[Soot-list] invokespecial side effects

[Bodden, Eric]

Hi Daniel.

I have to agree with Marc-Andre here. s3 cannot possibly modify $r2. You must be misinterpreting something.

Eric



On 04.11.2013, at 03:41, Marc-André Laverdière-Papineau <marc-andre.laverdiere-papineau at polymtl.ca> wrote:

> Hello Daniel,
> 
> The examples you show are running the constructor. While they do change
> the state of the object, they do not affect the def, as the local is not
> re-defined. This is exactly what I would expect. Am I missing something?
> 
> I would expect them to be in the uses though - are they?
> 
> Marc-André Laverdière-Papineau
> Doctorant - PhD Candidate
> 
> On 31/10/13 12:38 PM, Daniel Luchaup wrote:
>> Hello,
>> 
>> I was wondering what is the best practice to deal with the side-effects
>> of invokespecial; they are not listed as results.
>> 
>> Ideally each jimple statement that modifies a local should specify that
>> local as a result.
>> However, that is not the case for invokespecial. For instance (see
>> complete example at the end of the email):
>> ..............
>> (s1:)  $r2 = new java.lang.StringBuilder;
>> (s2:)  $r3 = ...
>> (s3:)  specialinvoke $r2.<java.lang.StringBuilder: void
>> <init>(java.lang.String)>($r3);
>> (s4:)  use($r2);
>> .............
>> If I use SmartLocalDefs.getDefsOfAt($r2, (s2)), I get s1, but in fact
>> $r2 was last modified at s3.
>> It seems that, at least in this case, specialinvoke should have a result:
>>  (s3:) $rX = specialinvoke $r2.<java.lang.StringBuilder: void
>> <init>(java.lang.String)>($r3);
>> 
>> So, to get the real definition of $r2 that reaches (s4:) one would have
>> to explicitly reason about the above code pattern.
>> 
>> Can this be done better?
>> 
>> Thank you
>> Daniel
>> 
>> P.S. FYI: A more complete example:
>> The jimple code for 'String copy1(String s1) { return s1+"!!!";}' contains:
>>>>>>> 
>>        r0 := @this: dummy;
>>        r1 := @parameter0: java.lang.String;
>>        $r2 = new java.lang.StringBuilder;
>>        $r3 = staticinvoke <java.lang.String: java.lang.String
>> valueOf(java.lang.Object)>(r1);
>>        specialinvoke $r2.<java.lang.StringBuilder: void
>> <init>(java.lang.String)>($r3);
>>        $r4 = virtualinvoke $r2.<java.lang.StringBuilder:
>> java.lang.StringBuilder append(java.lang.String)>("!!!");
>>        $r5 = virtualinvoke $r4.<java.lang.StringBuilder:
>> java.lang.String toString()>();
>>        return $r5;
>> <<<<<
>> 
>> 
>> 
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--
Prof. Eric Bodden, Ph.D., http://sse.ec-spride.de/ http://bodden.de/
Head of Secure Software Engineering  at Fraunhofer SIT, TU Darmstadt and EC SPRIDE
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