Hi While trying to figure out sensible semantics for XPATH() and scalar-value returning XPath expressions, I've stumbled upon a bug in XPATH() that allows invalid XML values to be produced. This is a serious problem because should such invalid values get inserted into an XML column, an un-restorable dump ensues.
Here's an example (REL9_0_STABLE as of a few days ago) template1=# SELECT (XPATH('/*/text()', '<root><</root>'))[1]; xpath ------- < Since XPATH() returns XML[], this value has type XML, but clearly isn't well-formed. And behold, casting to TEXT and back to XML complains loudly. template1=# SELECT (XPATH('/*/text()', '<root><</root>'))[1]::TEXT::XML; ERROR: invalid XML content DETAIL: Entity: line 1: parser error : StartTag: invalid element name < ^ The culprit is xml_xmlnodetoxmltype() in backend/utils/adt/xml.c. For non-element nodes, it returns the result of xmlXPathCastNodeToString() verbatim, even though that function doesn't reverse the entity replacement that was done during parsing. Adding a call to escape_xml() for non-element nodes fixes the problem template1=# SELECT (XPATH('/*/text()', '<root><</root>'))[1]; xpath ------- < Patch is attached. best regards, Florian Pflug
pg_xpath_invalidxml.v1.patch
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