Exceptionフローも解析可能に．

diff --git a/opcodes/src/main/java/jp/sourceforge/stigmata/birthmarks/BasicBlock.java b/opcodes/src/main/java/jp/sourceforge/stigmata/birthmarks/BasicBlock.java
index 3cae2dd..228336b 100755 (executable)
--- a/opcodes/src/main/java/jp/sourceforge/stigmata/birthmarks/BasicBlock.java
+++ b/opcodes/src/main/java/jp/sourceforge/stigmata/birthmarks/BasicBlock.java
@@ -8,13 +8,20 @@ import java.util.List;
 import java.util.Set;\r
 \r
 import org.objectweb.asm.Label;\r
+import org.objectweb.asm.Opcodes;\r
 import org.objectweb.asm.tree.AbstractInsnNode;\r
 import org.objectweb.asm.tree.InsnNode;\r
 \r
+/**\r
+ * 基本ブロックを表すクラス．\r
+ * \r
+ * @author tamada\r
+ */\r
 public class BasicBlock {\r
     private Set<BasicBlock> nexts = new HashSet<BasicBlock>();\r
     private List<Opcode> opcodes = new ArrayList<Opcode>();\r
     private Set<BasicBlock> prevs = new HashSet<BasicBlock>();\r
+    Set<Label> exceptionFlows = new HashSet<Label>();\r
 \r
     BasicBlock(){\r
     }\r
@@ -55,6 +62,9 @@ public class BasicBlock {
                 }\r
             }\r
         }\r
+        for(Label label: exceptionFlows){\r
+            targets.add(label);\r
+        }\r
 \r
         return targets.toArray(new Label[targets.size()]);\r
     }\r
@@ -91,19 +101,24 @@ public class BasicBlock {
         prevs.add(block);\r
     }\r
 \r
-    /*\r
     public String toString(){\r
         StringBuilder sb = new StringBuilder("---- block ----");\r
         String ln = System.getProperty("line.separator");\r
         for(Opcode opcode: opcodes){\r
             sb.append(ln).append(opcode);\r
         }\r
-        Label[] targets = getTargets();\r
         sb.append(ln).append("Targeter: ");\r
-        for(Label label: targets){\r
+        for(Label label: getTargets()){\r
             sb.append(label).append(", ");\r
         }\r
         return new String(sb);\r
     }\r
-    */\r
+\r
+    public boolean isFlowNext(){\r
+        Opcode opcode = getOpcode(getSize() - 1);\r
+        int op = opcode.getOpcode();\r
+\r
+        return op != Opcodes.GOTO && op != Opcodes.RETURN\r
+        && op != Opcodes.RET && op != Opcodes.ATHROW;\r
+    }\r
 }\r

diff --git a/opcodes/src/main/java/jp/sourceforge/stigmata/birthmarks/ControlFlowGraph.java b/opcodes/src/main/java/jp/sourceforge/stigmata/birthmarks/ControlFlowGraph.java
index 4b382c4..76fec2b 100755 (executable)
--- a/opcodes/src/main/java/jp/sourceforge/stigmata/birthmarks/ControlFlowGraph.java
+++ b/opcodes/src/main/java/jp/sourceforge/stigmata/birthmarks/ControlFlowGraph.java
@@ -7,6 +7,7 @@ import java.util.List;
 import java.util.Set;\r
 \r
 import org.objectweb.asm.Label;\r
+import org.objectweb.asm.Opcodes;\r
 import org.objectweb.asm.tree.AbstractInsnNode;\r
 import org.objectweb.asm.tree.JumpInsnNode;\r
 import org.objectweb.asm.tree.LabelNode;\r
@@ -15,8 +16,6 @@ import org.objectweb.asm.tree.MethodNode;
 import org.objectweb.asm.tree.TableSwitchInsnNode;\r
 import org.objectweb.asm.tree.TryCatchBlockNode;\r
 \r
-import com.sun.xml.internal.ws.org.objectweb.asm.Opcodes;\r
-\r
 public class ControlFlowGraph {\r
     private String name;\r
     private boolean includeException;\r
@@ -50,6 +49,7 @@ public class ControlFlowGraph {
                 matrix[i][j] = nextValue;\r
             }\r
         }\r
+\r
         return matrix;\r
     }\r
 \r
@@ -74,7 +74,7 @@ public class ControlFlowGraph {
     }\r
 \r
     private Set<LabelNode> collectLabels(MethodNode node){\r
-        Set<LabelNode> jumpedTarget = new HashSet<LabelNode>();\r
+        Set<LabelNode> jumpTarget = new HashSet<LabelNode>();\r
