Improving pattern tracking with a language-aware tree differencing algorithm

International audienceTracking code fragments of interest is important in monitoring a software project over multiple versions. Various approaches, including our previous work on Herodotos, exploit the notion of Longest Common Subsequence, as computed by readily available tools such as GNU Diff, to map corresponding code fragments. Nevertheless, the efficient code differencing algorithms are typically line-based or word-based, and thus do not report changes at the level of language constructs. Furthermore, they identify only additions and removals, but not the moving of a block of code from one part of a file to another. Code fragments of interest that fall within the added and removed regions of code have to be manually correlated across versions, which is tedious and error-prone. When studying a very large code base over a long time, the number of manual correlations can become an obstacle to the success of a study. In this paper, we investigate the effect of replacing the current line-based algorithm used by Herodotos by tree-matching, as provided by the algorithm of the differencing tool GumTree. In contrast to the line-based approach, the tree-based approach does not generate any manual correlations, but it incurs a high execution time. To address the problem, we propose a hybrid strategy that gives the best of both approaches

Faults in Linux 2.6

In August 2011, Linux entered its third decade. Ten years before, Chou et al. published a study of faults found by applying a static analyzer to Linux versions 1.0 through 2.4.1. A major result of their work was that the drivers directory contained up to 7 times more of certain kinds of faults than other directories. This result inspired numerous efforts on improving the reliability of driver code. Today, Linux is used in a wider range of environments, provides a wider range of services, and has adopted a new development and release model. What has been the impact of these changes on code quality? To answer this question, we have transported Chou et al.'s experiments to all versions of Linux 2.6; released between 2003 and 2011. We find that Linux has more than doubled in size during this period, but the number of faults per line of code has been decreasing. Moreover, the fault rate of drivers is now below that of other directories, such as arch. These results can guide further development and research efforts for the decade to come. To allow updating these results as Linux evolves, we define our experimental protocol and make our checkers available

Improving the security of infrastructure software using Coccinelle

International audienceFinding and fixing programming errors in deployed software is often a slow, painstaking, and expensive process. In order to minimise this problem, static analysis is increasingly being adopted as a way to find programming errors before the software application is released. Coccinelle is a program matching and transfor-mation tool that makes it easy for developers to express static analysis-based software defect-finding rules and scan software source code for potential defects

Clang and Coccinelle:synergising program analysis tools for CERT C Secure Coding Standard certification

Writing correct C programs is well-known to be hard, not least due to the many language features intrinsic to C. Writing secure C programs is even harder and, at times, seemingly impossible. To improve on this situation the US CERT has developed and published a set of coding standards, the “CERT C Secure Coding Standard”, that (in the current version) enumerates 118 rules and 182 recommendations with the aim of making C programs (more) secure. The large number of rules and recommendations makes automated tool support essential for certifying that a given system is in compliance with the standard. In this paper we report on ongoing work on integrating two state of the art analysis tools, Clang and Coccinelle, into a combined tool well suited for analysing and certifying C programs according to, e.g., the CERT C Secure Coding standard or the MISRA (the Motor Industry Software Reliability Assocation) C standard. We further argue that such a tool must be highly adaptable and customisable to each software project as well as to the certification rules required by a given standard. Clang is the C frontend for the LLVM compiler/virtual machine project which includes a comprehensive set of static analyses and code checkers. Coccinelle is a program transformation tool and bug-finder developed originally for the Linux kernel, but has been successfully used to find bugs in other Open Source projects such as WINE and OpenSSL

Clang and Coccinelle: Synergising program analysis tools for CERT C Secure Coding Standard certification

Writing correct C programs is well-known to be hard, not least due to the many language features intrinsic to C. Writing secure C programs is even harder and, at times, seemingly impossible. To improve on this situation the US CERT has developed and published a set of coding standards, the “CERT C Secure Coding Standard”, that (in the current version) enumerates 118 rules and 182 recommendations with the aim of making C programs (more) secure. The large number of rules and recommendations makes automated tool support essential for certifying that a given system is in compliance with the standard. In this paper we report on ongoing work on integrating two state of the art analysis tools, Clang and Coccinelle, into a combined tool well suited for analysing and certifying C programs according to, e.g., the CERT C Secure Coding standard or the MISRA (the Motor Industry Software Reliability Assocation) C standard. We further argue that such a tool must be highly adaptable and customisable to each software project as well as to the certification rules required by a given standard. Clang is the C frontend for the LLVM compiler/virtual machine project which includes a comprehensive set of static analyses and code checkers. Coccinelle is a program transformation tool and bug-finder developed originally for the Linux kernel, but has been successfully used to find bugs in other Open Source projects such as WINE and OpenSSL

