bpo-40330: Fix utf-8 size check in ShareableList (GH-19606)

The item size must be checked after encoding to bytes, not before.

Automerge-Triggered-By: @pitrou
This commit is contained in:
Antoine Pitrou 2020-04-20 20:54:55 +02:00 committed by GitHub
parent 5dd21f5d1c
commit eba9f6155d
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3 changed files with 22 additions and 6 deletions

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@ -445,11 +445,14 @@ class ShareableList:
if not isinstance(value, (str, bytes)):
new_format = self._types_mapping[type(value)]
encoded_value = value
else:
allocated_length = self._allocated_offsets[position + 1] - item_offset
if len(value) > allocated_length:
raise ValueError("exceeds available storage for existing str")
encoded_value = (value.encode(_encoding)
if isinstance(value, str) else value)
if len(encoded_value) > allocated_length:
raise ValueError("bytes/str item exceeds available storage")
if current_format[-1] == "s":
new_format = current_format
else:
@ -462,8 +465,7 @@ class ShareableList:
new_format,
value
)
value = value.encode(_encoding) if isinstance(value, str) else value
struct.pack_into(new_format, self.shm.buf, offset, value)
struct.pack_into(new_format, self.shm.buf, offset, encoded_value)
def __reduce__(self):
return partial(self.__class__, name=self.shm.name), ()

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@ -3995,9 +3995,21 @@ class _TestSharedMemory(BaseTestCase):
sl[4] = 'some' # Change type at a given position.
self.assertEqual(sl[4], 'some')
self.assertEqual(sl.format, '8s8sdq8sxxxxxxx?q')
with self.assertRaises(ValueError):
sl[4] = 'far too many' # Exceeds available storage.
with self.assertRaisesRegex(ValueError,
"exceeds available storage"):
sl[4] = 'far too many'
self.assertEqual(sl[4], 'some')
sl[0] = 'encodés' # Exactly 8 bytes of UTF-8 data
self.assertEqual(sl[0], 'encodés')
self.assertEqual(sl[1], b'HoWdY') # no spillage
with self.assertRaisesRegex(ValueError,
"exceeds available storage"):
sl[0] = 'encodées' # Exactly 9 bytes of UTF-8 data
self.assertEqual(sl[1], b'HoWdY')
with self.assertRaisesRegex(ValueError,
"exceeds available storage"):
sl[1] = b'123456789'
self.assertEqual(sl[1], b'HoWdY')
# Exercise count().
with warnings.catch_warnings():

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@ -0,0 +1,2 @@
In :meth:`ShareableList.__setitem__`, check the size of a new string item
after encoding it to utf-8, not before.