FOP-3110: NPE if link destination is missing with accessibility

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1905858 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 25 insertions, 3 deletions

diff --git a/fop-core/src/main/java/org/apache/fop/render/intermediate/IFSerializer.java b/fop-core/src/main/java/org/apache/fop/render/intermediate/IFSerializer.java
index ee6557d43..0bdcb0626 100644
--- a/fop-core/src/main/java/org/apache/fop/render/intermediate/IFSerializer.java
+++ b/fop-core/src/main/java/org/apache/fop/render/intermediate/IFSerializer.java
@@ -914,8 +914,11 @@ implements IFConstants, IFPainter, IFDocumentNavigationHandler {
         atts.addAttribute("", "rect", "rect",
                 XMLConstants.CDATA, IFUtil.toString(link.getTargetRect()));
         if (getUserAgent().isAccessibilityEnabled()) {
-            addStructRefAttribute(atts,
-                    ((IFStructureTreeElement) link.getAction().getStructureTreeElement()).getId());
+            IFStructureTreeElement structureTreeElement =
+                    (IFStructureTreeElement) link.getAction().getStructureTreeElement();
+            if (structureTreeElement != null) {
+                addStructRefAttribute(atts, structureTreeElement.getId());
+            }
         }
         try {
             handler.startElement(DocumentNavigationExtensionConstants.LINK, atts);
diff --git a/fop-core/src/test/java/org/apache/fop/intermediate/AbstractIFTest.java b/fop-core/src/test/java/org/apache/fop/intermediate/AbstractIFTest.java
index 48c3f335b..9e412a272 100644
--- a/fop-core/src/test/java/org/apache/fop/intermediate/AbstractIFTest.java
+++ b/fop-core/src/test/java/org/apache/fop/intermediate/AbstractIFTest.java
@@ -32,6 +32,10 @@ import javax.xml.transform.sax.SAXResult;
 import javax.xml.validation.Schema;
 import javax.xml.validation.SchemaFactory;
 import javax.xml.validation.Validator;
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathExpressionException;
+import javax.xml.xpath.XPathFactory;
 
 import org.w3c.dom.Document;
 import org.xml.sax.ErrorHandler;
@@ -105,6 +109,7 @@ abstract class AbstractIFTest extends AbstractIntermediateTest {
         DOMResult domResult = new DOMResult();
 
         FOUserAgent userAgent = createUserAgent();
+        userAgent.setAccessibility(isAccessibility(testDoc));
 
         //Create an instance of the target renderer so the XMLRenderer can use its font setup
         IFDocumentHandler targetHandler = userAgent.getRendererFactory().createDocumentHandler(
@@ -124,9 +129,23 @@ abstract class AbstractIFTest extends AbstractIntermediateTest {
         return (Document) domResult.getNode();
     }
 
+    private boolean isAccessibility(Document testDoc) {
+        try {
+            String s = eval(testDoc, "/testcase/cfg/accessibility");
+            return "true".equals(s);
+        } catch (XPathExpressionException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private String eval(Document doc, String xpath) throws XPathExpressionException {
+        XPath xPath = XPathFactory.newInstance().newXPath();
+        return (String) xPath.compile(xpath).evaluate(doc, XPathConstants.STRING);
+    }
+
     @Override
     protected void validate(Document doc) throws SAXException, IOException {
-        if (IF_SCHEMA == null) {
+        if (IF_SCHEMA == null || isAccessibility(testDoc)) {
             return; //skip validation;
         }
         Validator validator = IF_SCHEMA.newValidator();