[RFA/JDWP] VirtualMachineCommandSet.java

[Aaron Luchko <aluchko at redhat dot com>]

Ok this is a touch more complicated but not too bad, there's also a
couple possibly minor issues. This implements the VirtualMachine
CommandSet
http://java.sun.com/j2se/1.5.0/docs/guide/jpda/jdwp/jdwp-protocol.html#JDWP_VirtualMachine

The VERSION command is the first one that is a bit of an interpretation
http://java.sun.com/j2se/1.5.0/docs/guide/jpda/jdwp/jdwp-protocol.html#JDWP_VirtualMachine_Version
All the fields are pretty direct except for the first one.
"description: Text information on the VM version"
Sun along with IBM and BEA (they all actually return the exact same
response for this command) return
"Java Debug Wire Protocol (Reference Implementation) version 1.4?JVM
Debug Interface version 1.3?JVM version 1.4.2_06 (Java HotSpot(TM)
Client VM' mixed mode)"

Which seems pretty generic/non-standard so I just did 

Properties props = System.getProperties();

// The description field is pretty loosely defined
String description = "JVM version " + props.getProperty("java.vm.name")
                     + " " + props.getProperty("java.vm.version") + " "
                     + props.getProperty("java.version");

which for my rpm installed gcj gave,
"JVM version GNU libgcj 4.0.0 20050622 (Red Hat 4.0.0-13) 1.4.2"

The next issue, the commands 
AllThreads and TopLevelThreadGroups
http://java.sun.com/j2se/1.5.0/docs/guide/jpda/jdwp/jdwp-protocol.html#JDWP_VirtualMachine_Version

Rely on two things:
1. There can only be 1 top level thread group.
2. The aforesaid top level group can be attained via recursively going
group.getParent().

If those assumptions are incorrect then things could get more
complicated.

There's also the theoretical concern if these are true of a user run
program being able to find our Jdwp threads via the same way I do
executeAllTheads().

release/holdEvents
http://java.sun.com/j2se/1.5.0/docs/guide/jpda/jdwp/jdwp-protocol.html#JDWP_VirtualMachine_HoldEvents
should be fine being left on the back burner until later.

thanks,
Aaron

2005-07-12  Aaron Luchko  <aluchko@redhat.com>

        * gnu/classpath/jdwp/processor/VirtualMachineCommandSet.java:
        New file.

