[Lua] scene_:LoadXML() segfaults

Hi!

I’m trying to load a scene XML in lua but Urho3DPlayer is segfaulting. Am I doing something wrong, or is this an issue that needs to be fixed?

I created a scene in Urho3D’s editor and saved it under Data/Scenes/ramps.xml.

Loading the scene using C++ works fine:

[code]void App::CreateScene()
{
ResourceCache* cache = GetSubsystem();

scene_ = SharedPtr<Scene>(new Scene(context_));
XMLFile* sceneFile = cache->GetResource<XMLFile>("Scenes/Ramps.xml");
scene_->LoadXML(sceneFile->GetRoot());

}[/code]

I then tried to re-write the above in Lua and ran it using Urho3DPlayer, but it segfaults.

function CreateScene() scene_ = Scene() local sceneXML = cache:GetResource("XMLFile", "Scenes/Ramps.xml") scene_:LoadXML(sceneXML:GetRoot()) -- This line causes the segfault. end

Exact command and backtrace:

[1] 2680 segmentation fault /usr/urho3d/bin/Urho3DPlayer MyScript.lua -w #0 0x0000000000d877c4 in Urho3D::XMLFile::BeginLoad(Urho3D::Deserializer&) () #1 0x0000000000d94201 in Urho3D::Resource::Load(Urho3D::Deserializer&) () #2 0x0000000000d2a5f2 in Urho3D::Scene::LoadXML(Urho3D::Deserializer&) () #3 0x0000000000bf8955 in tolua_SceneLuaAPI_Scene_LoadXML01(lua_State*) () #4 0x0000000001184f07 in lj_BC_FUNCC () #5 0x0000000000a6d8bd in lua_pcall () #6 0x000000000104342f in Urho3D::LuaFunction::EndCall(int) () #7 0x000000000063117f in Urho3DPlayer::Start() ()

My version of Urho3D is on the master branch, commit hash 0906da48badacb227701e85b186581b580f9f778 (Fri Jan 15 21:02:56 2016 +0800). I built using the following options:

$ git clone git://github.com/urho3d/urho3d && cd urho3d $ mkdir build && cd build $ cmake \ -DURHO3D_C++11=ON \ -DURHO3D_DOCS=ON \ -DURHO3D_LUA=ON \ -DURHO3D_LUAJIT=ON \ -DCMAKE_INSTALL_PREFIX=/usr/urho3d \ .. $ make -j7 $ make install

OS:

$ uname -a Linux rainbowdash 4.1.12-gentoo #1 SMP Tue Nov 10 00:33:50 CET 2015 x86_64 Intel(R) Core(TM) i5-2410M CPU @ 2.30GHz GenuineIntel GNU/Linux

[size=150]Update[/size]

I re-built Urho3D and enabled all of the debug options and here’s the error message:

[Mon Jan 25 02:04:56 2016] ERROR: Execute Lua function failed: [string "hound"]:20: error in function 'LoadXML'. argument #2 is 'XMLFile'; 'File' expected.

Code:

scene_ = Scene() local sceneFile = cache:GetResource("XMLFile", "Scenes/Ramps.xml") scene_:LoadXML(sceneFile)

I’m pretty sure this is wrong and I’m not sure what Lua is really expecting.

Due to technical reasons (scene wants to be able to get a file checksum for e.g. networking) there isn’t an overload of Scene::LoadXML which takes a XMLFile. For Lua, it can take either a File* (which you get with ResourceCache::GetFile, be careful with memory management) or a string containing pathname.

Due to tolua++ being what it is, getting crashes with wrong parameters is easy. This is unfortunate, for now if you want a more robust scripting environment I’d recommend using AngelScript instead.

Thanks for the insight!