node-api: emit uncaught-exception on unhandled tsfn callbacks

PR-URL: #36510
Fixes: #36402
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/cli.md

@@ -427,6 +427,18 @@ under this flag.
 
 To allow polyfills to be added, `--require` runs before freezing intrinsics.
 
+### `--force-node-api-uncaught-exceptions-policy`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+Enforces `uncaughtException` event on Node-API asynchronous callbacks.
+
+To prevent from an existing add-on from crashing the process, this flag is not
+enabled by default. In the future, this flag will be enabled by default to
+enforce the correct behavior.
+
 ### `--heapsnapshot-near-heap-limit=max_count`
 
 <!-- YAML
@@ -1625,6 +1637,7 @@ Node.js options that are allowed are:
 * `--experimental-wasm-modules`
 * `--force-context-aware`
 * `--force-fips`
+* `--force-node-api-uncaught-exceptions-policy`
 * `--frozen-intrinsics`
 * `--heapsnapshot-near-heap-limit`
 * `--heapsnapshot-signal`

src/js_native_api_v8.h

@@ -57,15 +57,7 @@ struct napi_env__ {
     CHECK_EQ(isolate, context->GetIsolate());
     napi_clear_last_error(this);
   }
-  virtual ~napi_env__() {
-    // First we must finalize those references that have `napi_finalizer`
-    // callbacks. The reason is that addons might store other references which
-    // they delete during their `napi_finalizer` callbacks. If we deleted such
-    // references here first, they would be doubly deleted when the
-    // `napi_finalizer` deleted them subsequently.
-    v8impl::RefTracker::FinalizeAll(&finalizing_reflist);
-    v8impl::RefTracker::FinalizeAll(&reflist);
-  }
+  virtual ~napi_env__() { FinalizeAll(); }
   v8::Isolate* const isolate;  // Shortcut for context()->GetIsolate()
   v8impl::Persistent<v8::Context> context_persistent;
 
@@ -102,11 +94,23 @@ struct napi_env__ {
     }
   }
 
+  // This should be overridden to schedule the finalization to a properiate
+  // timing, like next tick of the event loop.
   virtual void CallFinalizer(napi_finalize cb, void* data, void* hint) {
     v8::HandleScope handle_scope(isolate);
     CallIntoModule([&](napi_env env) { cb(env, data, hint); });
   }
 
+  void FinalizeAll() {
+    // First we must finalize those references that have `napi_finalizer`
+    // callbacks. The reason is that addons might store other references which
+    // they delete during their `napi_finalizer` callbacks. If we deleted such
+    // references here first, they would be doubly deleted when the
+    // `napi_finalizer` deleted them subsequently.
+    v8impl::RefTracker::FinalizeAll(&finalizing_reflist);
+    v8impl::RefTracker::FinalizeAll(&reflist);
+  }
+
   v8impl::Persistent<v8::Value> last_exception;
 
   // We store references in two different lists, depending on whether they have

src/node_api.cc

@@ -9,6 +9,7 @@
 #include "node_buffer.h"
 #include "node_errors.h"
 #include "node_internals.h"
+#include "node_process.h"
 #include "node_url.h"
 #include "threadpoolwork-inl.h"
 #include "tracing/traced_value.h"
@@ -23,6 +24,11 @@ node_napi_env__::node_napi_env__(v8::Local<v8::Context> context,
   CHECK_NOT_NULL(node_env());
 }
 
+node_napi_env__::~node_napi_env__() {
+  destructing = true;
+  FinalizeAll();
+}
+
 bool node_napi_env__::can_call_into_js() const {
   return node_env()->can_call_into_js();
 }
@@ -35,19 +41,64 @@ v8::Maybe<bool> node_napi_env__::mark_arraybuffer_as_untransferable(
 }
 
