Add generic cmp observer metadata, rename cmp observers, fix cmplogmap reset

[novafacing]

Renames:

• ForkserverCmpObserver to StdCmpObserver
• AFLppForkserverCmpObserver to AFLppCmpObserver

Adds:

• CmpObserverMetadata trait, which defines a metadata that can have cmp information added to it from a CmpObserver, along with some auxiliary data type which right now is only used for AFLppCmpObserver's original field, but can be used for whatever custom thing users want
• Some accessor/setter methods for various CmpMap related structs, to make it easier for consumers of these structs to set them via other means than instrumentation (for example, I set them by tracing execution in a simulator, which modifies the map, but I had to cast it to a copy of the type with pub fields. This solves that and reduces my hackiness)

Fixes:

• Zeroed assignment fixed in Reset headers with a memcpy, not an assign from zeroed #1443 is also now fixed in CmpLogMap

[domenukk]

Awesome!

error[E0432]: unresolved import `libafl::prelude`
  --> libafl_targets/src/cmplog.rs:12:5
   |
[12](https://github.com/AFLplusplus/LibAFL/actions/runs/5968828500/job/16193481867?pr=1461#step:15:13) |     prelude::CmpValuesMetadata,
   |     ^^^^^^^ could not find `prelude` in `libafl`

Can't haz prelude in the lib

[novafacing]

Now I'm confused why this builds for me locally, RIP.

Will fix :)

[domenukk]

This will generally build (the prelude feature is set by default), just not if you build with --no-default-features

[novafacing]

Darn, I was hoping everything would work with no modifications. I'll fix the fuzzers :)

[domenukk]

The generics look a bit unfortunate, any way to get around them?

[domenukk]

How about having a type StdCmpValuesObserver<'a, B, C> = StdCmpObserver<'a, B, C, CmValuesMetadata> or something like that? Just an idea

[novafacing]

Sure that sounds good 🙂

[andreafioraldi]

LGTM, but StdCmpObserver was the original name, then #1291 changed it I see, we know why?

[domenukk]

I think simply because we introduced another cmplog map format for AFLpp... cc @tokatoka

[tokatoka]

because it's not really StdCmplogObserver.
It is a observer for forkserver. so i changed the name

• CmplogObserver (in libafl_targets) is for inproc cmplog
• FokserverCmplogObserver (in libafl/observers) is for forkserver cmplog
• AFLppForkserverCmplogObserver (in libafl/observers) is for aflpp forkserver cmplog

[tokatoka]

lgtm

[novafacing]

Ok, added that type alias (thanks for the suggestion) and also added accessors for the stored aux data. No need to update it imo but in this case if you wanted to do something like what AFLppCmpObserver does, you could just use the data_mut() method to change the original value.

@tokatoka I think calling them forkserver in your merge made sense, I just changed it back because with the changes I'm now using these in a context where they aren't used with a forkserver but inprocess, so figured maybe the more generic name makes sense now so people don't think they can't use 'em in other ways :)