Issue 6526 - *ToV8String() return MaybeLocal<> and check Call() return value

src/JsValue.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 165 matching lines @@
   return result;
 }
 
 
 AdblockPlus::JsValue AdblockPlus::JsValue::GetProperty(const std::string& name) const
 {
   if (!IsObject())
     throw std::runtime_error("Attempting to get property of a non-object");
 
   const JsContext context(*jsEngine);
-  v8::Local<v8::String> property = Utils::ToV8String(jsEngine->GetIsolate(), name);
+  auto isolate = jsEngine->GetIsolate();
+  v8::MaybeLocal<v8::String> property = Utils::ToV8String(isolate, name);
+  if (property.IsEmpty())
+    throw std::runtime_error("Invalid property name");

[hub, 2018/06/22 00:34:31]

Since we already can throw, I thought it was OK to throw too. This is defintely
an error if we can make the key.

[sergei, 2018/06/22 06:57:46]

I think here we should use CHECKED_TO_LOCAL.

[hub, 2018/06/22 15:50:56]

Done.

   v8::Local<v8::Object> obj = v8::Local<v8::Object>::Cast(UnwrapValue());
-  return JsValue(jsEngine, obj->Get(property));
+  auto maybe = obj->Get(isolate->GetCurrentContext(), property.ToLocalChecked());
+  if (maybe.IsEmpty())
+    return JsValue(jsEngine, v8::Undefined(isolate));

[hub, 2018/06/22 00:34:31]

If the property isn't found we return `undefined`.

[sergei, 2018/06/22 06:57:46]

If the property is not found then the result of obj->Get(property) already
contains v8::Undefined. However, if something is wrong with the engine, then
maybe.IsEmpty() is true. So, IMO we should rather stop our execution as well.
Could you please add a test here?

[hub, 2018/06/22 15:50:56]

Done.

+  return JsValue(jsEngine, maybe.ToLocalChecked());
 }
 
 void AdblockPlus::JsValue::SetProperty(const std::string& name, v8::Local<v8::Value> val)
 {
   if (!IsObject())
     throw std::runtime_error("Attempting to set property on a non-object");
-
-  v8::Local<v8::String> property = Utils::ToV8String(jsEngine->GetIsolate(), name);
+  auto isolate = jsEngine->GetIsolate();

[sergei, 2018/06/22 06:57:46]

I think here and below we should use CHECKED_TO_LOCAL.

[hub, 2018/06/22 15:50:56]

Done.

+  v8::MaybeLocal<v8::String> property = Utils::ToV8String(isolate, name);
+  if (property.IsEmpty())
+    throw std::runtime_error("Invalid property name");
   v8::Local<v8::Object> obj = v8::Local<v8::Object>::Cast(UnwrapValue());
-  obj->Set(property, val);
+  obj->Set(property.ToLocalChecked(), val);
 }
 
 v8::Local<v8::Value> AdblockPlus::JsValue::UnwrapValue() const
 {
   return v8::Local<v8::Value>::New(jsEngine->GetIsolate(), *value);
 }
 
 void AdblockPlus::JsValue::SetProperty(const std::string& name, const std::string& val)
 {
   const JsContext context(*jsEngine);
-  SetProperty(name, Utils::ToV8String(jsEngine->GetIsolate(), val));
+  auto maybe = Utils::ToV8String(jsEngine->GetIsolate(), val);
+  if (maybe.IsEmpty())
+    return;
+  SetProperty(name, maybe.ToLocalChecked());
 }
 
 void AdblockPlus::JsValue::SetStringBufferProperty(const std::string& name, const StringBuffer& val)
 {
   const JsContext context(*jsEngine);
-  SetProperty(name, Utils::StringBufferToV8String(jsEngine->GetIsolate(), val));
+  auto maybe = Utils::StringBufferToV8String(jsEngine->GetIsolate(), val);
+  if (maybe.IsEmpty())
+    return;
+  SetProperty(name, maybe.ToLocalChecked());
 }
 
 void AdblockPlus::JsValue::SetProperty(const std::string& name, int64_t val)
 {
   const JsContext context(*jsEngine);
   SetProperty(name, v8::Number::New(jsEngine->GetIsolate(), val));
 }
 
 void AdblockPlus::JsValue::SetProperty(const std::string& name, const JsValue& val)
 {
@@ skipping 49 matching lines @@
   return Call(argv, context.GetV8Context()->Global());
 }
 
 JsValue JsValue::Call(std::vector<v8::Local<v8::Value>>& args, v8::Local<v8::Object> thisObj) const
 {
   if (!IsFunction())
     throw std::runtime_error("Attempting to call a non-function");
   if (!thisObj->IsObject())
     throw std::runtime_error("`this` pointer has to be an object");
 
+  auto isolate = jsEngine->GetIsolate();
   const JsContext context(*jsEngine);
 
-  const v8::TryCatch tryCatch(jsEngine->GetIsolate());
+  const v8::TryCatch tryCatch(isolate);
   v8::Local<v8::Function> func = v8::Local<v8::Function>::Cast(UnwrapValue());
-  v8::Local<v8::Value> result = func->Call(thisObj, args.size(),
-    args.size() ? &args[0] : nullptr);
-  if (tryCatch.HasCaught())
-    throw JsError(jsEngine->GetIsolate(), tryCatch.Exception(), tryCatch.Message());
+  auto result = CHECKED_TO_LOCAL(
+    isolate, func->Call(
+      isolate->GetCurrentContext(),
+      thisObj, args.size(), args.size() ? &args[0] : nullptr), tryCatch);
 
   return JsValue(jsEngine, result);
 }