         int size = node.instructions.size();\r
         for(int i = 0; i < size; i++){\r
             AbstractInsnNode inst = node.instructions.get(i);\r
@@ -82,24 +82,24 @@ public class ControlFlowGraph {
             case AbstractInsnNode.JUMP_INSN:\r
             {\r
                 JumpInsnNode jump = (JumpInsnNode)inst;\r
-                jumpedTarget.add(jump.label);\r
+                jumpTarget.add(jump.label);\r
                 break;\r
             }\r
             case AbstractInsnNode.LOOKUPSWITCH_INSN:\r
             {\r
                 LookupSwitchInsnNode lookup = (LookupSwitchInsnNode)inst;\r
-                jumpedTarget.add(lookup.dflt);\r
+                jumpTarget.add(lookup.dflt);\r
                 for(Object label: lookup.labels){\r
-                    jumpedTarget.add((LabelNode)label);\r
+                    jumpTarget.add((LabelNode)label);\r
                 }\r
                 break;\r
             }\r
             case AbstractInsnNode.TABLESWITCH_INSN:\r
             {\r
                 TableSwitchInsnNode lookup = (TableSwitchInsnNode)inst;\r
-                jumpedTarget.add(lookup.dflt);\r
+                jumpTarget.add(lookup.dflt);\r
                 for(Object label: lookup.labels){\r
-                    jumpedTarget.add((LabelNode)label);\r
+                    jumpTarget.add((LabelNode)label);\r
                 }\r
                 break;\r
             }\r
@@ -107,30 +107,72 @@ public class ControlFlowGraph {
         }\r
         if(isIncludingExceptionFlow()){\r
             for(Object object: node.tryCatchBlocks){\r
-                jumpedTarget.add(((TryCatchBlockNode)object).handler);\r
+                jumpTarget.add(((TryCatchBlockNode)object).handler);\r
+            }\r
+        }\r
+        return jumpTarget;\r
+    }\r
+\r
+    /**\r
+     * TryCatchブロックの一覧を返します．\r
+     * Try Catchブロックが含まれていない場合や，\r
+     * {@link isIncludingExceptionFlow}がfalseを返す場合は長さ0の配列を返します．\r
+     * @param node\r
+     * @return\r
+     */\r
+    private TryCatchBlockNode[] buildTryCatchBlockNode(MethodNode node){\r
+        TryCatchBlockNode[] nodes = new TryCatchBlockNode[0];\r
+        if(isIncludingExceptionFlow()){\r
+            nodes = new TryCatchBlockNode[node.tryCatchBlocks.size()];\r
+            for(int i = 0; i < nodes.length; i++){\r
+                nodes[i] = (TryCatchBlockNode)node.tryCatchBlocks.get(i);\r
+            }\r
+        }\r
+        return nodes;\r
+    }\r
+\r
+    private void buildExceptionFlow(AbstractInsnNode inst, Set<Label> exceptionFlows, TryCatchBlockNode[] tryCatches){\r
+        if(inst.getType() == AbstractInsnNode.LABEL){\r
+            Label label = ((LabelNode)inst).getLabel();\r
+\r
+            for(TryCatchBlockNode node: tryCatches){\r
+                if(node.start.getLabel() == label){\r
+                    exceptionFlows.add(node.handler.getLabel());\r
+                }\r
+                else if(node.end.getLabel() == label){\r
+                    exceptionFlows.remove(node.handler.getLabel());\r
+                }\r
             }\r
         }\r
-        return jumpedTarget;\r
     }\r
 \r
-    private BasicBlock[] separateBasicBlock(MethodNode node, Set<LabelNode> jumpedTarget){\r
+    private BasicBlock[] separateBasicBlock(MethodNode node, Set<LabelNode> jumpTarget){\r
         int size = node.instructions.size();\r
 \r
         List<BasicBlock> blockList = new ArrayList<BasicBlock>();\r
+        Set<Label> exceptionFlows = new HashSet<Label>();\r
+        TryCatchBlockNode[] tryCatchBlocks = buildTryCatchBlockNode(node);\r
+\r
         BasicBlock block = new BasicBlock();\r
