From 375199c7e040e6a3f50c4fb35a7be2071cdd46f0 Mon Sep 17 00:00:00 2001
From: Haruaki Tamada <tamada@cc.kyoto-su.ac.jp>
Date: Tue, 4 May 2010 15:58:12 +0900
Subject: [PATCH 1/1] =?utf8?q?Exception=E3=83=95=E3=83=AD=E3=83=BC?=
 =?utf8?q?=E3=82=82=E8=A7=A3=E6=9E=90=E5=8F=AF=E8=83=BD=E3=81=AB=EF=BC=8E?=
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

---
 .../stigmata/birthmarks/BasicBlock.java            |  23 +++-
 .../stigmata/birthmarks/ControlFlowGraph.java      |  79 +++++++++---
 .../stigmata/birthmarks/ControlFlowGraphTest.java  | 135 +++++++++++++++++++--
 .../src/test/resources/resources/MyServer.class    | Bin 471 -> 360 bytes
 .../src/test/resources/resources/MyServer2.class   | Bin 0 -> 473 bytes
 .../resources/{MyServer.java => MyServer2.java}    |   4 +-
 .../test/resources/resources/MyServerBuilder.java  |  76 ++++++++++++
 7 files changed, 286 insertions(+), 31 deletions(-)
 mode change 100755 => 100644 opcodes/src/test/resources/resources/MyServer.class
 create mode 100644 opcodes/src/test/resources/resources/MyServer2.class
 rename opcodes/src/test/resources/resources/{MyServer.java => MyServer2.java} (83%)
 create mode 100644 opcodes/src/test/resources/resources/MyServerBuilder.java

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
--- 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;
 
 import org.objectweb.asm.Label;
+import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.tree.AbstractInsnNode;
 import org.objectweb.asm.tree.InsnNode;
 
+/**
+ * 基本ブロックを表すクラス．
+ * 
+ * @author tamada
+ */
 public class BasicBlock {
     private Set<BasicBlock> nexts = new HashSet<BasicBlock>();
     private List<Opcode> opcodes = new ArrayList<Opcode>();
     private Set<BasicBlock> prevs = new HashSet<BasicBlock>();
+    Set<Label> exceptionFlows = new HashSet<Label>();
 
     BasicBlock(){
     }
@@ -55,6 +62,9 @@ public class BasicBlock {
                 }
             }
         }
+        for(Label label: exceptionFlows){
+            targets.add(label);
+        }
 
         return targets.toArray(new Label[targets.size()]);
     }
@@ -91,19 +101,24 @@ public class BasicBlock {
         prevs.add(block);
     }
 
-    /*
     public String toString(){
         StringBuilder sb = new StringBuilder("---- block ----");
         String ln = System.getProperty("line.separator");
         for(Opcode opcode: opcodes){
             sb.append(ln).append(opcode);
         }
-        Label[] targets = getTargets();
         sb.append(ln).append("Targeter: ");
-        for(Label label: targets){
+        for(Label label: getTargets()){
             sb.append(label).append(", ");
         }
         return new String(sb);
     }
-    */
+
+    public boolean isFlowNext(){
+        Opcode opcode = getOpcode(getSize() - 1);
+        int op = opcode.getOpcode();
+
+        return op != Opcodes.GOTO && op != Opcodes.RETURN
+        && op != Opcodes.RET && op != Opcodes.ATHROW;
+    }
 }
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
--- 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;
 
 import org.objectweb.asm.Label;
+import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.tree.AbstractInsnNode;
 import org.objectweb.asm.tree.JumpInsnNode;
 import org.objectweb.asm.tree.LabelNode;
@@ -15,8 +16,6 @@ import org.objectweb.asm.tree.MethodNode;
 import org.objectweb.asm.tree.TableSwitchInsnNode;
 import org.objectweb.asm.tree.TryCatchBlockNode;
 
-import com.sun.xml.internal.ws.org.objectweb.asm.Opcodes;
-
 public class ControlFlowGraph {
     private String name;
     private boolean includeException;
@@ -50,6 +49,7 @@ public class ControlFlowGraph {
                 matrix[i][j] = nextValue;
             }
         }
+
         return matrix;
     }
 
