If you scan through the source (on github), the most notable thing is the lack of the "unsafe" keyword. I've seen too many people basically transliterate from C to Rust, along with all the unsafe operations. This one is pretty much unoptimized, but still seems to be performant enough, and doesn't do anything "unsafe".

That's not to say you could just throw this into the back-end of a public-facing website. It's still going to panic (abort) if someone unexpected happens, and it's still going to chew indeterminate amounts of CPU, memory or storage unless sandboxed (maybe even just ulimit). And there's still the danger one of the Rust standard library functions has a flaw in it. But this is the kind of starting point you wouldn't get with the plain C equivalent.