libafl_nyx: Allow custom input buffer size to be passed to NyxHelper

[l4yton]

Initially, I only wanted to add the option to specify the input buffer size, but I ended up changing a couple things:

• New NyxSettings struct that is passed to NyxHelper::new.
• NyxExecutor takes ownership of NyxHelper instead of taking a mutable reference, this removes some lifetime complexity and I didn't see any reason against it.
• Remove dry run in NyxHelper. If QEMU didn't spawn, it should be noticed by NyxExecutor anyway.

Let me know if this makes sense and what you think.

[domenukk]

Looks good!

[domenukk]

Should we upgrade this to the latest rev?

[l4yton]

I started working on using the latest libnyx revision here: https://github.com/l4yton/LibAFL/tree/libnyx_latest, but will have to do some more testing. Documentation and example fuzzers would also have to be updated since NyxProcess gets the config directly from the config.ron file in the share_dir.

[domenukk]

I left a few comments, and Clippy is still unhappy:

error: redundant closure
  --> libafl_nyx/src/helper.rs:79:18
   |
79 |         .map_err(|e| libafl::Error::illegal_argument(e))?;
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `libafl::Error::illegal_argument`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure
   = note: `-D clippy::redundant-closure` implied by `-D clippy::all`
   = help: to override `-D clippy::all` add `#[allow(clippy::redundant_closure)]`

error: this method could have a `#[must_use]` attribute
  --> libafl_nyx/src/settings.rs:20:5
   |
20 | /     pub fn new(
21 | |         cpu_id: u32,
22 | |         parent_cpu_id: Option<u32>,
23 | |         snap_mode: bool,
24 | |         parallel_mode: bool,
25 | |     ) -> Self {
   | |_____________^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#must_use_candidate
   = note: `-D clippy::must-use-candidate` implied by `-D clippy::pedantic`
   = help: to override `-D clippy::pedantic` add `#[allow(clippy::must_use_candidate)]`
help: add the attribute
   |
20 ~     #[must_use] pub fn new(
21 +         cpu_id: u32,
22 +         parent_cpu_id: Option<u32>,
23 +         snap_mode: bool,
24 +         parallel_mode: bool,
25 ~     ) -> Self {
   |

error: this method could have a `#[must_use]` attribute
  --> libafl_nyx/src/settings.rs:39:5
   |
39 |     pub fn with_cpu_id(mut self, cpu_id: u32) -> Self {
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add the attribute: `#[must_use] pub fn with_cpu_id(mut self, cpu_id: u32) -> Self`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#must_use_candidate

error: missing `#[must_use]` attribute on a method returning `Self`

error: missing `#[must_use]` attribute on a method returning `Self`
  --> libafl_nyx/src/settings.rs:64:5
   |
64 | /     pub fn with_timeout_secs(mut self, timeout_secs: u8) -> Self {
65 | |         self.timeout_secs = timeout_secs;
66 | |         self
67 | |     }
   | |_____^
   |
   = help: consider adding the `#[must_use]` attribute to the method or directly to the `Self` type
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#return_self_not_must_use

error: this method could have a `#[must_use]` attribute
  --> libafl_nyx/src/settings.rs:69:5
   |
69 |     pub fn with_timeout_micro_secs(mut self, timeout_micro_secs: u32) -> Self {
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add the attribute: `#[must_use] pub fn with_timeout_micro_secs(mut self, timeout_micro_secs: u32) -> Self`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#must_use_candidate

error: missing `#[must_use]` attribute on a method returning `Self`
  --> libafl_nyx/src/settings.rs:69:5
   |
69 | /     pub fn with_timeout_micro_secs(mut self, timeout_micro_secs: u32) -> Self {
70 | |         self.timeout_micro_secs = timeout_micro_secs;
71 | |         self
72 | |     }
   | |_____^
   |
   = help: consider adding the `#[must_use]` attribute to the method or directly to the `Self` type
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#return_self_not_must_use

error: could not compile `libafl_nyx` (lib test) due to 16 previous errors

[tokatoka]

thank you 👍

[domenukk]

If anyone should feel like it, it could be nice to have some doc comments for these fields