I’ve recently come back to an older project of mine (that powers this website), and as I did some maintenance work: upgrade to newer crates, upgrade to a newer rustc, I noticed that my build was taking too damn long!

For me, this is a big issue. Because I juggle a lot of things at any given time, and I have less and less time to just hyperfocus on an issue, I try to make my setup as productive as possible.

Writing Rust is pretty neat. But you know what’s even neater? Continuously testing Rust, releasing Rust, and eventually, shipping Rust to production. And for that, we want more than plug-in for a code editor.

We want… a workflow.

Why I specifically care about this

Has this ever happened to you?

You want to look at a JSON file in your terminal, so you pipe it into jq so you can look at it with colors and stuff.

…oh hey cool bear. No warm-up today huh.

Sure, fine, okay, I’ll read the darn man page for jq… okay it takes a “filter” and then some files. And the filter we want is.. . which, just like files, means “the current thing”:

So! Rust futures! Easy peasy lemon squeezy. Until it’s not. So let’s do the easy thing, and then instead of waiting for the hard thing to sneak up on us, we’ll go for it intentionally.

Cool Bear's hot tip

That’s all-around solid life advice.

Choo choo here comes the easy part 🚂💨

We make a new project:

$ cargo new waytoodeep Created binary (application) `waytoodeep` package

Welcome back to the eighteenth and final part of “Making our own executable packer”.

In the last article, we had a lot of fun. We already had a “packer” executable, minipak, which joined together stage1 (a launcher), and a compressed version of whichever executable we wanted to pack.

What we added, was a whole bunch of abstractions to parse ELF headers using deku, which we used from stage1 to be able to launch the guest executable from memory, instead of writing it to a file and using execve on it.

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’d like to think that my understanding of “async Rust” has increased over the past year or so. I’m 100% onboard with the basic principle: I would like to handle thousands of concurrent tasks using a handful of threads. That sounds great!

Welcome back!

In the last article, we did foundational work on minipak, our ELF packer.

It is now able to receive command-line arguments, environment variables, and auxiliary vectors. It can parse those command-line arguments into a set of options. It can make an ELF file smaller using the LZ4 compression algorithm, and pack it together with stage1, our launcher.