Fix memory leak introduced by fixing bug #78221

We have to free the retrieved text content; to keep the code readable,
we extract a helper function to check for empty nodes.  Unfortunately,
we cannot use xmlIsBlankNode(), because that also recognizes whitespace
only text content.

We also make sure to properly handle NULL returns from
xmlNodeGetContent().

Author: cmb69

ext/dom/php_dom.c

@@ -1358,6 +1358,14 @@ xmlNode *dom_get_elements_by_tag_name_ns_raw(xmlNodePtr nodep, char *ns, char *l
 /* }}} */
 /* }}} end dom_element_get_elements_by_tag_name_ns_raw */
 
+static inline zend_bool is_empty_node(xmlNodePtr nodep)
+{
+	xmlChar	*strContent = xmlNodeGetContent(nodep);
+	zend_bool ret = strContent == NULL || *strContent == '\0';
+	xmlFree(strContent);
+	return ret;
+}
+
 /* {{{ void dom_normalize (xmlNodePtr nodep) */
 void dom_normalize (xmlNodePtr nodep)
 {
@@ -1383,8 +1391,7 @@ void dom_normalize (xmlNodePtr nodep)
 						break;
 					}
 				}
-				strContent = xmlNodeGetContent(child);
-				if (*strContent == '\0') {
+				if (is_empty_node(child)) {
 					nextp = child->next;
 					xmlUnlinkNode(child);
 					php_libxml_node_free_resource(child);