From b55b4d90b99103fa2cf5c8e243177ccd6dedcba3 Mon Sep 17 00:00:00 2001
From: Christopher Cifra <christopher.cifra@ni.com>
Date: Mon, 12 Apr 2021 13:35:44 -0500
Subject: [PATCH] Fixing issues getting the correct LV exports on Linux.

---
 src/event_data.cc   |  4 ++--
 src/grpc_interop.cc |  2 +-
 src/lv_interop.cc   | 29 ++++++++++++++++++-----------
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/src/event_data.cc b/src/event_data.cc
index da906fb7..d40649d8 100644
--- a/src/event_data.cc
+++ b/src/event_data.cc
@@ -196,7 +196,7 @@ LVMessage::~LVMessage()
 google::protobuf::Message* LVMessage::New() const
 {
     assert(false); // not expected to be called
-    return NULL;
+    return nullptr;
 }
 
 //---------------------------------------------------------------------
@@ -1235,7 +1235,7 @@ GenericMethodData::GenericMethodData(CallData* call, ServerContext *context, std
 //---------------------------------------------------------------------
 //---------------------------------------------------------------------
 ServerStartEventData::ServerStartEventData()
-    : EventData(NULL)
+    : EventData(nullptr)
 {
     serverStartStatus = 0;
 }
\ No newline at end of file
diff --git a/src/grpc_interop.cc b/src/grpc_interop.cc
index ae35b251..9e98b7ea 100644
--- a/src/grpc_interop.cc
+++ b/src/grpc_interop.cc
@@ -89,7 +89,7 @@ LIBRARY_EXPORT int32_t RegisterMessageMetadata(LVgRPCServerid* id, LVMessageMeta
 //---------------------------------------------------------------------
 //---------------------------------------------------------------------
 LIBRARY_EXPORT int32_t RegisterServerEvent(LVgRPCServerid* id, const char* name, LVUserEventRef* item, const char* requestMessageName, const char* responseMessageName)
-{
+{    
     auto server = *(LabVIEWgRPCServer**)id;
 
     server->RegisterEvent(name, *item, requestMessageName, responseMessageName);
diff --git a/src/lv_interop.cc b/src/lv_interop.cc
index a4e5612c..33dbaddc 100644
--- a/src/lv_interop.cc
+++ b/src/lv_interop.cc
@@ -1,6 +1,7 @@
 //---------------------------------------------------------------------
 //---------------------------------------------------------------------
 #include <lv_interop.h>
+#include <iostream>
 #include <cstring>
 #include <memory>
 
@@ -19,8 +20,8 @@ typedef int (*PostLVUserEvent_T)(LVUserEventRef ref, void *data);
 
 //---------------------------------------------------------------------
 //---------------------------------------------------------------------
-static NumericArrayResize_T NumericArrayResize;
-static PostLVUserEvent_T PostLVUserEvent;
+static NumericArrayResize_T NumericArrayResize = nullptr;
+static PostLVUserEvent_T PostLVUserEvent = nullptr;
 
 #ifdef _WIN32
 
@@ -28,17 +29,17 @@ static PostLVUserEvent_T PostLVUserEvent;
 //---------------------------------------------------------------------
 void InitCallbacks()
 {
-    if (NumericArrayResize != NULL)
+    if (NumericArrayResize != nullptr)
     {
         return;
     }
 
     auto lvModule = GetModuleHandle("LabVIEW.exe");
-    if (lvModule == NULL)
+    if (lvModule == nullptr)
     {
         lvModule = GetModuleHandle("lvffrt.dll");
     }
-    if (lvModule == NULL)
+    if (lvModule == nullptr)
     {
         lvModule = GetModuleHandle("lvrt.dll");
     }
@@ -52,18 +53,24 @@ void InitCallbacks()
 //---------------------------------------------------------------------
 void InitCallbacks()
 {
-    if (NumericArrayResize != NULL)
+    if (NumericArrayResize != nullptr)
     {
         return;
     }
 
-    auto lvModule = dlopen("labview", RTLD_NOLOAD);
-    if (lvModule == NULL)
+    auto lvModule = dlopen(nullptr, RTLD_LAZY);
+    if (lvModule != nullptr)
     {
+        NumericArrayResize = (NumericArrayResize_T)dlsym(lvModule, "NumericArrayResize");
+        PostLVUserEvent = (PostLVUserEvent_T)dlsym(lvModule, "PostLVUserEvent");
+    }
+    if (NumericArrayResize == nullptr)
+    {
+        cout << "Loading LabVIEW Runtime engine!" << endl;
         lvModule = dlopen("liblvrt.so", RTLD_NOW);
+        NumericArrayResize = (NumericArrayResize_T)dlsym(lvModule, "NumericArrayResize");
+        PostLVUserEvent = (PostLVUserEvent_T)dlsym(lvModule, "PostLVUserEvent");
     }
-    NumericArrayResize = (NumericArrayResize_T)dlsym(lvModule, "NumericArrayResize");
-    PostLVUserEvent = (PostLVUserEvent_T)dlsym(lvModule, "PostLVUserEvent");
 }
 
 #endif
@@ -96,7 +103,7 @@ void SetLVString(LStrHandle* lvString, string str)
 //---------------------------------------------------------------------
 string GetLVString(LStrHandle lvString)
 {    
-    if (lvString == NULL || *lvString == NULL)
+    if (lvString == nullptr || *lvString == nullptr)
     {
         return string();
     }