Open source case studies for Frama-C

This repository is a collection of open source C codes to be used with Frama-C, in particular with the Eva (Evolved Value Analysis) plug-in.

Most directories contain open-source code that constitutes a "case study". A few contain sets of tests, benchmarks or tutorials.

Requirements

• GNU Make >= 4.0;
• (optional, for some scripts) Python >= 3.6.

Basic usage

• (required once) make submodules: initializes the local Frama-C submodule;
• (required once) make framac: prepares a git submodule with a clone of the public git of Frama-C, compiles it and installs it locally (in frama-c/build/bin);
• cd to one of the case studies; We recommend 2048 for a short and fast analysis, or debie1 for a finalized analysis.
• Run make to parse and run Eva on the predefined targets.

Makefile targets

The scripts provided with Frama-C create several Makefile targets, according to the intended usage. The main ones are:

• help: lists the base targets
• For each base target t, the following targets are generated:
  • t.parse: parse the sources;
  • t.eva: run Eva;
  • t.eva.gui: open the GUI.

Each target depends on the previous one: running t.eva.gui will automatically run t.eva if required; the same for t.parse.

Other generated targets:

• t.parse.gui: open the GUI with the result of the parsing, without running Eva. Mostly useful in conjunction with other plug-ins.
• t.stats: print time/memory usage.

Remarks

• The output of t.eva is verbose, but you can ignore it; the important information (warnings and alarms) can be inspected via the GUI.
• The result of each analysis is stored in a directory containing the full logs and Frama-C save files; successive runs are copied into timestamped directories, to allow comparing them (e.g. via meld);
• To try other parametrizations, simply edit variables CPPFLAGS/FCFLAGS/EVAFLAGS in GNUmakefile and re-run make.
• Technical remark: the default file used by GNU Make is GNUmakefile, if it exists. We use this to avoid renaming the original Makefile, if any. It also means that, if you want to compile the code using its Makefile, you have to explicitly name it (e.g. make -f Makefile).

Notes

Source code modifications

Only minor modifications were performed on each of these case studies:

• File GNUmakefile is added to each case study, with Frama-C/Eva-specific rules for parsing and running the analysis;
• When necessary, syntactic modifications were performed to ensure better C99-compliance and/or the inclusion of stubs to allow Frama-C to parse the files;
• In some cases, an eva_main function was added to provide a better initial context for the analysis;
• When recursive calls are present, the functions containing them need to be replaced with specifications;
• Some ACSL annotations were added to the sources (to illustrate their usage, or to improve the analysis);
• Some unnecessary files for the analysis (e.g. documentation, project setups for IDEs, non-code resources) were removed.

Rationale

The main objectives of these files are:

1. Non-regression tests;
2. Benchmarking;
3. Practical examples.

Therefore, some of the code bases are voluntarily parametrized with suboptimal parameters, for non-regression testing. Some code bases undergo partial, progressive improvements. Only a few constitute "finalized" case studies.

Contributions

If you know of other open source code bases where Frama-C/Eva produces interesting results, please contribute with pull requests including the sources and the GNUmakefile that you have devised to run Frama-C.

On the other hand, if you have some interesting open-source C software (ideally, C99-compatible) that you are unable to parse and/or run with Frama-C/Eva, consider creating an issue in this repository¹ with the description of the problem you are facing (e.g. missing/incompatible declarations in the Frama-C libc, problems when preprocessing/parsing the code, constructs unsupported by Eva, etc). Ideally, create a (WIP) pull request with the sources in a new directory, ready to be prepared for the case study.

¹ Note: direct account creation is disabled in Frama-C's Gitlab; linking a Github account is always possible.

License

License files are kept in each directory where they were originally found, when available. We also summarize the license of each directory below.

• 2048: MIT
• basic-cwe-examples: see LICENSE
• chrony: GPL
• debie1: distribution and use authorized by Patria Aviation Oy, Space Systems Finland Ltd. and Tidorum Ltd, see README.txt and terms_of_use-2014-05.pdf
• gzip124: GPL
• hiredis: Redis license (BSD-style), see COPYING
• icpc: Unlicense
• itc-benchmarks: BSD 2-clause, see COPYING
• jsmn: MIT
• khash: MIT
• kilo: BSD 2-clause "Simplified" (see https://github.com/antirez/kilo/blob/master/LICENSE)
• libmodbus: LGPL
• libspng: BSD 2-clause, see LICENSE
• mibench: several (see LICENSE file inside each subdirectory)
• mini-gmp: LGPL or GPL
• microstrain: GPL and others, see LICENSE
• monocypher: see README
• papabench: GPL
• polarssl: GPL
• qlz: GPL
• safestringlib: MIT
• semver: MIT
• solitaire: public domain (see solitaire.c)
• tweetnacl-usable: public domain (see LICENSE.txt)
• x509-parser : GPLv2 / BSD (see LICENSE)