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gh-148153: Do not use assert for parameter validation in base64 #148154

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Merged
serhiy-storchaka merged 1 commit into from
Apr 6, 2026
+7 −4
Merged

gh-148153: Do not use assert for parameter validation in base64 #148154

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3 changes: 0 additions & 3 deletions Doc/library/base64.rst
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Expand Up @@ -69,9 +69,6 @@ POST request.
after at most every *wrapcol* characters.
If *wrapcol* is zero (default), do not insert any newlines.

May assert or raise a :exc:`ValueError` if the length of *altchars* is not 2. Raises a
:exc:`TypeError` if *altchars* is not a :term:`bytes-like object`.

.. versionchanged:: 3.15
Added the *padded* and *wrapcol* parameters.

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1 change: 0 additions & 1 deletion Lib/base64.py
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Expand Up @@ -237,7 +237,6 @@ def b32decode(s, casefold=False, map01=None, *, padded=True, ignorechars=b''):
# either L (el) or I (eye).
if map01 is not None:
map01 = _bytes_from_decode_data(map01)
assert len(map01) == 1, repr(map01)
s = s.translate(bytes.maketrans(b'01', b'O' + map01))
if casefold:
s = s.upper()
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5 changes: 5 additions & 0 deletions Lib/test/test_base64.py
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Expand Up @@ -607,6 +607,11 @@ def test_b32decode_map01(self):
self.assertRaises(binascii.Error, base64.b32decode, b'M1O23456')
self.assertRaises(binascii.Error, base64.b32decode, b'ML023456')
self.assertRaises(binascii.Error, base64.b32decode, b'MI023456')
self.assertRaises(ValueError, base64.b32decode, b'', map01=b'')
self.assertRaises(ValueError, base64.b32decode, b'', map01=b'LI')
self.assertRaises(TypeError, base64.b32decode, b'', map01=0)
eq(base64.b32decode(b'MLO23456', map01=None), res_L)
self.assertRaises(binascii.Error, base64.b32decode, b'M1023456', map01=None)

data = b'M1023456'
data_str = data.decode('ascii')
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-04-06-11-20-24.gh-issue-148153.ZtsuTl.rst
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@@ -0,0 +1,2 @@
:func:`base64.b32encode` now always raises :exc:`ValueError` instead of
:exc:`AssertionError` for the value of *map01* with invalid length.
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