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pyexpat.c calls trace function incorrectly for exceptions #50608
Description
| BPO | 6359 |
|---|---|
| Nosy | @loewis, @freddrake, @birkenfeld, @nedbat, @ezio-melotti, @jeremyhylton |
| Superseder | |
| Files |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields:
assignee = None
closed_at = <Date 2014-10-06.13:08:08.240>
created_at = <Date 2009-06-28.22:43:21.910>
labels = ['expert-XML', 'type-bug']
title = 'pyexpat.c calls trace function incorrectly for exceptions'
updated_at = <Date 2014-10-06.13:08:08.238>
user = 'https://github.com/nedbat'bugs.python.org fields:
activity = <Date 2014-10-06.13:08:08.238>
actor = 'georg.brandl'
assignee = 'none'
closed = True
closed_date = <Date 2014-10-06.13:08:08.240>
closer = 'georg.brandl'
components = ['XML']
creation = <Date 2009-06-28.22:43:21.910>
creator = 'nedbat'
dependencies = []
files = ['14379', '29951']
hgrepos = []
issue_num = 6359
keywords = ['patch']
message_count = 6.0
messages = ['89798', '175234', '175246', '182723', '187426', '228679']
nosy_count = 6.0
nosy_names = ['loewis', 'fdrake', 'georg.brandl', 'nedbat', 'ezio.melotti', 'Jeremy.Hylton']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'test needed'
status = 'closed'
superseder = '22462'
type = 'behavior'
url = 'https://bugs.python.org/issue6359'
versions = ['Python 2.7', 'Python 3.2', 'Python 3.3', 'Python 3.4']
Activity
nedbat commentedon Jun 28, 2009
Pyexpat.c calls the tracing function explicitly (not sure why). When it
intercepts an exception, it calls the function with PyTrace_EXCEPTION,
but then leaves the scope without calling PyTrace_RETURN. This is
incorrect. There should always be a PyTrace_RETURN for every PyTrace_CALL.
I've attached domshow.py to demonstrate the problem.
Running it produces many lines of output, including:
The exception at line 905 in pyexpat.c should be followed with a return
from line 905 in pyexpat.c, but is not. After that exception, the
nesting is off by one because the Calls and Returns don't match.
ezio-melotti commentedon Nov 9, 2012
Can you provide a patch?
nedbat commentedon Nov 9, 2012
I have no idea why pyexpat.c invokes the trace function in the first place. Unless someone can explain why it does that when no other C extension does, my inclination would be to make it stop calling the trace function at all, not to fix how it calls it.
ezio-melotti commentedon Feb 23, 2013
The relevant changesets are 1c26eb768293 and e43126c470a7. See also bpo-534864.
nedbat commentedon Apr 20, 2013
Attached a patch which simply removes the code that invokes the trace function.
birkenfeld commentedon Oct 6, 2014
A more complete patch that also fixes up pyexpat's frame trickery is tracked in bpo-22462.