n-api: add code parameter to error helpers

doc/api/n-api.md

@@ -323,6 +323,31 @@ code needs to create an Error object: [`napi_create_error`][],
 where result is the napi_value that refers to the newly created
 JavaScript Error object.
 
+The Node.js project is adding error codes to all of the errors
+generated internally.  The goal is for applications to use these
+error codes for all error checking. The associated error messages
+will remain, but will only be meant to be used for logging and
+display with the expectation that the message can change without
+SemVer applying. In order to support this model with N-API, both
+in internal functionality and for module specific functionality
+(as its good practice), the `throw_` and `create_` functions
+take an optional code parameter which is the string for the code
+to be added to the error object.  If the optional parameter is NULL
+then no code will be associated with the error. If a code is provided,
+the name associated with the error is also updated to be:
+
+```
+originalName [code]
+```
+
+where originalName is the original name associated with the error
+and code is the code that was provided.  For example if the code
+is 'ERR_ERROR_1' and a TypeError is being created the name will be:
+
+```
+TypeError [ERR_ERROR_1]
+```
+
 #### napi_throw
 <!-- YAML
 added: v8.0.0
@@ -343,9 +368,12 @@ This API throws the JavaScript Error provided.
 added: v8.0.0
 -->
 ```C
-NODE_EXTERN napi_status napi_throw_error(napi_env env, const char* msg);
+NODE_EXTERN napi_status napi_throw_error(napi_env env,
+                                         const char* code,
+                                         const char* msg);
 ```
 - `[in] env`: The environment that the API is invoked under.
+- `[in] code`: Optional error code to be set on the error.
 - `[in] msg`: C string representing the text to be associated with
 the error.
 
@@ -358,9 +386,12 @@ This API throws a JavaScript Error with the text provided.
 added: v8.0.0
 -->
 ```C
-NODE_EXTERN napi_status napi_throw_type_error(napi_env env, const char* msg);
+NODE_EXTERN napi_status napi_throw_type_error(napi_env env,
+                                              const char* code,
+                                              const char* msg);
 ```
 - `[in] env`: The environment that the API is invoked under.
+- `[in] code`: Optional error code to be set on the error.
 - `[in] msg`: C string representing the text to be associated with
 the error.
 
@@ -373,9 +404,12 @@ This API throws a JavaScript TypeError with the text provided.
 added: v8.0.0
 -->
 ```C
-NODE_EXTERN napi_status napi_throw_range_error(napi_env env, const char* msg);
+NODE_EXTERN napi_status napi_throw_range_error(napi_env env,
+                                               const char* code,
+                                               const char* msg);
 ```
 - `[in] env`: The environment that the API is invoked under.
+- `[in] code`: Optional error code to be set on the error.
 - `[in] msg`: C string representing the text to be associated with
 the error.
 
@@ -409,10 +443,13 @@ added: v8.0.0
 -->
 ```C
 NODE_EXTERN napi_status napi_create_error(napi_env env,
+                                          napi_value code,
                                           napi_value msg,
                                           napi_value* result);
 ```
 - `[in] env`: The environment that the API is invoked under.
+- `[in] code`: Optional `napi_value` with the string for the error code to
+               be associated with the error.
 - `[in] msg`: napi_value that references a JavaScript String to be
 used as the message for the Error.
 - `[out] result`: `napi_value` representing the error created.
@@ -427,10 +464,13 @@ added: v8.0.0
 -->
 ```C
 NODE_EXTERN napi_status napi_create_type_error(napi_env env,
+                                               napi_value code,
                                                napi_value msg,
                                                napi_value* result);
 ```
 - `[in] env`: The environment that the API is invoked under.
+- `[in] code`: Optional `napi_value` with the string for the error code to
+               be associated with the error.
 - `[in] msg`: napi_value that references a JavaScript String to be
 used as the message for the Error.
 - `[out] result`: `napi_value` representing the error created.
@@ -446,10 +486,13 @@ added: v8.0.0
 -->
 ```C
 NODE_EXTERN napi_status napi_create_range_error(napi_env env,
+                                                napi_value code,
                                                 const char* msg,
                                                 napi_value* result);
 ```
 - `[in] env`: The environment that the API is invoked under.
+- `[in] code`: Optional `napi_value` with the string for the error code to
+               be associated with the error.
 - `[in] msg`: napi_value that references a JavaScript String to be
 used as the message for the Error.
 - `[out] result`: `napi_value` representing the error created.

