Minimal software

The bulk of the software I've written is available on Github, where I am @dancrossnyc.

• cat - No -v.
• pbpp - A very simple program for pretty-printing text-encoded protocol messages (the textual representation of Google's Protocol Buffers). I wrote this for use at Google and the company graciously allowed me to open source the code.
• Paredit Refcard (Latex source) - An updated version of the Paredit Cheat Sheet from the emacs wiki. This is not exactly software, but the original was only available as a bitmapped image file (and fairly low resolution, at that) so I recreated it in LaTeX. In the process, I cleaned up and/or expanded some of the examples. I'd love to credit the original author, but unfortunately no one seems to know who that is. A PDF version is also available.
• A simple unit testing framework for C - A variation on a theme I saw once: using C preprocessor macros to implement a minimal unit testing framework. One can see it in use for some of the string utilities linked below.
• Various C string utilities - Semi-portable versions of strcspn() (tests) and strspn(), strcasestr(), strlcat() and strlcpy(), strndup(), strsep(), strcasecmp() and strncasecmp() (tests), strnlen() (tests) and substr(). I wrote most of these functions over time to address portability issues (they didn't exist on systems I was using at the time) or as purely academic exercises. Please note: there is a version of strlcpy() similar to the one here and attributed to me on a site maintained by the late Jan Wolter. That copy has a bug (a conditional if (--size <= 0) { ... } against a variable of type size_t that is clearly incorrect since size_t is unsigned. It is easily correct by changing the conditional to if (size-- == 0) { ... }). I wrote to Jan asking that he either update or remove that version, but he did not and unfortunately he passed away in 2014. Please use this one instead. On a personal note, I was extremely sad about Jan's passing: he was a wonderful person.
• Implementations of bidirectional search in undirected, unweighted graphs in both Common Lisp and Go.
• spliton.lisp - A function in Common Lisp to split a string into tokens separated by any of a set of delimiters (specified in a second string). Used as a component of the HTTP server serving this site.
• uptoinit - Specific to BSD Unix. Starting with the current process, use the kvm(2) interface to trace parent processes through the proc table until we encounter init(8). In other words, follow a single path in the process tree from a leaf to the root. I wrote this for administrative purposes: to find incoming TELNET connections, back when I still ran a telnetd.
• trampoline - A Unix daemon for proxying incoming TCP connections. I wrote this for proxying connections to a Plan 9 machine through a Unix host.
• usrv - Serve a program over a Unix domain socket: when a new connection is accepted on a given socket name, fork and execute the given program with its standard input, output and error bound to the new socket.
• talkto - The inverse of usrv: open a file and read from and write to it; this an be used as a client for programs served by usrv. Relies on modern systems treating open(2) on a Unix domain socket as an implicit connect(2).
• xfilter - A Unix filter in the vein of xargs(1), except that for each line (or NUL-delimited string), pass as an argument to a given program and arguments, and print if the program returns success.
• d20 - A six function integer calculator (including exponentiation and square roots) that can include randomized values via dice factors. Dice are specified using the standard "d" notation (e.g. 3d6).
• spliton - Break the standard input stream into lines delimited by some seperator string (default is space).
• field - Extract fields from lines; uses syntax similar to awk(1) to specify fields. Note that this is in Plan 9 C; I wrote it for the Harvey operating system, which started without an awk port. On Unix, I build it with plan9port. It also has a man page. An older perl script that did much the same thing is also available. There is also a version that I wrote in Go for the u-root project.
• 44ripd - A specialized RIPv2 receiver that maintains routes and IPENCAP tunnels for the AMPRNet IPv4 network (44/8): the Amateur Radio TCP/IP network. This is an AMPRNet RIP daemon, similar to ampr-ripd or rip44d, but compatible with BSD Unix. I run it on a Ubiquity EdgeRouter Lite running OpenBSD.

Projects I Maintain or Participate On

While everything listed above was written by me, I also maintain or have ported various Open Source projects, and there are other collaborative efforts that I participate in.

• The Hypatia Hypervisor - A modern, Type-1 hypervisor written in Rust.
• The rxv64 operating system - A reimplementation of MIT's xv6 operating system in Rust, for x86_64.
• illumos - We use the descendent of Solaris at Oxide, and I work on it.
• The R9 Operating System - This is an implementation of Plan 9 in Rust.
• The Harvey Operating System - Harvey is a modern take on the Plan 9 operating system. I am a core team member.
• BSVC: A Microprocessor Simulation Framework - This is a framework for simulating microprocessors and simple computers with attached peripherals such as timers and UARTs. Originally written by Bradford Mott, he graciously allowed me to take over maintenance and relicense under the GPL version 2.1 in 2015. It comes with an MC68k simulator and assembler; the frontend uses Tcl/Tk.
• Xinu for 68K - An independent port of the PDP-11 version of Comer's Xinu operating system to the 68K. Can run under BSVC.
• libprint - A modernized, stand-alone version of the Plan 9-style formatting printing routines from Byron's clone of the 'rc' shell.
• The Akaros Operating System - I worked on the Akaros research operating system for some time.