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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.util.Properties;
+
+/*
+ * Linux implementation of HotSpotVirtualMachine
+ */
+public class LinuxVirtualMachine extends HotSpotVirtualMachine {
+ // "/tmp" is used as a global well-known location for the files
+ // .java_pid<pid>. and .attach_pid<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";
+
+ // Indicates if this machine uses the old LinuxThreads
+ static boolean isLinuxThreads;
+
+ // The patch to the socket file created by the target VM
+ String path;
+
+ /**
+ * Attaches to the target VM
+ */
+ public LinuxVirtualMachine(AttachProvider provider, String vmid)
+ throws AttachNotSupportedException, IOException
+ {
+ super(provider, vmid);
+
+ // This provider only understands pids
+ int pid;
+ try {
+ pid = Integer.parseInt(vmid);
+ } catch (NumberFormatException x) {
+ throw new AttachNotSupportedException("Invalid process identifier");
+ }
+
+ // Find the socket file. If not found then we attempt to start the
+ // attach mechanism in the target VM by sending it a QUIT signal.
+ // Then we attempt to find the socket file again.
+ path = findSocketFile(pid);
+ if (path == null) {
+ File f = createAttachFile(pid);
+ try {
+ // On LinuxThreads each thread is a process and we don't have the
+ // pid of the VMThread which has SIGQUIT unblocked. To workaround
+ // this we get the pid of the "manager thread" that is created
+ // by the first call to pthread_create. This is parent of all
+ // threads (except the initial thread).
+ if (isLinuxThreads) {
+ int mpid;
+ try {
+ mpid = getLinuxThreadsManager(pid);
+ } catch (IOException x) {
+ throw new AttachNotSupportedException(x.getMessage());
+ }
+ assert(mpid >= 1);
+ sendQuitToChildrenOf(mpid);
+ } else {
+ sendQuitTo(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) { }
+ path = findSocketFile(pid);
+ i++;
+ } while (i <= retries && path == null);
+ if (path == null) {
+ throw new AttachNotSupportedException(
+ "Unable to open socket file: target process not responding " +
+ "or HotSpot VM not loaded");
+ }
+ } finally {
+ f.delete();
+ }
+ }
+
+ // Check that the file owner/permission to avoid attaching to
+ // bogus process
+ checkPermissions(path);
+
+ // Check that we can connect to the process
+ // - this ensures we throw the permission denied error now rather than
+ // later when we attempt to enqueue a command.
+ int s = socket();
+ try {
+ connect(s, path);
+ } finally {
+ close(s);
+ }
+ }
+
+ /**
+ * Detach from the target VM
+ */
+ public void detach() throws IOException {
+ synchronized (this) {
+ if (this.path != null) {
+ this.path = null;
+ }
+ }
+ }
+
+ // protocol version
+ private final static String PROTOCOL_VERSION = "1";
+
+ // known errors
+ private final static int ATTACH_ERROR_BADVERSION = 101;
+
+ /**
+ * Execute the given command in the target VM.
+ */
+ InputStream execute(String cmd, Object ... args) throws AgentLoadException, IOException {
+ assert args.length <= 3; // includes null
+
+ // did we detach?
+ String p;
+ synchronized (this) {
+ if (this.path == null) {
+ throw new IOException("Detached from target VM");
+ }
+ p = this.path;
+ }
+
+ // create UNIX socket
+ int s = socket();
+
+ // connect to target VM
+ try {
+ connect(s, p);
+ } catch (IOException x) {
+ close(s);
+ throw x;
+ }
+
+ IOException ioe = null;
+
+ // connected - write request
+ // <ver> <cmd> <args...>
+ try {
+ writeString(s, PROTOCOL_VERSION);
+ writeString(s, cmd);
+
+ for (int i=0; i<3; i++) {
+ if (i < args.length && args[i] != null) {
+ writeString(s, (String)args[i]);
+ } else {
+ writeString(s, "");
+ }
+ }
+ } catch (IOException x) {
+ ioe = x;
+ }
+
+
+ // Create an input stream to read reply
+ SocketInputStream sis = new SocketInputStream(s);
+
+ // Read the command completion status
+ int completionStatus;
+ try {
+ completionStatus = readInt(sis);
+ } catch (IOException x) {
+ sis.close();
+ if (ioe != null) {
+ throw ioe;
+ } else {
+ throw x;
+ }
+ }
+
+ if (completionStatus != 0) {
+ sis.close();
+
+ // In the event of a protocol mismatch then the target VM
+ // returns a known error so that we can throw a reasonable
+ // error.
+ if (completionStatus == ATTACH_ERROR_BADVERSION) {
+ throw new IOException("Protocol mismatch with target VM");
+ }
+
+ // Special-case the "load" command so that the right exception is
+ // thrown.
+ 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 for the socket connection to get target VM
+ */
+ 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 LinuxVirtualMachine.read(s, bs, off, len);
+ }
+
+ public void close() throws IOException {
+ LinuxVirtualMachine.close(s);
+ }
+ }
+
+ // Return the socket file for the given process.
+ private String findSocketFile(int pid) {
+ File f = new File(tmpdir, ".java_pid" + pid);
+ if (!f.exists()) {
+ return null;
+ }
+ return f.getPath();
+ }
+
+ // On Solaris/Linux a simple handshake is used to start the attach mechanism
+ // if not already started. The client creates a .attach_pid<pid> file in the
+ // target VM's working directory (or temp 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;
+ }
+
+ /*
+ * Write/sends the given to the target VM. String is transmitted in
+ * UTF-8 encoding.
+ */
+ private void writeString(int fd, String s) throws IOException {
+ if (s.length() > 0) {
+ byte b[];
+ try {
+ b = s.getBytes("UTF-8");
+ } catch (java.io.UnsupportedEncodingException x) {
+ throw new InternalError();
+ }
+ LinuxVirtualMachine.write(fd, b, 0, b.length);
+ }
+ byte b[] = new byte[1];
+ b[0] = 0;
+ write(fd, b, 0, 1);
+ }
+
+
+ //-- native methods
+
+ static native boolean isLinuxThreads();
+
+ static native int getLinuxThreadsManager(int pid) throws IOException;
+
+ static native void sendQuitToChildrenOf(int pid) throws IOException;
+
+ static native void sendQuitTo(int pid) throws IOException;
+
+ static native void checkPermissions(String path) throws IOException;
+
+ static native int socket() throws IOException;
+
+ static native void connect(int fd, 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 write(int fd, byte buf[], int off, int bufLen) throws IOException;
+
+ static {
+ System.loadLibrary("attach");
+ isLinuxThreads = isLinuxThreads();
+ }
+}