@@ -74,7 +74,7 @@ public class ControlFlowGraph {
     }
 
     private Set<LabelNode> collectLabels(MethodNode node){
-        Set<LabelNode> jumpedTarget = new HashSet<LabelNode>();
+        Set<LabelNode> jumpTarget = new HashSet<LabelNode>();
         int size = node.instructions.size();
         for(int i = 0; i < size; i++){
             AbstractInsnNode inst = node.instructions.get(i);
@@ -82,24 +82,24 @@ public class ControlFlowGraph {
             case AbstractInsnNode.JUMP_INSN:
             {
                 JumpInsnNode jump = (JumpInsnNode)inst;
-                jumpedTarget.add(jump.label);
+                jumpTarget.add(jump.label);
                 break;
             }
             case AbstractInsnNode.LOOKUPSWITCH_INSN:
             {
                 LookupSwitchInsnNode lookup = (LookupSwitchInsnNode)inst;
-                jumpedTarget.add(lookup.dflt);
+                jumpTarget.add(lookup.dflt);
                 for(Object label: lookup.labels){
-                    jumpedTarget.add((LabelNode)label);
+                    jumpTarget.add((LabelNode)label);
                 }
                 break;
             }
             case AbstractInsnNode.TABLESWITCH_INSN:
             {
                 TableSwitchInsnNode lookup = (TableSwitchInsnNode)inst;
-                jumpedTarget.add(lookup.dflt);
+                jumpTarget.add(lookup.dflt);
                 for(Object label: lookup.labels){
-                    jumpedTarget.add((LabelNode)label);
+                    jumpTarget.add((LabelNode)label);
                 }
                 break;
             }
@@ -107,30 +107,72 @@ public class ControlFlowGraph {
         }
         if(isIncludingExceptionFlow()){
             for(Object object: node.tryCatchBlocks){
-                jumpedTarget.add(((TryCatchBlockNode)object).handler);
+                jumpTarget.add(((TryCatchBlockNode)object).handler);
+            }
+        }
+        return jumpTarget;
+    }
+
+    /**
+     * TryCatchブロックの一覧を返します．
+     * Try Catchブロックが含まれていない場合や，
+     * {@link isIncludingExceptionFlow}がfalseを返す場合は長さ0の配列を返します．
+     * @param node
+     * @return
+     */
+    private TryCatchBlockNode[] buildTryCatchBlockNode(MethodNode node){
+        TryCatchBlockNode[] nodes = new TryCatchBlockNode[0];
+        if(isIncludingExceptionFlow()){
+            nodes = new TryCatchBlockNode[node.tryCatchBlocks.size()];
+            for(int i = 0; i < nodes.length; i++){
+                nodes[i] = (TryCatchBlockNode)node.tryCatchBlocks.get(i);
+            }
+        }
+        return nodes;
+    }
+
+    private void buildExceptionFlow(AbstractInsnNode inst, Set<Label> exceptionFlows, TryCatchBlockNode[] tryCatches){
+        if(inst.getType() == AbstractInsnNode.LABEL){
+            Label label = ((LabelNode)inst).getLabel();
+
+            for(TryCatchBlockNode node: tryCatches){
+                if(node.start.getLabel() == label){
+                    exceptionFlows.add(node.handler.getLabel());
+                }
+                else if(node.end.getLabel() == label){
+                    exceptionFlows.remove(node.handler.getLabel());
+                }
             }
         }
-        return jumpedTarget;
     }
 
-    private BasicBlock[] separateBasicBlock(MethodNode node, Set<LabelNode> jumpedTarget){
+    private BasicBlock[] separateBasicBlock(MethodNode node, Set<LabelNode> jumpTarget){
         int size = node.instructions.size();
 
         List<BasicBlock> blockList = new ArrayList<BasicBlock>();
+        Set<Label> exceptionFlows = new HashSet<Label>();
+        TryCatchBlockNode[] tryCatchBlocks = buildTryCatchBlockNode(node);
+
         BasicBlock block = new BasicBlock();
         for(int i = 0; i < size; i++){
             AbstractInsnNode inst = node.instructions.get(i);
+            block.exceptionFlows.addAll(exceptionFlows);
 
