Fix GH-14652: segfault on node without document. (#14653)

do not bother trying to clone the inner document if there is none to
begin with.

Author: devnexen

ext/dom/php_dom.c

@@ -600,7 +600,9 @@ static zend_object *dom_objects_store_clone_obj(zend_object *zobject) /* {{{ */
 			if (cloned_node != NULL) {
 				dom_update_refcount_after_clone(intern, node, clone, cloned_node);
 			}
-			clone->document->private_data = php_dom_libxml_ns_mapper_header(ns_mapper);
+			if (ns_mapper != NULL) {
+				clone->document->private_data = php_dom_libxml_ns_mapper_header(ns_mapper);
+			}
 		}
 	}
 

ext/dom/tests/gh14652.phpt

@@ -0,0 +1,18 @@
+--TEST--
+GH-14652 segfault on object cloning
+--EXTENSIONS--
+dom
+--CREDITS--
+YuanchengJiang
+--FILE--
+<?php
+$attr = new DOMAttr('category', 'books');
+$clone = clone $attr;
+$attr->value = "hello";
+
+var_dump($attr->value);
+var_dump($clone->value);
+?>
+--EXPECT--
+string(5) "hello"
+string(5) "books"