Making StdOutObserver and StdErrObserver implement Observer (#2236)

* making stdout and stderr observers implement observer

* fixing imports

libafl/src/executors/command.rs

@@ -236,6 +236,7 @@ where
         use wait_timeout::ChildExt;
 
         *state.executions_mut() += 1;
+        self.observers.pre_exec_child_all(state, input)?;
 
         let mut child = self.configurer.spawn_child(input)?;
 
@@ -258,6 +259,11 @@ where
             }
         };
 
+        if let Ok(exit_kind) = res {
+            self.observers
+                .post_exec_child_all(state, input, &exit_kind)?;
+        }
+
         if let Some(ref mut ob) = &mut self.configurer.stdout_observer_mut() {
             let mut stdout = Vec::new();
             child.stdout.as_mut().ok_or_else(|| {

libafl/src/observers/stdio.rs

@@ -8,6 +8,8 @@ use std::vec::Vec;
 use libafl_bolts::Named;
 use serde::{Deserialize, Serialize};
 
+use crate::{inputs::UsesInput, observers::Observer, state::State, Error};
+
 /// An observer that captures stdout of a target.
 /// Only works for supported executors.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
@@ -41,6 +43,20 @@ impl Named for StdOutObserver {
     }
 }
 
+impl<S> Observer<S> for StdOutObserver
+where
+    S: State,
+{
+    fn pre_exec_child(
+        &mut self,
+        _state: &mut S,
+        _input: &<S as UsesInput>::Input,
+    ) -> Result<(), Error> {
+        self.stdout = None;
+        Ok(())
+    }
+}
+
 /// An observer that captures stderr of a target.
 /// Only works for supported executors.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
@@ -73,3 +89,17 @@ impl Named for StdErrObserver {
         &self.name
     }
 }
+
+impl<S> Observer<S> for StdErrObserver
+where
+    S: State,
+{
+    fn pre_exec_child(
+        &mut self,
+        _state: &mut S,
+        _input: &<S as UsesInput>::Input,
+    ) -> Result<(), Error> {
+        self.stderr = None;
+        Ok(())
+    }
+}