Fix callbacks for pre-1.02x SDKs

Author: NicknineTheEagle

dll/dll.cpp

@@ -235,6 +235,13 @@ Steam_Client *get_steam_client()
         if (!steamclient_instance) {
             load_old_steam_interfaces();
             steamclient_instance = new Steam_Client();
+
+            if (strstr(old_friends, "SteamFriends")) {
+                int friends_ver = atoi(old_friends + 12);
+                if (friends_ver != 0 && friends_ver <= 4) {
+                    steamclient_instance->using_old_callbacks = true;
+                }
+            }
         }
     }
 

dll/dll/callback_wrapper.h

@@ -0,0 +1,70 @@
+/* Copyright (C) 2019 Mr Goldberg
+   This file is part of the Goldberg Emulator
+
+   The Goldberg Emulator is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   The Goldberg Emulator is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the Goldberg Emulator; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef __INCLUDED_CALLBACK_WRAPPER_H__
+#define __INCLUDED_CALLBACK_WRAPPER_H__
+
+#include "base.h"
+
+class CCallbackBase001
+{
+public:
+    CCallbackBase001() { m_nCallbackFlags = 0; m_iCallback = 0; }
+    // don't add a virtual destructor because we export this binary interface across dll's
+    virtual void Run( void *pvParam ) = 0;
+    int GetICallback() { return m_iCallback; }
+
+protected:
+    enum { k_ECallbackFlagsRegistered = 0x01, k_ECallbackFlagsGameServer = 0x02 };
+    uint8 m_nCallbackFlags;
+    int m_iCallback;
+    friend class CCallbackMgr;
+    friend class CCallBackWrapper;
+
+private:
+    CCallbackBase001( const CCallbackBase001& );
+    CCallbackBase001& operator=( const CCallbackBase001& );
+};
+
+class CCallBackWrapper : public CCallbackBase
+{
+public:
+    CCallBackWrapper( CCallbackBase *callback )
+    {
+        old_callback = reinterpret_cast<CCallbackBase001 *>( callback );
+        m_nCallbackFlags = old_callback->m_nCallbackFlags;
+        m_iCallback = old_callback->m_iCallback;
+    }
+
+    void Run( void *pvParam )
+    {
+        old_callback->Run( pvParam );
+    }
+    void Run( void *pvParam, bool bIOFailure, SteamAPICall_t hSteamAPICall )
+    {
+        old_callback->Run( pvParam );
+    }
+    int GetCallbackSizeBytes()
+    {
+        return 0;
+    }
+
+private:
+    CCallbackBase001 *old_callback{};
+};
+
+#endif // __INCLUDED_CALLBACK_WRAPPER_H__

dll/dll/steam_client.h

@@ -64,6 +64,7 @@
 
 #include "overlay/steam_overlay.h"
 #include "playtime.h"
+#include "callback_wrapper.h"
 
 enum Steam_Pipe {
     NO_USER,
@@ -111,6 +112,8 @@ public ISteamClient
     common_helpers::KillableWorker *background_thread{};
     void background_thread_proc();
 
+    std::map<CCallbackBase *, CCallBackWrapper> old_callbacks_map;
+
 public:
     Networking *network{};
     SteamCallResults *callback_results_server{}, *callback_results_client{};
@@ -180,10 +183,11 @@ public ISteamClient
 
     PlaytimeCounter* playtime_counter{};
 
-    bool steamclient_server_inited = false;
+    bool steamclient_server_inited{};
 
     bool gameserver_has_ipv6_functions{};
     int steamclient_version{};
+    bool using_old_callbacks{};
 
     unsigned steam_pipe_counter = 1;
     std::map<HSteamPipe, enum Steam_Pipe> steam_pipes{};

dll/steam_client.cpp

@@ -484,9 +484,20 @@ void Steam_Client::Remove_SteamAPI_CPostAPIResultInProcess( SteamAPI_PostAPIResu
 
 void Steam_Client::RegisterCallback( class CCallbackBase *pCallback, int iCallback)
 {
+    CCallbackBase *callback_to_add = pCallback;
+
+    // 1.02x added an overload for CCallbackBase::Run. Because of how MSVC handles virtual function
+    // overloads, this changed the order of functions in vtable from 1.02, which breaks old games.
+    // We get around this using a wrapper for the old CCallbackBase variant.
+    if (using_old_callbacks) {
+        PRINT_DEBUG("creating a wrapper for old callback %08X %i", pCallback, iCallback);
+        auto [it, _] = old_callbacks_map.emplace(pCallback, pCallback);
+        callback_to_add = &(it->second);
+    }
+
     int base_callback = (iCallback / 100) * 100;
     int callback_id = iCallback % 100;
-    bool isGameServer = CCallbackMgr::isServer(pCallback);
+    bool isGameServer = CCallbackMgr::isServer(callback_to_add);
     PRINT_DEBUG("isGameServer %u %i %i", isGameServer, iCallback, base_callback);
 
     switch (base_callback) {
@@ -699,18 +710,26 @@ void Steam_Client::RegisterCallback( class CCallbackBase *pCallback, int iCallba
     };
 
     if (isGameServer) {
-        callbacks_server->addCallBack(iCallback, pCallback);
+        callbacks_server->addCallBack(iCallback, callback_to_add);
     } else {
-        callbacks_client->addCallBack(iCallback, pCallback);
+        callbacks_client->addCallBack(iCallback, callback_to_add);
     }
 }
 
 void Steam_Client::UnregisterCallback( class CCallbackBase *pCallback)
 {
-    int iCallback = pCallback->GetICallback();
+    CCallbackBase *callback_to_rm = pCallback;
+    if (using_old_callbacks) {
+        if (!old_callbacks_map.count(pCallback))
+            return;
+
+        callback_to_rm = &(old_callbacks_map.at(pCallback));
+    }
+
+    int iCallback = callback_to_rm->GetICallback();
     int base_callback = (iCallback / 100) * 100;
     int callback_id = iCallback % 100;
-    bool isGameServer = CCallbackMgr::isServer(pCallback);
+    bool isGameServer = CCallbackMgr::isServer(callback_to_rm);
     PRINT_DEBUG("isGameServer %u %i", isGameServer, base_callback);
 
     switch (base_callback) {
@@ -923,9 +942,13 @@ void Steam_Client::UnregisterCallback( class CCallbackBase *pCallback)
     };
 
     if (isGameServer) {
-        callbacks_server->rmCallBack(iCallback, pCallback);
+        callbacks_server->rmCallBack(iCallback, callback_to_rm);
     } else {
-        callbacks_client->rmCallBack(iCallback, pCallback);
+        callbacks_client->rmCallBack(iCallback, callback_to_rm);
+    }
+
+    if (using_old_callbacks) {
+        old_callbacks_map.erase(pCallback);
     }
 }