xml.etree.register_namespace dictionary changed size during iteration

[peterjc]

BPO	10777
Nosy	@birkenfeld, @peterjc

^{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 2010-12-28.10:38:45.452>
created_at = <Date 2010-12-27.00:11:54.358>
labels = ['expert-XML', 'type-crash']
title = 'xml.etree.register_namespace dictionary changed size during iteration'
updated_at = <Date 2010-12-28.10:38:45.450>
user = 'https://github.com/peterjc'

bugs.python.org fields:

activity = <Date 2010-12-28.10:38:45.450>
actor = 'georg.brandl'
assignee = 'none'
closed = True
closed_date = <Date 2010-12-28.10:38:45.452>
closer = 'georg.brandl'
components = ['XML']
creation = <Date 2010-12-27.00:11:54.358>
creator = 'maubp'
dependencies = []
files = []
hgrepos = []
issue_num = 10777
keywords = []
message_count = 2.0
messages = ['124688', '124781']
nosy_count = 2.0
nosy_names = ['georg.brandl', 'maubp']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue10777'
versions = ['Python 3.2']

[peterjc]

The following was found testing the Biopython unit tests (latest code from git) against Python 3.2 beta 2 (compiled from source on 64 bit Linux Ubuntu). Reduced test case:

$ python3.2
Python 3.2b2 (r32b2:87398, Dec 26 2010, 19:01:30) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from xml.etree import ElementTree
>>> ElementTree.register_namespace("xs", "http://www.w3.org/2001/XMLSchema")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/peterjc/lib/python3.2/xml/etree/ElementTree.py", line 1071, in register_namespace
    for k, v in _namespace_map.items():
RuntimeError: dictionary changed size during iteration

Suggested fix, replace this:

def register_namespace(prefix, uri):
    if re.match("ns\d+$", prefix):
        raise ValueError("Prefix format reserved for internal use")
    for k, v in _namespace_map.items():
        if k == uri or v == prefix:
            del _namespace_map[k]
    _namespace_map[uri] = prefix


with something like this:

def register_namespace(prefix, uri):
    if re.match("ns\d+$", prefix):
        raise ValueError("Prefix format reserved for internal use")
    for k, v in list(_namespace_map.items()):
        if k == uri or v == prefix:
            del _namespace_map[k]
    _namespace_map[uri] = prefix

Note that cElementTree seems to be OK.

Note that Python 3.1 was not affected as it didn't even have register_namespace,

$ python3
Python 3.1.2 (r312:79147, Sep 27 2010, 09:57:50) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from xml.etree import ElementTree
>>> ElementTree.register_namespace("xs", "http://www.w3.org/2001/XMLSchema")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'register_namespace'

[birkenfeld]

Thanks, this should be fixed in r87526.