Fix cloning attribute with namespace disappearing namespace

ext/dom/element.c

@@ -640,6 +640,7 @@ PHP_METHOD(DOMElement, setAttributeNode)
 	}
 
 	xmlAddChild(nodep, (xmlNodePtr) attrp);
+	php_dom_reconcile_attribute_namespace_after_insertion(attrp);
 
 	/* Returns old property if removed otherwise NULL */
 	if (existattrp != NULL) {
@@ -1012,6 +1013,7 @@ PHP_METHOD(DOMElement, setAttributeNodeNS)
 	}
 
 	xmlAddChild(nodep, (xmlNodePtr) attrp);
+	php_dom_reconcile_attribute_namespace_after_insertion(attrp);
 
 	/* Returns old property if removed otherwise NULL */
 	if (existattrp != NULL) {

ext/dom/node.c

@@ -1259,6 +1259,7 @@ PHP_METHOD(DOMNode, appendChild)
 		if (UNEXPECTED(new_child == NULL)) {
 			goto cannot_add;
 		}
+		php_dom_reconcile_attribute_namespace_after_insertion((xmlAttrPtr) new_child);
 	} else if (child->type == XML_DOCUMENT_FRAG_NODE) {
 		xmlNodePtr last = child->last;
 		new_child = _php_dom_insert_fragment(nodep, nodep->last, NULL, child, intern, childobj);
@@ -1362,6 +1363,13 @@ PHP_METHOD(DOMNode, cloneNode)
 		}
 	}
 
+	if (node->type == XML_ATTRIBUTE_NODE && n->ns != NULL && node->ns == NULL) {
+		/* Let reconciliation deal with this. The lifetime of the namespace poses no problem
+		 * because we're increasing the refcount of the document proxy at the return.
+		 * libxml2 doesn't set the ns because it can't know that this is safe. */
+		node->ns = n->ns;
+	}
+
 	/* If document cloned we want a new document proxy */
 	if (node->doc != n->doc) {
 		intern = NULL;

ext/dom/php_dom.c

@@ -1458,6 +1458,22 @@ static void dom_reconcile_ns_internal(xmlDocPtr doc, xmlNodePtr nodep, xmlNodePt
 	}
 }
 
+void php_dom_reconcile_attribute_namespace_after_insertion(xmlAttrPtr attrp)
+{
+	ZEND_ASSERT(attrp != NULL);
+
+	if (attrp->ns != NULL) {
+		/* Try to link to an existing namespace. If that won't work, reconcile. */
+		xmlNodePtr nodep = attrp->parent;
+		xmlNsPtr matching_ns = xmlSearchNs(nodep->doc, nodep, attrp->ns->prefix);
+		if (matching_ns && xmlStrEqual(matching_ns->href, attrp->ns->href)) {
+			attrp->ns = matching_ns;
+		} else {
+			xmlReconciliateNs(nodep->doc, nodep);
+		}
+	}
+}
+
 static void dom_libxml_reconcile_ensure_namespaces_are_declared(xmlNodePtr nodep)
 {
 	/* Ideally we'd use the DOM-wrapped version, but we cannot: https://github.com/php/php-src/pull/12308. */
@@ -1474,6 +1490,8 @@ static void dom_libxml_reconcile_ensure_namespaces_are_declared(xmlNodePtr nodep
 
 void dom_reconcile_ns(xmlDocPtr doc, xmlNodePtr nodep) /* {{{ */
 {
+	ZEND_ASSERT(nodep->type != XML_ATTRIBUTE_NODE);
+
 	/* Although the node type will be checked by the libxml2 API,
 	 * we still want to do the internal reconciliation conditionally. */
 	if (nodep->type == XML_ELEMENT_NODE) {

ext/dom/php_dom.h

@@ -152,6 +152,7 @@ zend_string *dom_node_get_node_name_attribute_or_element(const xmlNode *nodep);
 bool php_dom_is_node_connected(const xmlNode *node);
 bool php_dom_adopt_node(xmlNodePtr nodep, dom_object *dom_object_new_document, xmlDocPtr new_document);
 xmlNsPtr dom_get_ns_resolve_prefix_conflict(xmlNodePtr tree, const char *uri);
+void php_dom_reconcile_attribute_namespace_after_insertion(xmlAttrPtr attrp);
 
 /* parentnode */
 void dom_parent_node_prepend(dom_object *context, zval *nodes, uint32_t nodesc);

ext/dom/tests/DOMDocument_importNode_attribute_prefix_conflict.phpt

@@ -26,7 +26,9 @@ $dom1->loadXML('<?xml version="1.0"?><container xmlns:foo="http://php.net" foo:b
 $dom2->loadXML('<?xml version="1.0"?><container xmlns="http://php.net" xmlns:foo="http://php.net/2"/>');
 $attribute = $dom1->documentElement->getAttributeNode('foo:bar');
 $imported = $dom2->importNode($attribute);
+var_dump($imported->prefix, $imported->namespaceURI);
 $dom2->documentElement->setAttributeNodeNS($imported);
+var_dump($imported->prefix, $imported->namespaceURI);
 
 echo $dom1->saveXML();
 echo $dom2->saveXML();
@@ -54,6 +56,10 @@ echo $dom2->saveXML();
 <?xml version="1.0"?>
 <container xmlns:foo="http://php.net/2" xmlns:default="http://php.net" default:bar="yes"/>
 --- Non-default namespace test case with a default namespace in the destination ---
+string(7) "default"
+string(14) "http://php.net"
+string(7) "default"
+string(14) "http://php.net"
 <?xml version="1.0"?>
 <container xmlns:foo="http://php.net" foo:bar="yes"/>
 <?xml version="1.0"?>