 void node_napi_env__::CallFinalizer(napi_finalize cb, void* data, void* hint) {
+  CallFinalizer<true>(cb, data, hint);
+}
+
+template <bool enforceUncaughtExceptionPolicy>
+void node_napi_env__::CallFinalizer(napi_finalize cb, void* data, void* hint) {
+  if (destructing) {
+    // we can not defer finalizers when the environment is being destructed.
+    v8::HandleScope handle_scope(isolate);
+    v8::Context::Scope context_scope(context());
+    CallbackIntoModule<enforceUncaughtExceptionPolicy>(
+        [&](napi_env env) { cb(env, data, hint); });
+    return;
+  }
   // we need to keep the env live until the finalizer has been run
   // EnvRefHolder provides an exception safe wrapper to Ref and then
   // Unref once the lambda is freed
   EnvRefHolder liveEnv(static_cast<napi_env>(this));
   node_env()->SetImmediate(
       [=, liveEnv = std::move(liveEnv)](node::Environment* node_env) {
-        napi_env env = liveEnv.env();
+        node_napi_env__* env = static_cast<node_napi_env__*>(liveEnv.env());
         v8::HandleScope handle_scope(env->isolate);
         v8::Context::Scope context_scope(env->context());
-        env->CallIntoModule([&](napi_env env) { cb(env, data, hint); });
+        env->CallbackIntoModule<enforceUncaughtExceptionPolicy>(
+            [&](napi_env env) { cb(env, data, hint); });
       });
 }
 
+void node_napi_env__::trigger_fatal_exception(v8::Local<v8::Value> local_err) {
+  v8::Local<v8::Message> local_msg =
+      v8::Exception::CreateMessage(isolate, local_err);
+  node::errors::TriggerUncaughtException(isolate, local_err, local_msg);
+}
+
+// option enforceUncaughtExceptionPolicy is added for not breaking existing
+// running n-api add-ons, and should be deprecated in the next major Node.js
+// release.
+template <bool enforceUncaughtExceptionPolicy, typename T>
+void node_napi_env__::CallbackIntoModule(T&& call) {
+  CallIntoModule(call, [](napi_env env_, v8::Local<v8::Value> local_err) {
+    node_napi_env__* env = static_cast<node_napi_env__*>(env_);
+    node::Environment* node_env = env->node_env();
+    if (!node_env->options()->force_node_api_uncaught_exceptions_policy &&
+        !enforceUncaughtExceptionPolicy) {
+      ProcessEmitDeprecationWarning(
+          node_env,
+          "Uncaught N-API callback exception detected, please run node "
+          "with option --force-node-api-uncaught-exceptions-policy=true"
+          "to handle those exceptions properly.",
+          "DEP0XXX");
+      return;
+    }
+    // If there was an unhandled exception in the complete callback,
+    // report it as a fatal exception. (There is no JavaScript on the
+    // callstack that can possibly handle it.)
+    env->trigger_fatal_exception(local_err);
+  });
+}
+
 namespace v8impl {
 
 namespace {
@@ -60,20 +111,10 @@ class BufferFinalizer : private Finalizer {
         static_cast<BufferFinalizer*>(hint)};
     finalizer->_finalize_data = data;
 
-    node::Environment* node_env =
-        static_cast<node_napi_env>(finalizer->_env)->node_env();
-    node_env->SetImmediate(
-        [finalizer = std::move(finalizer)](node::Environment* env) {
-          if (finalizer->_finalize_callback == nullptr) return;
-
-          v8::HandleScope handle_scope(finalizer->_env->isolate);
-          v8::Context::Scope context_scope(finalizer->_env->context());
-
-          finalizer->_env->CallIntoModule([&](napi_env env) {
-            finalizer->_finalize_callback(
-                env, finalizer->_finalize_data, finalizer->_finalize_hint);
-          });
-        });
+    if (finalizer->_finalize_callback == nullptr) return;
+    finalizer->_env->CallFinalizer(finalizer->_finalize_callback,
+                                   finalizer->_finalize_data,
+                                   finalizer->_finalize_hint);
   }
 
   struct Deleter {
@@ -102,13 +143,6 @@ static inline napi_env NewEnv(v8::Local<v8::Context> context,
   return result;
 }
 
-static inline void trigger_fatal_exception(napi_env env,
-                                           v8::Local<v8::Value> local_err) {
-  v8::Local<v8::Message> local_msg =
-      v8::Exception::CreateMessage(env->isolate, local_err);
-  node::errors::TriggerUncaughtException(env->isolate, local_err, local_msg);
-}
-
 class ThreadSafeFunction : public node::AsyncResource {
  public:
   ThreadSafeFunction(v8::Local<v8::Function> func,
@@ -325,7 +359,7 @@ class ThreadSafeFunction : public node::AsyncResource {
             v8::Local<v8::Function>::New(env->isolate, ref);
         js_callback = v8impl::JsValueFromV8LocalValue(js_cb);
       }
-      env->CallIntoModule(
+      env->CallbackIntoModule<false>(
           [&](napi_env env) { call_js_cb(env, js_callback, context, data); });
     }
 