--- /dev/null	2005-06-09 16:29:11.371620296 -0400
+++ gnu/classpath/jdwp/processor/VirtualMachineCommandSet.java	2005-07-12 14:07:25.000000000 -0400
@@ -0,0 +1,451 @@
+/* VirtualMachineCommandSet.java -- class to implement the VirtualMachine
+   Command Set
+   Copyright (C) 2005 Free Software Foundation
+ 
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+02111-1307 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package gnu.classpath.jdwp.processor;
+
+import gnu.classpath.jdwp.IVirtualMachine;
+import gnu.classpath.jdwp.Jdwp;
+import gnu.classpath.jdwp.JdwpConstants;
+import gnu.classpath.jdwp.exception.JdwpException;
+import gnu.classpath.jdwp.exception.NotImplementedException;
+import gnu.classpath.jdwp.id.IdManager;
+import gnu.classpath.jdwp.id.JdwpId;
+import gnu.classpath.jdwp.id.ObjectId;
+import gnu.classpath.jdwp.id.ReferenceTypeId;
+import gnu.classpath.jdwp.util.JdwpString;
+import gnu.classpath.jdwp.util.Signature;
+
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Properties;
+
+/**
+ * A class representing the VirtualMachine Command Set.
+ * 
+ * @author Aaron Luchko <aluchko@redhat.com>
+ */
+public class VirtualMachineCommandSet implements CommandSet
+{
+  // Our hook into the jvm
+  private final IVirtualMachine vm = Jdwp.getIVirtualMachine();
+
+  // Manages all the different ids that are assigned by jdwp
+  private final IdManager idMan = Jdwp.getIdManager();
+
+  // The Jdwp object
+  private final Jdwp jdwp = Jdwp.getDefault();
+
+  public boolean runCommand(ByteBuffer bb, DataOutputStream os, byte command)
+    throws JdwpException
+  {
+    boolean keepRunning = true;
+    try
+      {
+        switch (command)
+          {
+          case JdwpConstants.CommandSet.VirtualMachine.VERSION:
+            executeVersion(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.CLASSES_BY_SIGNATURE:
+            executeClassesBySignature(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.ALL_CLASSES:
+            executeAllClasses(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.ALL_THREADS:
+            executeAllThreads(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.TOP_LEVEL_THREAD_GROUPS:
+            executeTopLevelThreadGroups(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.IDSIZES:
+            executeIDsizes(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.DISPOSE:
+            keepRunning = false;
+            executeDispose(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.SUSPEND:
+            executeSuspend(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.RESUME:
+            executeResume(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.EXIT:
+            keepRunning = false;
+            executeExit(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.CREATE_STRING:
+            executeCreateString(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.CAPABILITIES:
+            executeCapabilities(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.CLASS_PATHS:
+            executeClassPaths(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.DISPOSE_OBJECTS:
+            executeDisposeObjects(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.HOLD_EVENTS:
+            executeHoldEvents(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.RELEASE_EVENTS:
+            executeReleaseEvents(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.CAPABILITIES_NEW:
+            executeCapabilitiesNew(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.REDEFINE_CLASSES:
+            executeRedefineClasses(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.SET_DEFAULT_STRATUM:
+            executeSetDefaultStratum(bb, os);
+            break;
+          case JdwpConstants.CommandSet.VirtualMachine.ALL_CLASSES_WITH_GENERIC:
+            executeAllClassesWithGeneric(bb, os);
+            break;
+
+          default:
+            break;
+          }
+      }
+    catch (IOException ex)
+      {
+        // TODO: handle exception
+      }
+    return keepRunning;
+  }
+
+  private void executeVersion(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+
+    Properties props = System.getProperties();
+
+    // The description field is pretty loosely defined
+    String description = "JVM version " + props.getProperty("java.vm.name")
+                         + " " + props.getProperty("java.vm.version") + " "
+                         + props.getProperty("java.version");
+    int jdwpMajor = 1; // Get from jvm?
+    int jdwpMinor = 5; // Get from jvm?
+    String vmVersion = props.getProperty("java.version"); // Get from jvm?
+    String vmName = props.getProperty("java.vm.name");
+    JdwpString.writeString(os, description);
