[XALANJ-1139] XPathAPI throws NPE If Any Extension Function Used

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.4
• Component/s: XPath
• Environment: Operating System: All; Platform: All
• Bugzilla Id: 11792
• Assignee: Morris Kwan
• Reporter: Terry Rosenbaum
• Created: 18/Aug/02 00:32
• Updated: 11/Aug/05 13:39

Description

XPathAPI constructs an XPathContext using the
default ctor (i.e. not supplying an ExtensionProvider).

Thus, when any attempt is made to call an
extension function, a null ExtensionProvider pointer
is retrieved and dereferenced resulting in NPE at FuncExtFunction.java:196.

XPathContext is constructed in XPathAPI.java or
CachedXPathAPI.java (e.g. xpathSupport = new XPathContext().

XPath used: /ico/keywords/keyword[regexp:containsMatch('ll*', 'llal')]

containsMatch is defined in the PatternMatcher class (no package).

PatternMatcher source and instructions are available at:

http://www-106.ibm.com/developerworks/library/x-callbk/?open&l=976,t=gr

Tested using ApplyXPath sample.

Test Document used was:

<ico xmlns:regexp="xalan://PatternMatcher">
<id>423234</id>
<keywords>
<keyword>Haus</keyword>
<keyword>Baum</keyword>
<keyword>Auto</keyword>
<keyword>Boot</keyword>
<keyword>Sonne</keyword>
</keywords>
<faws>
<faw>Meier</faw>
<faw>Muller</faw>
<faw>Bremen</faw>
<faw>Winter</faw>
<faw>Boot</faw>
<faw>PC</faw>
</faws>
<author>Heiner Meier</author>
<words>502</words>
<date>19082002</date>
</ico>

Stack trace wass:

Exception in thread "main" java.lang.NullPointerException
at org.apache.xpath.functions.FuncExtFunction.execute
(FuncExtFunction.java:196)
at org.apache.xpath.axes.PredicatedNodeTest.executePredicates
(PredicatedNodeTest.java:326)
at org.apache.xpath.axes.PredicatedNodeTest.acceptNode
(PredicatedNodeTest.java:458)
at org.apache.xpath.axes.AxesWalker.nextNode(AxesWalker.java:406)
at org.apache.xpath.axes.WalkingIterator.nextNode
(WalkingIterator.java:176)
at org.apache.xpath.axes.NodeSequence.nextNode(NodeSequence.java:320)
at org.apache.xml.dtm.ref.DTMNodeIterator.nextNode
(DTMNodeIterator.java:195)
at ApplyXPath.doMain(ApplyXPath.java:134)
at ApplyXPath.main(ApplyXPath.java:183)

Have seen similar results attempting to use EXSLT functions via XPathAPI.

The implication, planned or not, is that XPathAPI and CachedXPathAPI
currently do not support the use of extension functions.