Affiliations: [a] VRAIN, Universitat Politècnica de València, Camino de Vera s/n, Valencia, Spain. alpuente@upv.es | [b] DSIC, Universitat Politècnica de València, Valencia, Spain. daparpon@dsic.upv.es | [c] VRAIN, Universitat Politècnica de València, Camino de Vera s/n, Valencia, Spain. alvilga1@upv.es
Correspondence:
[‡]
Address for correspondence: VRAIN, Universitat Politècnica de València, Camino de Vera s/n, Valencia, Spain.
Note: [*] This work has been partially supported by the EC H2020-EU grant agreement No. 952215 (TAILOR), the EU (FEDER) and the Spanish MCIU under grant RTI2018-094403-B-C32, by Generalitat Valenciana under grant PROMETEO/2019/098.
Note: [†] Daniel Pardo was supported by FPU-ME grant FPU14/01830.
Abstract: In this article, we propose a symbolic technique that can be used for automatically inferring software contracts from programs that are written in a non-trivial fragment of C, called KERNELC, that supports pointer-based structures and heap manipulation. Starting from the semantic definition of KERNELC in the 𝕂 semantic framework, we enrich the symbolic execution facilities recently provided by 𝕂 with novel capabilities for contract synthesis that are based on abstract subsumption. Roughly speaking, we define an abstract symbolic technique that axiomatically explains the execution of any (modifier) C function by using other (observer) routines in the same program. We implemented our technique in the automated tool KINDSPEC 2.1, which generates logical axioms that express pre- and post-condition assertions which define the precise input/output behavior of the C routines. Thanks to the integrated support for symbolic execution and deductive verification provided by 𝕂, some synthesized axioms that cannot be guaranteed to be correct by construction due to abstraction can finally be verified in our setting with little effort.
