Catch Rapier panics at FFI boundary to prevent crash

common/src/main/rust/rapier/src/lib.rs

@@ -421,31 +421,53 @@ pub extern "system" fn Java_dev_ryanhcode_sable_physics_impl_rapier_Rapier3D_ini
 }
 
 /// Computes buoyancy
+/// Extracts a message from a caught panic payload
+fn panic_message(payload: &Box<dyn std::any::Any + Send>) -> String {
+    if let Some(s) = payload.downcast_ref::<&str>() {
+        s.to_string()
+    } else if let Some(s) = payload.downcast_ref::<String>() {
+        s.clone()
+    } else {
+        "unknown panic".to_string()
+    }
+}
+
+/// Catches a panic and throws a JVM RuntimeException with the panic message
+fn throw_on_panic(env: &mut JNIEnv, result: Result<(), Box<dyn std::any::Any + Send>>) {
+    if let Err(payload) = result {
+        let msg = format!("Rapier native panic: {}", panic_message(&payload));
+        let _ = env.throw_new("java/lang/RuntimeException", &msg);
+    }
+}
+
 #[unsafe(no_mangle)]
 pub extern "system" fn Java_dev_ryanhcode_sable_physics_impl_rapier_Rapier3D_tick<'local>(
-    _env: JNIEnv<'local>,
+    mut env: JNIEnv<'local>,
     _class: JClass<'local>,
     scene_id: jint,
     _time_step: jdouble,
 ) {
-    unsafe {
-        if let Some(state) = &mut PHYSICS_STATE {
-            rope::tick(scene_id);
-            joints::tick(scene_id);
-
-            let Some(scene) = state.scenes.get_mut(&scene_id) else {
-                panic!("No scene with given ID!");
-            };
-
-            compute_buoyancy(scene);
+    let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
+        unsafe {
+            if let Some(state) = &mut PHYSICS_STATE {
+                rope::tick(scene_id);
+                joints::tick(scene_id);
+
+                let Some(scene) = state.scenes.get_mut(&scene_id) else {
+                    panic!("No scene with given ID!");
+                };
+
+                compute_buoyancy(scene);
+            }
         }
-    }
+    }));
+    throw_on_panic(&mut env, result);
 }
 
 /// Steps physics
 #[unsafe(no_mangle)]
 pub extern "system" fn Java_dev_ryanhcode_sable_physics_impl_rapier_Rapier3D_step<'local>(
-    _env: JNIEnv<'local>,
+    mut env: JNIEnv<'local>,
     _class: JClass<'local>,
     scene_id: jint,
     time_step: jdouble,
@@ -463,20 +485,23 @@ pub extern "system" fn Java_dev_ryanhcode_sable_physics_impl_rapier_Rapier3D_ste
 
             scene.manifold_info_map = SableManifoldInfoMap::default();
 
-            scene.pipeline.step(
-                scene.gravity,
-                &state.integration_parameters,
-                &mut scene.island_manager,
-                &mut scene.broad_phase,
-                &mut scene.narrow_phase,
-                &mut scene.rigid_body_set,
-                &mut scene.collider_set,
-                &mut scene.impulse_joint_set,
-                &mut scene.multibody_joint_set,
-                &mut scene.ccd_solver,
-                &scene.physics_hooks,
-                &scene.event_handler,
-            );
+            let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
+                scene.pipeline.step(
+                    scene.gravity,
+                    &state.integration_parameters,
+                    &mut scene.island_manager,
+                    &mut scene.broad_phase,
+                    &mut scene.narrow_phase,
+                    &mut scene.rigid_body_set,
+                    &mut scene.collider_set,
+                    &mut scene.impulse_joint_set,
+                    &mut scene.multibody_joint_set,
+                    &mut scene.ccd_solver,
+                    &scene.physics_hooks,
+                    &scene.event_handler,
+                );
+            }));
+            throw_on_panic(&mut env, result);
         }
     }
 }