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