+    os.write(jdwpMajor);
+    os.write(jdwpMinor);
+    JdwpString.writeString(os, vmName);
+    JdwpString.writeString(os, vmVersion);
+  }
+
+  private void executeClassesBySignature(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    String sig = JdwpString.readString(bb);
+
+    ArrayList allLoadedClasses, allMatchingClasses;
+
+    // This will be a vector of all loaded Classes
+    allLoadedClasses = vm.getAllLoadedClasses();
+
+    allMatchingClasses = new ArrayList();
+    for (int i = 0; i < allLoadedClasses.size(); i++)
+      {
+        Class clazz = (Class) allLoadedClasses.get(i);
+        String clazzSig = Signature.computeClassSignature(clazz);
+        if (clazzSig.equals(sig))
+          allMatchingClasses.add(clazz);
+      }
+
+    os.writeInt(allMatchingClasses.size());
+    for (int i = 0; i < allMatchingClasses.size(); i++)
+      {
+        Class clazz = (Class) allMatchingClasses.get(i);
+        ReferenceTypeId id = idMan.getReferenceTypeId(clazz);
+        id.writeTagged(os);
+        int status = vm.getStatus(clazz);
+        os.writeInt(status);
+      }
+  }
+
+  private void executeAllClasses(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    ArrayList allLoadedClasses;
+    // This will be a vector of all loaded Classes
+    allLoadedClasses = vm.getAllLoadedClasses();
+
+    os.writeInt(allLoadedClasses.size());
+    for (int i = 0; i < allLoadedClasses.size(); i++)
+      {
+        Class clazz = (Class) allLoadedClasses.get(i);
+        ReferenceTypeId id = idMan.getReferenceTypeId(clazz);
+        id.writeTagged(os);
+        String sig = Signature.computeClassSignature(clazz);
+        JdwpString.writeString(os, sig);
+        int status = vm.getStatus(clazz);
+        os.writeInt(status);
+      }
+  }
+
+  private void executeAllThreads(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    ThreadGroup jdwpGroup = jdwp.getJdwpThreadGroup();
+    ThreadGroup root = getRootThreadGroup(jdwpGroup);
+
+    int numThreads = root.activeCount();
+    Thread allThreads[] = new Thread[numThreads];
+    root.enumerate(allThreads, true);
+
+    // We need to loop through for the true count since some threads may have
+    // been destroyed since we got
+    // activeCount so those spots in the array will be null. As well we must
+    // ignore any threads that belong to jdwp
+    numThreads = 0;
+    for (int i = 0; i < allThreads.length; i++)
+      {
+        Thread thread = allThreads[i];
+        if (thread == null)
+          break; // No threads after this point
+        if (!thread.getThreadGroup().equals(jdwpGroup))
+          numThreads++;
+      }
+
+    os.writeInt(numThreads);
+
+    for (int i = 0; i < allThreads.length; i++)
+      {
+        Thread thread = allThreads[i];
+        if (thread == null)
+          break; // No threads after this point
+        if (!thread.getThreadGroup().equals(jdwpGroup))
+          idMan.getId(thread).write(os);
+      }
+  }
+
+  private void executeTopLevelThreadGroups(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    ThreadGroup jdwpGroup = jdwp.getJdwpThreadGroup();
+    ThreadGroup root = getRootThreadGroup(jdwpGroup);
+
+    os.writeInt(1); // Just one top level group allowed?
+    idMan.getId(root);
+  }
+
+  private void executeDispose(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException
+  {
+    // TODO: resumeAllThreads isn't sufficient as a thread may have been
+    // suspended multiple times, we likely need a way to keep track of how many
+    // times a thread has been suspended or else a stronger resume method for
+    // this purpose
+    vm.resumeAllThreadsExcept(jdwp.getJdwpThreadGroup());
+
+    // Simply shutting down the jdwp layer will take care of the rest of the
+    // shutdown other than disabling debugging in the VM
+    vm.disableDebugging();
+  }
+
+  private void executeIDsizes(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    ObjectId oid = new ObjectId();
+    os.writeInt(oid.size()); // fieldId
+    os.writeInt(oid.size()); // methodId
+    os.writeInt(oid.size()); // objectId
+    os.writeInt(new ReferenceTypeId((byte) 0x00).size()); // referenceTypeId
+    os.writeInt(oid.size()); // frameId
+  }
+
+  private void executeSuspend(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException
+  {
+    vm.suspendAllThreadsExcept(jdwp.getJdwpThreadGroup());
+  }
+
+  private void executeResume(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException
+  {
+    vm.resumeAllThreadsExcept(jdwp.getJdwpThreadGroup());
+  }
+
+  private void executeExit(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    int exitCode = bb.getInt();
