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README.md

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Collection of Verification Tasks

Repository Description

Purpose

This collection of verification tasks is constructed and maintained as a common benchmark for evaluating the effectiveness and efficiency of state-of-the-art verification technology.

This repository is used by many research groups to evaluate the effectiveness and efficiency of verification algorithms for software. The category structure was developed for the International Competition on Software Verification SV-COMP.

The verification tasks were contributed by several research and development groups. After the submission of verification tasks, a group of people (mainly SV-COMP organizer and participants) are working on improving the quality of the verification tasks. This means that after the sets were made public, some programs were removed (no property encoded, unknown architecture), and some programs got technically improved (compiler warnings, memory model). These changes have improved the overall quality of the final set of programs for the competition SV-COMP, and have not changed the intended verification result; all changes are tracked in the public repository.

This repository is open for submission of new verification tasks! Please refer to our contribution guidelines to see how to submit verification tasks to this repository.

Thanks to all contributors of programs, patches, and discussion comments.

Structure

The collection consists of three directories, which contain verification tasks written in different languages:

  • c/ (programming language C, follows the GNU C standard, many programs even adhere to ANSI C)
  • java/ (programming language Java)
  • causes/ (systems from the other directories translated to Horn clauses and stored in SMT format)

License

The programs are under different licenses, which are specified either via a file LICENSE*.txt in the same directory, or via a comment in the program header. Most of the programs are under an open-source license such as Apache 2.0 or GPL.

Origin, Description, and Attribution

The subdirectories that contain the programs contain files README.txt, which give further information about the programs, in particular, this is the place to trace the origin and to attribute the programs to their contributors. For some programs, this information is given in the header of the program as comment.

Categories

The verification tasks for C programs are grouped into (sub-)categories as defined by SV-COMP.

A (sub-)category <category> is defined by the following three files:

  • <category>.set contains patterns that specify the set of programs,
  • <category>.prp contains the specification, and
  • <category>.cfg contains the parameters (and a description of the (sub-)category).

Definitions

The following definitions are taken from the SV-COMP report 2016 (and previous years).

A verification task consists of

A category is a set of verification tasks.

A sub-category is a set of verification tasks that consist of the same specification and the same parameters as specified in the corresponding .cfg and .prp files.

A verification run is

  • a non-interactive execution
  • of one verification tool
  • on one verification task
  • under specific resource constraints in order to check whether the following statement is correct: "The program satisfies the specification."

A verification result is a triple (ANSWER, WITNESS, TIME) with

  • ANSWER is an element from {TRUE, FALSE, UNKNOWN},
  • WITNESS is a violation witness or correctness witness in the common witness format that supports validation of the (untrusted) answer, and
  • TIME is the CPU time that the verification run has consumed (in practice, also other resource measurement values are reported).

Programs

The program files in this repository are named as follows:

  • the original file name or short title of the program is given at the beginning,
  • for each property against which the program is to be verified, the string _false-<property> or _true-<property> is included, according to the expected verification answer, and
  • the filename ends with ending .c for not preprocessed files and .i for preprocessed files (for C files).

For example, the program minepump_spec5_product61_true-unreach-call_false-termination.cil.c is expected to satisfy property unreach-call and to violate property termination.

There are some old programs that have ending .c although they are preprocessed.

Specifications

There are several 'default' specifications that many people use:

  • unreach-call: A certain function call must not be reachable in the program.
  • valid-memsafety, valid-deref, valid-free, valid-memtrack: A certain memory safety property must hold in the program. "memsafety" is the conjunction the other three properties.
  • valid-memcleanup: All allocated memory must be deallocated before the program terminates (note that this is stronger then avoiding memory leaks).
  • no-overflow: A certain kind of undefined behavior (overflows of signed ints) must not be present in the program.
  • termination: The program must terminate on all execution paths.

The above specifications are used, e.g., by SV-COMP, and the rules page explains those specifications.

Parameters

The paramaters of a verification task are needed to make additional information about the verification task available to the verification run. The most prominent parameter is the machine model; currently, there are verification tasks for the ILP32 (32-bit) and the LP64 (64-bit) architecture (cf. http://www.unix.org/whitepapers/64bit.html).

Templates for Verification Tasks

In order to obtain a verification task from the programs and specifications in the repository, a simple template mechanism is used. For each program, the repository contains a .yml file that specifies

  • the subject files (the parts that a program consists of),
  • the results (for each specification of the program, the expected outcome is indicated), and
  • the parameters to be used for verification.