--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/versions/CheckClassFileVersion.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2004 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+import java.io.*;
+import java.nio.*;
+import java.nio.channels.*;
+
+
+public class CheckClassFileVersion {
+
+    static String get(String fn) throws IOException {
+        ByteBuffer bb = ByteBuffer.allocate(1024);
+        FileChannel fc = new FileInputStream(fn).getChannel();
+        try {
+            bb.clear();
+            if (fc.read(bb) < 0)
+                throw new IOException("Could not read any bytes");
+            bb.flip();
+            int minor = bb.getShort(4);
+            int major = bb.getShort(6);
+            return major + "." + minor;
+        } finally {
+            fc.close();
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        String cfv = get(args[0]);
+        if (args.length == 1) {
+            System.out.println(cfv);
+            return;
+        }
+        if (!cfv.equals(args[1])) {
+            System.err.println("Class-file version mismatch: Expected "
+                               + args[1] + ", got " + cfv);
+            System.exit(1);
+        }
+    }
+
+}