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MCR-3885 handle xsl:message when using Saxon #3188

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MCR-3885 handle xsl:message when using Saxon #3188

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1 change: 1 addition & 0 deletions mycore-base/pom.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -279,6 +279,7 @@
<dependency>
<groupId>net.sf.saxon</groupId>
<artifactId>Saxon-HE</artifactId>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
Expand Down
22 changes: 18 additions & 4 deletions mycore-base/src/main/java/org/mycore/common/content/transformer/MCRXSLTransformer.java
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Expand Up @@ -65,6 +65,8 @@
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

import net.sf.saxon.expr.instruct.TerminationException;

/**
* Transforms XML content using a static XSL stylesheet. The stylesheet is configured via
* <code>MCR.ContentTransformer.{ID}.Stylesheet</code>. You may choose your own instance of
Expand Down Expand Up @@ -273,7 +275,7 @@ public void transform(MCRContent source, OutputStream out, MCRParameterCollector
reader.parse(source.getInputSource());
} catch (TransformerConfigurationException | SAXException | IllegalArgumentException
| ParserConfigurationException e) {
throw new IOException(e);
throw new IOException(getErrorMessage(e), e);
} catch (RuntimeException e) {
if (el != null && e.getCause() == null && el.getExceptionThrown() != null) {
//typically if a RuntimeException has no cause,
Expand All @@ -286,6 +288,18 @@ public void transform(MCRContent source, OutputStream out, MCRParameterCollector
}
}

/**
* Returns the message for an exception wrapping the given exception. Saxon does not include the text of a
* terminating <code>xsl:message</code> in its exception message, so it is added here.
*/
private static String getErrorMessage(Exception e) {
if (e.getCause() instanceof TerminationException terminationException) {
return "Error while XSL transformation: " + MCRErrorListener.getMyMessageAndLocation(terminationException);
}
// same message as for new IOException(e) or new MCRException(e)
return e.toString();
}

protected MCRContent transform(MCRContent source, XMLReader reader, TransformerHandler transformerHandler,
MCRParameterCollector parameter)
throws IOException, SAXException, TransformerException, ParserConfigurationException {
Expand Down Expand Up @@ -332,11 +346,11 @@ protected Deque<TransformerHandler> getTransformHandlers(MCRParameterCollector p
throws TransformerConfigurationException, SAXException, ParserConfigurationException {
checkTemplateUptodate();
Deque<TransformerHandler> xslSteps = new ArrayDeque<>();
//every transformhandler shares the same ErrorListener instance
//every transformhandler gets its own ErrorListener instance
for (Templates template : templates) {
TransformerHandler handler = tFactory.newTransformerHandler(template);
parameterCollector.setParametersTo(handler.getTransformer());
handler.getTransformer().setErrorListener(new MCRErrorListener());
MCRErrorListener.setTo(handler.getTransformer());
if (!xslSteps.isEmpty()) {
Result result = new SAXResult(handler);
xslSteps.getLast().setResult(result);
Expand Down Expand Up @@ -436,7 +450,7 @@ public MCRContent getBaseContent() {
transformed.setMimeType(mimeType);
transformed.setEncoding(encoding);
} catch (IOException | SAXException e) {
throw new MCRException(e);
throw new MCRException(getErrorMessage(e), e);
} catch (RuntimeException e) {
MCRErrorListener el = (MCRErrorListener) transformerHandler.getTransformer().getErrorListener();
if (el != null && e.getCause() == null && el.getExceptionThrown() != null) {
Expand Down
104 changes: 87 additions & 17 deletions mycore-base/src/main/java/org/mycore/common/xsl/MCRErrorListener.java
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Expand Up @@ -20,12 +20,22 @@

import javax.xml.transform.ErrorListener;
import javax.xml.transform.SourceLocator;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.xml.utils.WrappedRuntimeException;

import net.sf.saxon.expr.instruct.TerminationException;
import net.sf.saxon.jaxp.StreamingTransformerImpl;
import net.sf.saxon.jaxp.TransformerImpl;
import net.sf.saxon.om.Item;
import net.sf.saxon.s9api.AbstractXsltTransformer;
import net.sf.saxon.s9api.Location;
import net.sf.saxon.s9api.Message;
import net.sf.saxon.trans.XPathException;

/**
* @author Thomas Scheffler (yagee)
*
Expand All @@ -37,10 +47,42 @@ public final class MCRErrorListener implements ErrorListener {

private String lastMessage;

/**
* Creates a new {@link MCRErrorListener} and sets it to the given transformer.
* <p>
* For Saxon transformers, <code>xsl:message</code> output is logged, too.
*
* @param transformer the transformer to configure
* @return the error listener set to the transformer
*/
public static MCRErrorListener setTo(Transformer transformer) {
MCRErrorListener errorListener = new MCRErrorListener();
transformer.setErrorListener(errorListener);
AbstractXsltTransformer xsltTransformer = null;
if (transformer instanceof TransformerImpl saxonTransformer) {
xsltTransformer = saxonTransformer.getUnderlyingXsltTransformer();
} else if (transformer instanceof StreamingTransformerImpl saxonTransformer) {
xsltTransformer = saxonTransformer.getUnderlyingXsltTransformer();
}
if (xsltTransformer != null) {
// Saxon does not report xsl:message to the ErrorListener but writes it to System.err
xsltTransformer.setMessageHandler(MCRErrorListener::logMessage);
}
return errorListener;
}

