Fix #63575: Root elements are not properly cloned

Cloning of root elements has to preserve that property, so they require
some special treatment.

Author: cmb69

NEWS

@@ -154,6 +154,7 @@ PHP                                                                        NEWS
 - SimpleXML:
   . Fixed bug #75245 (Don't set content of elements with only whitespaces).
     (eriklundin)
+  . Fixed bug #63575 (Root elements are not properly cloned). (cmb)
 
 - sodium:
   . Fixed bug #77646 (sign_detached() strings not terminated). (Frank)

ext/simplexml/simplexml.c

@@ -2035,12 +2035,20 @@ sxe_object_clone(zend_object *object)
 	php_sxe_object *clone;
 	xmlNodePtr nodep = NULL;
 	xmlDocPtr docp = NULL;
+	zend_bool is_root_element = sxe->node && sxe->node->node && sxe->node->node->parent
+		&& (sxe->node->node->parent->type == XML_DOCUMENT_NODE || sxe->node->node->parent->type == XML_HTML_DOCUMENT_NODE);
 
 	clone = php_sxe_object_new(sxe->zo.ce, sxe->fptr_count);
-	clone->document = sxe->document;
-	if (clone->document) {
-		clone->document->refcount++;
-		docp = clone->document->ptr;
+
+	if (is_root_element) {
+		docp = xmlCopyDoc(sxe->document->ptr, 1);
+		php_libxml_increment_doc_ref((php_libxml_node_object *)clone, docp);
+	} else {
+		clone->document = sxe->document;
+		if (clone->document) {
+			clone->document->refcount++;
+			docp = clone->document->ptr;
+		}
 	}
 
 	clone->iter.isprefix = sxe->iter.isprefix;
@@ -2053,7 +2061,11 @@ sxe_object_clone(zend_object *object)
 	clone->iter.type = sxe->iter.type;
 
 	if (sxe->node) {
-		nodep = xmlDocCopyNode(sxe->node->node, docp, 1);
+		if (is_root_element) {
+			nodep = xmlDocGetRootElement(docp);
+		} else {
+			nodep = xmlDocCopyNode(sxe->node->node, docp, 1);
+		}
 	}
 
 	php_libxml_increment_node_ptr((php_libxml_node_object *)clone, nodep, NULL);

ext/simplexml/tests/bug39662.phpt

@@ -23,7 +23,9 @@ object(SimpleXMLElement)#%d (0) {
 }
 object(SimpleXMLElement)#%d (0) {
 }
-string(15) "<test>
+string(%d) "<?xml version="1.0" encoding="utf-8"?>
+<test>
 
-</test>"
+</test>
+"
 Done

ext/simplexml/tests/bug63575.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Bug #63575 (Root elements are not properly cloned)
+--SKIPIF--
+<?php
+if (!extension_loaded('simplexml')) die('skip simplexml extension not available');
+?>
+--FILE--
+<?php
+$xml = '<a><b></b></a>';
+
+$o1 = new SimpleXMlElement($xml);
+$o2 = clone $o1;
+
+$r = current($o2->xpath('/a'));
+$r->addChild('c', new SimpleXMlElement('<c></c>'));
+
+echo $o1->asXML(), PHP_EOL, $o2->asXML();
+?>
+--EXPECT--
+<?xml version="1.0"?>
+<a><b/></a>
+
+<?xml version="1.0"?>
+<a><b/><c/></a>