Guard against bad memory access in RenderPassSystem (#1153)

Fixes a bad memory access that in RenderPassSystem that happens in some linux builds.

On Ubuntu with gcc, global_##classname##Factory is initialized after RenderPassSystem::renderPassMap, so the Register call in the constructor for ##classname##Factory works as expected.
However, on some linux builds, global_##classname##Factory may be initialized before RenderPassSystem::renderPassMap, leading to a bad memory access.

This is fixed by using the Construct On First Use idiom, where the static renderPassMap member variable is replaced by a GetRenderPassMap() member function in which the actual static render pass map is instantiated. This member function is then called in RenderPassSystem::Register() and in RenderPassSystem::CreateImpl() to write to/ read from the static render map.

Signed-off-by: Shameek Ganguly <[email protected]>

Author: shameekganguly

include/gz/rendering/RenderPassSystem.hh

@@ -81,7 +81,9 @@ namespace gz
 
       /// \brief A map of render pass type id name to its factory class
       GZ_UTILS_WARN_IGNORE__DLL_INTERFACE_MISSING
-      private: static std::map<std::string, RenderPassFactory *> renderPassMap;
+      private: typedef std::map<std::string, RenderPassFactory *>
+          RenderPassMap;
+      private: static RenderPassMap &GetRenderPassMap();
 
       /// \internal
       /// \brief Pointer to private data class

src/RenderPassSystem.cc

@@ -27,8 +27,6 @@ class gz::rendering::RenderPassSystemPrivate
 {
 };
 
-std::map<std::string, RenderPassFactory *> RenderPassSystem::renderPassMap;
-
 //////////////////////////////////////////////////
 // RenderPassSystem
 //////////////////////////////////////////////////
@@ -44,8 +42,8 @@ RenderPassSystem::~RenderPassSystem() = default;
 RenderPassPtr RenderPassSystem::CreateImpl(const std::string &_type)
 {
   RenderPassPtr pass;
-  auto it = renderPassMap.find(_type);
-  if (it != renderPassMap.end())
+  auto it = GetRenderPassMap().find(_type);
+  if (it != GetRenderPassMap().end())
   {
     pass.reset(it->second->New());
   }
@@ -61,5 +59,12 @@ RenderPassPtr RenderPassSystem::CreateImpl(const std::string &_type)
 void RenderPassSystem::Register(const std::string &_name,
     RenderPassFactory *_factory)
 {
-  renderPassMap[_name] = _factory;
+  GetRenderPassMap()[_name] = _factory;
+}
+
+//////////////////////////////////////////////////
+RenderPassSystem::RenderPassMap &RenderPassSystem::GetRenderPassMap()
+{
+  static RenderPassMap renderPassMap;
+  return renderPassMap;
 }