public TransformerException getExceptionThrown() {
return exceptionThrown;
}

private static void logMessage(Message message) {
Location location = message.getLocation();
LOGGER.info(() -> location == null
? getMessageAndLocation(null, 0, 0, message.getStringValue())
: getMessageAndLocation(location.getSystemId(), location.getLineNumber(), location.getColumnNumber(),
message.getStringValue()));
}

private boolean triggerException(TransformerException e) {
if (exceptionThrown != null) {
return false;
Expand Down Expand Up @@ -90,6 +132,10 @@ public void fatalError(TransformerException exception) throws TransformerExcepti
&& stackTrace[0].getClassName().endsWith("ElemMessage")) {
LOGGER.debug("Original exception: ", unwrappedException);
unwrappedException = new TransformerException(lastMessage);
} else if (unwrappedException instanceof TerminationException) {
//Saxon: xsl:message with terminate="yes", the exception message does not contain the message text
LOGGER.debug("Original exception: ", unwrappedException);
unwrappedException = new TransformerException(getMyMessageAndLocation(unwrappedException));
}
if (triggerException(unwrappedException)) {
LOGGER.fatal("Exception while XSL transformation.", unwrappedException);
Expand All @@ -114,27 +160,51 @@ public static TransformerException unwrapException(TransformerException exceptio

public static String getMyMessageAndLocation(TransformerException exception) {
SourceLocator locator = exception.getLocator();
StringBuilder msg = new StringBuilder();
if (locator != null) {
String systemID = locator.getSystemId();
int line = locator.getLineNumber();
int col = locator.getColumnNumber();
if (systemID != null) {
msg.append("SystemID: ");
msg.append(systemID);
}
if (line != 0) {
msg.append(" [");
msg.append(line);
if (col != 0) {
msg.append(',');
msg.append(col);
String message = getMessage(exception);
if (locator == null) {
return getMessageAndLocation(null, 0, 0, message);
}
return getMessageAndLocation(locator.getSystemId(), locator.getLineNumber(), locator.getColumnNumber(),
message);
}

/**
* Returns the message of the given exception. For a Saxon exception caused by <code>xsl:message</code> with
* <code>terminate="yes"</code> this is the text of the message, if it is not empty.
*/
private static String getMessage(TransformerException exception) {
if (exception instanceof TerminationException terminationException
&& terminationException.getErrorObject() != null) {
try {
Item content = terminationException.getErrorObject().head();
String text = content == null ? null : content.getStringValue();
if (text != null && !text.isBlank()) {
return text;
}
msg.append(']');
} catch (XPathException e) {
LOGGER.debug("Could not get text of terminating xsl:message.", e);
}
}
return exception.getMessage();
}

private static String getMessageAndLocation(String systemID, int line, int col, String message) {
StringBuilder msg = new StringBuilder();
if (systemID != null) {
msg.append("SystemID: ");
msg.append(systemID);
}
if (line > 0) {
msg.append(" [");
msg.append(line);
if (col > 0) {
msg.append(',');
msg.append(col);
}
msg.append(']');
}
msg.append(": ");
msg.append(exception.getMessage());
msg.append(message);
return msg.toString();
}
}
4 changes: 4 additions & 0 deletions mycore-base/src/main/java/org/mycore/frontend/cli/MCRCommandUtils.java
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Expand Up @@ -40,6 +40,7 @@
import org.mycore.common.MCRConstants;
import org.mycore.common.MCRUsageException;
import org.mycore.common.content.transformer.MCRXSLTransformer;
import org.mycore.common.xsl.MCRErrorListener;
import org.mycore.common.xsl.MCRXSLResourceHelper;
import org.mycore.common.xsl.uriresolver.MCRURIResolver;
import org.mycore.datamodel.common.MCRXMLMetadataManager;
Expand Down Expand Up @@ -188,6 +189,8 @@ public static Transformer getTransformer(String style, String defaultStyle, Map<
}
Transformer transformer = cache.get(style);
if (transformer != null) {
// fresh error listener, the old one keeps the exception of a previous transformation
MCRErrorListener.setTo(transformer);
return transformer;
}

Expand All @@ -202,6 +205,7 @@ public static Transformer getTransformer(String style, String defaultStyle, Map<
TransformerFactory transformerFactory = MCRXSLTransformer.createDefaultTransformerFactory();
transformerFactory.setURIResolver(MCRURIResolver.obtainInstance());
transformer = transformerFactory.newTransformer(new JDOMSource(element));
MCRErrorListener.setTo(transformer);
cache.put(style, transformer);
LOGGER.info("Loaded transformer from resource {} for style {}.", xslFilePath, style);
return transformer;
Expand Down
1 change: 1 addition & 0 deletions mycore-base/src/main/java/org/mycore/frontend/cli/MCRObjectCommands.java
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Expand Up @@ -977,6 +977,7 @@ private static void xslt(String objectId, String xslFilePath, boolean force) thr
xmlReader.setEntityResolver(MCREntityResolver.getInstance());
SAXSource styleSource = new SAXSource(xmlReader, style.getInputSource());
Transformer transformer = transformerFactory.newTransformer(styleSource);
MCRErrorListener.setTo(transformer);
for (Entry<String, String> property : MCRConfigurationBase.getAllPropertiesMap().entrySet()) {
transformer.setParameter(property.getKey(), property.getValue());
}
Expand Down
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