Handle libxml2 OOM more consistently (#11927)

This is a continuation of commit c2a58ab, in which several OOM error
handling was converted to throwing an INVALID_STATE_ERR DOMException.
Some places were missed and they still returned false without an
exception, or threw a PHP_ERR DOMException.
Convert all of these to INVALID_STATE_ERR DOMExceptions. This also
reduces confusion of users going through documentation [1].

Unfortunately, not all node creations are checked for a NULL pointer.
Some places therefore will not do anything if an OOM occurs (well,
except crash).
On the one hand it's nice to handle these OOM cases.
On the other hand, this adds some complexity and it's very unlikely to
happen in the real world. But then again, "unlikely" situations have
caused trouble before. Ideally all cases should be checked.

[1] php/doc-en#1741

NEWS

@@ -15,6 +15,7 @@ DOM:
   . Fix cloning attribute with namespace disappearing namespace. (nielsdos)
   . Implement DOM HTML5 parsing and serialization RFC. (nielsdos)
   . Fix DOMElement->prefix with empty string creates bogus prefix. (nielsdos)
+  . Handle OOM more consistently. (nielsdos)
 
 FPM:
   . Implement GH-12385 (flush headers without body when calling flush()).

UPGRADING

@@ -25,6 +25,11 @@ PHP 8.4 UPGRADE NOTES
     you might encounter errors if the declaration is incompatible.
     Consult sections 2. New Features and 6. New Functions for a list of
     newly implemented methods and constants.
+  . Some DOM methods previously returned false or a PHP_ERR DOMException if a new
+    node could not be allocated. They consistently throw an INVALID_STATE_ERR
+    DOMException now. This situation is extremely unlikely though and probably
+    will not affect you. As a result DOMImplementation::createDocument() now has
+    a tentative return type of DOMDocument instead of DOMDocument|false.
 
 - PDO_DBLIB:
   . setAttribute, DBLIB_ATTR_STRINGIFY_UNIQUEIDENTIFIER and DBLIB_ATTR_DATETIME_CONVERT

ext/dom/document.c

@@ -842,7 +842,12 @@ PHP_METHOD(DOM_Document, createElementNS)
 	if (errorcode == 0) {
 		if (xmlValidateName((xmlChar *) localname, 0) == 0) {
 			nodep = xmlNewDocNode(docp, NULL, (xmlChar *) localname, (xmlChar *) value);
-			if (nodep != NULL && uri != NULL) {
+			if (UNEXPECTED(nodep == NULL)) {
+				php_dom_throw_error(INVALID_STATE_ERR, /* strict */ true);
+				RETURN_THROWS();
+			}
+
+			if (uri != NULL) {
 				xmlNsPtr nsptr = xmlSearchNsByHref(nodep->doc, nodep, (xmlChar *) uri);
 				if (nsptr == NULL) {
 					nsptr = dom_get_ns(nodep, uri, &errorcode, prefix);
@@ -860,17 +865,11 @@ PHP_METHOD(DOM_Document, createElementNS)
 	}
 
 	if (errorcode != 0) {
-		if (nodep != NULL) {
-			xmlFreeNode(nodep);
-		}
+		xmlFreeNode(nodep);
 		php_dom_throw_error(errorcode, dom_get_strict_error(intern->document));
 		RETURN_FALSE;
 	}
 
-	if (nodep == NULL) {
-		RETURN_FALSE;
-	}
-
 	DOM_RET_OBJ(nodep, &ret, intern);
 }
 /* }}} end dom_document_create_element_ns */
@@ -904,7 +903,12 @@ PHP_METHOD(DOM_Document, createAttributeNS)
 		if (errorcode == 0) {
 			if (xmlValidateName((xmlChar *) localname, 0) == 0) {
 				nodep = (xmlNodePtr) xmlNewDocProp(docp, (xmlChar *) localname, NULL);
-				if (nodep != NULL && uri_len > 0) {
+				if (UNEXPECTED(nodep == NULL)) {
+					php_dom_throw_error(INVALID_STATE_ERR, /* strict */ true);
+					RETURN_THROWS();
+				}
+
+				if (uri_len > 0) {
 					nsptr = xmlSearchNsByHref(nodep->doc, root, (xmlChar *) uri);
 					if (nsptr == NULL || nsptr->prefix == NULL) {
 						nsptr = dom_get_ns(root, uri, &errorcode, prefix ? prefix : "default");
@@ -926,17 +930,11 @@ PHP_METHOD(DOM_Document, createAttributeNS)
 	}
 
 	if (errorcode != 0) {
-		if (nodep != NULL) {
-			xmlFreeProp((xmlAttrPtr) nodep);
-		}
+		xmlFreeProp((xmlAttrPtr) nodep);
 		php_dom_throw_error(errorcode, dom_get_strict_error(intern->document));
 		RETURN_FALSE;
 	}
 