-            if(jumpedTarget.contains(inst)){
+            if(jumpTarget.contains(inst)){
                 if(!block.isEmpty()){
                     blockList.add(block);
                     block = new BasicBlock();
+                    block.exceptionFlows.addAll(exceptionFlows);
                 }
             }
             block.addNode(inst);
+            buildExceptionFlow(inst, exceptionFlows, tryCatchBlocks);
             if(inst.getType() == AbstractInsnNode.JUMP_INSN
                     || inst.getType() == AbstractInsnNode.TABLESWITCH_INSN
-                    || inst.getType() == AbstractInsnNode.LOOKUPSWITCH_INSN){
+                    || inst.getType() == AbstractInsnNode.LOOKUPSWITCH_INSN
+                    || inst.getOpcode() == Opcodes.RETURN
+                    || inst.getOpcode() == Opcodes.ATHROW
+                    || inst.getOpcode() == Opcodes.RET){
                 if(!block.isEmpty()){
                     blockList.add(block);
                     BasicBlock block2 = new BasicBlock();
@@ -138,10 +180,13 @@ public class ControlFlowGraph {
                         block2.setPrev(block);
                     }
                     block = block2;
+                    block.exceptionFlows.addAll(exceptionFlows);
                 }
             }
         }
-        blockList.add(block);
+        if(!block.isEmpty()){
+            blockList.add(block);
+        }
         return blockList.toArray(new BasicBlock[blockList.size()]);
     }
 
@@ -156,7 +201,7 @@ public class ControlFlowGraph {
                     }
                 }
             }
-            if(labels.length == 0 && (i + 1) < blocks.length){
+            if((i + 1) < blocks.length && blocks[i].isFlowNext()){
                 blocks[i].setNext(blocks[i + 1]);
             }
         }
@@ -165,8 +210,8 @@ public class ControlFlowGraph {
     }
 
     private void parse(MethodNode node){
-        Set<LabelNode> jumpedTarget = collectLabels(node);
-        BasicBlock[] blocks = separateBasicBlock(node, jumpedTarget);
+        Set<LabelNode> jumpTarget = collectLabels(node);
+        BasicBlock[] blocks = separateBasicBlock(node, jumpTarget);
         this.blocks = joinBasicBlocks(blocks);
     }
 }
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
--- 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;
 
 public class ControlFlowGraphTest {
-    private ControlFlowGraphExtractVisitor visitor;
+    private ControlFlowGraphExtractVisitor cfVisitor;
+    private ControlFlowGraphExtractVisitor cfVisitor2;
 
     @Before
     public void setUp() throws Exception{
-        ClassReader reader = new ClassReader(getClass().getResource("/resources/MyServer.class").openStream());
+        ClassReader reader1 = new ClassReader(getClass().getResource("/resources/MyServer.class").openStream());
+        cfVisitor = new ControlFlowGraphExtractVisitor(new ClassWriter(0));
+        reader1.accept(cfVisitor, 0);
 
-        visitor = new ControlFlowGraphExtractVisitor(new ClassWriter(0));
-        reader.accept(visitor, 0);
+        ClassReader reader2 = new ClassReader(getClass().getResource("/resources/MyServer2.class").openStream());
+        cfVisitor2 = new ControlFlowGraphExtractVisitor(new ClassWriter(0));
+        reader2.accept(cfVisitor2, 0);
     }
 
     @Test
     public void testBasic() throws Exception{
-        Iterator<String> iterator = visitor.getMethodNames();
+        Iterator<String> iterator = cfVisitor.getMethodNames();
 
         Assert.assertTrue(iterator.hasNext());
         Assert.assertEquals("<init>(I)V", iterator.next());
         Assert.assertFalse(iterator.hasNext());
 
