From e36af6f9692993def310cc48ab5c2f65fb0f0267 Mon Sep 17 00:00:00 2001
From: red-001 <red-001@outlook.ie>
Date: Wed, 27 Jun 2018 16:45:40 +0100
Subject: [PATCH] Fix mod channels crash (#7481)

---
 src/script/lua_api/l_modchannels.cpp | 28 ++++++++++------------------
 src/script/lua_api/l_modchannels.h   |  8 ++++----
 2 files changed, 14 insertions(+), 22 deletions(-)

diff --git a/src/script/lua_api/l_modchannels.cpp b/src/script/lua_api/l_modchannels.cpp
index ac28e2ada..0485b276a 100644
--- a/src/script/lua_api/l_modchannels.cpp
+++ b/src/script/lua_api/l_modchannels.cpp
@@ -33,9 +33,8 @@ int ModApiChannels::l_mod_channel_join(lua_State *L)
 		return 0;
 
 	getGameDef(L)->joinModChannel(channel);
-	ModChannel *channelObj = getGameDef(L)->getModChannel(channel);
-	assert(channelObj);
-	ModChannelRef::create(L, channelObj);
+	assert(getGameDef(L)->getModChannel(channel) != nullptr);
+	ModChannelRef::create(L, channel);
 
 	int object = lua_gettop(L);
 	lua_pushvalue(L, object);
@@ -51,29 +50,22 @@ void ModApiChannels::Initialize(lua_State *L, int top)
  * ModChannelRef
  */
 
-ModChannelRef::ModChannelRef(ModChannel *modchannel) : m_modchannel(modchannel)
+ModChannelRef::ModChannelRef(const std::string &modchannel) :
+		m_modchannel_name(modchannel)
 {
 }
 
 int ModChannelRef::l_leave(lua_State *L)
 {
 	ModChannelRef *ref = checkobject(L, 1);
-	ModChannel *channel = getobject(ref);
-	if (!channel)
-		return 0;
-
-	getGameDef(L)->leaveModChannel(channel->getName());
-	// Channel left, invalidate the channel object ptr
-	// This permits to invalidate every object action from Lua because core removed
-	// channel consuming link
-	ref->m_modchannel = nullptr;
+	getGameDef(L)->leaveModChannel(ref->m_modchannel_name);
 	return 0;
 }
 
 int ModChannelRef::l_send_all(lua_State *L)
 {
 	ModChannelRef *ref = checkobject(L, 1);
-	ModChannel *channel = getobject(ref);
+	ModChannel *channel = getobject(L, ref);
 	if (!channel || !channel->canWrite())
 		return 0;
 
@@ -87,7 +79,7 @@ int ModChannelRef::l_send_all(lua_State *L)
 int ModChannelRef::l_is_writeable(lua_State *L)
 {
 	ModChannelRef *ref = checkobject(L, 1);
-	ModChannel *channel = getobject(ref);
+	ModChannel *channel = getobject(L, ref);
 	if (!channel)
 		return 0;
 
@@ -119,7 +111,7 @@ void ModChannelRef::Register(lua_State *L)
 	lua_pop(L, 1);			// Drop methodtable
 }
 
-void ModChannelRef::create(lua_State *L, ModChannel *channel)
+void ModChannelRef::create(lua_State *L, const std::string &channel)
 {
 	ModChannelRef *o = new ModChannelRef(channel);
 	*(void **)(lua_newuserdata(L, sizeof(void *))) = o;
@@ -145,9 +137,9 @@ ModChannelRef *ModChannelRef::checkobject(lua_State *L, int narg)
 	return *(ModChannelRef **)ud; // unbox pointer
 }
 
-ModChannel *ModChannelRef::getobject(ModChannelRef *ref)
+ModChannel *ModChannelRef::getobject(lua_State *L, ModChannelRef *ref)
 {
-	return ref->m_modchannel;
+	return getGameDef(L)->getModChannel(ref->m_modchannel_name);
 }
 
 // clang-format off
diff --git a/src/script/lua_api/l_modchannels.h b/src/script/lua_api/l_modchannels.h
index dbbf11a05..9b948002b 100644
--- a/src/script/lua_api/l_modchannels.h
+++ b/src/script/lua_api/l_modchannels.h
@@ -37,11 +37,11 @@ public:
 class ModChannelRef : public ModApiBase
 {
 public:
-	ModChannelRef(ModChannel *modchannel);
+	ModChannelRef(const std::string &modchannel);
 	~ModChannelRef() = default;
 
 	static void Register(lua_State *L);
-	static void create(lua_State *L, ModChannel *channel);
+	static void create(lua_State *L, const std::string &channel);
 
 	// leave()
 	static int l_leave(lua_State *L);
@@ -57,9 +57,9 @@ private:
 	static int gc_object(lua_State *L);
 
 	static ModChannelRef *checkobject(lua_State *L, int narg);
-	static ModChannel *getobject(ModChannelRef *ref);
+	static ModChannel *getobject(lua_State *L, ModChannelRef *ref);
 
-	ModChannel *m_modchannel = nullptr;
+	std::string m_modchannel_name;
 
 	static const char className[];
 	static const luaL_Reg methods[];
-- 
2.25.1