The OPAL Framework5.0.0 < Back

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package root
Definition Classes
root
package org
Definition Classes
root
package opalj
OPAL is a Scala-based framework for the static analysis, manipulation and creation of Java bytecode.
OPAL is a Scala-based framework for the static analysis, manipulation and creation of Java bytecode. OPAL is designed with performance, scalability and adaptability in mind.
Its main components are:
- a library (Common) which provides generally useful data-structures and algorithms for static analyses.
- a framework for implementing lattice based static analyses (Static Analysis Infrastructure)
- a framework for parsing Java bytecode (Bytecode Infrastructure) that can be used to create arbitrary representations.
- a library to create a one-to-one in-memory representation of Java bytecode (Bytecode Disassembler).
- a library to create a representation of Java bytecode that facilitates writing simple static analyses (Bytecode Representation - org.opalj.br).
- a scalable, easily customizable framework for the abstract interpretation of Java bytecode (Abstract Interpretation Framework - org.opalj.ai).
- a library to extract dependencies between code elements and to facilitate checking architecture definitions.
- a library for the lightweight manipulation and creation of Java bytecode (Bytecode Assembler).
General Design Decisions
Thread Safety
Unless explicitly noted, OPAL is thread safe. I.e., the classes defined by OPAL can be considered to be thread safe unless otherwise stated. (For example, it is possible to read and process class files concurrently without explicit synchronization on the client side.)
No null Values
Unless explicitly noted, OPAL does not null values I.e., fields that are accessible will never contain null values and methods will never return null. If a method accepts null as a value for a parameter or returns a null value it is always explicitly documented. In general, the behavior of methods that are passed null values is undefined unless explicitly documented.
No Typecasts for Collections
For efficiency reasons, OPAL sometimes uses mutable data-structures internally. After construction time, these data-structures are generally represented using their generic interfaces (e.g., scala.collection.{Set,Map}). However, a downcast (e.g., to add/remove elements) is always forbidden as it would effectively prevent thread-safety.
Assertions
OPAL makes heavy use of Scala's Assertion Facility to facilitate writing correct code. Hence, for production builds (after thorough testing(!)) it is highly recommend to build OPAL again using -Xdisable-assertions.
Definition Classes
org
package ai
Implementation of an abstract interpretation (ai) framework – also referred to as OPAL.
Implementation of an abstract interpretation (ai) framework – also referred to as OPAL.
Please note that OPAL/the abstract interpreter just refers to the classes and traits defined in this package (ai). The classes and traits defined in the sub-packages (in particular in domain) are not considered to be part of the core of OPAL/the abstract interpreter.
Definition Classes
opalj
Note
This framework assumes that the analyzed bytecode is valid; i.e., the JVM's bytecode verifier would be able to verify the code. Furthermore, load-time errors (e.g., LinkageErrors) are – by default – completely ignored to facilitate the analysis of parts of a project. In general, if the presented bytecode is not valid, the result is undefined (i.e., OPAL may report meaningless results, crash or run indefinitely).
See also
org.opalj.ai.AI - Implements the abstract interpreter that processes a methods code and uses an analysis-specific domain to perform the abstract computations.
org.opalj.ai.Domain - The core interface between the abstract interpretation framework and the abstract domain that is responsible for performing the abstract computations.
package common
Definition Classes
ai
package domain
This package contains definitions of common domains that can be used for the implementation of analyses.
This package contains definitions of common domains that can be used for the implementation of analyses.
Types of Domains
In general, we distinguish two types of domains. First, domains that define a general interface (on top of the one defined by Domain), but do not directly provide an implementation. Hence, whenever you develop a new Domain you should consider implementing/using these domains to maximize reusability. Second, Domains that implement a specific interface (trait). In this case, we further distinguish between domains that provide a default implementation (per interface only one of these Domains can be used to create a final Domain) and those that can be stacked and basically refine the overall functionality.
Examples
- Domains That Define a General Interface
  - Origin defines two types which domains that provide information abou the origin of a value should consider to implement.
  - TheProject defines a standard mechanism how a domain can access the current project.
  - ...
- Domains That Provide a Default Implementation
  - Origin defines the functionality to return a value's origin if the value supports that.
  - org.opalj.ai.domain.TheProject default implementation of the class hierarchy related methods using the project's class hierarchy.
  - org.opalj.ai.domain.DefaultHandlingOfMethodResults basically implements a Domain's methods related to return instructions an uncaught exceptions.
  - ...
- Domains That Implement Stackable Functionality
  - org.opalj.ai.domain.RecordThrownExceptions records information about all uncaught exceptions by intercepting a Domain's respective methods. However, it does provide a default implementation. Hence, a typical pattern is:
```
class MyDomain extends Domain with ...
    with DefaultHandlingOfMethodResults with RecordThrownExceptions
```
Thread Safety
Unless explicitly documented, a domain is never thread-safe. The general programming model is to use one Domain object per code block/method and therefore, thread-safety is not required for Domains that are used for the evaluation of methods. However domains that are used to adapt/transfer values should be thread safe (see org.opalj.ai.domain.ValuesCoordinatingDomain for further details).
Definition Classes
ai
package fpcf
Definition Classes
ai
package project
Definition Classes
ai
package util
Common utility functionality.
Common utility functionality.
Definition Classes
ai
AI
AIAborted
AICompleted
AIException
AIResult
AIResultBuilder
AITracer
BaseAI
BoundedInterruptableAI
CTC1
CTC2
Computation
ComputationFailed
ComputationWithException
ComputationWithResult
ComputationWithResultAndException
ComputationWithSideEffectOnly
ComputationWithSideEffectOrException
ComputedValue
ComputedValueOrException
Configuration
CoreDomainFunctionality
CorrelationalDomain
CorrelationalDomainSupport
CountingAI
CustomInitialization
Domain
DomainException
DoubleValuesDomain
DoubleValuesFactory
DynamicLoadsDomain
ExceptionsFactory
ExceptionsRaisedByCalledMethods
FieldAccessesDomain
FloatValuesDomain
FloatValuesFactory
GlobalLogContextProvider
IdentityBasedCorrelationChangeDetection
InstructionCountBoundedAI
IntegerRangeValuesFactory
IntegerValuesDomain
IntegerValuesFactory
InterpretationFailedException
InterruptableAI
JoinStabilization
LogContextProvider
LongValuesDomain
LongValuesFactory
MetaInformationUpdate
MetaInformationUpdateType
MethodCallsDomain
MonitorInstructionsDomain
MultiTracer
NoUpdate
NoUpdateType
PrimitiveValuesConversionsDomain
ReferenceValuesDomain
ReferenceValuesFactory
ReturnInstructionsDomain
SomeUpdate
StructuralUpdate
StructuralUpdateType
SubroutinesDomain
TheAI
TheCodeStructure
TheMemoryLayout
ThrowsException
TimeBoundedAI
TypedValuesFactory
Update
UpdateType
ValuesDomain

