It’s time for Day 4 of the Advent of Code 2020!

Now, I’ve already had a look at the problem statement, at least for part 1, and I’m not particularly excited.

But it will allow me to underline some of the points I’ve recently been *trying to make about types and correctness.

The problem is to parse passports, with fields like these:

Before we move on to parsing more of our raw packets, I want to take some time to improve our error handling strategy.

Currently, the ersatz codebase contains a mix of Result<T, E>, and some methods that panic, like unwrap() and expect().

We also have a custom Error enum that lets us return rawsock errors, IO errors, or Win32 errors:

pub enum rawsock stdio

Part 1

The day 5 challenge actually looks fun!

Our input looks like this:

[D] [N] [C] [Z] [M] [P] 1 2 3 move 1 from 2 to 1 move 3 from 1 to 3 move 2 from 2 to 1 move 1 from 1 to 2

Which is a visual representation of stacks, and so, for once, we have some serious parsing to do, and that means I finally have a good reason to bust out the nom crate.

There’s a question that always comes up when people pick up the Rust programming language: why are there two string types? Why is there String, and &str?

My Declarative Memory Management article answers the question partially, but there is a lot more to say about it, so let’s run a few experiments and see if we can conjure up a thorough defense of Rust’s approach over, say, C’s.

In the last article, we managed to load a program (hello-dl) that uses a single dynamic library (libmsg.so) containing a single exported symbol, msg.

Our program, hello-dl.asm, looked like this:

 global _start extern msg section .text _start: mov rdi, 1 ; stdout fd mov rsi, msg mov rdx, 38 ; 37 chars + newline , , ,

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.

Today I am joining you from the relative discomfort of my living room (since my better half has commandeered the home office due to Way Too Many Calls) to tackle the day 6 challenge, which I’m excited about: maybe despite, maybe because of, the low-grade fever I’m under.

Part 1

Our input is a jumble of letters, and we’re supposed to find the position of the first substring that’s “four different characters”.

Intro

When I started my Patreon, I had no idea if it would work at all. The whole thing seemed like a gamble: spend an inordinate amount of time writing quality articles, and hope that folks will like it enough to kick in 5, 10, or 50 bucks a month just to see more of them.

I’m happy to say the gamble paid off - literally. Take that, impostor syndrome!

What’s next? Well… poppler is the library Inkscape uses to import PDFs.

Turns out, poppler comes with a bunch of CLI tools, including pdftocairo!

I’ve been looking for this blog post everywhere, but it doesn’t exist, so I guess it’s my turn to write about Some Fun with Rust.

The task at hand

Let’s say you have a recursive, acyclic data structure, like so:

struct Node { values: Vec<i32>, children: Vec<Node>, }

This allows you to represent a tree-like structure:

[1, 2, 3] /\ / \ / \ / \ / \ [4, 5] [6, 7]