+    jdwp.setExit(exitCode);
+  }
+
+  private void executeCreateString(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    String string = JdwpString.readString(bb);
+    String internString = string.intern();
+    JdwpId stringId = Jdwp.getIdManager().getId(internString);
+    stringId.write(os);
+  }
+
+  private void executeCapabilities(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    // Store these somewhere?
+    os.writeBoolean(false); // canWatchFieldModification
+    os.writeBoolean(false); // canWatchFieldAccess
+    os.writeBoolean(false); // canGetBytecodes
+    os.writeBoolean(false); // canGetSyntheticAttribute
+    os.writeBoolean(false); // canGetOwnedMonitorInfo
+    os.writeBoolean(false); // canGetCurrentContendedMonitor
+    os.writeBoolean(false); // canGetMonitorInfo
+  }
+
+  private void executeClassPaths(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    String baseDir = System.getProperty("user.dir");
+    JdwpString.writeString(os, baseDir);
+
+    // Find and write the classpath
+    String classPath = System.getProperty("java.class.path");
+    String[] paths = classPath.split(":");
+
+    os.writeInt(paths.length);
+    for (int i = 0; i < paths.length; i++)
+      JdwpString.writeString(os, paths[i]);
+
+    // Now the bootpath
+    String bootPath = System.getProperty("sun.boot.class.path");
+    paths = bootPath.split(":");
+    os.writeInt(paths.length);
+    for (int i = 0; i < paths.length; i++)
+      JdwpString.writeString(os, paths[i]);
+  }
+
+  private void executeDisposeObjects(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException
+  {
+    // Instead of going through the list of objects they give us it's probably
+    // better just to find the garbage collected objects ourselves
+    idMan.update();
+  }
+
+  private void executeHoldEvents(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException
+  {
+    // Going to have to implement a send queue somewhere and do this without
+    // triggering events
+    // Until then just don't implement
+    throw new NotImplementedException(
+      "Command VirtualMachine.HoldEvents not implemented");
+  }
+
+  // Opposite of executeHoldEvents
+  private void executeReleaseEvents(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException
+  {
+    throw new NotImplementedException(
+      "Command VirtualMachine.ReleaseEvents not implemented");
+  }
+
+  private void executeCapabilitiesNew(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException, IOException
+  {
+    // Store these somewhere?
+    final int CAPABILITIES_NEW_SIZE = 32;
+    os.writeBoolean(false); // canWatchFieldModification
+    os.writeBoolean(false); // canWatchFieldAccess
+    os.writeBoolean(false); // canGetBytecodes
+    os.writeBoolean(false); // canGetSyntheticAttribute
+    os.writeBoolean(false); // canGetOwnedMonitorInfo
+    os.writeBoolean(false); // canGetCurrentContendedMonitor
+    os.writeBoolean(false); // canGetMonitorInfo
+    os.writeBoolean(false); // canRedefineClasses
+    os.writeBoolean(false); // canAddMethod
+    os.writeBoolean(false); // canUnrestrictedlyRedefineClasses
+    os.writeBoolean(false); // canPopFrames
+    os.writeBoolean(false); // canUseInstanceFilters
+    os.writeBoolean(false); // canGetSourceDebugExtension
+    os.writeBoolean(false); // canRequestVMDeathEvent
+    os.writeBoolean(false); // canSetDefaultStratum
+    for (int i = 15; i < CAPABILITIES_NEW_SIZE; i++)
+      // Future capabilities
+      // currently unused
+      os.writeBoolean(false); // Set to false
+  }
+
+  private void executeRedefineClasses(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException
+  {
+    // Optional command, don't implement
+    throw new NotImplementedException(
+      "Command VirtualMachine.RedefineClasses not implemented");
+  }
+
+  private void executeSetDefaultStratum(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException
+  {
+    // Optional command, don't implement
+    throw new NotImplementedException(
+      "Command VirtualMachine.SetDefaultStratum not implemented");
+  }
+
+  private void executeAllClassesWithGeneric(ByteBuffer bb, DataOutputStream os)
+    throws JdwpException
+  {
+    // We don't handle generics
+    throw new NotImplementedException(
+      "Command VirtualMachine.AllClassesWithGeneric not implemented");
+  }
+
+  /**
+   * Find the root ThreadGroup of this ThreadGroup
+   */
+  private ThreadGroup getRootThreadGroup(ThreadGroup group)
+  {
+    ThreadGroup parent = group.getParent();
+    if (parent == null)
+      return group; // This group was the root
+    else
+      return getRootThreadGroup(parent);
+  }
+}