring
non-base64-alphabet input characters is *not* mandated by the RFC that
references RFC 3548.
This commit is contained in:
R. David Murray 2010-11-11 20:09:20 +00:00
parent 49afa380fd
commit 6495136e40
4 changed files with 37 additions and 9 deletions
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13
Lib/base64.py
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@ -65,16 +65,19 @@ def b64encode(s, altchars=None):
return encoded
def b64decode(s, altchars=None):
def b64decode(s, altchars=None, validate=False):
"""Decode a Base64 encoded byte string.
s is the byte string to decode. Optional altchars must be a
string of length 2 which specifies the alternative alphabet used
instead of the '+' and '/' characters.
The decoded byte string is returned. binascii.Error is raised if
s were incorrectly padded or if there are non-alphabet characters
present in the string.
The decoded string is returned. A binascii.Error is raised if s is
incorrectly padded.
If validate is False (the default), non-base64-alphabet characters are
discarded prior to the padding check. If validate is True,
non-base64-alphabet characters in the input result in a binascii.Error.
"""
if not isinstance(s, bytes_types):
raise TypeError("expected bytes, not %s" % s.__class__.__name__)
@ -84,6 +87,8 @@ def b64decode(s, altchars=None):
% altchars.__class__.__name__)
assert len(altchars) == 2, repr(altchars)
s = _translate(s, {chr(altchars[0]): b'+', chr(altchars[1]): b'/'})
if validate and not re.match(b'^[A-Za-z0-9+/]*={0,2}$', s):
raise binascii.Error('Non-base64 digit found')
return binascii.a2b_base64(s)