[issue29838] Check that sq_length and mq_length return non-negative result

Changes by Serhiy Storchaka : -- resolution: -> fixed stage: patch review -> resolved status: open -> closed ___ Python tracker

[issue29838] Check that sq_length and mq_length return non-negative result

Serhiy Storchaka added the comment: New changeset 813f943c592cf225871b99cffc99304c8cbbee40 by Serhiy Storchaka in branch 'master': bpo-29838: Add asserts for checking results of sq_length and mq_length slots. (#700)

[issue29838] Check that sq_length and mq_length return non-negative result

Changes by Serhiy Storchaka : -- assignee: -> serhiy.storchaka ___ Python tracker ___

[issue29838] Check that sq_length and mq_length return non-negative result

Serhiy Storchaka added the comment: assert() is no-op in release build and that are not critical parts. Actually the patch decreases the number of checks in release build. Runtime check PyErr_Occurred() is moved into assert() in builtin_len(). --

[issue29838] Check that sq_length and mq_length return non-negative result

Raymond Hettinger added the comment: Please don't add more code to critical paths. There is no demonstrated need for an additional check here. The current code has worked well for millions of users for many years. Also, there are too many checks in common paths and some of them are

[issue29838] Check that sq_length and mq_length return non-negative result

Serhiy Storchaka added the comment: The alternate approach is raising SystemError rather than crashing in debug build on assertion. Since this check is used in exceptional case (when a raised exception is expected) it doesn't slow down working code. --

[issue29838] Check that sq_length and mq_length return non-negative result

Serhiy Storchaka added the comment: Mis-behaving classes have to be written in C. If the __len__ method in Python class returns a negative value, ValueError is raised in slot_sq_length(). PySequence_GetItem() already contains an assertion that sq_length returns negative value only when an

[issue29838] Check that sq_length and mq_length return non-negative result

Terry J. Reedy added the comment: The changes appear consistent within themselves (ie, no apparent typos), and the one for builtin len appears to fix a bug that would allow negative length. Can tests be written in Python that fail without the patch? Or would mis-behaving classes have to be

[issue29838] Check that sq_length and mq_length return non-negative result

Changes by Serhiy Storchaka : -- pull_requests: +574 ___ Python tracker ___ ___

[issue29838] Check that sq_length and mq_length return non-negative result

New submission from Serhiy Storchaka: Following PR adds several asserts for checking that sq_length and mq_length either return non-negative result or raise an exception. One assert already was in PySequence_GetItem(). -- components: Interpreter Core messages: 289777 nosy: haypo,