proguard.analysis.cpa.bam

Class BamTransferRelation<CfaNodeT extends CfaNode<CfaEdgeT,SignatureT>,CfaEdgeT extends CfaEdge<CfaNodeT>,SignatureT extends Signature>

java.lang.Object

proguard.analysis.cpa.bam.BamTransferRelation<CfaNodeT,CfaEdgeT,SignatureT>

All Implemented Interfaces:

TransferRelation

public class BamTransferRelation<CfaNodeT extends CfaNode<CfaEdgeT,SignatureT>,CfaEdgeT extends CfaEdge<CfaNodeT>,SignatureT extends Signature>
extends java.lang.Object
implements TransferRelation

This TransferRelation extends an analysis inter-procedurally. The transfer relation applies as close as possible the algorithms described in https://dl.acm.org/doi/pdf/10.1145/3368089.3409718. On a high level the task of this domain-independent transfer relation is to extend the intra-procedural domain-dependent transfer relation of a CpaWithBamOperators inter-procedurally. For more details on how the transfer relation works see generateAbstractSuccessors(AbstractState, Precision).

Constructor Summary

Constructors

Constructor and Description
BamTransferRelation(CpaWithBamOperators<CfaNodeT,CfaEdgeT,SignatureT> wrappedCpa, Cfa<CfaNodeT,CfaEdgeT,SignatureT> cfa, SignatureT mainFunction, BamCache<SignatureT> cache) Create a BAM transfer relation with an unlimited call stack.
BamTransferRelation(CpaWithBamOperators<CfaNodeT,CfaEdgeT,SignatureT> wrappedCpa, Cfa<CfaNodeT,CfaEdgeT,SignatureT> cfa, SignatureT mainFunction, BamCache<SignatureT> cache, int maxCallStackDepth, AbortOperator abortOperator) Create a BAM transfer relation with a specified maximum call stack depth.

Method Summary

Modifier and Type	Method and Description
java.util.Collection<? extends AbstractState>	generateAbstractSuccessors(AbstractState abstractState, Precision precision) In order to implement an inter-procedural analysis the abstract successors are calculated for the following cases:
BamCache<SignatureT>	getCache() Returns BAM cache storing analysis result for various method calls.
Cfa<CfaNodeT,CfaEdgeT,SignatureT>	getCfa() Returns the CFA used by the transfer relation.
int	getMaxCallStackDepth() Returns the maximal call stack depth.
protected ReachedSet	getReachedSet() By default the ReachedSet used by the applyBlockAbstraction algorithm is a ProgramLocationDependentReachedSet, this method can be overridden to provide a different reached set.
protected Waitlist	getWaitlist() By default the Waitlist used by the applyBlockAbstraction algorithm is a BreadthFirstWaitlist, this method can be overridden to provide a different waitlist.
CpaWithBamOperators<CfaNodeT,CfaEdgeT,SignatureT>	getWrappedCpa() Returns the wrapped domain-dependent intra-procedural CPA.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BamTransferRelation

public BamTransferRelation(CpaWithBamOperators<CfaNodeT,CfaEdgeT,SignatureT> wrappedCpa,
                           Cfa<CfaNodeT,CfaEdgeT,SignatureT> cfa,
                           SignatureT mainFunction,
                           BamCache<SignatureT> cache)

Create a BAM transfer relation with an unlimited call stack.

Parameters:

wrappedCpa - a wrapped CPA with BAM operators

cfa - a control flow automaton

mainFunction - the signature of the main function of an analyzed program

cache - a cache for the block abstractions

BamTransferRelation

public BamTransferRelation(CpaWithBamOperators<CfaNodeT,CfaEdgeT,SignatureT> wrappedCpa,
                           Cfa<CfaNodeT,CfaEdgeT,SignatureT> cfa,
                           SignatureT mainFunction,
                           BamCache<SignatureT> cache,
                           int maxCallStackDepth,
                           AbortOperator abortOperator)

Create a BAM transfer relation with a specified maximum call stack depth. When the call stack meets its size limit the method call analysis is delegated to the wrapped intra-procedural transfer relation.

Parameters:

wrappedCpa - a wrapped CPA with BAM operators

cfa - a control flow automaton

mainFunction - the signature of the main function of an analyzed program

cache - a cache for the block abstractions

maxCallStackDepth - maximum depth of the call stack analyzed inter-procedurally. 0 means intra-procedural analysis. < 0 means no maximum depth.

abortOperator - an abort operator used for computing block abstractions

Method Detail

generateAbstractSuccessors

public java.util.Collection<? extends AbstractState> generateAbstractSuccessors(AbstractState abstractState,
                                                                                Precision precision)

In order to implement an inter-procedural analysis the abstract successors are calculated for the following cases:

- Run the fixed point algorithm from the entry of the main method, continuing the analysis until a fixed point is reached (i.e. a function summary is provided for each function, also the recursive ones). If there are no recursive calls the fixed point is reached after the first iteration, while in case of recursive calls, depending on the domain-dependent transfer relation, they can be unrolled at each iteration until the fixed point is reached.

- Run the applyBlockAbstraction algorithm at every known procedure call. This algorithm takes care of retrieving the summary of the procedure from the cache (if available) or calls CpaAlgorithm recursively on the new function to compute and store in the cache the summary of the procedure when called from the specified AbstractState (i.e. different parameters or global state result in a different summary). Since we have no information on the code of the target of SymbolicCall this type of calls is delegated to the intra-procedural transfer relation instead of being analyzed by the applyBlockAbstraction algorithm. The result of the block abstraction on the intra-procedural level is simply generating a successor (or successors in case there are multiple call edges, e.g. for unknown runtime type of an object) abstract state that has as location the next node of the Cfa. The recursion can be limited at a maximum call stack size. The intra-procedural transfer relation is also applied in case the max call stack size is reached.

- Apply the underlying intra-procedural transfer relation to all the other non-exit nodes in order to act as the wrapped transfer relation when procedure calls are not involved.

- Exit nodes reached are the base cases of the recursion (along with the stop operator), in this case the transfer relation returns with no successors.

Specified by:

generateAbstractSuccessors in interface TransferRelation

getMaxCallStackDepth

public int getMaxCallStackDepth()

Returns the maximal call stack depth. If negative the maximum call stack depth is unlimited.

getWrappedCpa

public CpaWithBamOperators<CfaNodeT,CfaEdgeT,SignatureT> getWrappedCpa()

Returns the wrapped domain-dependent intra-procedural CPA.

getWaitlist

protected Waitlist getWaitlist()

By default the Waitlist used by the applyBlockAbstraction algorithm is a BreadthFirstWaitlist, this method can be overridden to provide a different waitlist.

getReachedSet

protected ReachedSet getReachedSet()

By default the ReachedSet used by the applyBlockAbstraction algorithm is a ProgramLocationDependentReachedSet, this method can be overridden to provide a different reached set.

getCache

public BamCache<SignatureT> getCache()

Returns BAM cache storing analysis result for various method calls.

getCfa

public Cfa<CfaNodeT,CfaEdgeT,SignatureT> getCfa()

Returns the CFA used by the transfer relation.