duke@1: /*
ohair@554:  * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
duke@1:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@1:  *
duke@1:  * This code is free software; you can redistribute it and/or modify it
duke@1:  * under the terms of the GNU General Public License version 2 only, as
duke@1:  * published by the Free Software Foundation.
duke@1:  *
duke@1:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@1:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@1:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@1:  * version 2 for more details (a copy is included in the LICENSE file that
duke@1:  * accompanied this code).
duke@1:  *
duke@1:  * You should have received a copy of the GNU General Public License version
duke@1:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@1:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@1:  *
ohair@554:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
ohair@554:  * or visit www.oracle.com if you need additional information or have any
ohair@554:  * questions.
duke@1:  */
duke@1: 
duke@1: import java.io.*;
duke@1: import java.nio.*;
duke@1: import java.nio.channels.*;
duke@1: 
duke@1: 
duke@1: public class CheckClassFileVersion {
duke@1: 
duke@1:     static String get(String fn) throws IOException {
duke@1:         ByteBuffer bb = ByteBuffer.allocate(1024);
duke@1:         FileChannel fc = new FileInputStream(fn).getChannel();
duke@1:         try {
duke@1:             bb.clear();
duke@1:             if (fc.read(bb) < 0)
duke@1:                 throw new IOException("Could not read any bytes");
duke@1:             bb.flip();
duke@1:             int minor = bb.getShort(4);
duke@1:             int major = bb.getShort(6);
duke@1:             return major + "." + minor;
duke@1:         } finally {
duke@1:             fc.close();
duke@1:         }
duke@1:     }
duke@1: 
duke@1:     public static void main(String[] args) throws IOException {
duke@1:         String cfv = get(args[0]);
duke@1:         if (args.length == 1) {
duke@1:             System.out.println(cfv);
duke@1:             return;
duke@1:         }
duke@1:         if (!cfv.equals(args[1])) {
duke@1:             System.err.println("Class-file version mismatch: Expected "
duke@1:                                + args[1] + ", got " + cfv);
duke@1:             System.exit(1);
duke@1:         }
duke@1:     }
duke@1: 
duke@1: }