Transformation of Java Card into Diet Java Semester Project Presentation Erich Laube

Overview 1. Introduction to Jive and Background 2. Transformation Basics 3. Examples 4. Future Work 5. Conclusion

Jive Java Interactive Verification Environment Code (Java) vs. Specification (JML) Diet Java

Goals Transformation of forbidden constructs. Reporting errors at compile time for constructs that are not transformed.

Involved Tools ANTLR parser, lexer Abstract Syntax Tree (AST) Multijava java compiler static checks, type information JML Multijava enhanced with JML

Difficulties Tracking (nested Expressions) Still knowing where one is Execution order Genericity Constructs forbidden in program but allowed in specification part large amount of node classes non-uniform node layout

Try-Catch try { // something } catch (Exception1 e1){ // handler1 } catch (Exception2 e2){ // handler2 } try{ // something } catch (Exception1 e1){ // handler1 } catch (Exception2 e2){ // handler2 } Only one Catch per Try done in Grammar file

Do While => While do { [body] } while (cond) [body] while (cond){ [body] } do { if (x) break; } while (cond) if (x) break; while (cond){ if (x) break; } { boolean b = true while (b||cond){ if (x) break; b = false }} { boolean b = true while (b){ if (x) break; b = cond; }

Constructors conversion to method: alter all constructor calls  find them, spread all over the code call constructor of super method  create default constructor method  but only if no other constructor specified special case: this() calls call the initializer method (not always there) also needs a JML specification

Constructor conversion example Class K extends M{ int f; K(int i){ super(i); f = i; } K(){ this(2); } Class K extends M{ int f; void °cK(int i){ super.°cM(i); f = i; } void °cK(){ °cK(2); } Class K extends M{ int f = 2; K(int i){ super(i); f = i; } K(){ this(f); } Class K extends M{ int f; °inst_init(){ f = 2; } void °cK(int i){ °inst_init(); super.°cM(i); f = i; } void °cK(){ °inst_init(); °cK(f); } Class K extends M{ int f; boolean °init; void °inst_init(){ if (°init){} else { f = 2; °init = true; }} void °cK(int i){ super.°cM(i); °inst_init(); f = i;} void °cK(){ °inst_init(); °cK(f); }

Future Work Remaining Transformations non-strict operators pre- and postfix operators (++,--) inner classes Optimizations: reuse temporary variables simple trafos for simple cases

Conclusion Many constructs covered Mangled code: difficult for user to still understand Interesting and complex project

Implemented Transformations constructors nonstatic initializers variable initializers local variables only at beginning of blocks short if, for and do-loops, switch-blocks multiple catch blocks for a try-block casts within expressions array access within expressions compound assignment assignment within expressions assignments with side effects (partially) pre- and postfix operators (partially)

Questions...?

Grammar File (ANTLR) Passes every code construct No Type Information Also affects JML part Work done here: finding and forbidding types simple transformations If-then-else Try-catch

Abstract Syntax Tree (Multijava) Statements can hold more Statements can hold Expressions Expressions never hold Statements can hold further Expressions