Static program analysis

This article is about certain software quality assessment methods. For the statistical method, see Static analysis.

Static program analysis (also Static code analysis or SCA) is the analysis of computer software that is performed without actually executing programs built from that software (analysis performed on executing programs is known as dynamic analysis)^[1] In most cases the analysis is performed on some version of the source code and in the other cases some form of the object code. The term is usually applied to the analysis performed by an automated tool, with human analysis being called program understanding, program comprehension or code review.

The sophistication of the analysis performed by tools varies from those that only consider the behavior of individual statements and declarations, to those that include the complete source code of a program in their analysis. Uses of the information obtained from the analysis vary from highlighting possible coding errors (e.g., the lint tool) to formal methods that mathematically prove properties about a given program (e.g., its behavior matches that of its specification).

It can be argued that software metrics and reverse engineering are forms of static analysis. In fact deriving software metrics and static analysis are increasingly deployed together, especially in creation of embedded systems, by defining so called software quality objectives^[2].

A growing commercial use of static analysis is in the verification of properties of software used in safety-critical computer systems and locating potentially vulnerable code^[3]. For example the following industries have identified the use of static code analysis as a means of improving the quality of increasingly sophisticated and complex software:

1. Medical software: In the U.S. Food and Drug Administration (FDA) has identified the use of static analysis for medical devices.^[4]
2. Nuclear software: In the UK the Health and Safety Executive recommends the use of Static Analysis on Reactor Protection Systems.^[5]

In application security industry also Static Application Security Testing (SAST) name is used.

Tools

Main article: List of tools for static code analysis

Formal methods

Formal methods is the term applied to the analysis of software (and hardware) whose results are obtained purely through the use of rigorous mathematical methods. The mathematical techniques used include denotational semantics, axiomatic semantics, operational semantics, and abstract interpretation.

By a straightforward reduction to the halting problem it is possible to prove that (for any Turing complete language) finding all possible run-time errors in an arbitrary program (or more generally any kind of violation of a specification on the final result of a program) is undecidable: there is no mechanical method that can always answer truthfully whether a given program may or may not exhibit runtime errors. This result dates from the works of Church, Gödel and Turing in the 1930s (see the halting problem and Rice's theorem). As with most^{[citation needed]} undecidable questions, one can still attempt to give useful approximate solutions.

Some of the implementation techniques of formal static analysis include:

• Model checking considers systems that have finite state or may be reduced to finite state by abstraction;
• Data-flow analysis is a lattice-based technique for gathering information about the possible set of values;
• Abstract interpretation models the effect that every statement has on the state of an abstract machine (i.e., it 'executes' the software based on the mathematical properties of each statement and declaration). This abstract machine over-approximates the behaviours of the system: the abstract system is thus made simpler to analyze, at the expense of incompleteness (not every property true of the original system is true of the abstract system). If properly done, though, abstract interpretation is sound (every property true of the abstract system can be mapped to a true property of the original system).^[6] The Frama-c framework and Polyspace heavily rely on abstract interpretation.
• Use of assertions in program code as first suggested by Hoare logic. There is tool support for some programming languages (e.g., the SPARK programming language (a subset of Ada) and the Java Modeling Language — JML — using ESC/Java and ESC/Java2, ANSI/ISO C Specification Language for the C language).

See also

Software Testing portal

• Program analysis (computer science)
• Dynamic program analysis
• Shape analysis (software)
• Formal semantics of programming languages
• Formal verification
• Software testing
• Documentation generator
• List of tools for static code analysis

References

1. ^ Industrial Perspective on Static Analysis. Software Engineering Journal Mar. 1995: 69-75Wichmann, B. A., A. A. Canning, D. L. Clutterbuck, L. A. Winsbarrow, N. J. Ward, and D. W. R. Marsh. http://www.ida.liu.se/~TDDC90/papers/industrial95.pdf
2. ^ Software Quality Objectives for Source Code. Proceedings Embedded Real Time Software and Systems 2010 Conference, ERTS2, Toulouse, France: Patrick Briand, Martin Brochet, Thierry Cambois, Emmanuel Coutenceau, Olivier Guetta, Daniel Mainberte, Frederic Mondot, Patrick Munier, Loic Noury, Philippe Spozio, Frederic Retailleau http://www.erts2010.org/Site/0ANDGY78/Fichier/PAPIERS%20ERTS%202010/ERTS2010_0035_final.pdf
3. ^ Improving Software Security with Precise Static and Runtime Analysis, Benjamin Livshits, section 7.3 “Static Techniques for Security,” Stanford doctoral thesis, 2006. http://research.microsoft.com/en-us/um/people/livshits/papers/pdf/thesis.pdf
4. ^ FDA (2010-09-08). "Infusion Pump Software Safety Research at FDA". Food and Drug Administration. http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/GeneralHospitalDevicesandSupplies/InfusionPumps/ucm202511.htm. Retrieved 2010-09-09. 
5. ^ Computer based safety systems - technical guidance for assessing software aspects of digital computer based protection systems, http://www.hse.gov.uk/foi/internalops/nsd/tech_asst_guides/tast046app1.htm
6. ^ Jones, Paul (2010-02-09). "A Formal Methods-based verification approach to medical device software analysis". Embedded Systems Design. http://embeddeddsp.embedded.com/design/opensource/222700533. Retrieved 2010-09-09. 

Bibliography

• Syllabus and readings for Alex Aiken’s Stanford CS295 course.
• Nathaniel Ayewah, David Hovemeyer, J. David Morgenthaler, John Penix, William Pugh, “Using Static Analysis to Find Bugs,” IEEE Software, vol. 25, no. 5, pp. 22-29, Sep./Oct. 2008, doi:10.1109/MS.2008.130
• Brian Chess, Jacob West (Fortify Software) (2007). Secure Programming with Static Analysis. Addison-Wesley. ISBN 978-0321424778. 
• Flemming Nielson, Hanne R. Nielson, Chris Hankin (1999, corrected 2004). Principles of Program Analysis. Springer. ISBN 978-3540654100. 
• “Abstract interpretation and static analysis,” International Winter School on Semantics and Applications 2003, by David A. Schmidt

External links

• The SAMATE Project, a resource for Automated Static Analysis tools
• Integrate static analysis into a software development process
• Code Quality Improvement - Coding standards conformance checking (DDJ)
• Episode 59: Static Code Analysis Interview (Podcast) at Software Engineering Radio
• Implementing Automated Governance for Coding Standards Explains why and how to integrate static code analysis into the build process
• What is Static Code Analysis? explanation in Hebrew (Hebrew: ?מהו ניתוח קוד סטטי‎)
• .NET Static Analysis (InfoQ)