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gh-90494: Reject 6th element of the __reduce__() tuple (GH-93609) (GH…
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…-93632)

copy.copy() and copy.deepcopy() now always raise a TypeError if
__reduce__() returns a tuple with length 6 instead of silently ignore
the 6th item or produce incorrect result.
(cherry picked from commit a365dd6)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
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miss-islington and serhiy-storchaka authored Jun 10, 2022
1 parent 2ad51c6 commit a0c7df0
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Showing 4 changed files with 27 additions and 2 deletions.
2 changes: 1 addition & 1 deletion Lib/copy.py
Original file line number Diff line number Diff line change
Expand Up @@ -258,7 +258,7 @@ def _keep_alive(x, memo):

def _reconstruct(x, memo, func, args,
state=None, listiter=None, dictiter=None,
deepcopy=deepcopy):
*, deepcopy=deepcopy):
deep = memo is not None
if deep and args:
args = (deepcopy(arg, memo) for arg in args)
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2 changes: 1 addition & 1 deletion Lib/pickle.py
Original file line number Diff line number Diff line change
Expand Up @@ -619,7 +619,7 @@ def save_pers(self, pid):
"persistent IDs in protocol 0 must be ASCII strings")

def save_reduce(self, func, args, state=None, listitems=None,
dictitems=None, state_setter=None, obj=None):
dictitems=None, state_setter=None, *, obj=None):
# This API is called by some subclasses

if not isinstance(args, tuple):
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22 changes: 22 additions & 0 deletions Lib/test/test_copy.py
Original file line number Diff line number Diff line change
Expand Up @@ -678,6 +678,28 @@ def __eq__(self, other):
self.assertIsNot(x, y)
self.assertIsNot(x["foo"], y["foo"])

def test_reduce_6tuple(self):
def state_setter(*args, **kwargs):
self.fail("shouldn't call this")
class C:
def __reduce__(self):
return C, (), self.__dict__, None, None, state_setter
x = C()
with self.assertRaises(TypeError):
copy.copy(x)
with self.assertRaises(TypeError):
copy.deepcopy(x)

def test_reduce_6tuple_none(self):
class C:
def __reduce__(self):
return C, (), self.__dict__, None, None, None
x = C()
with self.assertRaises(TypeError):
copy.copy(x)
with self.assertRaises(TypeError):
copy.deepcopy(x)

def test_copy_slots(self):
class C(object):
__slots__ = ["foo"]
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
:func:`copy.copy` and :func:`copy.deepcopy` now always raise a TypeError if
``__reduce__()`` returns a tuple with length 6 instead of silently ignore
the 6th item or produce incorrect result.

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