Report 100% stability if no unstable edges are found (extends #2215) (#2217)

* Report 100% stability if no unstable edges are found

* Use metadtata

---------

Co-authored-by: sadeli413 <[email protected]>

Author: domenukk

libafl/src/stages/calibrate.rs

@@ -40,10 +40,10 @@ impl_serdeany!(UnstableEntriesMetadata);
 impl UnstableEntriesMetadata {
     #[must_use]
     /// Create a new [`struct@UnstableEntriesMetadata`]
-    pub fn new(entries: HashSet<usize>, map_len: usize) -> Self {
+    pub fn new() -> Self {
         Self {
-            unstable_entries: entries,
-            map_len,
+            unstable_entries: HashSet::new(),
+            map_len: 0,
         }
     }
 
@@ -60,6 +60,12 @@ impl UnstableEntriesMetadata {
     }
 }
 
+impl Default for UnstableEntriesMetadata {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 /// Default name for `CalibrationStage`; derived from AFL++
 pub const CALIBRATION_STAGE_NAME: &str = "calibration";
 /// The calibration stage will measure the average exec time and the target's stability for this input.
@@ -220,25 +226,20 @@ where
             i += 1;
         }
 
+        let mut send_default_stability = false;
         let unstable_found = !unstable_entries.is_empty();
         if unstable_found {
+            let metadata = state.metadata_or_insert_with(UnstableEntriesMetadata::new);
+
             // If we see new stable entries executing this new corpus entries, then merge with the existing one
-            if state.has_metadata::<UnstableEntriesMetadata>() {
-                let existing = state
-                    .metadata_map_mut()
-                    .get_mut::<UnstableEntriesMetadata>()
-                    .unwrap();
-                for item in unstable_entries {
-                    existing.unstable_entries.insert(item); // Insert newly found items
-                }
-                existing.map_len = map_len;
-            } else {
-                state.add_metadata::<UnstableEntriesMetadata>(UnstableEntriesMetadata::new(
-                    HashSet::from_iter(unstable_entries),
-                    map_len,
-                ));
+            for item in unstable_entries {
+                metadata.unstable_entries.insert(item); // Insert newly found items
             }
-        };
+            metadata.map_len = map_len;
+        } else if !state.has_metadata::<UnstableEntriesMetadata>() {
+            send_default_stability = true;
+            state.add_metadata(UnstableEntriesMetadata::new());
+        }
 
         // If weighted scheduler or powerscheduler is used, update it
         if state.has_metadata::<SchedulerMetadata>() {
@@ -300,6 +301,7 @@ where
             if let Some(meta) = state.metadata_map().get::<UnstableEntriesMetadata>() {
                 let unstable_entries = meta.unstable_entries().len();
                 let map_len = meta.map_len();
+                debug_assert_ne!(map_len, 0, "The map_len must never be 0");
                 mgr.fire(
                     state,
                     Event::UpdateUserStats {
@@ -315,6 +317,18 @@ where
                     },
                 )?;
             }
+        } else if send_default_stability {
+            mgr.fire(
+                state,
+                Event::UpdateUserStats {
+                    name: Cow::from("stability"),
+                    value: UserStats::new(
+                        UserStatsValue::Ratio(map_len as u64, map_len as u64),
+                        AggregatorOps::Avg,
+                    ),
+                    phantom: PhantomData,
+                },
+            )?;
         }
 
         Ok(())