Initial commit

.gitignore

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+# Compiled class file
+*.class
+
+# Log file
+*.log
+
+# BlueJ files
+*.ctxt
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.nar
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+replay_pid*
+/.project
+/.classpath
+/.settings
+/target

LICENSE

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+BSD 3-Clause License
+
+Copyright (c) 2023, Johannes Kuhn
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

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+# lamarr
+Attach JShell to an existing Java Process

pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>pw.dasbrain</groupId>
+    <artifactId>lamarr</artifactId>
+    <version>1.0</version>
+    <description>Attach JShell to existing Java Processes</description>
+    <packaging>jar</packaging>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-jar-plugin</artifactId>
+                <version>3.3.0</version>
+                <configuration>
+                    <archive>
+                        <index>true</index>
+                        <manifestEntries>
+                            <Agent-Class>pw.dasbrain.lamarr.agent.AgentMain</Agent-Class>
+                            <Can-Redefine-Classes>true</Can-Redefine-Classes>
+                        </manifestEntries>
+                    </archive>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+    <properties>
+        <maven.compiler.release>9</maven.compiler.release>
+        <maven.compiler.target>9</maven.compiler.target>
+        <maven.compiler.source>9</maven.compiler.source>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+    </properties>
+</project>

src/main/java/module-info.java

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+module pw.dasbrain.lamarr {
+
+    requires transitive java.instrument;
+    requires jdk.jshell;
+    requires jdk.attach;
+
+    exports pw.dasbrain.lamarr.agent to java.instrument;
+    opens pw.dasbrain.lamarr.agent to java.instrument;
+
+    provides jdk.jshell.spi.ExecutionControlProvider with
+        pw.dasbrain.lamarr.InstrumentationExecutionControlProvider;
+}

src/main/java/pw/dasbrain/lamarr/InstrumentationExecutionControlProvider.java

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+package pw.dasbrain.lamarr;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.net.URISyntaxException;
+import java.util.HashMap;
+import java.util.Map;
+
+import com.sun.tools.attach.AgentInitializationException;
+import com.sun.tools.attach.AgentLoadException;
+import com.sun.tools.attach.AttachNotSupportedException;
+import com.sun.tools.attach.VirtualMachine;
+
+import jdk.jshell.execution.StreamingExecutionControl;
+import jdk.jshell.spi.ExecutionControl;
+import jdk.jshell.spi.ExecutionControlProvider;
+import jdk.jshell.spi.ExecutionEnv;
+
+public class InstrumentationExecutionControlProvider implements ExecutionControlProvider {
+
+    @Override
+    public String name() {
+        return "instrumentation";
+    }
+
+    @Override
+    public ExecutionControl generate(ExecutionEnv env, Map<String, String> parameters)
+            throws Throwable {
+        ServerSocket so = new ServerSocket(0);
+        so.setSoTimeout(5000);
+        attach(parameters.get("pid"), so.getLocalPort());
+        Socket s = so.accept();
+        ObjectOutputStream out = new ObjectOutputStream(s.getOutputStream());
+        out.flush();
+        ObjectInputStream in = new ObjectInputStream(s.getInputStream());
+        return new StreamingExecutionControl(out, in);
+    }
+
+    @Override
+    public Map<String, String> defaultParameters() {
+        Map<String, String> result = new HashMap<>();
+        result.put("pid", "");
+        return result;
+    }
+
+    private static void attach(String pid, int port) throws AttachNotSupportedException,
+            IOException, AgentLoadException, AgentInitializationException, URISyntaxException {
+        VirtualMachine vm = VirtualMachine.attach(pid);
+        try {
+            vm.loadAgent(new File(InstrumentationExecutionControlProvider.class
+                    .getProtectionDomain().getCodeSource().getLocation().toURI()).toString(),
+                    port + "");
+        } finally {
+            vm.detach();
+        }
+    }
+}

src/main/java/pw/dasbrain/lamarr/agent/AgentMain.java

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+package pw.dasbrain.lamarr.agent;
+
+import java.lang.instrument.Instrumentation;
+
+public class AgentMain {
+
+    public static void agentmain(String arg, Instrumentation inst) {
+        Thread t = new Thread(new InstrumentationRemoteExecutionControl(inst, arg), "rjshell");
+        t.setDaemon(false);
+        t.start();
+    }
+}

src/main/java/pw/dasbrain/lamarr/agent/InstrumentationRemoteExecutionControl.java

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+package pw.dasbrain.lamarr.agent;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.lang.instrument.ClassDefinition;
+import java.lang.instrument.Instrumentation;
+import java.lang.instrument.UnmodifiableClassException;
+import java.net.InetAddress;
+import java.net.Socket;
+
+import jdk.jshell.execution.RemoteExecutionControl;
+import jdk.jshell.execution.Util;
+
+class InstrumentationRemoteExecutionControl extends RemoteExecutionControl implements Runnable {
+
+    private final Instrumentation inst;
+    private final String arg;
+
+    public InstrumentationRemoteExecutionControl(Instrumentation inst, String arg) {
+        this.inst = inst;
+        this.arg = arg;
+    }
+
+    @Override
+    public void redefine(ClassBytecodes[] cbcs)
+            throws ClassInstallException, NotImplementedException, EngineTerminationException {
+        try {
+            ClassDefinition[] defs = new ClassDefinition[cbcs.length];
+            for (int i = 0; i < cbcs.length; i++) {
+                defs[i] = new ClassDefinition(findClass(cbcs[i].name()), cbcs[i].bytecodes());
+            }
+            inst.redefineClasses(defs);
+        } catch (ClassNotFoundException | UnmodifiableClassException
+                | UnsupportedOperationException e) {
+            // In this case no classes have been redefined.
+            ClassInstallException cie = new ClassInstallException(e.getMessage(), new boolean[cbcs.length]);
+            cie.initCause(e);
+            throw cie;
+        }
+        super.redefine(cbcs);
+    }
+
+    @Override
+    public void run() {
+        try (Socket s = new Socket(InetAddress.getLoopbackAddress(), Integer.parseInt(arg));
+                ObjectOutputStream out = new ObjectOutputStream(s.getOutputStream());
+                ObjectInputStream in = new ObjectInputStream(s.getInputStream());) {
+            out.flush();
+            Util.forwardExecutionControl(this, in, out);
+        } catch (IOException  e) {
+            // TODO: Better error handling
+            throw new InternalError(e);
+        }
+    }
+}