1. Slide 1, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Masters Project Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI Vanderlande Industries B.V. (Veghel) Dennie van Zeeland d.h.a.v.zeeland@student.tue.nl

2. Slide 2, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Outline Introduction Project goal Related work Tools State Machine patterns Switch-Case / Switch-Case pattern Overview of design of Cpp2XMI CPPML Case Study - FSC Problems encoutered Conclusions / Future work

3. Slide 3, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Introduction Vanderlande Industries (VI) -Automated material handling systems: distribution centres baggage handling at airports express parcel sortation facilities Flow System Controller (FSC) -Controls the product flows in conveyor systems for transport and sortation -Controls all motors, photocells and other active components -Send and receive control and status information -Realtime control of equipment -Separated GUI -Standard interfaces with equipment -Fully configurable for all VI sorting equipment

4. Slide 4, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Project goal Reverse Engineering documentation from C/C++ source code -Why: Limited documentation available for V5/V6 - State machine diagrams Identifying possible flaws in current versions V7 is being developed from scratch Extracting dynamic behavior from source code for V7 Identifying requirements -Building a tool for extracting state machine diagrams from code Preprocessing source code Parsing source code Finding patterns in source code of state machines Creating diagrams

5. Slide 5, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Related work ESPaRT [KNOR98] -Finding state machine patterns and replacing them by better constructs Bandera [CORB00] -Extract state machines and produce input for model checkers Symbolic Execution [WALK08] -Program conditioning Brastra [YUAN06] -Extracting state machines using unit tests Log based state machine extraction [GANN06]

6. Slide 6, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Tools Cpp2XMI -Developed by Elena Korshunova for LaQuSo -C++ to UML-diagrams Class diagram Sequence diagram Activity diagram Columbus/CAN toolset -Pre-processor + Parser + Linker -Static analyser (Class diagram extraction) -CPPML (C++ Markup Language) Use Cpp2XMI as basis and extend it with -State machine diagram

7. Slide 7, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland State Machine Patterns Global type of patterns for implementing state machines -Nested Choice Patterns Switch/Case – Switch/Case pattern (mainly used in FSC) Switch/Case – If/Else If/Else – Switch/Case If/Else – If/Else -Jump Tables Pointer to a function pointer array represents state variable Function pointer array is the jumb table Table contains the event handler functions -Object oriented approach States as classes -Goto statements Use goto statements to jump through program Each goto statement corresponds to a state transition

8. Slide 8, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Switch/Case – Switch/Case pattern (1) States Source CodeDiagram 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 /* State of the object */ enum OBJ_STATE { STATE_A, STATE_B, STATE_C };... switch (...) { case STATE_A:... case STATE_B:... case STATE_C:... default:... }... All possible states Determine current state

9. Slide 9, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Switch/Case – Switch/Case pattern (2) Transitions Source CodeDiagram 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 /* events to react on */ enum OBJ_EVENT{ EVENT1, EVENT2, EVENT3 };... switch (...) { case STATE_A: switch (event) { case EVENT1:... case EVENT2:... } break; case STATE_B: switch (event) { case EVENT1:... case EVENT2:... } break;... } Determine arrived event All possible events

10. Slide 10, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Switch/Case – Switch/Case pattern (3) Object with current state variable Source CodeDiagram 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 typedef struct { bool initialised; OBJ_STATE state; } OBJ;... switch (obj->state) { case STATE_A: switch (event) { case EVENT1: obj->state = STATE_B; break; case EVENT2: obj->state = STATE_C; break; } break; case STATE_B: switch (event) { case EVENT1: obj->state = STATE_B; break; case EVENT2: obj->state = STATE_C; break; } break;... } Assign new state to state variable Object with variable for current state

11. Slide 11, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Control Function Switch/Case – Switch/Case pattern (4) Source CodeDiagram 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 static void OBJ_control(OBJ *obj, OBJ_EVENT event) { switch (obj->state) { case STATE_A: switch (event) { case EVENT1: obj->state = STATE_B; break; case EVENT2: obj->state = STATE_C; break; } break; case STATE_B: switch (event) { case EVENT1: obj->state = STATE_B; break; case EVENT2: obj->state = STATE_C; break; } break;... } Control Function Event that needs to be handled

12. Slide 12, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Multiple events with the same event-handler Switch/Case – Switch/Case pattern (5) Source CodeDiagram 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 static void OBJ_control(OBJ *obj, OBJ_EVENT event) { switch (obj->state) { case STATE_A: switch (event) { case EVENT1: case EVENT2: obj->state = STATE_C; break; } break; case STATE_B: switch (event) { case EVENT1: obj->state = STATE_B; break; case EVENT2: obj->state = STATE_C; break; } break;... } Multiple events are handled the same way

