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Reject negative cache item sizes #401

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Merged
tkem merged 1 commit into from
Jul 2, 2026
+11 −0
Merged

Reject negative cache item sizes #401

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2 changes: 2 additions & 0 deletions src/cachetools/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,8 @@ def __getitem__(self, key):
def __setitem__(self, key, value):
maxsize = self.__maxsize
size = self.getsizeof(value)
if size < 0:
raise ValueError("value size must be non-negative")
if size > maxsize:
raise ValueError("value too large")
if key not in self.__data or self.__size[key] < size:
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9 changes: 9 additions & 0 deletions tests/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -284,6 +284,15 @@ def _test_getsizeof(self, cache):
def test_getsizeof_param(self):
self._test_getsizeof(self.Cache(maxsize=3, getsizeof=lambda x: x))

def test_getsizeof_negative(self):
cache = self.Cache(maxsize=3, getsizeof=lambda x: -1)

with self.assertRaises(ValueError):
cache[1] = 1

self.assertEqual(0, len(cache))
self.assertEqual(0, cache.currsize)

def test_getsizeof_subclass(self):
class Cache(self.Cache):
@staticmethod
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