lib/internal/errors.js

@@ -161,6 +161,8 @@ E('ERR_IPC_ONE_PIPE', 'Child process can have only one IPC pipe');
 E('ERR_IPC_SYNC_FORK', 'IPC cannot be used with synchronous forks');
 E('ERR_MISSING_ARGS', missingArgs);
 E('ERR_MULTIPLE_CALLBACK', 'Callback called multiple times');
+E('ERR_NAPI_CONS_FUNCTION', 'Constructor must be a function');
+E('ERR_NAPI_CONS_PROTOTYPE_OBJECT', 'Constructor.prototype must be an object');
 E('ERR_NO_CRYPTO', 'Node.js is not compiled with OpenSSL crypto support');
 E('ERR_PARSE_HISTORY_DATA', 'Could not parse history data in %s');
 E('ERR_SOCKET_ALREADY_BOUND', 'Socket is already bound');

src/node_api.cc

@@ -18,6 +18,7 @@
 #include "uv.h"
 #include "node_api.h"
 #include "node_internals.h"
+#include "util.h"
 
 #define NAPI_VERSION  1
 
@@ -1522,7 +1523,61 @@ napi_status napi_create_symbol(napi_env env,
   return GET_RETURN_STATUS(env);
 }
 
+static napi_status set_error_code(napi_env env,
+                                  v8::Local<v8::Value> error,
+                                  napi_value code,
+                                  const char* code_cstring) {
+  if ((code != nullptr) || (code_cstring != nullptr)) {
+    v8::Isolate* isolate = env->isolate;
+    v8::Local<v8::Context> context = isolate->GetCurrentContext();
+    v8::Local<v8::Object> err_object = error.As<v8::Object>();
+
+    v8::Local<v8::Value> code_value = v8impl::V8LocalValueFromJsValue(code);
+    if (code != nullptr) {
+      code_value = v8impl::V8LocalValueFromJsValue(code);
+      RETURN_STATUS_IF_FALSE(env, code_value->IsString(), napi_string_expected);
+    } else {
+      CHECK_NEW_FROM_UTF8(env, code_value, code_cstring);
+    }
+
+    v8::Local<v8::Name> code_key;
+    CHECK_NEW_FROM_UTF8(env, code_key, "code");
+
+    v8::Maybe<bool> set_maybe = err_object->Set(context, code_key, code_value);
+    RETURN_STATUS_IF_FALSE(env,
+                           set_maybe.FromMaybe(false),
+                           napi_generic_failure);
+
+    // now update the name to be "name [code]" where name is the
+    // original name and code is the code associated with the Error
+    v8::Local<v8::String> name_string;
+    CHECK_NEW_FROM_UTF8(env, name_string, "");
+    v8::Local<v8::Name> name_key;
+    CHECK_NEW_FROM_UTF8(env, name_key, "name");
+
+    auto maybe_name = err_object->Get(context, name_key);
+    if (!maybe_name.IsEmpty()) {
+      v8::Local<v8::Value> name = maybe_name.ToLocalChecked();
+      if (name->IsString()) {
+        name_string = v8::String::Concat(name_string, name.As<v8::String>());
+      }
+    }
+    name_string = v8::String::Concat(name_string,
+                                     FIXED_ONE_BYTE_STRING(isolate, " ["));
+    name_string = v8::String::Concat(name_string, code_value.As<v8::String>());
+    name_string = v8::String::Concat(name_string,
+                                     FIXED_ONE_BYTE_STRING(isolate, "]"));
+
+    set_maybe = err_object->Set(context, name_key, name_string);
+    RETURN_STATUS_IF_FALSE(env,
+                           set_maybe.FromMaybe(false),
+                           napi_generic_failure);
+  }
+  return napi_ok;
+}
+
 napi_status napi_create_error(napi_env env,
+                              napi_value code,
                               napi_value msg,
                               napi_value* result) {
   NAPI_PREAMBLE(env);
@@ -1532,13 +1587,18 @@ napi_status napi_create_error(napi_env env,
   v8::Local<v8::Value> message_value = v8impl::V8LocalValueFromJsValue(msg);
   RETURN_STATUS_IF_FALSE(env, message_value->IsString(), napi_string_expected);
 