         for(int i = 0; i < size; i++){\r
             AbstractInsnNode inst = node.instructions.get(i);\r
+            block.exceptionFlows.addAll(exceptionFlows);\r
 \r
-            if(jumpedTarget.contains(inst)){\r
+            if(jumpTarget.contains(inst)){\r
                 if(!block.isEmpty()){\r
                     blockList.add(block);\r
                     block = new BasicBlock();\r
+                    block.exceptionFlows.addAll(exceptionFlows);\r
                 }\r
             }\r
             block.addNode(inst);\r
+            buildExceptionFlow(inst, exceptionFlows, tryCatchBlocks);\r
             if(inst.getType() == AbstractInsnNode.JUMP_INSN\r
                     || inst.getType() == AbstractInsnNode.TABLESWITCH_INSN\r
-                    || inst.getType() == AbstractInsnNode.LOOKUPSWITCH_INSN){\r
+                    || inst.getType() == AbstractInsnNode.LOOKUPSWITCH_INSN\r
+                    || inst.getOpcode() == Opcodes.RETURN\r
+                    || inst.getOpcode() == Opcodes.ATHROW\r
+                    || inst.getOpcode() == Opcodes.RET){\r
                 if(!block.isEmpty()){\r
                     blockList.add(block);\r
                     BasicBlock block2 = new BasicBlock();\r
@@ -138,10 +180,13 @@ public class ControlFlowGraph {
                         block2.setPrev(block);\r
                     }\r
                     block = block2;\r
+                    block.exceptionFlows.addAll(exceptionFlows);\r
                 }\r
             }\r
         }\r
-        blockList.add(block);\r
+        if(!block.isEmpty()){\r
+            blockList.add(block);\r
+        }\r
         return blockList.toArray(new BasicBlock[blockList.size()]);\r
     }\r
 \r
@@ -156,7 +201,7 @@ public class ControlFlowGraph {
                     }\r
                 }\r
             }\r
-            if(labels.length == 0 && (i + 1) < blocks.length){\r
+            if((i + 1) < blocks.length && blocks[i].isFlowNext()){\r
                 blocks[i].setNext(blocks[i + 1]);\r
             }\r
         }\r
@@ -165,8 +210,8 @@ public class ControlFlowGraph {
     }\r
 \r
     private void parse(MethodNode node){\r
-        Set<LabelNode> jumpedTarget = collectLabels(node);\r
-        BasicBlock[] blocks = separateBasicBlock(node, jumpedTarget);\r
+        Set<LabelNode> jumpTarget = collectLabels(node);\r
+        BasicBlock[] blocks = separateBasicBlock(node, jumpTarget);\r
         this.blocks = joinBasicBlocks(blocks);\r
     }\r
 }\r

diff --git a/opcodes/src/test/java/jp/sourceforge/stigmata/birthmarks/ControlFlowGraphTest.java b/opcodes/src/test/java/jp/sourceforge/stigmata/birthmarks/ControlFlowGraphTest.java
index e4faf43..532764c 100755 (executable)
--- a/opcodes/src/test/java/jp/sourceforge/stigmata/birthmarks/ControlFlowGraphTest.java
+++ b/opcodes/src/test/java/jp/sourceforge/stigmata/birthmarks/ControlFlowGraphTest.java
@@ -10,25 +10,144 @@ import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.ClassWriter;\r
 \r
 public class ControlFlowGraphTest {\r
-    private ControlFlowGraphExtractVisitor visitor;\r
+    private ControlFlowGraphExtractVisitor cfVisitor;\r
+    private ControlFlowGraphExtractVisitor cfVisitor2;\r
 \r
     @Before\r
     public void setUp() throws Exception{\r
-        ClassReader reader = new ClassReader(getClass().getResource("/resources/MyServer.class").openStream());\r
+        ClassReader reader1 = new ClassReader(getClass().getResource("/resources/MyServer.class").openStream());\r
+        cfVisitor = new ControlFlowGraphExtractVisitor(new ClassWriter(0));\r
+        reader1.accept(cfVisitor, 0);\r
 \r
