Diomidis Spinellis

One important use of dependency information is for the identification and discovery of vulnerabilities. The presentations present diverse interesting projects and approaches. We want to understand if the current approaches address the needs of cybersecurity efforts, how they compare to threats beyond dependency vulnerabilities, and how they can be combined, extended, and learn from each other.

Git-issue is a minimalist decentralized issue management system based on Git, offering (optional) biderectional integration with GitHub and GitLab issue management. It has the following advantages over other systems.

• No backend, no dependencies: You can install and use git issue with a single shell script. There's no need for a server or a database back-end, and the corresponding problems and requirements for their administration.
• Decentralized asynchronous management: Anyone can add, comment, and edit issues without requiring online access to a centralized server. There's no need for online connectivity; you can pull and push issues when you're online.
• Transparent text file format: Issues are stored as simple text files, which you can view, edit, share, and backup with any tool you like. There's no risk of losing access to your issues because a server has failed.
• Git-based: Issues are changed and shared through Git. This provides git issue with a robust, efficient, portable, and widely available infrastructure. It allows you to reuse your Git credentials and infrastructure, allows the efficient merging of work, and also provides a solid audit trail regarding any changes. You can even use Git and command-line tools directly to make sophisticated changes to your issue database.

Based on a GitHub repository recording the history of the Unix code from 1970 until today, we look at the most significant elements and milestones of the system's architectural evolution and the lessons we can learn from it.

The Unix operating system has had a profound influence on the development of open source software and associated communities. Many of today's systems trace their code or design to a 1970 unnamed operating system kernel, implemented in 2489 lines of PDP-7 assembly language. This evolved into the Unix operating system, whose direct descendants include today's BSD systems and intellectual heirs form the various GNU/Linux distributions.

How did the architecture of Unix evolve over the past half century? Based on a GitHub repository recording the system's history from 1970 until today, a database recording the evolution of provided facilities, and the reconstruction of the Third and Fourth Edition Unix manuals, we will examine the most significant milestones of this development and the lessons we can learn. Many architectural features, such as layering, system calls, devices as files, an interpreter, and process management, were already visible in the 1970 version. Other ideas followed quickly: the tree directory structure, user contributed code, I/O redirection, the shell as a user program, groups, pipes, and scripting. Later versions added domain-specific languages, environment variables, a documented file system hierarchy, software packages, virtual memory support, optimized screen handling, networking, storage pools, dynamic tracing, and a packet capture library. Based on a record of facilities documented over the years we will see areas in which evolution continues at an unchanged pace and areas where it appears stalled. We will also see how one measure of code complexity has followed a self-correcting path. Lessons we can derive from this amazing ride include the durability of early architectural features, the value of establishing conventions over the imposition of rigid mechanisms, the importance of additions made after the system's gestation, and the increasing difficulty of bringing about ground-breaking changes as Unix ages.

The Unix dgsh shell provides an expressive way to construct sophisticated and efficient data processing pipelines using standard Unix tools, as well as third-party and custom-built components. Dgsh allows the specification of pipelines of non-uniform non-linear operations. For example tee can feed three processes whose output can then be collected by paste. The pipelines form a directed acyclic process graph, which is typically executed by multiple processor cores, thus increasing the task's processing throughput. We will see how to use dgsh in practice through a number of general data processing and domain-specific examples, and how to adapt tools for use with dgsh.

The evolution of the Unix operating system is made available as a version-control repository, covering the period from its inception in 1972 as a five thousand line kernel, to 2015 as a widely-used 26 million line system. The repository contains 659 thousand commits and 2306 merges. The repository employs the commonly used Git system for its storage, and is hosted on the popular GitHub archive. It has been created by synthesizing with custom software 24 snapshots of systems developed at Bell Labs, Berkeley University, and the 386BSD team, two legacy repositories, and the modern repository of the open source FreeBSD system. In total, 850 individual contributors are identified, the early ones through primary research. The data set can be used for empirical research in software engineering, information systems, and software archaeology. Community contributions to improve the included data and extend the covered systems are more than welcomed.

Despite its maturity and popularity, the C programming language still lacks tool support for reliably performing even simple refactoring, browsing, or analysis operations. This is primarily due to identifier scope complications introduced by the C preprocessor. The CScout refactoring browser analyses complete program families by tagging the original identifiers with their precise location and classifying them into equivalence classes orthogonal to the C language's namespace and scope extents. A web-based user interface provides programmers with an intuitive source code analysis and navigation front-end, while an SQL-based backend allows more complex source code analysis and manipulation. CScout has been successfully applied to many medium and large open source and proprietary projects identifying thousands of modest refactoring opportunities. Projects where CScout has been applied include the Linux, FreeBSD, and Solaris kernels, Apache httpd, awk, PostgreSQL, and gdb.