Bug #6340: using `saxon:capture="yes"` in an accumlator rule with streamable="yes" can throw java.util.EmptyStackException - Saxon - Saxonica Developer Community

Actions

Send by e-mail Copy link

Bug #6340

closed

using `saxon:capture="yes"` in an accumlator rule with streamable="yes" can throw java.util.EmptyStackException

Added by Matt Patterson 10 months ago. Updated 5 months ago.

Status:

Closed

Priority:

Low

Assignee:

Michael Kay

Category:

Sprint/Milestone:

Start date:

2024-02-06

Due date:

% Done:

100%

Estimated time:

Legacy ID:

Applies to branch:

12, trunk

Fix Committed on Branch:

12, trunk

Fixed in Maintenance Release:

12.5

Platforms:

.NET, Java

Description

I managed to create a use of <xsl:accumulator> that causes exceptions if streaming is enabled and not otherwise.

It seems to be triggered when the accumulator rules selects a text node: if the accumulator rule is changed to use the pattern tag instead of tag/text() the exception does not occur.

Stylesheet was executed with java -cp /opt/saxon/current/saxon-ee-12.4.jar:/Users/matt/.saxon:'/opt/saxon/current/lib/*' com.saxonica.Transform -xsl:bug.xsl -s:input.xml

With the /opt/saxon/current directory containing the contents of the 12.4 .zip downloaded from https://downloads.saxonica.com/SaxonJ/EE/12/SaxonEE12-4J.zip

java.util.EmptyStackException
	at java.base/java.util.Stack.peek(Stack.java:101)
	at java.base/java.util.Stack.pop(Stack.java:83)
	at com.saxonica.ee.stream.watch.AccumulatorWatch.applyRule(AccumulatorWatch.java:194)
	at com.saxonica.ee.stream.watch.AccumulatorWatch.processItem(AccumulatorWatch.java:264)
	at com.saxonica.ee.stream.watch.MultiAccumulatorWatch.processItem(MultiAccumulatorWatch.java:95)
	at com.saxonica.ee.stream.watch.WatchManager.characters(WatchManager.java:464)
	at com.saxonica.ee.stream.ContentDetector.characters(ContentDetector.java:58)
	at net.sf.saxon.event.ReceivingContentHandler.flush(ReceivingContentHandler.java:701)
	at net.sf.saxon.event.ReceivingContentHandler.endElement(ReceivingContentHandler.java:576)
	at java.xml/com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:618)
	at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1728)
	at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2899)
	at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:605)
	at java.xml/com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:112)
	at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:542)
	at java.xml/com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:889)
	at java.xml/com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:825)
	at java.xml/com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
	at java.xml/com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1224)
	at java.xml/com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:637)
	at net.sf.saxon.resource.ActiveSAXSource.deliver(ActiveSAXSource.java:192)
	at net.sf.saxon.resource.ActiveStreamSource.deliver(ActiveStreamSource.java:73)
	at net.sf.saxon.event.Sender.send(Sender.java:104)
	at net.sf.saxon.trans.XsltController.applyStreamingTemplates(XsltController.java:969)
	at net.sf.saxon.s9api.AbstractXsltTransformer.applyTemplatesToSource(AbstractXsltTransformer.java:422)
	at net.sf.saxon.s9api.Xslt30Transformer.applyTemplates(Xslt30Transformer.java:306)
	at net.sf.saxon.Transform.processFile(Transform.java:1389)
	at net.sf.saxon.Transform.doTransform(Transform.java:879)
	at net.sf.saxon.Transform.main(Transform.java:83)
Fatal error during transformation: java.util.EmptyStackException:  (no message)

A simple repro XSL and input XML are attached.

Files

Download all files

bug.xsl (1.24 KB) bug.xsl		Matt Patterson, 2024-02-06 15:11
input.xml (215 Bytes) input.xml		Matt Patterson, 2024-02-06 15:11

Actions

Copy link

Updated by Michael Kay 10 months ago

Status changed from New to In Progress
Assignee set to Michael Kay
Fix Committed on Branch 9.8 added

Problem reproduced.

saxon:capture="yes" on a text node doesn't make much sense, because there's no sub-tree to capture. But of course we shouldn't crash - we should probably ignore it with a warning.

What actually happens is that on a start-element event, if we see that there's a capturing rule for the element, we record information about it on a stack of active captures. When we get to the end-element event, we pull off the captured subtree. What's happening in this case is that we're executing the end-element code without having executed the corresponding start-element code, so we're trying to pop the stack when nothing was pushed onto it.

Actions

Copy link