-        visitor = new ControlFlowGraphExtractVisitor(new ClassWriter(0));\r
-        reader.accept(visitor, 0);\r
+        ClassReader reader2 = new ClassReader(getClass().getResource("/resources/MyServer2.class").openStream());\r
+        cfVisitor2 = new ControlFlowGraphExtractVisitor(new ClassWriter(0));\r
+        reader2.accept(cfVisitor2, 0);\r
     }\r
 \r
     @Test\r
     public void testBasic() throws Exception{\r
-        Iterator<String> iterator = visitor.getMethodNames();\r
+        Iterator<String> iterator = cfVisitor.getMethodNames();\r
 \r
         Assert.assertTrue(iterator.hasNext());\r
         Assert.assertEquals("<init>(I)V", iterator.next());\r
         Assert.assertFalse(iterator.hasNext());\r
 \r
-        ControlFlowGraph graph = visitor.getGraph("<init>(I)V");\r
+        ControlFlowGraph graph = cfVisitor.getGraph("<init>(I)V");\r
+        Assert.assertEquals(6, graph.getBasicBlockSize());\r
+        graph.setIncludingExceptionFlow(true);\r
+\r
+        Assert.assertEquals(6, graph.getBasicBlockSize());\r
+    }\r
+\r
+    @Test\r
+    public void testGraph() throws Exception{\r
+        int[][] graph = cfVisitor.getGraph("<init>(I)V").getGraphMatrix();\r
+\r
+        Assert.assertEquals(6, graph.length);\r
+\r
+        Assert.assertEquals(0, graph[0][0]);\r
+        Assert.assertEquals(1, graph[0][1]);\r
+        Assert.assertEquals(1, graph[0][2]);\r
+        Assert.assertEquals(0, graph[0][3]);\r
+        Assert.assertEquals(0, graph[0][4]);\r
+        Assert.assertEquals(0, graph[0][5]);\r
+\r
+        Assert.assertEquals(0, graph[1][0]);\r
+        Assert.assertEquals(0, graph[1][1]);\r
+        Assert.assertEquals(0, graph[1][2]);\r
+        Assert.assertEquals(1, graph[1][3]);\r
+        Assert.assertEquals(0, graph[1][4]);\r
+        Assert.assertEquals(0, graph[1][5]);\r
+\r
+        Assert.assertEquals(0, graph[2][0]);\r
+        Assert.assertEquals(0, graph[2][1]);\r
+        Assert.assertEquals(0, graph[2][2]);\r
+        Assert.assertEquals(1, graph[2][3]);\r
+        Assert.assertEquals(0, graph[2][4]);\r
+        Assert.assertEquals(0, graph[2][5]);\r
+\r
+        Assert.assertEquals(0, graph[3][0]);\r
+        Assert.assertEquals(0, graph[3][1]);\r
+        Assert.assertEquals(0, graph[3][2]);\r
+        Assert.assertEquals(0, graph[3][3]);\r
+        Assert.assertEquals(0, graph[3][4]);\r
+        Assert.assertEquals(1, graph[3][5]);\r
+\r
+        Assert.assertEquals(0, graph[4][0]);\r
+        Assert.assertEquals(0, graph[4][1]);\r
+        Assert.assertEquals(0, graph[4][2]);\r
+        Assert.assertEquals(0, graph[4][3]);\r
+        Assert.assertEquals(0, graph[4][4]);\r
+        Assert.assertEquals(1, graph[4][5]);\r
+\r
+        Assert.assertEquals(0, graph[5][0]);\r
+        Assert.assertEquals(0, graph[5][1]);\r
+        Assert.assertEquals(0, graph[5][2]);\r
+        Assert.assertEquals(0, graph[5][3]);\r
+        Assert.assertEquals(0, graph[5][4]);\r
+        Assert.assertEquals(0, graph[5][5]);\r
+    }\r
+\r
+    @Test\r
+    public void testExceptionGraph() throws Exception{\r
+        ControlFlowGraph cfgraph = cfVisitor.getGraph("<init>(I)V");\r
+        cfgraph.setIncludingExceptionFlow(true);\r
+        int[][] graph = cfgraph.getGraphMatrix();\r
+\r
+        Assert.assertEquals(6, graph.length);\r
+\r
+        Assert.assertEquals(0, graph[0][0]);\r
+        Assert.assertEquals(1, graph[0][1]);\r
+        Assert.assertEquals(1, graph[0][2]);\r
+        Assert.assertEquals(0, graph[0][3]);\r
+        Assert.assertEquals(1, graph[0][4]);\r
+        Assert.assertEquals(0, graph[0][5]);\r
+\r
