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	/*
	* Copyright (c) 2005, 2013, 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. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* 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.
	*/

	package sun.tools.jstack;

	import java.lang.reflect.Method;
	import java.lang.reflect.Constructor;
	import java.io.IOException;
	import java.io.InputStream;

	import com.sun.tools.attach.VirtualMachine;
	import com.sun.tools.attach.AttachNotSupportedException;
	import sun.tools.attach.HotSpotVirtualMachine;

	/*
	* This class is the main class for the JStack utility. It parses its arguments
	* and decides if the command should be executed by the SA JStack tool or by
	* obtained the thread dump from a target process using the VM attach mechanism
	*/
	public class JStack {
	public static void main(String[] args) throws Exception {
	if (args.length == 0) {
	usage(1); // no arguments
	}

	boolean useSA = false;
	boolean mixed = false;
	boolean locks = false;

	// Parse the options (arguments starting with "-" )
	int optionCount = 0;
	while (optionCount < args.length) {
	String arg = args[optionCount];
	if (!arg.startsWith("-")) {
	break;
	}
	if (arg.equals("-help") \|\| arg.equals("-h")) {
	usage(0);
	}
	else if (arg.equals("-F")) {
	useSA = true;
	}
	else {
	if (arg.equals("-m")) {
	mixed = true;
	} else {
	if (arg.equals("-l")) {
	locks = true;
	} else {
	usage(1);
	}
	}
	}
	optionCount++;
	}

	// mixed stack implies SA tool
	if (mixed) {
	useSA = true;
	}

	// Next we check the parameter count. If there are two parameters
	// we assume core file and executable so we use SA.
	int paramCount = args.length - optionCount;
	if (paramCount == 0 \|\| paramCount > 2) {
	usage(1);
	}
	if (paramCount == 2) {
	useSA = true;
	} else {
	// If we can't parse it as a pid then it must be debug server
	if (!args[optionCount].matches("[0-9]+")) {
	useSA = true;
	}
	}

	// now execute using the SA JStack tool or the built-in thread dumper
	if (useSA) {
	// parameters (<pid> or <exe> <core>
	String params[] = new String[paramCount];
	for (int i=optionCount; i<args.length; i++ ){
	params[i-optionCount] = args[i];
	}
	runJStackTool(mixed, locks, params);
	} else {
	// pass -l to thread dump operation to get extra lock info
	String pid = args[optionCount];
	String params[];
	if (locks) {
	params = new String[] { "-l" };
	} else {
	params = new String[0];
	}
	runThreadDump(pid, params);
	}
	}


	// SA JStack tool
	private static void runJStackTool(boolean mixed, boolean locks, String args[]) throws Exception {
	Class<?> cl = loadSAClass();
	if (cl == null) {
	usage(1); // SA not available
	}

	// JStack tool also takes -m and -l arguments
	if (mixed) {
	args = prepend("-m", args);
	}
	if (locks) {
	args = prepend("-l", args);
	}

	Class[] argTypes = { String[].class };
	Method m = cl.getDeclaredMethod("main", argTypes);

	Object[] invokeArgs = { args };
	m.invoke(null, invokeArgs);
	}

	// Returns sun.jvm.hotspot.tools.JStack if available, otherwise null.
	private static Class<?> loadSAClass() {
	//
	// Attempt to load JStack class - we specify the system class
	// loader so as to cater for development environments where
	// this class is on the boot class path but sa-jdi.jar is on
	// the system class path. Once the JDK is deployed then both
	// tools.jar and sa-jdi.jar are on the system class path.
	//
	try {
	return Class.forName("sun.jvm.hotspot.tools.JStack", true,
	ClassLoader.getSystemClassLoader());
	} catch (Exception x) { }
	return null;
	}

	// Attach to pid and perform a thread dump
	private static void runThreadDump(String pid, String args[]) throws Exception {
	VirtualMachine vm = null;
	try {
	vm = VirtualMachine.attach(pid);
	} catch (Exception x) {
	String msg = x.getMessage();
	if (msg != null) {
	System.err.println(pid + ": " + msg);
	} else {
	x.printStackTrace();
	}
	if ((x instanceof AttachNotSupportedException) &&
	(loadSAClass() != null)) {
	System.err.println("The -F option can be used when the target " +
	"process is not responding");
	}
	System.exit(1);
	}

	// Cast to HotSpotVirtualMachine as this is implementation specific
	// method.
	InputStream in = ((HotSpotVirtualMachine)vm).remoteDataDump((Object[])args);

	// read to EOF and just print output
	byte b[] = new byte[256];
	int n;
	do {
	n = in.read(b);
	if (n > 0) {
	String s = new String(b, 0, n, "UTF-8");
	System.out.print(s);
	}
	} while (n > 0);
	in.close();
	vm.detach();
	}

	// return a new string array with arg as the first element
	private static String[] prepend(String arg, String args[]) {
	String[] newargs = new String[args.length+1];
	newargs[0] = arg;
	System.arraycopy(args, 0, newargs, 1, args.length);
	return newargs;
	}

	// print usage message
	private static void usage(int exit) {
	System.err.println("Usage:");
	System.err.println(" jstack [-l] <pid>");
	System.err.println(" (to connect to running process)");

	if (loadSAClass() != null) {
	System.err.println(" jstack -F [-m] [-l] <pid>");
	System.err.println(" (to connect to a hung process)");
	System.err.println(" jstack [-m] [-l] <executable> <core>");
	System.err.println(" (to connect to a core file)");
	System.err.println(" jstack [-m] [-l] [server_id@]<remote server IP or hostname>");
	System.err.println(" (to connect to a remote debug server)");
	}

	System.err.println("");
	System.err.println("Options:");

	if (loadSAClass() != null) {
	System.err.println(" -F to force a thread dump. Use when jstack <pid> does not respond" +
	" (process is hung)");
	System.err.println(" -m to print both java and native frames (mixed mode)");
	}

	System.err.println(" -l long listing. Prints additional information about locks");
	System.err.println(" -h or -help to print this help message");
	System.exit(exit);
	}
	}

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