ext/dom/tests/clone_attribute_namespace_01.phpt

@@ -0,0 +1,84 @@
+--TEST--
+Cloning an attribute should retain its namespace 01
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+function createTestDocument() {
+    $dom = new DOMDocument;
+    $dom->loadXML('<?xml version="1.0"?><container/>');
+    $dom->documentElement->setAttributeNs("some:ns", "foo:bar", "value");
+
+    $attr = $dom->documentElement->getAttributeNodeNs("some:ns", "bar");
+    $clone = $attr->cloneNode(true);
+
+    return [$dom, $clone];
+}
+
+[$dom, $clone] = createTestDocument();
+var_dump($clone->prefix, $clone->namespaceURI);
+
+echo "--- Re-adding a namespaced attribute ---\n";
+
+[$dom, $clone] = createTestDocument();
+$dom->documentElement->removeAttributeNs("some:ns", "bar");
+echo $dom->saveXML();
+$dom->documentElement->setAttributeNodeNs($clone);
+echo $dom->saveXML();
+
+echo "--- Re-adding a namespaced attribute, with the namespace deleted (setAttributeNodeNs variation) ---\n";
+
+function readd_test(string $method) {
+    [$dom, $clone] = createTestDocument();
+    $dom->documentElement->removeAttributeNs("some:ns", "bar");
+    $dom->documentElement->removeAttribute("xmlns:foo");
+    echo $dom->saveXML();
+    $child = $dom->documentElement->appendChild($dom->createElement("child"));
+    $child->{$method}($clone);
+    echo $dom->saveXML();
+}
+
+readd_test("setAttributeNodeNs");
+
+echo "--- Re-adding a namespaced attribute, with the namespace deleted (setAttributeNode variation) ---\n";
+
+readd_test("setAttributeNode");
+
+echo "--- Re-adding a namespaced attribute, with the namespace deleted (appendChild variation) ---\n";
+
+readd_test("appendChild");
+
+echo "--- Removing the document reference should not crash ---\n";
+
+[$dom, $clone] = createTestDocument();
+unset($dom);
+var_dump($clone->prefix, $clone->namespaceURI);
+
+?>
+--EXPECT--
+string(3) "foo"
+string(7) "some:ns"
+--- Re-adding a namespaced attribute ---
+<?xml version="1.0"?>
+<container xmlns:foo="some:ns"/>
+<?xml version="1.0"?>
+<container xmlns:foo="some:ns" foo:bar="value"/>
+--- Re-adding a namespaced attribute, with the namespace deleted (setAttributeNodeNs variation) ---
+<?xml version="1.0"?>
+<container/>
+<?xml version="1.0"?>
+<container><child xmlns:foo="some:ns" foo:bar="value"/></container>
+--- Re-adding a namespaced attribute, with the namespace deleted (setAttributeNode variation) ---
+<?xml version="1.0"?>
+<container/>
+<?xml version="1.0"?>
+<container><child xmlns:foo="some:ns" foo:bar="value"/></container>
+--- Re-adding a namespaced attribute, with the namespace deleted (appendChild variation) ---
+<?xml version="1.0"?>
+<container/>
+<?xml version="1.0"?>
+<container><child xmlns:foo="some:ns" foo:bar="value"/></container>
+--- Removing the document reference should not crash ---
+string(3) "foo"
+string(7) "some:ns"

ext/dom/tests/clone_attribute_namespace_02.phpt

@@ -0,0 +1,26 @@
+--TEST--
+Cloning an attribute should retain its namespace 02
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$dom = new DOMDocument;
+$dom->loadXML(<<<XML
+<?xml version="1.0"?>
+<container xmlns:foo="some:ns" foo:bar="1">
+    <child xmlns:foo="some:other"/>
+</container>
+XML);
+
+$clone = $dom->documentElement->getAttributeNodeNs("some:ns", "bar")->cloneNode(true);
+$dom->documentElement->firstElementChild->setAttributeNodeNs($clone);
+
+echo $dom->saveXML();
+
+?>
+--EXPECT--
+<?xml version="1.0"?>
+<container xmlns:foo="some:ns" foo:bar="1">
+    <child xmlns:foo="some:other" xmlns:foo1="some:ns" foo1:bar="1"/>
+</container>

ext/dom/tests/import_attribute_namespace.phpt

@@ -0,0 +1,37 @@
+--TEST--
+Cloning an attribute should retain its namespace 02
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$dom = new DOMDocument;
+$dom->loadXML(<<<XML
+<?xml version="1.0"?>
+<container xmlns:foo="some:ns" foo:bar="1"/>
+XML);
+
+$dom2 = new DOMDocument;
+$dom2->loadXML(<<<XML
+<?xml version="1.0"?>
+<container xmlns:foo="some:other"/>
+XML);
+
+$imported = $dom2->importNode($dom->documentElement->getAttributeNodeNs("some:ns", "bar"));
+var_dump($imported->prefix, $imported->namespaceURI);
+$dom2->documentElement->setAttributeNodeNs($imported);
+var_dump($imported->prefix, $imported->namespaceURI);
+
+echo $dom->saveXML();
+echo $dom2->saveXML();
+
+?>
+--EXPECT--
+string(7) "default"
+string(7) "some:ns"
+string(7) "default"
+string(7) "some:ns"
+<?xml version="1.0"?>
+<container xmlns:foo="some:ns" foo:bar="1"/>
+<?xml version="1.0"?>
+<container xmlns:foo="some:other" xmlns:default="some:ns" default:bar="1"/>