fuzzcheck-rs VS wg-allocators

Agreed. A while back I played around with fuzzcheck [1], which let's you write coverage-guided, structure-aware property tests, but the generation is smarter than just slamming a fuzzer's `&[u8]` input into `Arbitrary`. It also supports shrinking, which is nice. Don't know that I would recommend it though. It seemed difficult to write your own `Mutator`s. It also looks somewhat unmaintained nowadays, but I think the direction is worth exploring.

[1]: https://github.com/loiclec/fuzzcheck-rs/

Fuzzcheck is a structure-aware fuzzer for rust. "Fuzzing" means feeding large amounts of data into a program and checking for crashes (Fuzzcheck also checks to make sure that all the properties your program should uphold – e.g. a sorting algorithm applied to a list of n items should always return a list of n items – are upheld). Fuzzcheck is an "evolutionary" fuzzer – this means that it generates a set of random inputs, sees what percentage of the program is executed for each input, and keeps inputs which have high levels of percentage of program executed. It then "mutates" these inputs – whereas fuzzers such as AFL/Hongfuzz/etc mutate raw bytes in place (e.g. they swap bytes at different positions, or insert a random byte at a given position to generate inputs similar to the chosen "high coverage" inputs), Fuzzcheck works directly on the Rust types (so it might swap the order of two items in a vec, or randomly insert a new item). It's a really powerful tool for finding lots of bugs.

If you want help with Win support (issues/8) maybe post it here to get it added to TWIR.

I am working on a code coverage viewer for my fuzzer (fuzzcheck). I described what I've done so far in this issue and I am hoping to release the first version within two weeks.

The implications for my fuzzer, fuzzcheck, are huge! Compiling fuzz tests is a lot easier. There should be no more need to create a separate fuzz folder, fuzz tests can be regular #[test] functions, private implementation details can be fuzz-tested as well, rust-analyser works as expected, documentation can be easily generated, etc. I can also attach a human-readable coverage report to every test case :)

Since I graduated, I have had a lot more time to work on fuzzcheck. I am trying to flesh it out, test it, and document it for a new release. It has always felt a bit rushed/experimental and now I am hoping to make it into something solid. I have also played with an egui interface for it, to visualise the tested code coverage, understand how the fuzzer’s decisions are made, and also to interactively tweak the fuzzer’s behaviour. It's a lot of work but it's slowly all coming together! :)

fuzzcheck-rs is really cool. It combines property-testing with fuzzing, getting the nice, structured nature of the former, and the coverage-driven search of the latter, but it works by mutating the structure directly instead of going through a bit string. So if you have a binary tree, going from A(B, C) to A(C, B) can be a single mutation away if that makes sense in your use case, instead of being arbitrarily far away in the bitstring approach.

Yeah that makes sense. Maybe arenas will be viable once the working group makes progress on allocators. https://github.com/rust-lang/wg-allocators

Tracking issue for Storages, and a TLDR on what it is

I must have gotten confused, since from your brief discussion with CAD97 it seemed like there was a way for the concepts to live separately and that Storage could complicate things in comparison. But if implementing Allocator in terms of Storage is basically equivalent and Storage is flexible enough that I could write one to pass memory out to unsafe code, that works just as well.

https://rust-lang.github.io/rfcs/1974-global-allocators.html was the original RFC.

My vague understanding is that there's a working group https://github.com/rust-lang/wg-allocators

The further I get from working on Rust day to day, the less I know about these things, so that's all I've got for you.

If you self-reference using pointers and guarantee the struct will never move, you don't even need unsafe. If you self-reference using offsets from the struct's base pointer, you need a splash of unsafe but your struct can be freely moved without invalidating its self-referential "pointers".

Per-struct allocators are a work in progress (see https://github.com/rust-lang/wg-allocators/issues/48).

Not sure what "non thread local addresses" means, but in my experience Rust is pretty good at sending data between threads (without moving it).

Besides that allocation is not really a problem for no_std. It's resolved by using alloc crate directly, so anything usable with custom allocators is supported. Example in dasp sources - https://github.com/RustAudio/dasp/blob/master/dasp_slice/src/boxed.rs#L14-L19 . Also worth looking at this issue to check what is usable already - https://github.com/rust-lang/wg-allocators/issues/7

But that's on track for rust as well: https://github.com/rust-lang/wg-allocators/issues/7

Here: https://github.com/rust-lang/rfcs/pull/1398. there is also a working group for this: https://github.com/rust-lang/wg-allocators.