@@ -336,7 +370,9 @@ class ThreadSafeFunction : public node::AsyncResource {
     v8::HandleScope scope(env->isolate);
     if (finalize_cb) {
       CallbackScope cb_scope(this);
-      env->CallIntoModule(
+      // Do not use CallFinalizer since it will defer the invocation, which
+      // would lead to accessing a deleted ThreadSafeFunction.
+      env->CallbackIntoModule<false>(
           [&](napi_env env) { finalize_cb(env, finalize_data, context); });
     }
     EmptyQueueAndDelete();
@@ -719,7 +755,7 @@ napi_status NAPI_CDECL napi_fatal_exception(napi_env env, napi_value err) {
   CHECK_ARG(env, err);
 
   v8::Local<v8::Value> local_err = v8impl::V8LocalValueFromJsValue(err);
-  v8impl::trigger_fatal_exception(env, local_err);
+  static_cast<node_napi_env>(env)->trigger_fatal_exception(local_err);
 
   return napi_clear_last_error(env);
 }
@@ -1064,16 +1100,9 @@ class Work : public node::AsyncResource, public node::ThreadPoolWork {
 
     CallbackScope callback_scope(this);
 
-    _env->CallIntoModule(
-        [&](napi_env env) {
-          _complete(env, ConvertUVErrorCode(status), _data);
-        },
-        [](napi_env env, v8::Local<v8::Value> local_err) {
-          // If there was an unhandled exception in the complete callback,
-          // report it as a fatal exception. (There is no JavaScript on the
-          // callstack that can possibly handle it.)
-          v8impl::trigger_fatal_exception(env, local_err);
-        });
+    _env->CallbackIntoModule<true>([&](napi_env env) {
+      _complete(env, ConvertUVErrorCode(status), _data);
+    });
 
     // Note: Don't access `work` after this point because it was
     // likely deleted by the complete callback.

src/node_api_internals.h

@@ -11,18 +11,26 @@
 struct node_napi_env__ : public napi_env__ {
   node_napi_env__(v8::Local<v8::Context> context,
                   const std::string& module_filename);
+  ~node_napi_env__();
 
   bool can_call_into_js() const override;
   v8::Maybe<bool> mark_arraybuffer_as_untransferable(
       v8::Local<v8::ArrayBuffer> ab) const override;
   void CallFinalizer(napi_finalize cb, void* data, void* hint) override;
+  template <bool enforceUncaughtExceptionPolicy>
+  void CallFinalizer(napi_finalize cb, void* data, void* hint);
+
+  void trigger_fatal_exception(v8::Local<v8::Value> local_err);
+  template <bool enforceUncaughtExceptionPolicy, typename T>
+  void CallbackIntoModule(T&& call);
 
   inline node::Environment* node_env() const {
     return node::Environment::GetCurrent(context());
   }
   inline const char* GetFilename() const { return filename.c_str(); }
 
   std::string filename;
+  bool destructing = false;
 };
 
 using node_napi_env = node_napi_env__*;

src/node_options.cc

@@ -432,6 +432,12 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             &EnvironmentOptions::force_async_hooks_checks,
             kAllowedInEnvironment,
             true);
+  AddOption(
+      "--force-node-api-uncaught-exceptions-policy",
+      "enforces 'uncaughtException' event on Node API asynchronous callbacks",
+      &EnvironmentOptions::force_node_api_uncaught_exceptions_policy,
+      kAllowedInEnvironment,
+      false);
   AddOption("--addons",
             "disable loading native addons",
             &EnvironmentOptions::allow_native_addons,

src/node_options.h

@@ -120,6 +120,7 @@ class EnvironmentOptions : public Options {
   bool experimental_repl_await = true;
   bool experimental_vm_modules = false;
   bool expose_internals = false;
+  bool force_node_api_uncaught_exceptions_policy = false;
   bool frozen_intrinsics = false;
   int64_t heap_snapshot_near_heap_limit = 0;
   std::string heap_snapshot_signal;

