In Android, how to invoke sun.misc.Unsafe methods using Java reflection?

Question

Although there are similar questions (such as A, B and C), their answers do not solve my problem.

I am using Android Studio 1.5.1 targeting Android API 18 (before Android KitKat 4.4, so I’m dealing with Dalvik, not ART runtime).

My questions are:

(1) When I use the following code, I can print a list of all sun.misc.Unsafe methods available in Android, so I think I have access to them using reflection but I do not know how to call them using reflection.

(2) If (1) is possible, how to find the magicNumber (in the code below) address using sun.misc.Unsafe methods in Android via reflection?

(3) If (1) is possible but (2) is not possible, how to put an integer number (say int test=123) in any native memory address and print its memory address using sun.misc.Unsafe methods in Android via reflection?

        String ClassName = "sun.misc.Unsafe";
        int magicNumber = 0x23420023 ;
    try {
        Class classToInvestigate = Class.forName(ClassName);
        Constructor[] aClassConstructors = classToInvestigate.getDeclaredConstructors();
        for(Constructor c : aClassConstructors){
            System.out.println("********************* constructor="+c);
        }

        Method[] aClassMethods = classToInvestigate.getDeclaredMethods();
        for(Method m : aClassMethods){
            System.out.println("********************* method="+m);

        }
        Field theUnsafe = classToInvestigate.getDeclaredField("THE_ONE");
        theUnsafe.setAccessible(true);
        Object unsafe = theUnsafe.get(null);

    } catch (ClassNotFoundException e) {
        // Class not found!
    }
    catch (Exception e) {
        // Unknown exception
    }

I don't see any method in Unsafe that will let you get the address of a local variable, and I fail to see the relevance of any of your cited questions, especially the C# one. — user207421
– user207421, Commented Jan 10, 2016 at 7:24

Alexander Efremenkov · Accepted Answer · 2016-08-13 09:26:17Z

1

Unfortunately sun.misc.Unsafe class not included in android standard library and you should use it between reflection but I found another solution: to use it between pre-compiled direct proxy class from my library: https://github.com/iamironz/unsafe

edited Aug 13, 2016 at 9:26

answered Aug 13, 2016 at 9:18

Alexander Efremenkov

1471 gold badge2 silver badges9 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

noctarius · Accepted Answer · 2016-01-10 12:17:32Z

-3

This class will return you an Unsafe instance on almost all existing JVM implementations including Android (both VM versions): https://github.com/noctarius/tengi/blob/master/java/tengi-core/src/main/java/com/noctarius/tengi/core/impl/UnsafeUtil.java

answered Jan 10, 2016 at 12:17

noctarius

6,12423 silver badges24 bronze badges

5 Comments

User Over a year ago

Can you give the steps how to include UnsafeUtil.java in my app using Android Studio? I mean do I need to copy it some folder and how to include it in my Android Studio project?

noctarius Over a year ago

Just copy the source to some class

User Over a year ago

Copying the source into some class does not work, it gives me three errors in Android Studio: (1) unexpected token for: package com.noctarius.tengi.core.impl; (2) cannot resolve symbol: import com.noctarius.tengi.core.model.Identifier; and (3) cannot resolve symbol: import sun.misc.Unsafe;

User Over a year ago

If I remove import sun.misc.Unsafe which is the most important item, nothing works.

noctarius Over a year ago

I'm pretty sure it is an Android Studio thing to "prevent" access to sun.misc.Unsafe. Have you tried to compile on command line?

Collectives™ on Stack Overflow

In Android, how to invoke sun.misc.Unsafe methods using Java reflection?

2 Answers 2

Comments

5 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

5 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related