feat: handle errors when calling js-functions from lua

Author: quaternion

binding.gyp

@@ -22,25 +22,20 @@
         "<@(lua_libraries)"
       ],
       "dependencies": [
-        "<!(node -p \"require('node-addon-api').targets\"):node_addon_api"
+        "<!(node -p \"require('node-addon-api').targets\"):node_addon_api_except"
       ],
       "defines": [ 
         "NAPI_VERSION=8",
         "NDEBUG"
       ],
-      "cflags!": [ 
-        "-fno-exceptions" 
-      ],
-      "cflags_cc!": [ 
-        "-fno-exceptions" 
-      ],
       "cflags+": [
         "-flto",
         "-fdata-sections",
         "-ffunction-sections",
         "-fvisibility=hidden"
       ],
       "cflags_cc+": [
+        "-fexceptions",
         "-flto",
         "-fdata-sections",
         "-ffunction-sections",

src/lua-state-context.cpp

@@ -610,33 +610,50 @@ namespace {
       return luaL_error(L, "Invalid js-function reference");
     }
 
-    Napi::Env env = js_function_holder->ref->Env();
-    Napi::HandleScope scope(env);
-
-    // cast lua arguments to javascript
-    int top_index = lua_gettop(L);
-
-    std::vector<napi_value> js_args;
-    js_args.reserve(top_index - 1);
-    for (int i = 2; i <= top_index; ++i) {
-      auto js_arg = ReadJsValueFromStack(L, env, i);
-      js_args.push_back(js_arg);
-    }
+    try {
+      Napi::Env env = js_function_holder->ref->Env();
+      Napi::HandleScope scope(env);
+
+      // cast lua arguments to javascript
+      int top_index = lua_gettop(L);
+
+      std::vector<napi_value> js_args;
+      js_args.reserve(top_index - 1);
+      for (int i = 2; i <= top_index; ++i) {
+        auto js_arg = ReadJsValueFromStack(L, env, i);
+        js_args.push_back(js_arg);
+      }
 
-    // call js function
-    Napi::Value js_function_result = js_function_holder->ref->Call(js_args);
+      // call js function
+      Napi::Value js_function_result = js_function_holder->ref->Call(js_args);
 
-    if (js_function_result.IsArray()) {
-      Napi::Array js_function_results = js_function_result.As<Napi::Array>();
-      uint32_t js_function_results_length = js_function_results.Length();
-      for (uint32_t i = 0; i < js_function_results_length; ++i) {
-        Napi::Value result = js_function_results.Get(i);
-        PushJsValueToStack(L, result);
+      // return function call result to lua
+      if (js_function_result.IsArray()) {
+        Napi::Array js_function_results = js_function_result.As<Napi::Array>();
+        uint32_t js_function_results_length = js_function_results.Length();
+        for (uint32_t i = 0; i < js_function_results_length; ++i) {
+          Napi::Value result = js_function_results.Get(i);
+          PushJsValueToStack(L, result);
+        }
+        return js_function_results_length;
+      } else {
+        PushJsValueToStack(L, js_function_result);
+        return 1;
       }
-      return js_function_results_length;
-    } else {
-      PushJsValueToStack(L, js_function_result);
-      return 1;
+    } catch (const Napi::Error& e) {
+      auto js_name = e.Get("name");
+      std::string name;
+      if (js_name.IsString()) {
+        name = js_name.As<Napi::String>().Utf8Value();
+      } else {
+        name = "Error";
+      }
+      std::string msg = name + ": " + e.Message();
+      return luaL_error(L, msg.c_str());
+    } catch (const std::exception& e) {
+      return luaL_error(L, e.what());
+    } catch (...) {
+      return luaL_error(L, "Unknown error from JS function");
     }
   }
 

tests/lua-state.set-global.test.js

@@ -109,7 +109,7 @@ describe(`${LuaState.name}#${LuaState.prototype.setGlobal.name}`, () => {
   })
 
   describe('with function', () => {
-    it('should set the function', () => {
+    it('should set function', () => {
       const func = mock.fn((num, str, bool, tbl) => {
         return { args: { num, str, bool, tbl } }
       })
@@ -141,5 +141,17 @@ describe(`${LuaState.name}#${LuaState.prototype.setGlobal.name}`, () => {
       luaState.eval(`r1, r2 = func()`)
       deepStrictEqual(luaState.eval(`return { r1, r2 }`), { 1: 1, 2: 'foo' })
     })
+
+    it('should set function with exception', () => {
+      const err = new Error('hello world')
+      luaState.setGlobal('throw', () => {
+        throw err
+      })
+      const res = luaState.eval(`
+        local ok, err = pcall(throw)
+        return { ok, err }
+      `)
+      deepStrictEqual(res, { 1: false, 2: `${err.name}: ${err.message}` })
+    })
   })
 })