revert SchemaValidatableElementTrait change

Author: ioigoume

src/XML/SchemaValidatableElementTrait.php

@@ -5,7 +5,6 @@
 namespace SimpleSAML\XML;
 
 use Dom;
-use LogicException;
 use SimpleSAML\XML\Assert\Assert;
 use SimpleSAML\XML\Exception\IOException;
 use SimpleSAML\XML\Exception\RuntimeException;
@@ -42,57 +41,29 @@ public static function schemaValidate(Dom\Document $document, ?string $schemaFil
         $internalErrors = libxml_use_internal_errors(true);
         libxml_clear_errors();
 
-        try {
-            if ($schemaFile === null) {
-                $schemaFile = self::getSchemaFile();
-            }
-
-            if (!$document instanceof Dom\XMLDocument) {
-                throw new LogicException('Schema validation requires an instance of Dom\\XMLDocument.');
-            }
+        if ($schemaFile === null) {
+            $schemaFile = self::getSchemaFile();
+        }
 
-            $root = $document->documentElement;
-            if ($root === null) {
-                throw new SchemaViolationException('The document has no document element.');
-            }
+        // Must suppress the warnings here in order to throw them as an error below.
+        $result = @$document->schemaValidate($schemaFile);
 
-            $xml = $document->saveXml($root);
-            if ($xml === false || trim($xml) === '') {
-                throw new SchemaViolationException('Could not serialize XML for schema validation.');
+        if ($result === false) {
+            $msgs = [];
+            foreach (libxml_get_errors() as $err) {
+                $msgs[] = trim($err->message) . ' on line ' . $err->line;
             }
 
-            /**
-             * Validates using a legacy \DOMDocument round-trip (serialize + re-parse) before running schema validation.
-             * This avoids false negatives seen with Dom\Document::schemaValidate(), especially around xs:QName
-             * prefix scope. Validation is performed against the exact serialized XML that would be
-             * exchanged externally.
-             * TODO: Revisit when Dom\Document::schemaValidate() reliably handles xs:QName prefix scope
-             *       (avoid legacy \DOMDocument round-trip).
-             */
-            $legacy = new \DOMDocument('1.0', 'UTF-8');
-            $legacy->preserveWhiteSpace = true;
-            $legacy->formatOutput = false;
-            $legacy->loadXML($xml);
-
-            $result = $legacy->schemaValidate($schemaFile);
-
-            if ($result === false) {
-                $msgs = [];
-                foreach (libxml_get_errors() as $err) {
-                    $msgs[] = trim($err->message) . ' on line ' . $err->line;
-                }
+            throw new SchemaViolationException(sprintf(
+                "XML schema validation errors:\n - %s",
+                implode("\n - ", array_unique($msgs)),
+            ));
+        }
 
-                throw new SchemaViolationException(sprintf(
-                    "XML schema validation errors:\n - %s",
-                    implode("\n - ", array_unique($msgs)),
-                ));
-            }
+        libxml_use_internal_errors($internalErrors);
+        libxml_clear_errors();
 
-            return $document;
-        } finally {
-            libxml_clear_errors();
-            libxml_use_internal_errors($internalErrors);
-        }
+        return $document;
     }