Reverse Engineering for Beginners

CHAPTER 54. JAVA CHAPTER 54. JAVA

public static void main(java.lang.String[]);

flags: ACC_PUBLIC, ACC_STATIC

Code:

stack=3, locals=2, args_size=1

0: iconst_5

1: bipush 10

3: bipush 15

5: multianewarray #2, 3 // class "[[[I"

9: astore_1

10: aload_1

11: iconst_1

12: aaload

13: iconst_2

14: aaload

15: iconst_3

16: iconst_4

17: iastore

18: aload_1

19: invokestatic #3 // Method get_elem:([[[I)I

22: pop

23: return

Now it takes twoaaloadinstructions to find rightreference:

public static int get_elem (int[][][] a)

{

return a[1][2][3];

}

public static int get_elem(int[][][]);

flags: ACC_PUBLIC, ACC_STATIC

Code:

stack=2, locals=1, args_size=1

0: aload_0

1: iconst_1

2: aaload

3: iconst_2

4: aaload

5: iconst_3

6: iaload

7: ireturn

54.13.8Summary.

Is it possible to do a buffer overflow in Java? No, because the array’s length is always present in an array object, array
bounds are controlled, and an exception is to be raised in case of out-of-bounds access.

There are no multi-dimensional arrays in Java in the C/C++ sense, so Java is not very suited for fast scientific computations.

54.14Strings

54.14.1First example.

Strings are objects and are constructed in the same way as other objects (and arrays).

public static void main(String[] args)

{

System.out.println("What is your name?");

String input = System.console().readLine();

System.out.println("Hello, "+input);

}