org.opalj.ai

AITracer

trait AITracer extends AnyRef

Defines the interface between the abstract interpreter and a module for tracing and debugging the interpreter's progress. In general, a tracer is first registered with an abstract interpreter. After that, when a method is analyzed, the AI calls the tracer's methods at the respective points in time.

A tracer is registered with an abstract interpreter by creating a new subclass of AI and overriding the method AI.tracer.

Source: AITracer.scala
Note: All data structures passed to the tracer are the original data structures used by the abstract interpreter. Hence, if a value is mutated (e.g., for debugging purposes) it has to be guaranteed that the state remains meaningful. Hence, using the AITracer it is possible to develop a debugger for OPAL and to enable the user to perform certain mutations.

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abstract def abruptMethodExecution(domain: Domain)(pc: Int, exception: Domain.ExceptionValue): Unit
Called when the analyzed method throws an exception that is not caught within the method.
Called when the analyzed method throws an exception that is not caught within the method. I.e., the interpreter evaluates an athrow instruction or some other instruction that throws an exception.
abstract def abruptSubroutineTermination(domain: Domain)(details: String, sourcePC: Int, targetPC: Int, jumpToSubroutineId: Int, terminatedSubroutinesCount: Int, forceScheduling: Boolean, oldWorklist: List[Int], newWorklist: List[Int]): Unit
Called when the evaluation of a subroutine terminated abruptly due to an unhandled exception.
Called when the evaluation of a subroutine terminated abruptly due to an unhandled exception.
jumpToSubroutineId
The subroutine that will be continued. The id is the pc of the first instruction of the subroutine. It is 0 if it is the method as such.
terminatedSubroutinesCount
The number of subroutines that are terminated.
abstract def continuingInterpretation(code: Code, domain: Domain)(initialWorkList: List[Int], alreadyEvaluatedPCs: IntArrayStack, operandsArray: Domain.OperandsArray, localsArray: Domain.LocalsArray, memoryLayoutBeforeSubroutineCall: List[(Int, Domain.OperandsArray, Domain.LocalsArray)]): Unit
Called immediately before the abstract interpretation of the specified code is performed.
Called immediately before the abstract interpretation of the specified code is performed.
If the tracer changes the operandsArray and/or localsArray, it is the responsibility of the tracer to ensure that the data structures are still valid afterwards.
abstract def deadLocalVariable(domain: Domain)(pc: Int, lvIndex: Int): Unit
Called by the interpret when a local variable with the given index (lvIndex) was set to a new value and, therefore, the reference stored in the local variable previously was useless/dead.
abstract def domainMessage(domain: Domain, source: Class[_], typeID: String, pc: Option[Int], message: => String): Unit
Called by the domain if something noteworthy was determined.
Called by the domain if something noteworthy was determined.
domain
The domain.
source
The class (typically the (partial) domain) that generated the message.
typeID
A String that identifies the message. This value must not be null, but it can be the empty string.
message
The message; a non-null String that is formatted for the console.
abstract def establishedConstraint(domain: Domain)(pc: Int, effectivePC: Int, operands: Domain.Operands, locals: Domain.Locals, newOperands: Domain.Operands, newLocals: Domain.Locals): Unit
Called by the framework if a constraint is established.
Called by the framework if a constraint is established. Constraints are generally established whenever a conditional jump is performed and the evaluation of the condition wasn't definitive. In this case a constraint will be established for each branch. In general the constraint will be applied before the join of the stack and locals with the successor instruction is done.
abstract def flow(domain: Domain)(currentPC: Int, targetPC: Int, isExceptionalControlFlow: Boolean): Unit
Called by the interpreter after an instruction (currentPC) was evaluated and before the instruction with the program counter targetPC may be evaluated.
Called by the interpreter after an instruction (currentPC) was evaluated and before the instruction with the program counter targetPC may be evaluated.
