用 c 手撸一个 Java 的 decompiler

失业在家重新学习 c 语言，本来想写一个 arm 的 hook 框架，结果心血来潮，手撸一个 java 的 decompiler

已经支持

lambda 表达式
三元表达式
赋值链
while/do while 循环
数据类型推断
LocalVariableTable signature 还原
class annotation
filed annotation
method annotation
method 参数 annotation

还在开发

android dex 支持
for 循环
for in 循环
java code label 支持
优化掉 goto 语句
StringConcatFactory
varargs 方法支持
code attribute annotation
。。。。。

没有支持的还有一大堆，大体的框子已经写完了，剩下的大部分是体力活了。

收获

更恨 c++了
c 语言不完全掌握，三级指针不敢用，二级指针用的哆哆嗦嗦
jvm 的运行逻辑算是了解了一知半解
android dex
能写一堆超级复杂的，没有注释谁也看不懂的宏
参考了好多 nginx 的代码，写的真好啊！

希望大佬帮忙

哪位大佬有类似编译原理或者编译器开发的交流群或者社区，需要理论指导的时候，十分抓狂。龙书/虎书/鲸书理论看起来太枯燥。

成果

源码

import java.nio.channels.NotYetBoundException;
import java.util.HashMap;
import java.util.concurrent.ExecutionException;

public class TryCatchNestedInCatch {

    public static void demo(String name, String ye) {
        try {
            int mmm = 1000;
        } catch (Exception e) {
            // String e3 = "Exception";
            try {
                int mmm1 = 1000;
                //demo2();
            } catch (NotYetBoundException e100) {
                String e1 = "NotYetBoundException";
                // System.out.println(e1);
            } catch(Exception e1) {
                String e2 = "Exception";
                // System.out.println(e2);
            } finally {
                int mmm2 = 2000;
                // System.out.println(mmm2);
            }
            // System.out.println(e3);
        } finally {
            int ccc = 2000;
            // System.out.println(ccc);
        }

    }
}

反编译结果：

import java.nio.channels.NotYetBoundException;
import java.util.HashMap;
import java.util.concurrent.ExecutionException;

public class TryCatchNestedInCatch  {

	public static void demo(String var_0_0, String var_1_1) {
		exception { // block_id: 1  range: 0 - 35  parent_id: 0
			try { // block_id: 2  range: 0 - 4  parent_id: 1
				int var_2_2(1) = 1000;
				goto 74;
			}
			catch { // block_id: 3  range: 5 - 30  parent_id: 1
				exception { // block_id: 5  range: 6 - 27  parent_id: 3
					try { // block_id: 6  range: 6 - 10  parent_id: 5
						int var_3_4(1) = 1000;
						goto 57;
					}
					catch { // block_id: 7  range: 11 - 16  parent_id: 5
						String var_4_9(1) = "NotYetBoundException";
						goto 57;
					}
					catch { // block_id: 8  range: 17 - 22  parent_id: 5
						String var_4_12(1) = "Exception";
						goto 57;
					}
					finally { // block_id: 9  range: 23 - 27  parent_id: 5
						int var_6_15(1) = 2000;
						athrow(var_5_14);
					}
				}
				goto 74;
			}
			finally { // block_id: 4  range: 31 - 35  parent_id: 1
				int var_8_7(1) = 2000;
			}
		}
	}

}

源码：

import java.util.Random;

public class Or {
    public static int a1;
    public static int a2;
    public static int a3;

    public int b1;
    public int b2;
    public int b3;
    public static void main(String[] args)
    {
        Random r = new Random();
        boolean q = 100 < r.nextInt() || 20 > r.nextInt() && r.nextInt() > 0; 
        int m = 200000;
        boolean s = r.nextInt() > 20 && r.nextInt() < 100;
    }

    public static void st()
    {
        Random r = new Random();

        boolean q = 100 < r.nextInt() || (Or.a1 = Or.a2 = Or.a3 = 20) > r.nextInt() && r.nextInt() > 0;
    }

    public void field()
    {
        Random r = new Random();
         int[] d = {0, 0, 2, 3};
        boolean q = 100 < r.nextInt() || (this.b1 = this.b2 = this.b3 = 20) > r.nextInt() && r.nextInt() > 0;

        boolean cd = 100 < r.nextInt() || (d[0] = d[2] = this.b3 = 20) > r.nextInt() && r.nextInt() > 0;
    }


   public boolean define_or()
   {
       int m = 0;
       int k = 0;
       int n = 0;
       int z = 0;
       Random r = new Random();

      boolean dddd =
           (m = 20) > 100 || (
                   30 > ((r.nextInt() > 100 && r.nextInt() != 1000) ? (100 & r.nextInt()) : 20) ?
                   (Or.a1 = this.b1 = m = k = n = 100 > r.nextInt() ? r.nextInt() : 0) :
                   // (100 > r.nextInt() ? r.nextInt() : 0) :
                   (r.nextInt() > 2000 ? 100 : 20)
                   ) <
           (z = r.nextInt() > 1000 ? 0 : 1);


      System.out.println(m);
      System.out.println(k);
      System.out.println(n);

      return true;

   }




}

反编译结果：

import java.util.Random;
import java.io.PrintStream;

public class Or  {

  public static int a1;

  public static int a2;

  public static int a3;

  public int b1;

  public int b2;

  public int b3;


  public static void main(String[] var_0_0) {
    Random var_1_1(1) = new Random();
    int var_2_6(1) = 100 < var_1_1.nextInt() || 20 > var_1_1.nextInt() && var_1_1.nextInt() > 0 ? 0 : 1;
    int var_3_3(1) = 200000;
    int var_4_5(1) = var_1_1.nextInt() > 20 && var_1_1.nextInt() < 100 ? 0 : 1;
  }

  public static void st() {
    Random var_0_0(1) = new Random();
    int var_1_2(1) = 100 < var_0_0.nextInt() || Or.a1 = Or.a2 = Or.a3 = 20 > var_0_0.nextInt() && var_0_0.nextInt() > 0 ? 0 : 1;
  }

  public void field() {
    Random var_1_1(1) = new Random();
    int[] var_2_2(1) = new int[4]{0, 0, 2, 3};
    int var_3_6(1) = 100 < var_1_1.nextInt() || this.b1 = this.b2 = this.b3 = 20 > var_1_1.nextInt() && var_1_1.nextInt() > 0 ? 0 : 1;
    int var_4_5(1) = 100 < var_1_1.nextInt() || var_2_2[0] = var_2_2[2] = this.b3 = 20 > var_1_1.nextInt() && var_1_1.nextInt() > 0 ? 0 : 1;
  }

  public boolean define_or() {
    int var_1_1(1) = 0;
    int var_2_2(1) = 0;
    int var_3_3(1) = 0;
    int var_4_4(1) = 0;
    Random var_5_5(1) = new Random();
    int var_6_7(1) = var_1_1 = 20 > 100 || 30 > var_5_5.nextInt() > 100 && var_5_5.nextInt() != 1000 ? 20 : 100 & var_5_5.nextInt() ? var_5_5.nextInt() > 2000 ? 20 : 100 : 100 > var_5_5.nextInt() ? Or.a1 = this.b1 = var_1_1 = var_2_2 = var_3_3 = 0 : Or.a1 = this.b1 = var_1_1 = var_2_2 = var_3_3 = var_5_5.nextInt() < var_5_5.nextInt() > 1000 ? var_4_4 = 1 : var_4_4 = 0 ? 0 : 1;
    System.out.println(var_1_1);
    System.out.println(var_2_2);
    System.out.println(var_3_3);
    return true;
  }

}