agent works

.gitignore

@@ -0,0 +1,2 @@
+/out/
+/agent/agent.jar

.idea/modules.xml

@@ -4,6 +4,7 @@
     <modules>
       <module fileurl="file://$PROJECT_DIR$/agent/agent.iml" filepath="$PROJECT_DIR$/agent/agent.iml" />
       <module fileurl="file://$PROJECT_DIR$/application/application.iml" filepath="$PROJECT_DIR$/application/application.iml" />
+      <module fileurl="file://$PROJECT_DIR$/lab-6-maggicl.iml" filepath="$PROJECT_DIR$/lab-6-maggicl.iml" />
       <module fileurl="file://$PROJECT_DIR$/profiler/profiler.iml" filepath="$PROJECT_DIR$/profiler/profiler.iml" />
     </modules>
   </component>

README.md

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+# Agent
+
+### Compile the agent as JAR
+
+```shell
+cd agent/src
+find . -name '*.java' -print -exec javac -d ../../out/production/agent \{\} \;
+cd ..
+jar cfm agent.jar manifest.txt -C ../out/production/agent .
+```
+
+### Run application with agent
+
+```shell
+java -javaagent:agent/agent.jar=hello -cp out/production/application ch.usi.inf.sp.dbi.Application
+```

agent/manifest.txt

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+Manifest-Version: 1.0
+Premain-Class: ch.usi.inf.sp.dbi.agent.Agent

agent/src/ch/usi/inf/sp/dbi/agent/Agent.java

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+package ch.usi.inf.sp.dbi.agent;
+
+import java.lang.instrument.Instrumentation;
+
+public class Agent {
+    public static void premain(String agentArgs, Instrumentation inst) {
+        System.out.println("Agent starting (arguments: '" + agentArgs + "')");
+        inst.addTransformer(new ClassTransformer());
+    }
+}

agent/src/ch/usi/inf/sp/dbi/agent/ClassTransformer.java

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+package ch.usi.inf.sp.dbi.agent;
+
+import java.lang.instrument.ClassFileTransformer;
+import java.lang.instrument.IllegalClassFormatException;
+import java.security.ProtectionDomain;
+
+public class ClassTransformer implements ClassFileTransformer {
+    @Override
+    public byte[] transform(ClassLoader loader,
+                            String className,
+                            Class<?> classBeingRedefined,
+                            ProtectionDomain protectionDomain,
+                            byte[] classfileBuffer) throws IllegalClassFormatException {
+        System.out.println("About to transform class <" + loader + ", " + className + ">");
+        return classfileBuffer; // no changes
+    }
+}

application/src/ch/usi/inf/sp/dbi/Application.java

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+package ch.usi.inf.sp.dbi;
+
+public class Application {
+    public static void main(String... args) {
+        sayHi();
+    }
+
+    public static void sayHi() {
+        System.out.println("Hello!");
+    }
+}

lab-6-maggicl.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>