-        ControlFlowGraph graph = visitor.getGraph("<init>(I)V");
+        ControlFlowGraph graph = cfVisitor.getGraph("<init>(I)V");
+        Assert.assertEquals(6, graph.getBasicBlockSize());
+        graph.setIncludingExceptionFlow(true);
+
+        Assert.assertEquals(6, graph.getBasicBlockSize());
+    }
+
+    @Test
+    public void testGraph() throws Exception{
+        int[][] graph = cfVisitor.getGraph("<init>(I)V").getGraphMatrix();
+
+        Assert.assertEquals(6, graph.length);
+
+        Assert.assertEquals(0, graph[0][0]);
+        Assert.assertEquals(1, graph[0][1]);
+        Assert.assertEquals(1, graph[0][2]);
+        Assert.assertEquals(0, graph[0][3]);
+        Assert.assertEquals(0, graph[0][4]);
+        Assert.assertEquals(0, graph[0][5]);
+
+        Assert.assertEquals(0, graph[1][0]);
+        Assert.assertEquals(0, graph[1][1]);
+        Assert.assertEquals(0, graph[1][2]);
+        Assert.assertEquals(1, graph[1][3]);
+        Assert.assertEquals(0, graph[1][4]);
+        Assert.assertEquals(0, graph[1][5]);
+
+        Assert.assertEquals(0, graph[2][0]);
+        Assert.assertEquals(0, graph[2][1]);
+        Assert.assertEquals(0, graph[2][2]);
+        Assert.assertEquals(1, graph[2][3]);
+        Assert.assertEquals(0, graph[2][4]);
+        Assert.assertEquals(0, graph[2][5]);
+
+        Assert.assertEquals(0, graph[3][0]);
+        Assert.assertEquals(0, graph[3][1]);
+        Assert.assertEquals(0, graph[3][2]);
+        Assert.assertEquals(0, graph[3][3]);
+        Assert.assertEquals(0, graph[3][4]);
+        Assert.assertEquals(1, graph[3][5]);
+
+        Assert.assertEquals(0, graph[4][0]);
+        Assert.assertEquals(0, graph[4][1]);
+        Assert.assertEquals(0, graph[4][2]);
+        Assert.assertEquals(0, graph[4][3]);
+        Assert.assertEquals(0, graph[4][4]);
+        Assert.assertEquals(1, graph[4][5]);
+
+        Assert.assertEquals(0, graph[5][0]);
+        Assert.assertEquals(0, graph[5][1]);
+        Assert.assertEquals(0, graph[5][2]);
+        Assert.assertEquals(0, graph[5][3]);
+        Assert.assertEquals(0, graph[5][4]);
+        Assert.assertEquals(0, graph[5][5]);
+    }
+
+    @Test
+    public void testExceptionGraph() throws Exception{
+        ControlFlowGraph cfgraph = cfVisitor.getGraph("<init>(I)V");
+        cfgraph.setIncludingExceptionFlow(true);
+        int[][] graph = cfgraph.getGraphMatrix();
+
+        Assert.assertEquals(6, graph.length);
+
+        Assert.assertEquals(0, graph[0][0]);
+        Assert.assertEquals(1, graph[0][1]);
+        Assert.assertEquals(1, graph[0][2]);
+        Assert.assertEquals(0, graph[0][3]);
+        Assert.assertEquals(1, graph[0][4]);
+        Assert.assertEquals(0, graph[0][5]);
+
+        Assert.assertEquals(0, graph[1][0]);
+        Assert.assertEquals(0, graph[1][1]);
+        Assert.assertEquals(0, graph[1][2]);
+        Assert.assertEquals(1, graph[1][3]);
+        Assert.assertEquals(1, graph[1][4]);
+        Assert.assertEquals(0, graph[1][5]);
+
+        Assert.assertEquals(0, graph[2][0]);
+        Assert.assertEquals(0, graph[2][1]);
+        Assert.assertEquals(0, graph[2][2]);
+        Assert.assertEquals(1, graph[2][3]);
+        Assert.assertEquals(1, graph[2][4]);
+        Assert.assertEquals(0, graph[2][5]);
+
+        Assert.assertEquals(0, graph[3][0]);
+        Assert.assertEquals(0, graph[3][1]);
+        Assert.assertEquals(0, graph[3][2]);
+        Assert.assertEquals(0, graph[3][3]);
+        Assert.assertEquals(1, graph[3][4]);
+        Assert.assertEquals(1, graph[3][5]);
+
+        Assert.assertEquals(0, graph[4][0]);
+        Assert.assertEquals(0, graph[4][1]);
+        Assert.assertEquals(0, graph[4][2]);
+        Assert.assertEquals(0, graph[4][3]);
+        Assert.assertEquals(0, graph[4][4]);
+        Assert.assertEquals(1, graph[4][5]);
+
+        Assert.assertEquals(0, graph[5][0]);
+        Assert.assertEquals(0, graph[5][1]);
+        Assert.assertEquals(0, graph[5][2]);
+        Assert.assertEquals(0, graph[5][3]);
+        Assert.assertEquals(0, graph[5][4]);
+        Assert.assertEquals(0, graph[5][5]);
+    }
+
+    @Test
+    public void testBasic2() throws Exception{
+        Iterator<String> iterator = cfVisitor2.getMethodNames();
+
+        Assert.assertTrue(iterator.hasNext());
+        Assert.assertEquals("<init>(I)V", iterator.next());
+        Assert.assertFalse(iterator.hasNext());
+
+        ControlFlowGraph graph = cfVisitor2.getGraph("<init>(I)V");
 
