Traps not handled properly when analyzing source code

[thebesttv]

Hello, I was trying to analyze the following Java source code:

public class HelloWorld {
    public static void main(String[] var0) {
        int x = 0, y = 0;
        try {
            System.out.println(x / y);
        } catch (Exception e){
            System.out.println("Exception caught");
        }
    }
}

using code from the BasicSetup.java example, but got the following exception:

Exception in thread "main" java.lang.RuntimeException: StmtGraph of <HelloWorld: void main(java.lang.String[])> is invalid.
        at sootup.core.model.Body$BodyBuilder.build(Body.java:520)
        at sootup.java.sourcecode.frontend.WalaIRToJimpleConverter.createBody(WalaIRToJimpleConverter.java:557)
        at sootup.java.sourcecode.frontend.WalaIRToJimpleConverter.convertMethod(WalaIRToJimpleConverter.java:278)
        at sootup.java.sourcecode.frontend.WalaIRToJimpleConverter.convertToClassSource(WalaIRToJimpleConverter.java:175)
        at java.util.Optional.map(Optional.java:215)
        at sootup.java.sourcecode.frontend.WalaJavaClassProvider.getClassSource(WalaJavaClassProvider.java:298)
        at sootup.java.sourcecode.frontend.WalaJavaClassProvider.createClassSource(WalaJavaClassProvider.java:354)
        at sootup.java.sourcecode.inputlocation.JavaSourcePathAnalysisInputLocation.getClassSource(JavaSourcePathAnalysisInputLocation.java:162)
        at sootup.java.core.views.JavaView.lambda$getAbstractClass$1(JavaView.java:130)
        at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
        at java.util.ArrayList$ArrayListSpliterator.tryAdvance(ArrayList.java:1361)
        at java.util.stream.ReferencePipeline.forEachWithCancel(ReferencePipeline.java:126)
        at java.util.stream.AbstractPipeline.copyIntoWithCancel(AbstractPipeline.java:499)
        at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:486)
        at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
        at java.util.stream.FindOps$FindOp.evaluateSequential(FindOps.java:152)
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
        at java.util.stream.ReferencePipeline.findAny(ReferencePipeline.java:536)
        at sootup.java.core.views.JavaView.getAbstractClass(JavaView.java:136)
        at sootup.java.core.views.JavaView.getClass(JavaView.java:118)
        at thebesttv.sootup.Main.main(Main.java:65)
Caused by: java.lang.IllegalStateException: visualize invalid StmtGraph: http://magjac.com/graphviz-visual-editor/?dot=digraph+G+%7B%0A%09compound%3Dtrue%0A%09labelloc%3Db%0A%09style%3Dfilled%0A%09color%3Dgray90%0A%09node+%5Bshape%3Dbox%2Cstyle%3Dfilled%2Ccolor%3Dwhite%5D%0A%09edge+%5Bfontsize%3D10%2Carrowsize%3D1.5%2Cfontcolor%3Dgrey40%5D%0A%09fontsize%3D10%0A%0A%2F%2F++lines+%5B6%3A+7%5D+%0A%09subgraph+cluster_573424492+%7B+%0A%09%09label+%3D+%22Block+%231%22%0A%09%09979865152%5Blabel%3D%22%24r2+%3A%3D+%40caughtexception%22%5D%0A%09%09876994034%5Blabel%3D%22%24r3+%3D+%24r2%22%5D%0A%09%09666389658%5Blabel%3D%22%24r4+%3D+%26lt%3Bjava.lang.System%3A+java.io.PrintStream+out%26gt%3B%22%5D%0A%09%09564908963%5Blabel%3D%22virtualinvoke+%24r4.%26lt%3Bjava.io.PrintStream%3A+void+println%28java.lang.String%29%26gt%3B%28%26quot%3BException+caught%26quot%3B%29%22%5D%0A%0A%09%09979865152+-%3E+876994034+-%3E+666389658+-%3E+564908963%0A%09%7D%0A%09564908963%3As+-%3E+1788841007%3An%0A%0A%2F%2F++lines+%5B3%3A+4%5D+%0A%09subgraph+cluster_596403167+%7B+%0A%09%09label+%3D+%22Block+%232%22%0A%09%091605393415%5Blabel%3D%22%24r0+%3A%3D+%40parameter0%3A+java.lang.String%5B%5D%22%2Cshape%3DMdiamond%2Ccolor%3Dgrey50%2Cfillcolor%3Dwhite%5D%0A%09%09422278820%5Blabel%3D%22%24i0+%3D+0%22%5D%0A%09%091838590101%5Blabel%3D%22%24i1+%3D+0%22%5D%0A%09%09815497540%5Blabel%3D%22%24r1+%3D+%26lt%3Bjava.lang.System%3A+java.io.PrintStream+out%26gt%3B%22%5D%0A%09%091892261395%5Blabel%3D%22%24i2+%3D+%24i0+%2F+%24i1%22%5D%0A%09%09840259832%5Blabel%3D%22virtualinvoke+%24r1.%26lt%3Bjava.io.PrintStream%3A+void+println%28int%29%26gt%3B%28%24i2%29%22%5D%0A%09%091047698758%5Blabel%3D%22goto%22%5D%0A%0A%09%091605393415+-%3E+422278820+-%3E+1838590101+-%3E+815497540+-%3E+1892261395+-%3E+840259832+-%3E+1047698758%0A%09%7D%0A%091047698758%3As+-%3E+1788841007%3An%0A%0A%2F%2F++lines+%5B7%3A+7%5D+%0A%09subgraph+cluster_107131289+%7B+%0A%09%09label+%3D+%22Block+%233%22%0A%09%091788841007%5Blabel%3D%22return%22%2Cshape%3DMdiamond%2Ccolor%3Dgrey50%2Cfillcolor%3Dwhite%5D%0A%09%7D%0A%0A%7D
        at sootup.core.graph.StmtGraph.validateStmtConnectionsInGraph(StmtGraph.java:242)
        at sootup.core.model.Body$BodyBuilder.build(Body.java:518)
        ... 20 more
Caused by: java.lang.IllegalStateException: Stmt '$r2 := @caughtexception' which is neither the StartingStmt nor a TrapHandler is missing a predecessor!
        at sootup.core.graph.StmtGraph.validateStmtConnectionsInGraph(StmtGraph.java:188)
        ... 21 more

