ext/libxml: Fixed custom external entity loader returning an invalid resource leading to a confusing TypeError message

Author: Girgias

NEWS

@@ -29,6 +29,10 @@ PHP                                                                        NEWS
   . Fixed bug GH-18081 (Memory leaks in error paths of fuzzer SAPI).
     (Lung-Alexandra)
 
+- libxml:
+  . Fixed custom external entity loader returning an invalid resource leading
+    to a confusing TypeError message. (Girgias)
+
 - Mbstring:
   . Fixed bug GH-17989 (mb_output_handler crash with unset
     http_output_conv_mimetypes). (nielsdos)

ext/libxml/libxml.c

@@ -793,13 +793,19 @@ static xmlParserInputPtr _php_libxml_external_entity_loader(const char *URL,
 is_string:
 			resource = Z_STRVAL(retval);
 		} else if (Z_TYPE(retval) == IS_RESOURCE) {
-			php_stream *stream;
-			php_stream_from_zval_no_verify(stream, &retval);
-			if (stream == NULL) {
+			php_stream *stream = (php_stream*)zend_fetch_resource2_ex(&retval, NULL, php_file_le_stream(), php_file_le_pstream());
+			if (UNEXPECTED(stream == NULL)) {
+				zval callable;
+				zend_get_callable_zval_from_fcc(&LIBXML(entity_loader_callback), &callable);
+
+				zend_string *callable_name = zend_get_callable_name(&callable);
+
 				php_libxml_ctx_error(context,
-						"The user entity loader callback '%s' has returned a "
+						"The user entity loader callback \"%s\" has returned a "
 						"resource, but it is not a stream",
-						ZSTR_VAL(LIBXML(entity_loader_callback).function_handler->common.function_name));
+						ZSTR_VAL(callable_name));
+				zend_string_release(callable_name);
+				zval_ptr_dtor(&callable);
 			} else {
 				/* TODO: allow storing the encoding in the stream context? */
 				xmlCharEncoding enc = XML_CHAR_ENCODING_NONE;

ext/libxml/tests/libxml_get_external_entity_loader_error_callback_name.phpt

@@ -39,5 +39,8 @@ try {
 $file = __DIR__ . '/db.dba';
 unlink($file);
 ?>
---EXPECT--
-string(73) "DOMDocument::validate(): supplied resource is not a valid stream resource"
+--EXPECTF--
+Warning: DOMDocument::validate(): The user entity loader callback "Handler::handle" has returned a resource, but it is not a streamFailed to load external entity "-//FOO/BAR" in %s on line %d
+
+Warning: DOMDocument::validate(): Could not load the external subset "http://example.com/foobar" in %s on line %d
+bool(false)