test/js-native-api/test_reference/test_finalizer.js

@@ -0,0 +1,20 @@
+'use strict';
+// Flags: --expose-gc --force-node-api-uncaught-exceptions-policy
+
+const common = require('../../common');
+const test_reference = require(`./build/${common.buildType}/test_reference`);
+const assert = require('assert');
+
+process.on('uncaughtException', common.mustCall((err) => {
+  assert.throws(() => { throw err; }, /finalizer error/);
+}));
+
+(async function() {
+  {
+    test_reference.createExternalWithJsFinalize(
+      common.mustCall(() => {
+        throw new Error('finalizer error');
+      }));
+  }
+  global.gc();
+})().then(common.mustCall());

test/js-native-api/test_reference/test_reference.c

@@ -21,6 +21,20 @@ static void FinalizeExternal(napi_env env, void* data, void* hint) {
   finalize_count++;
 }
 
+static void FinalizeExternalCallJs(napi_env env, void* data, void* hint) {
+  int *actual_value = data;
+  NODE_API_ASSERT_RETURN_VOID(env, actual_value == &test_value,
+      "The correct pointer was passed to the finalizer");
+
+  napi_ref finalizer_ref = (napi_ref)hint;
+  napi_value js_finalizer;
+  napi_value recv;
+  NODE_API_CALL_RETURN_VOID(env, napi_get_reference_value(env, finalizer_ref, &js_finalizer));
+  NODE_API_CALL_RETURN_VOID(env, napi_get_global(env, &recv));
+  NODE_API_CALL_RETURN_VOID(env, napi_call_function(env, recv, js_finalizer, 0, NULL, NULL));
+  NODE_API_CALL_RETURN_VOID(env, napi_delete_reference(env, finalizer_ref));
+}
+
 static napi_value CreateExternal(napi_env env, napi_callback_info info) {
   int* data = &test_value;
 
@@ -99,6 +113,31 @@ CreateExternalWithFinalize(napi_env env, napi_callback_info info) {
   return result;
 }
 
+static napi_value
+CreateExternalWithJsFinalize(napi_env env, napi_callback_info info) {
+  size_t argc = 1;
+  napi_value args[1];
+  NODE_API_CALL(env, napi_get_cb_info(env, info, &argc, args, NULL, NULL));
+  NODE_API_ASSERT(env, argc == 1, "Wrong number of arguments");
+  napi_value finalizer = args[0];
+  napi_valuetype finalizer_valuetype;
+  NODE_API_CALL(env, napi_typeof(env, finalizer, &finalizer_valuetype));
+  NODE_API_ASSERT(env, finalizer_valuetype == napi_function, "Wrong type of first argument");
+  napi_ref finalizer_ref;
+  NODE_API_CALL(env, napi_create_reference(env, finalizer, 1, &finalizer_ref));
+
+  napi_value result;
+  NODE_API_CALL(env,
+      napi_create_external(env,
+                           &test_value,
+                           FinalizeExternalCallJs,
+                           finalizer_ref, /* finalize_hint */
+                           &result));
+
+  finalize_count = 0;
+  return result;
+}
+
 static napi_value CheckExternal(napi_env env, napi_callback_info info) {
   size_t argc = 1;
   napi_value arg;
@@ -223,6 +262,8 @@ napi_value Init(napi_env env, napi_value exports) {
     DECLARE_NODE_API_PROPERTY("createExternal", CreateExternal),
     DECLARE_NODE_API_PROPERTY("createExternalWithFinalize",
         CreateExternalWithFinalize),
+    DECLARE_NODE_API_PROPERTY("createExternalWithJsFinalize",
+        CreateExternalWithJsFinalize),
     DECLARE_NODE_API_PROPERTY("checkExternal", CheckExternal),
     DECLARE_NODE_API_PROPERTY("createReference", CreateReference),
     DECLARE_NODE_API_PROPERTY("createSymbol", CreateSymbol),
@@ -234,7 +275,7 @@ napi_value Init(napi_env env, napi_value exports) {
     DECLARE_NODE_API_PROPERTY("decrementRefcount", DecrementRefcount),
     DECLARE_NODE_API_GETTER("referenceValue", GetReferenceValue),
     DECLARE_NODE_API_PROPERTY("validateDeleteBeforeFinalize",
-        ValidateDeleteBeforeFinalize),
+                          ValidateDeleteBeforeFinalize),
   };
 
   NODE_API_CALL(env, napi_define_properties(