In the last article, we found where code was hiding in our samples/hello executable, by disassembling the whole file and then looking for syscalls.

Later on, we learned how to inspect which memory ranges are mapped for a given PID (process identifier). We saw that memory areas weren’t all equal: they can be readable, writable, and/or executable.

There are news!

Here’s a sentence I find myself saying several times a week:

…or we could just box it.

There’s two remarkable things about this sentence.

The first, is that the advice is very rarely heeded, and instead, whoever I just said it to disappears for two days, emerging victorious, basking in the knowledge that, YES, the compiler could inline that, if it wanted to.

I love diagrams. I love them so much!

In fact, I have fairly poor visualization skills, so making a diagram is extremely helpful to me: I’ll have some vague idea of how different things are connected, and then I’ll make a diagram, and suddenly there’s a tangible thing I can look at and talk about.

Of course the diagram only represents a fraction of what I had in mind in the first place, but that’s okay: the point is to be able to talk about some aspect of a concept, and so I have to make choices about what to include in the diagram. And maybe make several diagrams.

Wait wait wait, so we’re not talking about nix yet?

Well, no! The service we have is pretty simple, and I want to complicate things a bit, to show how things would work in both the Dockerfile and the nix scenario.

And because I don’t like contrived examples, we’re going to do something somewhat real-world: we’re going to geo-locate visitors, and track how many visits we get from each country.

This is going to be a short one.

Hey internet! So, someone broke into some of my accounts.

I’m taking entire responsibility for this - there’s the part where I fucked up, and if I didn’t fuck up, then none of this would’ve happened.

But there’s also the part where a series of design decisions from various vendors combined into the perfect storm for me.

And we’re going to talk about both! Separately! And calmly.

There’s one thing that bothers me. In part 1, why are we using hyper-staticfile? Couldn’t we just use file:/// URLs?

Well, first off: showing off how easy it is to serve some static files, even in a “scary” language like Rust, is just not something I could pass up.

But also: think about distributing salvage as a tool. Will we want to distribute all those HTML/CSS/JS/font files alongside it?