[bugfix] Stop Xerces prolog stderr spam during filesystem backup restore

FileSystemBackupDescriptor was parsing every backup payload file as XML
when counting resources, which printed [Fatal Error] for binary entries.
Count __contents__.xml descriptors only (matching zip backups) and route
SAX parse errors through DefaultHandler instead of a null error handler.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: duncdrum

exist-core/src/main/java/org/exist/backup/DescriptorResourceCounter.java

@@ -56,6 +56,8 @@ public DescriptorResourceCounter() throws ParserConfigurationException, SAXExcep
         this.counterHandler = new CounterHandler();
 
         xmlReader.setContentHandler(counterHandler);
+        // Suppress Xerces "[Fatal Error]" stderr noise; fatal errors still propagate via DefaultHandler.
+        xmlReader.setErrorHandler(counterHandler);
     }
 
     public long count(final InputStream descriptorInputStream) throws IOException, SAXException {

exist-core/src/main/java/org/exist/backup/FileSystemBackupDescriptor.java

@@ -30,7 +30,6 @@
 import org.xml.sax.SAXException;
 
 import javax.xml.parsers.ParserConfigurationException;
-import java.io.BufferedInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
@@ -196,23 +195,25 @@ public Path getRepoBackup() throws IOException {
         return null;
     }
 
+    /**
+     * Count resources declared in {@link BackupDescriptor#COLLECTION_DESCRIPTOR} files under this
+     * collection subtree (same approach as {@link ZipArchiveBackupDescriptor}).
+     */
     private void countFileEntries(final Path descriptor) {
-
-        // Only count files from top level.
-        if (!descriptor.toString().endsWith("/db/" + COLLECTION_DESCRIPTOR)) {
+        final Path collectionDir = descriptor.getParent();
+        if (collectionDir == null) {
             return;
         }
 
         try {
             final DescriptorResourceCounter descriptorResourceCounter = new DescriptorResourceCounter();
 
-            try (final Stream<Path> walk = Files.walk(descriptor.getParent());
-                final Stream<Path> ds = walk
-                        .filter(f -> !Files.isDirectory(f))
-                        .filter(f -> !COLLECTION_DESCRIPTOR.equals(f.getFileName().toString()))) {
-
-                for (final Path d : ds.collect(Collectors.toList())) {
-                    try (final InputStream is = new BufferedInputStream(Files.newInputStream(d))) {
+            try (final Stream<Path> walk = Files.walk(collectionDir)) {
+                for (final Path contentsFile : walk
+                        .filter(p -> !Files.isDirectory(p))
+                        .filter(p -> COLLECTION_DESCRIPTOR.equals(p.getFileName().toString()))
+                        .toList()) {
+                    try (final InputStream is = Files.newInputStream(contentsFile)) {
                         numberOfFiles += descriptorResourceCounter.count(is);
                     }
                 }

exist-core/src/main/java/org/exist/util/XMLReaderObjectFactory.java

@@ -39,6 +39,7 @@
 import org.xml.sax.SAXNotRecognizedException;
 import org.xml.sax.SAXNotSupportedException;
 import org.xml.sax.XMLReader;
+import org.xml.sax.helpers.DefaultHandler;
 import org.xmlresolver.Resolver;
 
 import java.util.Map;
@@ -51,6 +52,9 @@ public class XMLReaderObjectFactory extends BasePooledObjectFactory<XMLReader> i
 
     private static final Logger LOG = LogManager.getLogger(XMLReaderObjectFactory.class);
 
+    /** Shared handler: routes parse errors through SAX without Xerces stderr spam. */
+    private static final DefaultHandler SILENT_SAX_ERROR_HANDLER = new DefaultHandler();
+
     public static final String CONFIGURATION_ENTITY_RESOLVER_ELEMENT_NAME = "entity-resolver";
     public static final String CONFIGURATION_CATALOG_ELEMENT_NAME = "catalog";
     public static final String CONFIGURATION_ELEMENT_NAME = "validation";
@@ -98,7 +102,7 @@ public XMLReader create() throws Exception {
         final SAXParser saxParser = saxParserFactory.newSAXParser();
         final XMLReader xmlReader = saxParser.getXMLReader();
 
-        xmlReader.setErrorHandler(null);  // disable default Xerces Error Handler
+        xmlReader.setErrorHandler(SILENT_SAX_ERROR_HANDLER);
 
         return xmlReader;
     }
@@ -136,14 +140,16 @@ public void activateObject(final PooledObject<XMLReader> pooledXmlReader) {
                 setReaderFeature(xmlReader, feature.getKey(), feature.getValue());
             }
         }
+
+        xmlReader.setErrorHandler(SILENT_SAX_ERROR_HANDLER);
     }
 
     @Override
     public void passivateObject(final PooledObject<XMLReader> pooledXmlReader) throws Exception {
         final XMLReader xmlReader = pooledXmlReader.getObject();
 
         xmlReader.setContentHandler(null);
-        xmlReader.setErrorHandler(null);
+        xmlReader.setErrorHandler(SILENT_SAX_ERROR_HANDLER);
         xmlReader.setProperty(Namespaces.SAX_LEXICAL_HANDLER, null);
     }