From 87cad475e3d2576ed5ae74f3c069267cafa6a3d5 Mon Sep 17 00:00:00 2001
From: Andrea Fioraldi <andreafioraldi@gmail.com>
Date: Tue, 9 Mar 2021 15:12:48 +0100
Subject: [PATCH] TimeFeedback

---
 libafl/src/feedbacks/mod.rs | 60 ++++++++++++++++++++++++++++++++++++-
 libafl/src/observers/mod.rs |  8 +++--
 2 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/libafl/src/feedbacks/mod.rs b/libafl/src/feedbacks/mod.rs
index 10a8606a54..79dddaaf5d 100644
--- a/libafl/src/feedbacks/mod.rs
+++ b/libafl/src/feedbacks/mod.rs
@@ -11,10 +11,12 @@ use crate::{
     corpus::Testcase,
     executors::ExitKind,
     inputs::Input,
-    observers::ObserversTuple,
+    observers::{ObserversTuple, TimeObserver},
     Error,
 };
 
+use core::time::Duration;
+
 /// Feedbacks evaluate the observers.
 /// Basically, they reduce the information provided by an observer to a value,
 /// indicating the "interestingness" of the last run.
@@ -154,3 +156,59 @@ impl Default for CrashFeedback {
         Self::new()
     }
 }
+
+/// Nop feedback that annotates execution time in the new testcase, if any
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct TimeFeedback {
+    exec_time: Option<Duration>,
+}
+
+impl<I> Feedback<I> for TimeFeedback
+where
+    I: Input,
+{
+    fn is_interesting<OT: ObserversTuple>(
+        &mut self,
+        _input: &I,
+        observers: &OT,
+        _exit_kind: ExitKind,
+    ) -> Result<u32, Error> {
+        let observer = observers.match_first_type::<TimeObserver>().unwrap();
+        self.exec_time = *observer.last_runtime();
+        Ok(0)
+    }
+
+    /// Append to the testcase the generated metadata in case of a new corpus item
+    #[inline]
+    fn append_metadata(&mut self, testcase: &mut Testcase<I>) -> Result<(), Error> {
+        *testcase.exec_time_mut() = self.exec_time;
+        self.exec_time = None;
+        Ok(())
+    }
+
+    /// Discard the stored metadata in case that the testcase is not added to the corpus
+    #[inline]
+    fn discard_metadata(&mut self, _input: &I) -> Result<(), Error> {
+        self.exec_time = None;
+        Ok(())
+    }
+}
+
+impl Named for TimeFeedback {
+    #[inline]
+    fn name(&self) -> &str {
+        "TimeFeedback"
+    }
+}
+
+impl TimeFeedback {
+    pub fn new() -> Self {
+        Self { exec_time: None }
+    }
+}
+
+impl Default for TimeFeedback {
+    fn default() -> Self {
+        Self::new()
+    }
+}
diff --git a/libafl/src/observers/mod.rs b/libafl/src/observers/mod.rs
index ddf3d19203..7404ceeeb9 100644
--- a/libafl/src/observers/mod.rs
+++ b/libafl/src/observers/mod.rs
@@ -9,7 +9,7 @@ use core::time::Duration;
 use serde::{Deserialize, Serialize};
 
 use crate::{
-    bolts::tuples::{MatchNameAndType, MatchType, Named, TupleList},
+    bolts::tuples::{MatchFirstType, MatchNameAndType, MatchType, Named, TupleList},
     utils::current_time,
     Error,
 };
@@ -52,7 +52,7 @@ pub trait Observer: Named + serde::Serialize + serde::de::DeserializeOwned + 'st
 
 /// A hastkel-style tuple of observers
 pub trait ObserversTuple:
-    MatchNameAndType + MatchType + serde::Serialize + serde::de::DeserializeOwned
+    MatchNameAndType + MatchType + MatchFirstType + serde::Serialize + serde::de::DeserializeOwned
 {
     /// Reset all executors in the tuple
     /// This is called right before the next execution.
@@ -105,6 +105,10 @@ impl TimeObserver {
             last_runtime: None,
         }
     }
+
+    pub fn last_runtime(&self) -> &Option<Duration> {
+        &self.last_runtime
+    }
 }
 
 impl Observer for TimeObserver {