Fix serialization of entity references in attributes

ext/dom/html5_serializer.c

@@ -196,13 +196,21 @@ static zend_result dom_html5_serialize_element_start(dom_html5_serialize_context
 				TRY(ctx->write_string(ctx->application_data, (const char *) attr->name));
 			}
 		}
+
 		TRY(ctx->write_string_len(ctx->application_data, "=\"", strlen("=\"")));
-		xmlChar *content = xmlNodeGetContent((const xmlNode *) attr);
-		if (content != NULL) {
-			zend_result result = dom_html5_escape_string(ctx, (const char *) content, true);
-			xmlFree(content);
-			TRY(result);
+
+		for (xmlNodePtr child = attr->children; child != NULL; child = child->next) {
+			if (child->type == XML_TEXT_NODE) {
+				if (child->content != NULL) {
+					TRY(dom_html5_escape_string(ctx, (const char *) child->content, true));
+				}
+			} else if (child->type == XML_ENTITY_REF_NODE) {
+				TRY(ctx->write_string_len(ctx->application_data, "&", strlen("&")));
+				TRY(dom_html5_escape_string(ctx, (const char *) child->name, true));
+				TRY(ctx->write_string_len(ctx->application_data, ";", strlen(";")));
+			}
 		}
+
 		TRY(ctx->write_string_len(ctx->application_data, "\"", strlen("\"")));
 	}
 

ext/dom/tests/modern/common/serialize_entity_reference_in_attribute.phpt

@@ -0,0 +1,29 @@
+--TEST--
+Serialize entity reference within attribute
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$xml = DOM\XMLDocument::createFromString(<<<XML
+<!DOCTYPE root [
+    <!ENTITY foo "foo">
+]>
+<root><el x="&foo;bar&foo;"/></root>
+XML);
+
+$el = $xml->documentElement->firstChild;
+echo $xml->saveXML(), "\n";
+
+$html = DOM\HTMLDocument::createEmpty();
+$html->append($html->importNode($el, true));
+echo $html->saveHTML(), "\n";
+
+?>
+--EXPECT--
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE root [
+<!ENTITY foo "foo">
+]>
+<root><el x="&foo;bar&foo;"/></root>
+<el x="&foo;bar&foo;"></el>

ext/dom/xml_serializer.c

@@ -542,17 +542,32 @@ static zend_always_inline int dom_xml_serialize_text_node(xmlOutputBufferPtr out
 	return dom_xml_common_text_serialization(out, (const char *) text->content, false);
 }
 
+static int dom_xml_serialize_attribute_node_value(xmlOutputBufferPtr out, xmlAttrPtr attr)
+{
+	TRY(xmlOutputBufferWriteString(out, (const char *) attr->name));
+	TRY(xmlOutputBufferWrite(out, strlen("=\""), "=\""));
+	for (xmlNodePtr child = attr->children; child != NULL; child = child->next) {
+		if (child->type == XML_TEXT_NODE) {
+			if (child->content != NULL) {
+				TRY(dom_xml_common_text_serialization(out, (const char *) child->content, true));
+			}
+		} else if (child->type == XML_ENTITY_REF_NODE) {
+			TRY(xmlOutputBufferWrite(out, strlen("&"), "&"));
+			TRY(dom_xml_common_text_serialization(out, (const char *) child->name, true));
+			TRY(xmlOutputBufferWrite(out, strlen(";"), ";"));
+		}
+	}
+	return xmlOutputBufferWrite(out, strlen("\""), "\"");
+}
+
 /* Spec says to do nothing, but that's inconsistent/wrong, see https://github.com/w3c/DOM-Parsing/issues/28 */
 static int dom_xml_serialize_attribute_node(xmlOutputBufferPtr out, xmlNodePtr attr)
 {
 	if (attr->ns != NULL && attr->ns->prefix != NULL) {
 		TRY(xmlOutputBufferWriteString(out, (const char *) attr->ns->prefix));
 		TRY(xmlOutputBufferWrite(out, strlen(":"), ":"));
 	}
-	TRY(xmlOutputBufferWriteString(out, (const char *) attr->name));
-	TRY(xmlOutputBufferWrite(out, strlen("=\""), "=\""));
-	TRY(dom_xml_common_text_serialization(out, (const char *) dom_get_attribute_value((xmlAttrPtr) attr), true));
-	return xmlOutputBufferWrite(out, strlen("\""), "\"");
+	return dom_xml_serialize_attribute_node_value(out, (xmlAttrPtr) attr);
 }
 
 /* https://w3c.github.io/DOM-Parsing/#dfn-xml-serializing-a-comment-node */
@@ -730,10 +745,7 @@ static int dom_xml_serialize_attributes(
 		 *      => N/A */
 
 		/* 3.9. Append the following strings to result, in the order listed: */
-		TRY(xmlOutputBufferWriteString(out, (const char *) attr->name));
-		TRY(xmlOutputBufferWrite(out, strlen("=\""), "=\""));
-		TRY(dom_xml_common_text_serialization(out, (const char *) dom_get_attribute_value(attr), true));
-		TRY(xmlOutputBufferWrite(out, strlen("\""), "\""));
+		dom_xml_serialize_attribute_node_value(out, attr);
 	}
 
 	/* 4. Return the value of result.