13. Slide 13, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland State assignment in called function Switch/Case – Switch/Case pattern (6) Source CodeDiagram 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 do_Function(OBJ *obj) {... obj->state = STATE_C;... }... static void OBJ_control(OBJ *obj, OBJ_EVENT event) { switch (obj->state) { case STATE_A: switch (event) { case EVENT1: do_Function(obj); break; case EVENT2: obj->state = STATE_C; break; } break;... }... State assignment in called function

14. Slide 14, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Conditional transitions Switch/Case – Switch/Case pattern (7) Source CodeDiagram 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 bool y = true; switch (obj->state) { case STATE_A: switch (event) { case EVENT1: if (y) { obj->state = STATE_B; } else { obj->state = STATE_C; } break; case EVENT2: obj->state = STATE_C; break; } break; case STATE_B: switch (event) { case EVENT1: obj->state = STATE_B; break; case EVENT2: obj->state = STATE_C; break; } break;... } Conditional transitions

15. Slide 15, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Overview of design of Cpp2XMI (1) Abstract Syntax Tree in XML-format Class Diagram in XML (XMI)-format Class, Sequence, Activity Diagram in XML (XMI)-format

16. Slide 16, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Overview of design of Cpp2XMI (2) Could be improved X

17. Slide 17, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Case Study - FSC (1) Applied Cpp2XMI to FSC V6

18. Slide 18, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Case Study - FSC (2) Example: SPUR

19. Slide 19, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Case Study - FSC (3) Example: Triplesorter

20. Slide 20, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Case Study (4) Some results of the Cpp2XMI State Machine Diagram Extractor -V6: 27 State Machine Diagrams, 2 false positives -Extracted state machine is for 70% identical to original documented state machine (Gappex) -Correctness was checked and confirmed by domain experts

21. Slide 21, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Problems encountered Preprocessing issues -Columbus Parser doesn’t understand anonymous structs/enums Sax parser issues -Sax parser halts on the escape character (0x1B) CPPML should have a tree-structure (1 on 1 with AST) -However it’s a DAG, which makes pattern recognition is tricky Cpp2XMI doesn’t extract control-statements (do, while, if, switch break, continue, etc.) correctly (for C) Performance issues with CPPML parser -JDOM (Memory peak level: 1,8GB) -SAX (will not solve memory peaks) Bug in XMI-part -Duplicate id’s, which raises errors when importing XMI into case-tools (Enterprise Architect) Position information not part of XMI -Enterprise Architect doesn’t do anything with position information

22. Slide 22, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Conclusions / Future work Conclusions: -UML state machines are useful for the developers and maintainers -Can be derived automatically from source code (by finding patterns) -Was very successful in the case study and is in general promising Future work: -Expanding the state machine patterns -Combine with logging to get a general state machine -Export function for model checkers -On Entry / On Exit -Metrics / analysis over overlap of state machine diagrams -Filter / Zoom -Use original CPPML parser -XMI conversion -Improve performance issues (due to choice of parser)

23. Slide 23, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland Questions?

24. Slide 24, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland References (1) [KNOR98] -Roland Knor, Georg Trausmuth and Johannes Weidl -Reengineering C/C++ Source Code by Transforming State Machines -Proceedings of the Second International ESPRIT ARES Workshop on Development and Evolution of Software Architectures for Product Families -1998 -ISBN: 3-540-64916-6, Page 97—105 -Springer-Verlag [CORB00] -James C. Corbett, et al. -Bandera: extracting finite-state models from Java source code -Proceedings of the 22nd international conference on Software engineering, -2000 -ISBN: 1-58113-206-9, Page 439—448 -ACM [WALK08] -Neil Walkinshaw et al. -Automated discovery of state transitions and their functions in source code -Journal: Software Testing Verification Reliability (Vol 18, nr 2) -2008 -ISBN 0960-0833, Page 99—121 -John Wiley and Sons Ltd.

25. Slide 25, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland References (2) [YUAN06] -Tao Xie and Evan Martin and Hai Yuan -Automatic extraction of abstract-object-state machines from unit-test executions -Proceedings of the 28th international conference on Software engineering -2006 -ISBN: 1-59593-375-1, Page 835—838 -ACM [GANN02] -Gerald C. Gannod and Shilpa Murthy -Using Log Files to Reconstruct State-Based Software Architectures -Workshop on Software Architecture Reconstruction at WCRE 2002 -2002 [FERE02] -Rudolf Ferenc et al. -Columbus - Reverse Engineering Tool and Schema for C++ -Proceedings of the International Conference on Software Maintenance -2002 -ISBN: 0-7695-1819-2, Page 172 -IEEE Computer Society [KORS06] -E. Korshunova and M. Petkovic and M. G. J. van den Brand and M. R. Mousavi -CPP2XMI: Reverse Engineering of UML Class, Sequence, and Activity Diagrams from C++ Source Code -WCRE '06: Proceedings of the 13th Working Conference on Reverse Engineering -2006 -ISBN: 0-7695-2719-1, Page 297—298 -IEEE Computer Society