AttachSelf.java

/*
 * Copyright (c) 2017, 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.
 *
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 */

import com.sun.tools.attach.VirtualMachine;

import java.io.IOException;

/**
 * @test
 * @modules jdk.attach
 * @run main AttachSelf
 * @run main/othervm -Djdk.attach.allowAttachSelf AttachSelf
 * @run main/othervm -Djdk.attach.allowAttachSelf=true AttachSelf
 * @run main/othervm -Djdk.attach.allowAttachSelf=false AttachSelf
 */

public class AttachSelf {

    public static void main(String[] args) throws Exception {

        String value = System.getProperty("jdk.attach.allowAttachSelf");
        boolean canAttachSelf = (value != null) && !value.equals("false");

        String vmid = "" + ProcessHandle.current().pid();

        VirtualMachine vm = null;
        try {
            vm = VirtualMachine.attach(vmid);
            if (!canAttachSelf)
                throw new RuntimeException("Attached to self not expected");
        } catch (IOException ioe) {
            if (canAttachSelf)
                throw ioe;
        } finally {
            if (vm != null) vm.detach();
        }

    }

}