-	if (nodep == NULL) {
-		RETURN_FALSE;
-	}
-
 	DOM_RET_OBJ(nodep, &ret, intern);
 }
 /* }}} end dom_document_create_attribute_ns */

ext/dom/domimplementation.c

@@ -138,6 +138,8 @@ PHP_METHOD(DOMImplementation, createDocument)
 			RETURN_THROWS();
 		}
 		if (doctype->doc != NULL) {
+			/* As the new document is the context node, and the default for strict error checking
+			 * is true, this will always throw. */
 			php_dom_throw_error(WRONG_DOCUMENT_ERR, 1);
 			RETURN_THROWS();
 		}
@@ -172,7 +174,9 @@ PHP_METHOD(DOMImplementation, createDocument)
 		if (localname != NULL) {
 			xmlFree(localname);
 		}
-		RETURN_FALSE;
+		/* See above for strict error checking argument. */
+		php_dom_throw_error(INVALID_STATE_ERR, /* strict */ true);
+		RETURN_THROWS();
 	}
 
 	if (doctype != NULL) {
@@ -195,8 +199,7 @@ PHP_METHOD(DOMImplementation, createDocument)
 			}
 			xmlFreeDoc(docp);
 			xmlFree(localname);
-			/* Need some better type of error here */
-			php_dom_throw_error(PHP_ERR, 1);
+			php_dom_throw_error(INVALID_STATE_ERR, /* strict */ true);
 			RETURN_THROWS();
 		}
 

ext/dom/node.c

@@ -687,7 +687,8 @@ zend_result dom_node_prefix_write(dom_object *obj, zval *newval)
 					(nodep->type == XML_ATTRIBUTE_NODE && zend_string_equals_literal(prefix_str, "xmlns") &&
 					 strcmp(strURI, (char *) DOM_XMLNS_NAMESPACE)) ||
 					(nodep->type == XML_ATTRIBUTE_NODE && !strcmp((char *) nodep->name, "xmlns"))) {
-					ns = NULL;
+					php_dom_throw_error(NAMESPACE_ERR, dom_get_strict_error(obj->document));
+					return FAILURE;
 				} else {
 					curns = nsnode->nsDef;
 					while (curns != NULL) {
@@ -699,14 +700,15 @@ zend_result dom_node_prefix_write(dom_object *obj, zval *newval)
 					}
 					if (ns == NULL) {
 						ns = xmlNewNs(nsnode, nodep->ns->href, (xmlChar *)prefix);
+						/* Sadly, we cannot distinguish between OOM and namespace conflict.
+						 * But OOM will almost never happen. */
+						if (UNEXPECTED(ns == NULL)) {
+							php_dom_throw_error(NAMESPACE_ERR, /* strict */ true);
+							return FAILURE;
+						}
 					}
 				}
 
-				if (ns == NULL) {
-					php_dom_throw_error(NAMESPACE_ERR, dom_get_strict_error(obj->document));
-					return FAILURE;
-				}
-
 				xmlSetNs(nodep, ns);
 			}
 			break;

ext/dom/php_dom.stub.php

@@ -477,8 +477,8 @@ public function hasFeature(string $feature, string $version): bool {}
         /** @return DOMDocumentType|false */
         public function createDocumentType(string $qualifiedName, string $publicId = "", string $systemId = "") {}
 
-        /** @return DOMDocument|false */
-        public function createDocument(?string $namespace = null, string $qualifiedName = "", ?DOMDocumentType $doctype = null) {}
+        /** @tentative-return-type */
+        public function createDocument(?string $namespace = null, string $qualifiedName = "", ?DOMDocumentType $doctype = null): DOMDocument {}
     }
 
     /** @alias DOM\DocumentFragment */

ext/dom/text.c

@@ -152,8 +152,8 @@ PHP_METHOD(DOMText, splitText)
 	xmlFree(second);
 
 	if (nnode == NULL) {
-		/* TODO Add warning? */
-		RETURN_FALSE;
+		php_dom_throw_error(INVALID_STATE_ERR, /* strict */ true);
+		RETURN_THROWS();
 	}
 
 	if (node->parent != NULL) {