/*

 * Copyright (c) 2004, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.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);

        }

    }

}