78,236 research outputs found
Soft Contract Verification
Behavioral software contracts are a widely used mechanism for governing the
flow of values between components. However, run-time monitoring and enforcement
of contracts imposes significant overhead and delays discovery of faulty
components to run-time.
To overcome these issues, we present soft contract verification, which aims
to statically prove either complete or partial contract correctness of
components, written in an untyped, higher-order language with first-class
contracts. Our approach uses higher-order symbolic execution, leveraging
contracts as a source of symbolic values including unknown behavioral values,
and employs an updatable heap of contract invariants to reason about
flow-sensitive facts. We prove the symbolic execution soundly approximates the
dynamic semantics and that verified programs can't be blamed.
The approach is able to analyze first-class contracts, recursive data
structures, unknown functions, and control-flow-sensitive refinements of
values, which are all idiomatic in dynamic languages. It makes effective use of
an off-the-shelf solver to decide problems without heavy encodings. The
approach is competitive with a wide range of existing tools---including type
systems, flow analyzers, and model checkers---on their own benchmarks.Comment: ICFP '14, September 1-6, 2014, Gothenburg, Swede
Automatic Software Repair: a Bibliography
This article presents a survey on automatic software repair. Automatic
software repair consists of automatically finding a solution to software bugs
without human intervention. This article considers all kinds of repairs. First,
it discusses behavioral repair where test suites, contracts, models, and
crashing inputs are taken as oracle. Second, it discusses state repair, also
known as runtime repair or runtime recovery, with techniques such as checkpoint
and restart, reconfiguration, and invariant restoration. The uniqueness of this
article is that it spans the research communities that contribute to this body
of knowledge: software engineering, dependability, operating systems,
programming languages, and security. It provides a novel and structured
overview of the diversity of bug oracles and repair operators used in the
literature
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Contract-driven data structure repair : a novel approach for error recovery
textSoftware systems are now pervasive throughout our world. The reliability of these systems is an urgent necessity. A large degree of research effort on increasing software reliability is dedicated to requirements, architecture, design, implementation and testing---activities that are performed before system deployment. While such approaches have become substantially more advanced, software remains buggy and failures remain expensive. We take a radically different approach to reliability from previous approaches, namely contract-driven data structure repair for runtime error recovery, where erroneous executions of deployed software are corrected on-the-fly using rich behavioral contracts. Our key insight is to transform the software contract---which gives a high level description of the expected behavior---to an efficient implementation which repairs the erroneous data structures in the program state upon an error. To improve efficiency, scalability, and effectiveness of repair, in addition to rich behavioral contracts, we leverage the current erroneous state, dynamic behavior of the program, as well as repair history and abstraction. A core technical problem our approach to repair addresses is construction of structurally complex data that satisfy desired properties. We present a novel structure generation technique based on dynamic programming---a classic optimization approach---to utilize the recursive nature of the structures. We use our technique for constraint-based testing. It provides better scalability than previous work. We applied it to test widely-used web browsers and found some known and unknown bugs. Our use of dynamic programming in structure generation opens a new future direction to tackle the scalability problem of data structure repair. This research advances our ability to develop correct programs. For programs that already have contracts, error recovery using our approach can come at a low cost. The same contracts can be used for systematically testing code before deployment using existing as well as our new techniques. Thus, we enable a novel unification of software verification and error recovery.Electrical and Computer Engineerin
Contracts and Behavioral Patterns for SoS: The EU IP DANSE approach
This paper presents some of the results of the first year of DANSE, one of
the first EU IP projects dedicated to SoS. Concretely, we offer a tool chain
that allows to specify SoS and SoS requirements at high level, and analyse them
using powerful toolsets coming from the formal verification area. At the high
level, we use UPDM, the system model provided by the british army as well as a
new type of contract based on behavioral patterns. At low level, we rely on a
powerful simulation toolset combined with recent advances from the area of
statistical model checking. The approach has been applied to a case study
developed at EADS Innovation Works.Comment: In Proceedings AiSoS 2013, arXiv:1311.319
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