-  *result = v8impl::JsValueFromV8LocalValue(v8::Exception::Error(
-      message_value.As<v8::String>()));
+  v8::Local<v8::Value> error_obj =
+      v8::Exception::Error(message_value.As<v8::String>());
+  napi_status status = set_error_code(env, error_obj, code, nullptr);
+  if (status != napi_ok) return status;
+
+  *result = v8impl::JsValueFromV8LocalValue(error_obj);
 
   return GET_RETURN_STATUS(env);
 }
 
 napi_status napi_create_type_error(napi_env env,
+                                   napi_value code,
                                    napi_value msg,
                                    napi_value* result) {
   NAPI_PREAMBLE(env);
@@ -1548,13 +1608,18 @@ napi_status napi_create_type_error(napi_env env,
   v8::Local<v8::Value> message_value = v8impl::V8LocalValueFromJsValue(msg);
   RETURN_STATUS_IF_FALSE(env, message_value->IsString(), napi_string_expected);
 
-  *result = v8impl::JsValueFromV8LocalValue(v8::Exception::TypeError(
-      message_value.As<v8::String>()));
+  v8::Local<v8::Value> error_obj =
+      v8::Exception::TypeError(message_value.As<v8::String>());
+  napi_status status = set_error_code(env, error_obj, code, nullptr);
+  if (status != napi_ok) return status;
+
+  *result = v8impl::JsValueFromV8LocalValue(error_obj);
 
   return GET_RETURN_STATUS(env);
 }
 
 napi_status napi_create_range_error(napi_env env,
+                                    napi_value code,
                                     napi_value msg,
                                     napi_value* result) {
   NAPI_PREAMBLE(env);
@@ -1564,8 +1629,12 @@ napi_status napi_create_range_error(napi_env env,
   v8::Local<v8::Value> message_value = v8impl::V8LocalValueFromJsValue(msg);
   RETURN_STATUS_IF_FALSE(env, message_value->IsString(), napi_string_expected);
 
-  *result = v8impl::JsValueFromV8LocalValue(v8::Exception::RangeError(
-      message_value.As<v8::String>()));
+  v8::Local<v8::Value> error_obj =
+      v8::Exception::RangeError(message_value.As<v8::String>());
+  napi_status status = set_error_code(env, error_obj, code, nullptr);
+  if (status != napi_ok) return status;
+
+  *result = v8impl::JsValueFromV8LocalValue(error_obj);
 
   return GET_RETURN_STATUS(env);
 }
@@ -1738,40 +1807,58 @@ napi_status napi_throw(napi_env env, napi_value error) {
   return napi_clear_last_error(env);
 }
 
-napi_status napi_throw_error(napi_env env, const char* msg) {
+napi_status napi_throw_error(napi_env env,
+                             const char* code,
+                             const char* msg) {
   NAPI_PREAMBLE(env);
 
   v8::Isolate* isolate = env->isolate;
   v8::Local<v8::String> str;
   CHECK_NEW_FROM_UTF8(env, str, msg);
 
-  isolate->ThrowException(v8::Exception::Error(str));
+  v8::Local<v8::Value> error_obj = v8::Exception::Error(str);
+  napi_status status = set_error_code(env, error_obj, nullptr, code);
+  if (status != napi_ok) return status;
+
+  isolate->ThrowException(error_obj);
   // any VM calls after this point and before returning
   // to the javascript invoker will fail
   return napi_clear_last_error(env);
 }
 
-napi_status napi_throw_type_error(napi_env env, const char* msg) {
+napi_status napi_throw_type_error(napi_env env,
+                                  const char* code,
+                                  const char* msg) {
   NAPI_PREAMBLE(env);
 
   v8::Isolate* isolate = env->isolate;
   v8::Local<v8::String> str;
   CHECK_NEW_FROM_UTF8(env, str, msg);
 
-  isolate->ThrowException(v8::Exception::TypeError(str));
+  v8::Local<v8::Value> error_obj = v8::Exception::TypeError(str);
+  napi_status status = set_error_code(env, error_obj, nullptr, code);
+  if (status != napi_ok) return status;
+
+  isolate->ThrowException(error_obj);
   // any VM calls after this point and before returning
   // to the javascript invoker will fail
   return napi_clear_last_error(env);
 }
 
