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Allows dynamic loading of agents. Stolen from JMockIt.
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/*
* Copyright (c) 2005, 2010, 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.attach;
import com.sun.tools.attach.VirtualMachine;
import com.sun.tools.attach.AgentLoadException;
import com.sun.tools.attach.AttachNotSupportedException;
import com.sun.tools.attach.spi.AttachProvider;
import java.io.InputStream;
import java.io.IOException;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Properties;
/*
* Solaris implementation of HotSpotVirtualMachine.
*/
public class SolarisVirtualMachine extends HotSpotVirtualMachine {
// "/tmp" is used as a global well-known location for the files
// .java_pid. and .attach_pid. It is important that this
// location is the same for all processes, otherwise the tools
// will not be able to find all Hotspot processes.
// Any changes to this needs to be synchronized with HotSpot.
private static final String tmpdir = "/tmp";
// door descriptor;
private int fd = -1;
/**
* Attaches to the target VM
*/
public SolarisVirtualMachine(AttachProvider provider, String vmid)
throws AttachNotSupportedException, IOException
{
super(provider, vmid);
// This provider only understands process-ids (pids).
int pid;
try {
pid = Integer.parseInt(vmid);
} catch (NumberFormatException x) {
throw new AttachNotSupportedException("invalid process identifier");
}
// Opens the door file to the target VM. If the file is not
// found it might mean that the attach mechanism isn't started in the
// target VM so we attempt to start it and retry.
try {
fd = openDoor(pid);
} catch (FileNotFoundException fnf1) {
File f = createAttachFile(pid);
try {
// kill -QUIT will tickle target VM to check for the
// attach file.
sigquit(pid);
// give the target VM time to start the attach mechanism
int i = 0;
long delay = 200;
int retries = (int)(attachTimeout() / delay);
do {
try {
Thread.sleep(delay);
} catch (InterruptedException x) { }
try {
fd = openDoor(pid);
} catch (FileNotFoundException fnf2) { }
i++;
} while (i <= retries && fd == -1);
if (fd == -1) {
throw new AttachNotSupportedException(
"Unable to open door: target process not responding or " +
"HotSpot VM not loaded");
}
} finally {
f.delete();
}
}
assert fd >= 0;
}
/**
* Detach from the target VM
*/
public void detach() throws IOException {
synchronized (this) {
if (fd != -1) {
close(fd);
fd = -1;
}
}
}
/**
* Execute the given command in the target VM.
*/
InputStream execute(String cmd, Object ... args) throws AgentLoadException, IOException {
assert args.length <= 3; // includes null
// first check that we are still attached
int door;
synchronized (this) {
if (fd == -1) {
throw new IOException("Detached from target VM");
}
door = fd;
}
// enqueue the command via a door call
int s = enqueue(door, cmd, args);
assert s >= 0; // valid file descriptor
// The door call returns a file descriptor (one end of a socket pair).
// Create an input stream around it.
SocketInputStream sis = new SocketInputStream(s);
// Read the command completion status
int completionStatus;
try {
completionStatus = readInt(sis);
} catch (IOException ioe) {
sis.close();
throw ioe;
}
// If non-0 it means an error but we need to special-case the
// "load" command to ensure that the right exception is thrown.
if (completionStatus != 0) {
sis.close();
if (cmd.equals("load")) {
throw new AgentLoadException("Failed to load agent library");
} else {
throw new IOException("Command failed in target VM");
}
}
// Return the input stream so that the command output can be read
return sis;
}
// InputStream over a socket
private class SocketInputStream extends InputStream {
int s;
public SocketInputStream(int s) {
this.s = s;
}
public synchronized int read() throws IOException {
byte b[] = new byte[1];
int n = this.read(b, 0, 1);
if (n == 1) {
return b[0] & 0xff;
} else {
return -1;
}
}
public synchronized int read(byte[] bs, int off, int len) throws IOException {
if ((off < 0) || (off > bs.length) || (len < 0) ||
((off + len) > bs.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0)
return 0;
return SolarisVirtualMachine.read(s, bs, off, len);
}
public void close() throws IOException {
SolarisVirtualMachine.close(s);
}
}
// The door is attached to .java_pid in the temporary directory.
private int openDoor(int pid) throws IOException {
String path = tmpdir + "/.java_pid" + pid;;
fd = open(path);
// Check that the file owner/permission to avoid attaching to
// bogus process
try {
checkPermissions(path);
} catch (IOException ioe) {
close(fd);
throw ioe;
}
return fd;
}
// On Solaris/Linux a simple handshake is used to start the attach mechanism
// if not already started. The client creates a .attach_pid file in the
// target VM's working directory (or temporary directory), and the SIGQUIT
// handler checks for the file.
private File createAttachFile(int pid) throws IOException {
String fn = ".attach_pid" + pid;
String path = "/proc/" + pid + "/cwd/" + fn;
File f = new File(path);
try {
f.createNewFile();
} catch (IOException x) {
f = new File(tmpdir, fn);
f.createNewFile();
}
return f;
}
//-- native methods
static native int open(String path) throws IOException;
static native void close(int fd) throws IOException;
static native int read(int fd, byte buf[], int off, int buflen) throws IOException;
static native void checkPermissions(String path) throws IOException;
static native void sigquit(int pid) throws IOException;
// enqueue a command (and arguments) to the given door
static native int enqueue(int fd, String cmd, Object ... args)
throws IOException;
static {
System.loadLibrary("attach");
}
}