Introduce NautilusUnparseToMetadataFeedback (AFLplusplus#3480)

* Introduce NautilusUnparseToMetadataFeedback

* Add a note about the interestingness of NautilusUnparseToMetadataFeedback

* Add implementation for track_hit_feedbacks on NautilusUnparseToMetadataFeedback

* Re-add the unparsing logic to the feedback after accidental removal

* Switch to manual invocation of the serdeany macro

* Re-add last_result implementation

* Clippy fixes

* Rely on default behavior for is_interesting

* Clippy

Author: riesentoaster

crates/libafl/src/feedbacks/nautilus.rs

@@ -1,5 +1,8 @@
 //! Nautilus grammar mutator, see <https://github.com/nautilus-fuzz/nautilus>
-use alloc::{borrow::Cow, string::String};
+use alloc::{
+    borrow::Cow,
+    string::{String, ToString},
+};
 use core::fmt::Debug;
 use std::fs::create_dir_all;
 
@@ -10,7 +13,6 @@ use crate::{
     Error, HasMetadata,
     common::nautilus::grammartec::{chunkstore::ChunkStore, context::Context},
     corpus::{Corpus, Testcase},
-    executors::ExitKind,
     feedbacks::{Feedback, StateInitializer},
     generators::NautilusContext,
     inputs::NautilusInput,
@@ -94,29 +96,72 @@ impl<EM, OT, S> Feedback<EM, NautilusInput, OT, S> for NautilusFeedback<'_>
 where
     S: HasMetadata + HasCorpus<NautilusInput>,
 {
-    fn is_interesting(
+    fn append_metadata(
         &mut self,
-        _state: &mut S,
+        state: &mut S,
         _manager: &mut EM,
-        _input: &NautilusInput,
         _observers: &OT,
-        _exit_kind: &ExitKind,
-    ) -> Result<bool, Error> {
+        testcase: &mut Testcase<NautilusInput>,
+    ) -> Result<(), Error> {
+        self.append_nautilus_metadata_to_state(state, testcase)
+    }
+
+    #[cfg(feature = "track_hit_feedbacks")]
+    fn last_result(&self) -> Result<bool, Error> {
         Ok(false)
     }
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug)]
+struct NautilusUnparseMetadata {
+    unparsed: String,
+}
+
+libafl_bolts::impl_serdeany!(NautilusUnparseMetadata);
+
+/// Add the unparsed input to the testcase metadata. Useful e.g. if you want to have the input be unparsed on any solution automatically.
+///
+/// Returns a constant `false` for `is_interesting`.
+#[derive(Debug)]
+pub struct NautilusUnparseToMetadataFeedback<'a> {
+    context: &'a NautilusContext,
+}
+
+impl<'a> NautilusUnparseToMetadataFeedback<'a> {
+    /// Create a new [`NautilusUnparseToMetadataFeedback`]
+    #[must_use]
+    pub fn new(context: &'a NautilusContext) -> Self {
+        Self { context }
+    }
+}
+impl<S> StateInitializer<S> for NautilusUnparseToMetadataFeedback<'_> {}
 
+impl<EM, OT, S> Feedback<EM, NautilusInput, OT, S> for NautilusUnparseToMetadataFeedback<'_> {
     fn append_metadata(
         &mut self,
-        state: &mut S,
+        _state: &mut S,
         _manager: &mut EM,
         _observers: &OT,
         testcase: &mut Testcase<NautilusInput>,
     ) -> Result<(), Error> {
-        self.append_nautilus_metadata_to_state(state, testcase)
+        let input = testcase.input().as_ref().unwrap().clone();
+        let mut unparse_target = vec![];
+        input.unparse(self.context, &mut unparse_target);
+        let unparsed = String::from_utf8_lossy(&unparse_target).to_string();
+        testcase.metadata_or_insert_with(|| NautilusUnparseMetadata { unparsed });
+
+        Ok(())
     }
 
     #[cfg(feature = "track_hit_feedbacks")]
     fn last_result(&self) -> Result<bool, Error> {
         Ok(false)
     }
 }
+
+impl Named for NautilusUnparseToMetadataFeedback<'_> {
+    fn name(&self) -> &Cow<'static, str> {
+        static NAME: Cow<'static, str> = Cow::Borrowed("NautilusUnparseToMetadataFeedback");
+        &NAME
+    }
+}

crates/libafl/src/generators/nautilus.rs

@@ -101,7 +101,8 @@ impl NautilusContext {
             #[cfg(not(feature = "nautilus_py"))]
             {
                 return Err(Error::illegal_argument(format!(
-                    "Feature `nautilus_py` is required to load grammar from {grammar_file:?}"
+                    "Feature `nautilus_py` is required to load grammar from {}",
+                    grammar_file.display()
                 )));
             }
         }