When analyzing the compiled Java bytecode, everything seems fine.

I think this has something to do with the commented code at line 535 of WalaIRToJimpleConverter.java, because once I changed it to:

          AbstractCFG<? extends SSAInstruction, IBasicBlock<SSAInstruction>> newCfg =
                  (AbstractCFG<? extends SSAInstruction, IBasicBlock<SSAInstruction>>) cfg;
          final Collection<IBasicBlock<SSAInstruction>> exceptionalPredecessors = newCfg.getExceptionalPredecessors(block);

          for (IBasicBlock<SSAInstruction> exceptionalPredecessor : exceptionalPredecessors) {
            Stmt from = index2Stmt.get(exceptionalPredecessor.getFirstInstructionIndex());
            Stmt to = index2Stmt.get(exceptionalPredecessor.getLastInstructionIndex() + 1); // exclusive!

            Stmt handlerStmt = index2Stmt.get(block.getFirstInstructionIndex());
            for (TypeReference type : exceptionTypes) {
              ClassType exception = (ClassType) convertType(type);
              traps.add(new Trap(exception, from, to, handlerStmt));
            }
          }

the analysis seems to work.

Is the support for try-catch block in Java source code not yet available, or am I missing something?
Thanks a lot!

[swissiety]

Hello,
yes this can work occasionally, but the commented code worked just with those simple non nested trycatch blocks - the generated jimple for nested trycatch was wrong semantically (#482) - so currently its not supported for the sourcecodefrontend, yet.

[thebesttv]

Thanks for the clarification!