-napi_status napi_throw_range_error(napi_env env, const char* msg) {
+napi_status napi_throw_range_error(napi_env env,
+                                   const char* code,
+                                   const char* msg) {
   NAPI_PREAMBLE(env);
 
   v8::Isolate* isolate = env->isolate;
   v8::Local<v8::String> str;
   CHECK_NEW_FROM_UTF8(env, str, msg);
 
-  isolate->ThrowException(v8::Exception::RangeError(str));
+  v8::Local<v8::Value> error_obj = v8::Exception::RangeError(str);
+  napi_status status = set_error_code(env, error_obj, nullptr, code);
+  if (status != napi_ok) return status;
+
+  isolate->ThrowException(error_obj);
   // any VM calls after this point and before returning
   // to the javascript invoker will fail
   return napi_clear_last_error(env);
@@ -2391,7 +2478,9 @@ napi_status napi_instanceof(napi_env env,
   CHECK_TO_OBJECT(env, context, ctor, constructor);
 
   if (!ctor->IsFunction()) {
-    napi_throw_type_error(env, "constructor must be a function");
+    napi_throw_type_error(env,
+                          "ERR_NAPI_CONS_FUNCTION",
+                          "Constructor must be a function");
 
     return napi_set_last_error(env, napi_function_expected);
   }
@@ -2459,7 +2548,10 @@ napi_status napi_instanceof(napi_env env,
 
   v8::Local<v8::Value> prototype_property = maybe_prototype.ToLocalChecked();
   if (!prototype_property->IsObject()) {
-    napi_throw_type_error(env, "constructor.prototype must be an object");
+    napi_throw_type_error(
+        env,
+        "ERR_NAPI_CONS_PROTOTYPE_OBJECT",
+        "Constructor.prototype must be an object");
 
     return napi_set_last_error(env, napi_object_expected);
   }

src/node_api.h

@@ -142,12 +142,15 @@ NAPI_EXTERN napi_status napi_create_function(napi_env env,
                                              void* data,
                                              napi_value* result);
 NAPI_EXTERN napi_status napi_create_error(napi_env env,
+                                          napi_value code,
                                           napi_value msg,
                                           napi_value* result);
 NAPI_EXTERN napi_status napi_create_type_error(napi_env env,
+                                               napi_value code,
                                                napi_value msg,
                                                napi_value* result);
 NAPI_EXTERN napi_status napi_create_range_error(napi_env env,
+                                                napi_value code,
                                                 napi_value msg,
                                                 napi_value* result);
 
@@ -404,9 +407,15 @@ NAPI_EXTERN napi_status napi_escape_handle(napi_env env,
 
 // Methods to support error handling
 NAPI_EXTERN napi_status napi_throw(napi_env env, napi_value error);
-NAPI_EXTERN napi_status napi_throw_error(napi_env env, const char* msg);
-NAPI_EXTERN napi_status napi_throw_type_error(napi_env env, const char* msg);
-NAPI_EXTERN napi_status napi_throw_range_error(napi_env env, const char* msg);
+NAPI_EXTERN napi_status napi_throw_error(napi_env env,
+                                         const char* code,
+                                         const char* msg);
+NAPI_EXTERN napi_status napi_throw_type_error(napi_env env,
+                                         const char* code,
+                                         const char* msg);
+NAPI_EXTERN napi_status napi_throw_range_error(napi_env env,
+                                         const char* code,
+                                         const char* msg);
 NAPI_EXTERN napi_status napi_is_error(napi_env env,
                                       napi_value value,
                                       bool* result);

test/addons-napi/common.h

@@ -12,7 +12,7 @@
       const char* error_message = error_info->error_message != NULL ?    \
         error_info->error_message :                                      \
         "empty error message";                                           \
-      napi_throw_error((env), error_message);                            \
+      napi_throw_error((env), NULL, error_message);                      \
     }                                                                    \
   } while (0)
 
@@ -21,6 +21,7 @@
     if (!(assertion)) {                                                  \
       napi_throw_error(                                                  \
           (env),                                                         \
+        NULL,                                                            \
           "assertion (" #assertion ") failed: " message);                \
       return ret_val;                                                    \
     }                                                                    \