[bugfix] fn:parse-xml-fragment#1 should return a document-node() when there is an XML document that has a XML declaration

Author: adamretter

exist-core/src/main/java/org/exist/xquery/functions/fn/ParsingFunctions.java

@@ -64,7 +64,6 @@
 
 import java.io.IOException;
 import java.io.StringReader;
-import java.nio.charset.StandardCharsets;
 
 import static org.exist.util.ByteOrderMark.stripXmlBom;
 
@@ -134,7 +133,27 @@ private ValidationReport validate(String xmlContent, final SAXAdapter saxAdapter
         xmlContent = stripXmlBom(xmlContent);
         final String xml;
 	    if (isCalledAs("parse-xml-fragment")) {
-            xml = "<" + FRAGMENT_WRAPPER_NAME + ">" + xmlContent + "</" + FRAGMENT_WRAPPER_NAME + ">";
+            String declStr = xmlContent.toLowerCase();
+            final int startIdx = declStr.indexOf("<?xml ");
+            if (startIdx > -1) {
+
+                // NOTE(AR) for parsing fragments the input must be an external entity, so validate that the declaration is a TextDecl (https://www.w3.org/TR/REC-xml/#NT-TextDecl) and not a full XMLDecl (https://www.w3.org/TR/REC-xml/#NT-XMLDecl) with standalone attribute
+
+                declStr = declStr.substring(startIdx);
+                int endIdx = declStr.indexOf("?>");
+                if (endIdx > -1) {
+                    endIdx += 2;
+                }
+                declStr = declStr.substring(0, endIdx);
+                if (declStr.contains("standalone=")) {
+                    throw new XPathException(this, ErrorCodes.FODC0006, "Input to fn:parse-xml-fragment must be a valid external entity, but 'standalone' attribute was detected in the declaration");
+                }
+
+                xml = xmlContent;
+
+            } else {
+                xml = "<" + FRAGMENT_WRAPPER_NAME + ">" + xmlContent + "</" + FRAGMENT_WRAPPER_NAME + ">";
+            }
         } else {
 	        xml = xmlContent;
         }