HelloTransform-Soot

Getting started with Soot Transformer and Packs

Setup Project in IDE

1. Create an empty Java project and include pre-compile Soot as jar located under /libs. (For IntelliJ follow here and continue to step 2)
2. Add Main.java located under /src to your project.
3. Add VNTransformer.java located under /src to your project.
4. Download Test.class located under /inputs and provide path in Main.java, where "inputs" is a directory containing .class file.

String classPath =  "inputs";

5. Configure Soot as it mentioned in Part 1 and follow next for code reference inside both provided classes.
6. Inside main method of Main.java, create object for our VNTransformer class.

VNTransformer mVNTransformer = new VNTransformer();

7. Then, create an object for Transform.

Transform mVNTransform = new Transform("wjtp.valNumbering", mVNTransformer);
//First Argument is name of Transform, second argument is an object of our Transformer

8. Add Transform to the whole-jimple transformation pack.

PackManager.v().getPack("wjtp").add(mVNTransform);

Code Guidelines for VNTransformer.java

1. Next, here are pointers for Soot APIs used in VNTransformer class. Get Main class as a SootClass Object.

SootClass mainClass = Scene.v().getMainClass();

2. Get test method as a SootMethod Object and get method body.

SootMethod testMethod = mainClass.getMethodByName("test");
Body methodBody = testMethod.retrieveActiveBody();

3. Create Directed graph object for method body.

UnitGraph graph = new BriefUnitGraph(methodBody);

4. Next, iterate over the UnitGraph object and go through the statements.

Iterator<Unit> unitIt = graph.iterator();  
while (unitIt.hasNext()) { 
  Unit unit = unitIt.next();
  ...
}

5. Following API helps to get Used Boxes of current Unit (statement) -- These are the things appearing right hand side of the statement. Local is Soot's representation of local variables of a method.

for (ValueBox useBox : unit.getUseBoxes()) {  
    // if Value of defBox is Local variable  
  if (useBox.getValue() instanceof Local) {  
        Local useLocal = (Local) useBox.getValue();  
    System.out.println("Used:" + useLocal.getName());  
  }  
}

6. Comparing and casting to Assignment Statement.

if (unit instanceof AssignStmt) {
  AssignStmt assignStmt = (AssignStmt) unit;
}

7. Comparing and casting Right hand operands of Assignment Statement.

if (assignStmt.getRightOp() instanceof AddExpr) {
  // This is Add Operation on right
}
if (assignStmt.getRightOp() instanceof MulExpr) { 
  // This is Multiply Operation on right
}
if (assignStmt.getRightOp() instanceof DivExpr) { 
  // This is Divide operation on right
}  
if (assignStmt.getRightOp() instanceof SubExpr) {
  // This is Subtract operation on right
}

8. Following API helps to get Defined Boxes of current Unit (statement) -- These are the things appearing left hand side of the statement.

for (ValueBox defBox : unit.getDefBoxes()) {  
    // if Value of defBox is Local variable  
  if (defBox.getValue() instanceof Local) {  
        Local defLocal = (Local) defBox.getValue();  
    System.out.println("Defined:" + defLocal.getName());  
  }  
}

IntelliJ Import instructions

1. Import project to IntelliJ idea (You might need to configure dependencies, Click File → Project Structure → Modules → click + → JARs or directories → Browse the jar file in lib directory)