Herodotos: A Tool to Expose Bugs' Lives

Software is continually evolving, to improve performance, correct errors, and add new features. Code modifications, however, inevitably lead to the introduction of defects. To prevent the introduction of defects, one has to understand why they occur. Thus, it is important to develop tools and practices that aid in defect finding, tracking and prevention. In this paper, we propose a methodology and associated tool, Herodotos, to study defects over time. Herodotos semi-automatically tracks defects over multiple versions of a software project, independent of other changes in the source files. It builds a graphical history of each defect and gives some statistics based on the results. We have evaluated this approach on the history of a representative range of open source projects over the last three years. For each project, we explore several kinds of defects that have been found by static code analysis. We analyze the generated results to compare the selected software projects and defect kinds

A Stepwise Approach to Developing Languages for SIP Telephony Service Creation

International audienceDeveloping a SIP-based telephony service requires a programmer to have expertise in telephony rules and constraints, the SIP protocol, distributed systems, and a SIP API, which is often large and complex. These requirements make the development of telephony software an overwhelming challenge. To overcome this challenge, various programming languages have been proposed to develop telephony services. Nevertheless, none of these languages as yet has a formal semantics. Therefore, the reference implementation, which may not be available, becomes the only source of information for the programmer to understand the subtleties of the language. Furthermore, this situation makes it difficult for third-party developers to port the language to another runtime system or to provide another implementation of the runtime system. This paper presents a semantics-based stepwise approach for designing and developing a scripting language dedicated to the development of telephony services. This approach enables critical properties of services to be guaranteed and captures expertise on the operational behavior of a service. We have applied this approach to developing the Session Processing Language (SPL) [3] dedicated to SIP-based service creation. A variety of services have been written in SPL for our university department

Pantaxou: a Domain-Specific Language for Developing Safe Coordination Services

International audienceCoordinating entities in a networked environment has always been a significant challenge for software developers. In recent years, however, it has become even more difficult, because devices have increasingly rich capabilities, combining an ever larger range of technologies (networking, multimedia, sensors, etc.). To address this challenge, we propose a language-based approach to covering the life-cycle of applications coordinating networked entities. Our approach covers the characterization of the networked environment, the specification of coordination applications, the verification of a networked environment and its deployment. It is carried out in practice by a domain-specific language, named Pantaxou. This paper presents the domain-specific language Pantaxou, dedicated to the development of applications for networked heterogeneous entities. Pantaxou has been used to specify a number of coordination scenarios in areas ranging from home automation to telecommunications. The language semantics has been formally defined and a compiler has been developed. The compiler verifies the coherence of a coordination scenario and generates coordination code in Java

A Domain-Specific IDL and its Compiler for Pervasive Computing Applications

Pervasive computing environments introduce new challenges for application development, due to the heterogeneity of the devices involved. In practice, pervasive computing applications rely on general-purpose middleware to manage this heterogeneity, but this approach does not provide programming support and verifications specific to the pervasive computing environment. In this paper, we present a domain-specific IDL and its compiler, dedicated to the development of pervasive computing applications. Our IDL is based on that of CORBA and provides declarative support for concisely characterizing a pervasive computing environment. This description is (1) to be used by programmers as a high-level reference to develop applications that coordinate entities of the target environment and (2) to be passed to a compiler that generates a framework dedicated to the target environment. This process enables verifications to be performed prior to runtime on both the declared environment and a given application. Furthermore, customized operations are automatically generated to support the development of pervasive computing activities, such as service discovery and session negotiation for stream-oriented devices. We have implemented a framework generator and have used it to generate frameworks targeting pervasive computing areas such as building surveillance, advanced telecommunications and home automation

A High-Level, Open-Ended Architecture For SIP-based Services

International audienceNow that Internet Telephony can interact with systems such as databases, e-mail facilities and Web services, it can offer a host of new functionalities. However, developing enriched, real-size services is quite a challenge considering the requirements that must be fulfilled by the service developer. Such developer must (1) have an extensive knowledge on network protocols and distributed systems; (2) be familiar with often large and complex platform APIs (e.g., JAIN); and (3) fully understand the signaling protocol (e.g., SIP) to develop services that do not compromise the processing of the calls, nor the platform. All these areas of expertise are required by most existing platforms. They offer unrestricted APIs and support mainstream programming languages such as C, C# and Java. They provide little abstraction, and thus rely on the programmer to manage the intricacies of the underlying technologies (protocols, network layers, and signaling). Other platforms enable service creation through a scripting language, such as CPL and LESS, that offers a restricted expressiveness and mostly targets the creation of individual user services. We present a high-level architecture of an Application Server for SIP-based services. Our architecture abstracts over the intricacies of the underlying technologies and facilitates both the development and the management of services. By revolving around an Application Server, our approach allows a uniform and coherent basis of telephony services to be offered to the platform users, regardless of the heterogeneity of their end systems