List observer and feedback (#553)

libafl/src/feedbacks/mod.rs

@@ -32,7 +32,7 @@ use crate::{
     events::EventFirer,
     executors::ExitKind,
     inputs::Input,
-    observers::{ObserversTuple, TimeObserver},
+    observers::{ListObserver, ObserversTuple, TimeObserver},
     state::HasClientPerfMonitor,
     Error,
 };
@@ -913,3 +913,74 @@ impl TimeFeedback {
         }
     }
 }
+
+/// Consider interesting a testcase if the list in ListObserver is not empty.
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct ListFeedback<T>
+where
+    T: Debug + Serialize + serde::de::DeserializeOwned,
+{
+    name: String,
+    phantom: PhantomData<T>,
+}
+
+impl<I, S, T> Feedback<I, S> for ListFeedback<T>
+where
+    I: Input,
+    S: HasClientPerfMonitor,
+    T: Debug + Serialize + serde::de::DeserializeOwned,
+{
+    #[allow(clippy::wrong_self_convention)]
+    fn is_interesting<EM, OT>(
+        &mut self,
+        _state: &mut S,
+        _manager: &mut EM,
+        _input: &I,
+        observers: &OT,
+        _exit_kind: &ExitKind,
+    ) -> Result<bool, Error>
+    where
+        EM: EventFirer<I>,
+        OT: ObserversTuple<I, S>,
+    {
+        // TODO Replace with match_name_type when stable
+        let observer = observers
+            .match_name::<ListObserver<T>>(self.name())
+            .unwrap();
+        // TODO register the list content in a testcase metadata
+        Ok(!observer.list().is_empty())
+    }
+}
+
+impl<T> Named for ListFeedback<T>
+where
+    T: Debug + Serialize + serde::de::DeserializeOwned,
+{
+    #[inline]
+    fn name(&self) -> &str {
+        self.name.as_str()
+    }
+}
+
+impl<T> ListFeedback<T>
+where
+    T: Debug + Serialize + serde::de::DeserializeOwned,
+{
+    /// Creates a new [`ListFeedback`], deciding if the value of a [`ListObserver`] with the given `name` of a run is interesting.
+    #[must_use]
+    pub fn new(name: &'static str) -> Self {
+        Self {
+            name: name.to_string(),
+            phantom: PhantomData,
+        }
+    }
+
+    /// Creates a new [`TimeFeedback`], deciding if the given [`ListObserver`] value of a run is interesting.
+    #[must_use]
+    pub fn new_with_observer(observer: &ListObserver<T>) -> Self {
+        Self {
+            name: observer.name().to_string(),
+            phantom: PhantomData,
+        }
+    }
+}

libafl/src/observers/mod.rs

@@ -30,6 +30,7 @@ use serde::{Deserialize, Serialize};
 use crate::{
     bolts::{
         current_time,
+        ownedref::OwnedRefMut,
         tuples::{MatchName, Named},
     },
     executors::ExitKind,
@@ -229,6 +230,61 @@ impl Named for TimeObserver {
     }
 }
 
+/// A simple observer with a list of things.
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(bound = "T: serde::de::DeserializeOwned")]
+pub struct ListObserver<'a, T>
+where
+    T: Debug + Serialize + serde::de::DeserializeOwned,
+{
+    name: String,
+    /// The list
+    list: OwnedRefMut<'a, Vec<T>>,
+}
+
+impl<'a, T> ListObserver<'a, T>
+where
+    T: Debug + Serialize + serde::de::DeserializeOwned,
+{
+    /// Creates a new [`ListObserver`] with the given name.
+    #[must_use]
+    pub fn new(name: &'static str, list: &'a mut Vec<T>) -> Self {
+        Self {
+            name: name.to_string(),
+            list: OwnedRefMut::Ref(list),
+        }
+    }
+
+    /// Get a list ref
+    pub fn list(&self) -> &Vec<T> {
+        self.list.as_ref()
+    }
+
+    /// Get a list mut
+    pub fn list_mut(&mut self) -> &mut Vec<T> {
+        self.list.as_mut()
+    }
+}
+
+impl<'a, I, S, T> Observer<I, S> for ListObserver<'a, T>
+where
+    T: Debug + Serialize + serde::de::DeserializeOwned,
+{
+    fn pre_exec(&mut self, _state: &mut S, _input: &I) -> Result<(), Error> {
+        self.list.as_mut().clear();
+        Ok(())
+    }
+}
+
+impl<'a, T> Named for ListObserver<'a, T>
+where
+    T: Debug + Serialize + serde::de::DeserializeOwned,
+{
+    fn name(&self) -> &str {
+        &self.name
+    }
+}
+
 #[cfg(feature = "std")]
 #[cfg(test)]
 mod tests {