New submission from Aaron Oakley:
When the _elementtree module is in use, the TreeBuilder class will raise an
IndexError in treebuilder_handle_end if __init__ was passed "None".
I discovered this while writing a subclass of TreeBuilder with a modified
__init__ method that delegated to TreeBuilder:
class MyTreeBuilder(ET.TreeBuilder):
def __init__(self, element_factory=None):
super().__init__(element_factory)
Used as a target, this class (and also simply "TreeBuilder(None)") will cause
the IndexError when "parser.feed(data)" is called.
>>> import xml.etree.ElementTree as ET
>>> parser = ET.XMLParser(target=ET.TreeBuilder(None))
>>> parser.feed('<file><line>22</line></file>')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: pop from empty stack
The error is raised from treebuilder_handle_end, but the cause appears to be in
treebuilder_handle_start.
if (self->element_factory) {
node = PyObject_CallFunction(self->element_factory, "OO", tag, attrib);
} else {
node = create_new_element(tag, attrib);
}
I included a patch adding a check against Py_None to the "if" test above which
seems to fix the issue. I also included a simple test case for it.
----------
components: XML
files: _elementtree.c-340a0.patch
keywords: patch
messages: 188326
nosy: Aaron.Oakley
priority: normal
severity: normal
status: open
title: _elementtree.TreeBuilder raises IndexError on end if constructed with
element_factory=None
type: behavior
versions: Python 3.2, Python 3.3, Python 3.4
Added file: http://bugs.python.org/file30117/_elementtree.c-340a0.patch
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<http://bugs.python.org/issue17901>
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