1 / 21

Model Checking C# Code: A Translation Approach

Model Checking C# Code: A Translation Approach. Contents. Overview Model Structure Key Features Flow Control State Representation Thread management What's Next. Overview. C Source Code Model Checkers: BLAST, SLAM and CBMC etc 

chen
Download Presentation

Model Checking C# Code: A Translation Approach

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Model Checking C# Code: A Translation Approach

  2. Contents • Overview • Model Structure • Key Features • Flow Control • State Representation • Thread management • What's Next

  3. Overview • C Source Code Model Checkers: BLAST, SLAM and CBMC etc  • Translate to Boolean Program or CIL (C Intermediate Language) • use Theorem Prover or SAT Solver to check predicates • Translate to Promela and use SPIN to check •  Java and C# Model Checkers • Java PathFinder • MoonWalker • act as a virtual machine to "run" the program

  4. Objectives • Going down to byte-code level might not be necessary • PAT is a general Model Checker with good performance and extensibility • PAT can import C# library, the polymorphism could be handled smoothly and efficiently Extra • improve the traceability for testing, model checking and debugging. • Refinement checking to ensure consistency (different dev phases or branches)

  5. Structure

  6. Flow Control • Statement • Branch • Loop • Block of Code • Return • Exception 

  7. {... statement1; statement2; ... } if(cond) {//block 1} else {//block 2} Block(..) = ((tau{statement1;} -> Skip); ((tau{statement1;} -> Skip); ... )); if (cond) { Block_1(..)}  else { Block_2(..) } Flow Control

  8. for(init; cond; increment) {//block 1} For_1(..) =     Block_1();     increment;     if(Cond) {For_1(..)}      else {Skip}; ... init; if(cond) For_1(...); ... Flow Control

  9. State Representation • Classes and Objects • Fields remain • Methods: Based on defined atomicity 

  10. class Philosopher { int name; Fork left; Fork right; } class Philosopher : ExpressionValue { public int name; public int Get_name()              {return name; } public void Set_name(int val)                 {name = val; } public int left; public int Get_left() {return left; } public void Set_left(int val)              {left = val; } ... State Representation

  11. State Representation public class Memory : ExpressionValue {...      public int Philosopher_Get_name(int obj) {              return philosopherList.GetObj(obj).Get_name();          } public void Philosopher_Set_name(int obj, int val) {             philosopherList.GetObj(obj).Set_name(val);          } public int Philosopher_Get_left(int obj) {             return philosopherList.GetObj(obj).Get_left();          } public void Philosopher_Set_left(int obj, int val) {             PhilosopherList.GetObj(obj).Set_left(val);          }... }

  12. Thread Management CreateNewThread() =      create_thread?ti.pid.obj -> NewThread(ti, pid, obj); NewThread(ti, pid, obj) = case { (ti == 1) : Philosopher_run(pid, obj) default: Skip } || CreateNewThread(); Sys() = Main() || CreateNewThread();

  13. ...//origin Thread newThread = new Thread(new ThreadStart(run)); newThread.Start(); ... ...//translated ((create_thread!1.pid.objx -> Skip); (atomic {tau{cpid++} -> Philosopher_run_chan_in!cpid.objx -> Skip}; ... Philosopher_run() = (Philosopher_run_chan_in?pid.obj -> ... Thread Management

  14. Lock Fork_Lock(pid, obj) = [0 == memory.Fork_Get_LOCK(obj)] ((tau{ memory.Fork_Set_LOCK(obj, pid); } -> Skip) ); Fork_Unlock(pid, obj) = assert(memory.Fork_Get_LOCK(obj) == pid); ((tau{ memory.Fork_Set_LOCK(obj, 0); } -> Skip) );

  15. (Fork_Lock(pid, memory.Philosopher_Get_left(obj)); (Fork_Lock(pid, memory.Philosopher_Get_right(obj)); ... (Fork_Unlock(pid, memory.Philosopher_Get_right(obj)); (Fork_Unlock(pid, memory.Philosopher_Get_left(obj)) Lock lock (left) {   lock (right) {     // eat!   } }

  16. Parameter Pass and Local Variable //origin public Philosopher (Fork le, Fork ri, int na) { left = le; right = ri; name = na; ... }

  17. Parameter Pass and Local Variable //translated version 1 Philosopher_CreateObj() = (Philosopher_CreateObj_chan_in?pid.le.ri.na ->  ((tau{ memory.Philosopher_Set_le(le); } -> Skip); ((tau{ memory.Philosopher_Set_ri(ri); } -> Skip); ((tau{ memory.Philosopher_Set_na(na); } -> Skip); ((tau{ objx = memory.Philosopher_CreateObj(); } -> Skip); ((tau{ memory.Philosopher_Set_left(objx, memory.Philosopher_Get_le()); } -> Skip); ((tau{ memory.Philosopher_Set_right(objx, memory.Philosopher_Get_ri()); } -> Skip); ((tau{ memory.Philosopher_Set_name(objx, memory.Philosopher_Get_na()); } -> Skip); ... ))))))))));

  18. Parameter Pass and Local Variable //translated version 2 Philosopher_CreateObj() = (Philosopher_CreateObj_chan_in?pid.le.ri.na ->  ((tau{ objx = memory.Philosopher_CreateObj(); } -> Skip); ((tau{ memory.Philosopher_Set_left(objx, le); } -> Skip); ((tau{ memory.Philosopher_Set_right(objx, ri); } -> Skip); ((tau{ memory.Philosopher_Set_name(objx, na); } -> Skip); ... ))))))));

  19. What's next • Exception handling • Atomicity control

  20. Thank You!

  21. Reference [1]  J. Sun, Y. Liu, J. S. Dong, and J. Pang, “PAT: towards flexible verification under fairness,” in Proceedings of the 21thInternational Conference on Computer Aided Verification(CAV’09). [2]  K. Havelund and T. Pressburger, “Model checking javaprograms using java pathfinder,” International Journal onSoftware Tools for Technology Transfer (STTT), vol. 2, no. 4,pp. 366 – 381, 2000. [3]  Wendi Zhah,  Yet Another Model Checker for PROMELA, to be appear..

More Related