Fix #76712: Assignment of empty string creates extraneous text node

We work around this peculiarity of libxml by using xmlNodeSetContent(),
which does not exhibit this behavior.  This also saves us from manually
calculating the string length.

Author: cmb69

NEWS

@@ -24,6 +24,10 @@ PHP                                                                        NEWS
   . Fixed bug #76747 (Opcache treats path containing "test.pharma.tld" as a phar
     file). (Laruence)
 
+- SimpleXML:
+  . Fixed bug #76712 (Assignment of empty string creates extraneous text node).
+    (cmb)
+
 - SPL:
   . Fixed bug #68825 (Exception in DirectoryIterator::getLinkTarget()). (cmb)
   . Fixed bug #68175 (RegexIterator pregFlags are NULL instead of 0). (Tim

ext/simplexml/simplexml.c

@@ -384,7 +384,6 @@ static zval *sxe_dimension_read(zval *object, zval *offset, int type, zval *rv)
 static void change_node_zval(xmlNodePtr node, zval *value)
 {
 	xmlChar *buffer;
-	int buffer_len;
 
 	if (!value)
 	{
@@ -401,10 +400,9 @@ static void change_node_zval(xmlNodePtr node, zval *value)
 			/* break missing intentionally */
 		case IS_STRING:
 			buffer = xmlEncodeEntitiesReentrant(node->doc, (xmlChar *)Z_STRVAL_P(value));
-			buffer_len = xmlStrlen(buffer);
 			/* check for NULL buffer in case of memory error in xmlEncodeEntitiesReentrant */
 			if (buffer) {
-				xmlNodeSetContentLen(node, buffer, buffer_len);
+				xmlNodeSetContent(node, buffer);
 				xmlFree(buffer);
 			}
 			break;

ext/simplexml/tests/bug76712.phpt

@@ -0,0 +1,24 @@
+--TEST--
+BUg #76712 (Assignment of empty string creates extraneous text node)
+--SKIPIF--
+<?php
+if (!extension_loaded('simplexml')) die('skip simplexml not available');
+?>
+--FILE--
+<?php
+$sxe = new SimpleXMLElement('<foo></foo>');
+$sxe->addChild('bar', '');
+echo $sxe->asXML();
+
+$sxe = new SimpleXMLElement('<foo></foo>');
+$sxe->addChild('bar');
+$sxe->bar = '';
+echo $sxe->asXML();
+?>
+===DONE===
+--EXPECT--
+<?xml version="1.0"?>
+<foo><bar/></foo>
+<?xml version="1.0"?>
+<foo><bar/></foo>
+===DONE===