This method is only called if the instruction with the program counter targetPC will be evaluated in the future and was not yet scheduled. I.e., when the abstract interpreter determines that the evaluation of an instruction does not change the abstract state (associated with the successor instruction) and, therefore, will not schedule the successor instruction this method is not called.
In case of if or switch instructions flow may be called multiple times (even with the same targetPC) before the method instructionEvaluation is called again.
Note
OPAL performs a depth-first exploration. However, subroutines are always first finished analyzing before an exception handler - that handles abrupt executions of the subroutine - is evaluated.
abstract def initialLocals(domain: Domain)(locals: Domain.Locals): Unit
The set of initial locals computed when the method is interpreted for the first time.
abstract def instructionEvalution(domain: Domain)(pc: Int, instruction: Instruction, operands: Domain.Operands, locals: Domain.Locals): Unit
Called before an instruction is evaluated.
Called before an instruction is evaluated.
This enables the tracer to precisely log the behavior of the abstract interpreter, but also enables the tracer to interrupt the evaluation to, e.g., enable stepping through a program.
operands
The operand stack before the execution of the instruction.
locals
The registers before the execution of the instruction.
abstract def join(domain: Domain)(pc: Int, thisOperands: Domain.Operands, thisLocals: Domain.Locals, otherOperands: Domain.Operands, otherLocals: Domain.Locals, result: Update[(Domain.Operands, Domain.Locals)]): Unit
Called by the abstract interpreter whenever two paths converge and the values on the operand stack and the registers are joined.
Called by the abstract interpreter whenever two paths converge and the values on the operand stack and the registers are joined.
thisOperands
The operand stack as it was used the last time when the instruction with the given program counter was evaluated.
thisLocals
The registers as they were used the last time when the instruction with the given program counter was evaluated.
otherOperands
The current operand stack when we re-reach the instruction
otherLocals
The current registers.
result
The result of joining the operand stacks and register assignment.
abstract def jumpToSubroutine(domain: Domain)(pc: Int, target: Int, nestingLevel: Int): Unit
Called before a jump to a subroutine.
abstract def noFlow(domain: Domain)(currentPC: Int, targetPC: Int): Unit
Called by the interpreter if a successor instruction is NOT scheduled, because the abstract state didn't change.
abstract def rescheduled(domain: Domain)(sourcePC: Int, targetPC: Int, isExceptionalControlFlow: Boolean, worklist: List[Int]): Unit
Called if the instruction with the targetPC was already scheduled.
Called if the instruction with the targetPC was already scheduled. I.e., the instruction was already scheduled for evaluation, but is now moved to the first position in the list of all instructions to be executed (related to the specific subroutine). A rescheduled event is also issued if the instruction was the the first in the list of instructions executed next. However, further instructions may be appended to the list before the next instructionEvaluation takes place.
Note
OPAL performs a depth-first exploration.
abstract def result(result: AIResult): Unit
Called when the abstract interpretation of a method has completed/was interrupted.
abstract def ret(domain: Domain)(pc: Int, returnAddressPC: Int, oldWorklist: List[Int], newWorklist: List[Int]): Unit
Called when a RET instruction is encountered.
Called when a RET instruction is encountered. (That does not necessary imply that the evaluation of the subroutine as such has finished. It is possible that other paths still need to be pursued.)
abstract def returnFromSubroutine(domain: Domain)(pc: Int, returnAddressPC: Int, subroutinePCs: List[Int]): Unit
Called when the evaluation of a subroutine (JSR/RET) as a whole is completed.
Called when the evaluation of a subroutine (JSR/RET) as a whole is completed. I.e., all possible paths are analyzed and the fixpoint is reached.

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General Design Decisions

Thread Safety

No `null` Values

No Typecasts for Collections

Assertions

Types of Domains

Thread Safety

AITracer

trait AITracer extends AnyRef

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No null Values

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Thread Safety

AITracer

trait AITracer extends AnyRef

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AITracer