+        Assert.assertEquals(0, graph[1][0]);\r
+        Assert.assertEquals(0, graph[1][1]);\r
+        Assert.assertEquals(0, graph[1][2]);\r
+        Assert.assertEquals(1, graph[1][3]);\r
+        Assert.assertEquals(1, graph[1][4]);\r
+        Assert.assertEquals(0, graph[1][5]);\r
+\r
+        Assert.assertEquals(0, graph[2][0]);\r
+        Assert.assertEquals(0, graph[2][1]);\r
+        Assert.assertEquals(0, graph[2][2]);\r
+        Assert.assertEquals(1, graph[2][3]);\r
+        Assert.assertEquals(1, graph[2][4]);\r
+        Assert.assertEquals(0, graph[2][5]);\r
+\r
+        Assert.assertEquals(0, graph[3][0]);\r
+        Assert.assertEquals(0, graph[3][1]);\r
+        Assert.assertEquals(0, graph[3][2]);\r
+        Assert.assertEquals(0, graph[3][3]);\r
+        Assert.assertEquals(1, graph[3][4]);\r
+        Assert.assertEquals(1, graph[3][5]);\r
+\r
+        Assert.assertEquals(0, graph[4][0]);\r
+        Assert.assertEquals(0, graph[4][1]);\r
+        Assert.assertEquals(0, graph[4][2]);\r
+        Assert.assertEquals(0, graph[4][3]);\r
+        Assert.assertEquals(0, graph[4][4]);\r
+        Assert.assertEquals(1, graph[4][5]);\r
+\r
+        Assert.assertEquals(0, graph[5][0]);\r
+        Assert.assertEquals(0, graph[5][1]);\r
+        Assert.assertEquals(0, graph[5][2]);\r
+        Assert.assertEquals(0, graph[5][3]);\r
+        Assert.assertEquals(0, graph[5][4]);\r
+        Assert.assertEquals(0, graph[5][5]);\r
+    }\r
+\r
+    @Test\r
+    public void testBasic2() throws Exception{\r
+        Iterator<String> iterator = cfVisitor2.getMethodNames();\r
+\r
+        Assert.assertTrue(iterator.hasNext());\r
+        Assert.assertEquals("<init>(I)V", iterator.next());\r
+        Assert.assertFalse(iterator.hasNext());\r
+\r
+        ControlFlowGraph graph = cfVisitor2.getGraph("<init>(I)V");\r
 \r
         Assert.assertEquals(6, graph.getBasicBlockSize());\r
 \r
@@ -37,8 +156,8 @@ public class ControlFlowGraphTest {
     }\r
 \r
     @Test\r
-    public void testGraph() throws Exception{\r
-        ControlFlowGraph graph = visitor.getGraph("<init>(I)V");\r
+    public void testGraph2() throws Exception{\r
+        ControlFlowGraph graph = cfVisitor2.getGraph("<init>(I)V");\r
         int[][] graphMatrix = graph.getGraphMatrix();\r
 \r
         Assert.assertEquals(6, graphMatrix.length);\r

diff --git a/opcodes/src/test/resources/resources/MyServer.class b/opcodes/src/test/resources/resources/MyServer.class
old mode 100755 (executable)
new mode 100644 (file)
index a2b2a95..2b04744
Binary files a/opcodes/src/test/resources/resources/MyServer.class and b/opcodes/src/test/resources/resources/MyServer.class differ

diff --git a/opcodes/src/test/resources/resources/MyServer2.class b/opcodes/src/test/resources/resources/MyServer2.class
new file mode 100644 (file)
index 0000000..68ae778
Binary files /dev/null and b/opcodes/src/test/resources/resources/MyServer2.class differ

diff --git a/opcodes/src/test/resources/resources/MyServer.java b/opcodes/src/test/resources/resources/MyServer2.java
similarity index 83%
rename from opcodes/src/test/resources/resources/MyServer.java
rename to opcodes/src/test/resources/resources/MyServer2.java
index fe91ae0..35e6c56 100644 (file)
--- a/opcodes/src/test/resources/resources/MyServer.java
+++ b/opcodes/src/test/resources/resources/MyServer2.java
@@ -1,11 +1,11 @@
 import java.io.*;
 import java.net.*;
 
-public class MyServer{
+public class MyServer2{
   private int port;
   private ServerSocket server;
 
-  public MyServer(int defaultPort){
+  public MyServer2(int defaultPort){
     try{
       if(defaultPort > 0){
