xml.dom.pulldom.DOMEventStream leaks file handles opened by parse()

pulldom.parse() opens a file when called with a filename string, but the resulting DOMEventStream never closes it. The class has no close() method, no context manager support, and clear() just sets self.stream = None without closing.

This produces ResourceWarning: unclosed file and can lead to file descriptor exhaustion in long-running processes.

The documentation example at https://docs.python.org/3/library/xml.dom.pulldom.html#module-xml.dom.pulldom shows:

doc = pulldom.parse('sales_items.xml')
for event, node in doc:
    ...

— with no cleanup, so users following the docs will hit this.

Reproduction

import warnings, tempfile, os, gc
from xml.dom import pulldom

warnings.simplefilter('always', ResourceWarning)

fd, path = tempfile.mkstemp(suffix='.xml')
os.write(fd, b'<root><item>test</item></root>')
os.close(fd)

events = pulldom.parse(path)
for event, node in events:
    pass

# stream is still open after full iteration
print(f'stream.closed: {events.stream.closed}')  # False

# clear() doesn't close it either
events.clear()

del events
gc.collect()  # ResourceWarning: unclosed file ...

os.unlink(path)

The existing test in test_pulldom.py already works around this with self.addCleanup(handler.stream.close) (line 36), which further confirms the leak.

Suggested fix

Track whether parse() opened the file (vs. receiving a user-provided stream), then add close(), __enter__/__exit__, and __del__ with ResourceWarning to DOMEventStream. Update clear() to close owned streams.

This follows the same approach used for ElementTree.iterparse() (gh-140601).

Linked PRs

• gh-148437

Commencez par DOMEventStream et pulldom.parse(), puis examinez test_pulldom.py, en particulier le nettoyage existant autour de la ligne 36. Reproduisez la ResourceWarning et vérifiez le comportement de propriété pour filename et les streams fournis par l’utilisateur. C’est terminé lorsque le nettoyage du cycle de vie et le comportement du gestionnaire de contexte sont couverts par des tests sans fuite de handles.