From a862952b8e0aaaa71c020c1fa13f60273210e681 Mon Sep 17 00:00:00 2001
From: Anton Khorin <antkhorin@gmail.com>
Date: Mon, 15 May 2017 01:58:43 +0300
Subject: [PATCH] Update Agent.kt

---
 src/main/kotlin/agent/Agent.kt | 41 +++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/main/kotlin/agent/Agent.kt b/src/main/kotlin/agent/Agent.kt
index 0afc55b..d7611ca 100644
--- a/src/main/kotlin/agent/Agent.kt
+++ b/src/main/kotlin/agent/Agent.kt
@@ -1,12 +1,51 @@
 package agent
 
-import java.lang.instrument.Instrumentation
+import jdk.internal.org.objectweb.asm.*
+import java.lang.instrument.*
+import java.security.ProtectionDomain
 
 class Agent {
+
     companion object {
         @JvmStatic
         fun premain(agentArgs: String?, inst: Instrumentation) {
             println("Agent started.")
+            inst.addTransformer(MyClassTransformer())
+        }
+    }
+}
+
+class MyClassTransformer : ClassFileTransformer {
+
+    override fun transform(loader: ClassLoader?, className: String?, classBeingRedefined: Class<*>?, protectionDomain: ProtectionDomain?, classfileBuffer: ByteArray?): ByteArray? {
+        val cw = ClassWriter(0)
+        val cv = MyClassVisitor(Opcodes.ASM5, cw)
+        val cr = ClassReader(classfileBuffer)
+        cr.accept(cv, 0)
+        return cw.toByteArray()
+    }
+}
+
+class MyClassVisitor(val apii: Int, cv: ClassVisitor) : ClassVisitor(apii, cv) {
+
+    override fun visitMethod(access: Int, name: String?, desc: String?, signature: String?, exceptions: Array<String>?): MethodVisitor {
+        val mv = super.visitMethod(access, name, desc, signature, exceptions)
+        return MyMethodVisitor(apii, mv)
+    }
+}
+
+class MyMethodVisitor(api: Int, mv: MethodVisitor) : MethodVisitor(api, mv) {
+    val opcode = Opcodes.INVOKESTATIC
+    val owner = "example/CoroutineExampleKt"
+    val name = "test"
+    val desc = "(Lkotlin/coroutines/experimental/Continuation;)Ljava/lang/Object;"
+
+    override fun visitMethodInsn(opcode: Int, owner: String, name: String, desc: String, itf: Boolean) {
+        if (opcode == this.opcode && owner == this.owner && name == this.name && desc == this.desc) {
+            super.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;")
+            super.visitLdcInsn("Test detected")
+            super.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false)
         }
+        super.visitMethodInsn(opcode, owner, name, desc, itf)
     }
 }