TFM

• TFM
  • Introduction
  • Quick start
    • Build a graph
    • Slice a program
  • Structure
    • Summary
  • Current state
    • Graphs
    • Statements covered
  • To do list
    • SDG
    • General
  • Code samples
    • Build a CFG from a program
    • Get a slice of the PDG of a program
  • Workflow

Introduction

The main goal of this work is to develop a Java slicer. This is done by building a System Dependence Graph of the program being sliced

Quick start

Build a graph

Find Main class (tfm/exec), modify static fields of the class (the program being analyzed, the graph to build, etc.) and execute it. You will find the output in tfm/out as a png image

Slice a program

Find Slice class (tfm/slicing), set the program path and execute. The sliced program will be in tfm/out

Structure

Graphs are built using a library called graphlib, located in lib/graphlib.jar. This library is old and has some issues I had to fix...

The main class is the Graph class, which extends from graphlib's Graph class. This class includes some behaviour fixes, and some general interest methods (like toString, toGraphvizRepresentation, etc.)

Every graph has a set of nodes and arrows. GraphNode and Arc classes are used to represent them respectively.

A set of visitors is implemented for many things, such as graph building, data dependence building, etc... (available in tfm/visitors)

A bunch of programs are written in tfm/programs, you can write more there.

Some naive testing is implemented in the tfm/validation folder. Currently, a PDG can be compared with a program to check their equality.

Some util methods are available in tfm/utils (such as AST utils, logger, etc.)

Forget about the tfm/scopes folder, it was an idea I had to discard and it has to be deleted.

Summary

• Graphs (tfm/graphs)

  • CFGGraph
  • PDGGraph
  • SDGGraph

• Nodes (tfm/nodes)

  • CFGNode, PDGNode, SDGNode (Deprecated)
  • GraphNode
  • MethodCallNode (idk if this is necessary, maybe it can be deleted)

• Arcs (tfm/arcs)

  • ControlFlowArc
  • DataDependencyArc
  • ControlDependencyArc

• Visitors (tfm/visitors)

  • CFGBuilder
  • PDGVisitor (Deprecated, it was an intent to build a PDG with no CFG needed)
  • PDGBuilder
  • ControlDependencyBuilder
  • DataDependencyBuilder
  • SDGBuilder (Probably deprecated)
  • NewSDGBuilder -Work in progress-
  • MethodCallReplacerVisitor (Replaces method call nodes with in and out variable nodes) -Work in progress-

Current state

Graphs

• CFG: Done!
• PDG: Done!
• SDG: PDGs are built for each method

Statements covered

• Expressions (ExpressionStmt)
• If (IfStmt)
• While, DoWhile (WhileStmt, DoStmt)
• For, Foreach (ForStmt, ForeachStmt)
• Switch (SwitchStmt, SwitchEntryStmt)
• Break (BreakStmt)
• Continue (ContinueStmt)

To do list

SDG

• Replace method call nodes with in and out variables nodes and build arrows for them
• Build summary arrows

General

• Switch to a (much) better graph library like JGraphT. It also supports graph visualization
• Performance review
• Make a test suite (test graph building, slicing, etc.)
• Add support to more Java language features (lambdas, etc.)

Code samples

Build a CFG from a program

public CFGGraph buildCFG(File programFile) {
    JavaParser.getStaticConfiguration().setAttributeComments(false); // Always disable comments, just in case

    Node astRoot = JavaParser.parse(programFile);

    return Graphs.CFG.fromASTNode(astRoot); // Creates a new graph representing the program
}

Get a slice of the PDG of a program

public PDGGraph getSlice(File program, SlicingCriterion slicingCriterion) {
    JavaParser.getStaticConfiguration().setAttributeComments(false); // Always disable comments, just in case

    Node astRoot = JavaParser.parse(programFile);

    PDGGraph pdgGraph = Graphs.PDG.fromASTNode(astRoot);

    return pdgGraph.slice(slicingCriterion);
}

Workflow

• Branches:
  • master (only for stable versions)
  • develop (main branch)
  • <issue number>

1. Discover a new feature/fix
2. Open an issue describing it and assign it
3. Create a new branch from develop with the same name as the issue number (e.g. for issue #12 the new branch is called 12)
4. Write the solution to the issue
5. Once resolved, open a pull request from the issue branch to develop branch
6. Finally, when pull request is merged, remove branch