Part 1

Let’s tackle the day 4 challenge!

In this one, we get an input like this:

2-4,6-8 2-3,4-5 5-7,7-9 2-8,3-7 6-6,4-6 2-6,4-8

Each line has two ranges: the first line has ranges containing 2, 3, 4, and 6, 7, 8. We must count how many pairs have ranges where one fully contains the other.

In Rust, we can express this with “inclusive ranges” (std::ops::RangeInclusive), and those implement Iterator, so we can do:

It’s refactor time!

Our complete program is now about a hundred lines, counting blank lines (see the end of part 3 for a complete listing).

While this is pretty good for a zero-dependency project (save for pretty-hex), we can do better.

First off, concerns are mixed up. In the same file, we:

• Expose LoadLibraryA / GetProcAddress
• Expose the Win32 ICMP API

When I get a little bit too emotional about my current baby, the itch.io app, there’s always a timely support ticket reminding me that it is currently, still a glorified game downloader.

However true that is, that doesn’t mean it’s easy! In the past year, I’ve had to account for a bunch of failure conditions that can happen, some of which I didn’t realize were even possible. Let’s review them, for fun!

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.

In the day 8 problem, our input is a height map:

30373 25512 65332 33549 35390

This is a 5x5 grid, and every number denotes the height of a tree. For part 1, we must find out how many trees are visible from the outside of the grid.

If we consider the first row, from the left: only the 3 is visible: it obscures the 0. From the right, 3 and 7 are visible.

Disclaimer:

At the time of this writing, I benefit from the fly.io “Employee Free Tier”. I don’t pay for side projects hosted there “within reasonable limits”. The project discussed here qualifies for that.

Why you might want a remote dev environment

Fearmongering aside — and Cthulhu knows there’s been a bunch, since this unfortunate tweet — there’s a bunch of reasons to want a remote dev environment.

I still get excited about programming languages. But these days, it’s not so much because of what they let me do, but rather what they don’t let me do.

Ultimately, what you can with a programming language is seldom limited by the language itself: there’s nothing you can do in C++ that you can’t do in C, given infinite time.

As long as a language is turing-complete and compiles down to assembly, no matter the interface, it’s the same machine you’re talking to. You’re limited by… what your hardware can do, how much memory it has (and how fast it is), what kind of peripherals are plugged into it, and so on.

Background

I recently had a bit of impromptu disaster recovery, and it gave me a hunger for more! More downtime! More kubernetes manifest! More DNS! Ahhhh!

The plan was really simple. I love dedicated Hetzner servers with all my heart but they are not very fungible.

You have to wait entire minutes for a new dedicated server to be provisioned. Sometimes you pay a setup fee, et cetera. And at some point to server static websites and serve as a K3S server, it’s simply just too big, and approximately twice the price that I should pay.

Earlier this week, an npm supply chain attack.

It’s turn for crates.io, the main public repository for Rust crates (packages).

The phishing e-mail looks like this:

And it leads to a GitHub login page that looks like this:

Several maintainers received it — the issue is being discussed on GitHub.

The crates.io team has acknowledged the attack and said they’d see if they can do something about it.