In my previous article, I said I needed to stop thinking of Rust generics as Java generics, because in Rust, generic types are erased.

Someone gently pointed out that they are also erased in Java, the difference was elsewhere. And so, let’s learn the difference together.

Java generics

I learned Java first (a long, long time ago), and their approach to generics made sense to me at the time.

So far, we’ve seen many ways to read a file from different programming languages, we’ve learned about syscalls, how to make those from assembly, then we’ve learned about memory mapping, virtual address spaces, and generally some of the mechanisms in which userland and the kernel interact.

But in our exploration, we’ve always considered the kernel more or less like a “black box”. It’s time to change that.

A few days ago I posted an ooc quine. But while browing HackerNews, I found an even shorter one. The shortest!

Here it is, in its full glory

Can’t see anything? That’s an empty file. It will compile and run just fine. ooc doesn’t require a main function - you can just shove code in there that will run at the program’s initialization. If there’s none, no big deal! It’ll just not run anything.

So, how does ping.exe actually send a ping? It seems unrealistic that ping.exe itself implements all the protocols involved in sending a ping. So it must be calling some sort of library. Also, since it ends up talking to the outside world via a NIC (network interface controller), the kernel is probably involved at some point.

In reading files the hard way - part 2, we learned about dynamic libraries (like libc), and the Linux kernel, and how syscalls allowed us to ask the Linux kernel to do our bidding. For this series, we’re going to have to look at the Windows equivalents.

In the last part, we’ve finally parsed some IPv4 packets. We even found a way to filter only IPv4 packets that contain ICMP packets.

There’s one thing we haven’t done though, and that’s verify their checksum. Folks could be sending us invalid IPv4 packets and we’d be parsing them like a fool!

This series is getting quite long, so let’s jump right into it.

During a recent Rust Q&A Session on my twitch channel, someone asked a question that seemed simple: why are small string types, like SmartString or SmolStr, the same size as String, but small vec types, like SmallVec, are larger than Vec?

Now I know I just used the adjective simple, but the truth of the matter is: to understand the question, we’re going to need a little bit of background.

I know what you’re thinking: haven’t we strayed from the whole “content pipeline” theme in this series?

Well… fair. But compiling and distributing software is part of software engineering, and unless you’re in specific circles, I see that taught a lot less than the “just write code and stuff happens” part.

Update: Lestac is now available in Early Access on itch.io! Read more on the official page

So, Lestac is out! Ain’t that something? For those who don’t know, it’s Sylvain and I’s entry for Ludum Dare 28, a video game jam that happens every four months.

Here’s how it looks:

You can play it now if you haven’t yet - it’s available for Linux, OS/X, and Windows. And then you can come back and read this postmortem if you will!

The last article, Position-independent code, was a mess. But who could blame us? We looked at the world, and found it to be a chaotic and seemingly nonsensical place. So, in order to blend in, we had to let go of a little bit of sanity.

The time has come to reclaim it.

Short of faulty memory sticks, memory locations don’t magically turn from 0x0 into valid addresses. Someone is doing the turning, and we’re going to find out who, if it takes the rest of the series.

I use the draw.io desktop app to make diagrams for my website. I run it on an actual desktop, like Windows or macOS, but the asset pipeline that converts .drawio files, to .pdf, to .svg, and then to .svg again (but smaller) runs on Linux.

So I have a Rust program somewhere that opens headless chromium, and loads just the HTML/JS/CSS part of draw.io I need to render my diagrams, and then use Chromium’s “print to PDF” functionality to save a PDF.