         port = defaultPort;

diff --git a/opcodes/src/test/resources/resources/MyServerBuilder.java b/opcodes/src/test/resources/resources/MyServerBuilder.java
new file mode 100644 (file)
index 0000000..6110168
--- /dev/null
+++ b/opcodes/src/test/resources/resources/MyServerBuilder.java
@@ -0,0 +1,76 @@
+import java.io.*;
+import org.objectweb.asm.*;
+import org.objectweb.asm.tree.*;
+
+/**
+ * 以下の原稿にあるクラスファイルを作成するためのクラス．
+ * ASMを使ってバイトコードを直接生成している．
+ * <ul>
+ *   <li>Heewan Park, Hyun-il Lim, Seokwoo Choi, Taisook Han, ``Detecting Common Modules in Java Packages Based on Static Object Trace Birthmark,'' The Computer Journal (Advance Access), Nov 5 2009, doi:10.1093/comjnl/bxp095</li>
+ * </ul>
+ */
+public class MyServerBuilder{
+    public MyServerBuilder(){
+    }
+
+    public void write(OutputStream out) throws Exception{
+        ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
+
+        writer.visit(50, Opcodes.ACC_PUBLIC, "MyServer", null, "java/lang/Object", null);
+        FieldVisitor fv1 = writer.visitField(Opcodes.ACC_PRIVATE, "Port", "I", null, 9999);
+        fv1.visitEnd();
+        FieldVisitor fv2 = writer.visitField(Opcodes.ACC_PRIVATE, "Sock", "Ljava/net/ServerSocket;", null, null);
+        fv2.visitEnd();
+        MethodVisitor mv = writer.visitMethod(Opcodes.ACC_PUBLIC, "<init>", "(I)V", null, null);
+
+        Label label1 = new Label();
+        Label label2 = new Label();
+        Label label3 = new Label();
+        Label startTry = new Label();
+        Label catchLabel = new Label();
+        mv.visitCode();
+        mv.visitVarInsn(Opcodes.ALOAD, 0);
+        mv.visitMethodInsn(Opcodes.INVOKESPECIAL, "java/lang/Object", "<init>", "()V");
+        mv.visitVarInsn(Opcodes.ALOAD, 0);
+        mv.visitIntInsn(Opcodes.SIPUSH, 9999);
+        mv.visitFieldInsn(Opcodes.PUTFIELD, "MyServer", "Port", "I");
+        mv.visitLabel(startTry);
+        mv.visitVarInsn(Opcodes.ILOAD, 1);
+        mv.visitJumpInsn(Opcodes.IFLE, label1);
+        mv.visitVarInsn(Opcodes.ALOAD, 0);
+        mv.visitVarInsn(Opcodes.ILOAD, 1);
+        mv.visitFieldInsn(Opcodes.PUTFIELD, "MyServer", "Port", "I");
+        mv.visitVarInsn(Opcodes.ALOAD, 0);
+        mv.visitTypeInsn(Opcodes.NEW, "java/net/ServerSocket");
+        mv.visitInsn(Opcodes.DUP);
+        mv.visitVarInsn(Opcodes.ILOAD, 1);
+        mv.visitMethodInsn(Opcodes.INVOKESPECIAL, "java/net/ServerSocket", "<init>", "(I)V");
+        mv.visitFieldInsn(Opcodes.PUTFIELD, "MyServer", "Sock", "Ljava/net/ServerSocket;");
+        mv.visitJumpInsn(Opcodes.GOTO, label2);
+        mv.visitLabel(label1);
+        mv.visitVarInsn(Opcodes.ALOAD, 0);
+        mv.visitTypeInsn(Opcodes.NEW, "java/net/ServerSocket");
+        mv.visitInsn(Opcodes.DUP);
+        mv.visitMethodInsn(Opcodes.INVOKESPECIAL, "java/net/ServerSocket", "<init>", "()V");
+        mv.visitFieldInsn(Opcodes.PUTFIELD, "MyServer", "Sock", "Ljava/net/ServerSocket;");
+        mv.visitLabel(label2);
+        mv.visitJumpInsn(Opcodes.GOTO, label3);
+        mv.visitLabel(catchLabel);
+        mv.visitVarInsn(Opcodes.ASTORE, 2);
+        mv.visitLabel(label3);
+        mv.visitInsn(Opcodes.RETURN);
+        mv.visitTryCatchBlock(startTry, label2, catchLabel, "java/io/IOException");
+        mv.visitEnd();
+        writer.visitEnd();
+
+        out.write(writer.toByteArray());
+    }
+
+    public static void main(String[] args) throws Exception{
+        MyServerBuilder builder = new MyServerBuilder();
+
+        OutputStream out = new FileOutputStream(args[0]);
+        builder.write(out);
+        out.close();
+    }
+}
\ No newline at end of file