         Assert.assertEquals(6, graph.getBasicBlockSize());
 
@@ -37,8 +156,8 @@ public class ControlFlowGraphTest {
     }
 
     @Test
-    public void testGraph() throws Exception{
-        ControlFlowGraph graph = visitor.getGraph("<init>(I)V");
+    public void testGraph2() throws Exception{
+        ControlFlowGraph graph = cfVisitor2.getGraph("<init>(I)V");
         int[][] graphMatrix = graph.getGraphMatrix();
 
         Assert.assertEquals(6, graphMatrix.length);
diff --git a/opcodes/src/test/resources/resources/MyServer.class b/opcodes/src/test/resources/resources/MyServer.class
old mode 100755
new mode 100644
index a2b2a95236f4166c095057106ba794702fab057b..2b04744cf33cfe6d22f680b55df7f36f26d1885c
GIT binary patch
literal 360
zcmZvXPfNo<5XIj#v1!x9{<B7n_qI70)T831hy*MZ3IUHXE|OYyC9Xxkj91SdN<hI6
z;D-_?@hZzK^V@y%9`pV4@de-r`-H~yWiIlS$Sn||vq)A+xJ=|-IJ;ShR9i3z=9S7d
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zn!Ij}4+k^vRb(-<Gxxk&nZ~!zbiu`o;y5U<8FYv3H9Gz)yujxs_(bp8FR-=7_8Whf
TSiq~uoW8R~3kNvFE*sz%=!rtN

literal 471
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z6Cc2bQm1RYna$45%ziV!-TC}_`v7o=T^(tZ(@0@cU`s~=l{l!zURj_fur08|z^6eN
zF|am6@=k_x88VbRBWLbdzKkqerR=~R%jk$C$DZ#+CsfvGH~Vy)1vio**YSLLIlCRm
z@X8rXD3h@x#~pW_sfrb>#-Q85EOh0CrzG8n-|nrLW+02Y0UfIhrGN3UB4@xrhM}kw
zUSPF*=l8ChMqc1Er2aZG<dtCJ_(Q8V7)h7Dm}oTn*rOSwX+Rn+VkwV0(n&Lj0c7(O
zJ%ZDq0Lxs0Ri98Xs|#r6I}+FCE3_r}0xQqRs>~8e74hy1m2;RlfFMAD8tfAgv^n8Y
m1kBI}>Vz?|Mydi@D3S-V{F^Q`fg%I+Q-SsPO(nY0u<-+%c~#*6

diff --git a/opcodes/src/test/resources/resources/MyServer2.class b/opcodes/src/test/resources/resources/MyServer2.class
new file mode 100644
index 0000000000000000000000000000000000000000..68ae778d6a81b78f44d2bb6b1b7f7ecd97d9062b
GIT binary patch
literal 473
zcmZvY&q~8U5XQevW7EX+pS4!oYSmL4uz_9`4~jyewTDQ-V;UDpTayseqIaLet7pMd
zQ1AhKD0OxPPqOUn%<MPw+nvv^w+{dv>>AKf(UHNXhAjgrR7Fq|UPVJ)!?uPU1~m%f
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o!et1Ur5`j1V_}U{MYK^O4`kJEx==Kf7+{=eSQl?9)0KjaA7~d=M*si-

literal 0
HcmV?d00001

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
--- 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
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
-- 
2.11.0