Engine: ensure that restricted game options not loaded from save

This fixes occasional problem with save overriding game options that must not be changed at runtime.

Common/ac/gamesetupstructbase.h

@@ -196,6 +196,18 @@ struct GameSetupStructBase
         return IsLegacyAudioSystem() ? "music.vox" : "audio.vox";
     }
 
+    // Returns a list of game options that are forbidden to change at runtime
+    inline static std::array<int, 17> GetRestrictedOptions()
+    {
+        return std::array<int,17> {{
+            OPT_DEBUGMODE, OPT_LETTERBOX, OPT_HIRES_FONTS, OPT_SPLITRESOURCES,
+            OPT_STRICTSCRIPTING, OPT_LEFTTORIGHTEVAL, OPT_COMPRESSSPRITES, OPT_STRICTSTRINGS,
+            OPT_NATIVECOORDINATES, OPT_SAFEFILEPATHS, OPT_DIALOGOPTIONSAPI, OPT_BASESCRIPTAPI,
+            OPT_SCRIPTCOMPATLEV, OPT_RELATIVEASSETRES, OPT_GAMETEXTENCODING, OPT_KEYHANDLEAPI,
+            OPT_CUSTOMENGINETAG
+        }};
+    }
+
 private:
     void SetDefaultResolution(GameResolutionType type, Size game_res);
     void SetNativeResolution(GameResolutionType type, Size game_res);

Engine/ac/global_game.cpp

@@ -433,33 +433,19 @@ int SetGameOption (int opt, int newval) {
     }
 
     // Handle forbidden options
-    switch (opt)
+    const auto restricted_opts = GameSetupStructBase::GetRestrictedOptions();
+    for (auto r_opt : restricted_opts)
     {
-    case OPT_DEBUGMODE: // we don't support switching OPT_DEBUGMODE from script
-    case OPT_LETTERBOX:
-    case OPT_HIRES_FONTS:
-    case OPT_SPLITRESOURCES:
-    case OPT_STRICTSCRIPTING:
-    case OPT_LEFTTORIGHTEVAL:
-    case OPT_COMPRESSSPRITES:
-    case OPT_STRICTSTRINGS:
-    case OPT_NATIVECOORDINATES:
-    case OPT_SAFEFILEPATHS:
-    case OPT_DIALOGOPTIONSAPI:
-    case OPT_BASESCRIPTAPI:
-    case OPT_SCRIPTCOMPATLEV:
-    case OPT_RELATIVEASSETRES:
-    case OPT_GAMETEXTENCODING:
-    case OPT_KEYHANDLEAPI:
-    case OPT_CUSTOMENGINETAG:
-        debug_script_warn("SetGameOption: option %d cannot be modified at runtime", opt);
-        return game.options[opt];
-    default:
-        break;
+        if (r_opt == opt)
+        {
+            debug_script_warn("SetGameOption: option %d cannot be modified at runtime", opt);
+            return game.options[opt];
+        }
     }
 
+    // Test if option already has this value
     if (game.options[opt] == newval)
-        return game.options[opt]; // no change necessary
+        return game.options[opt];
 
     const int oldval = game.options[opt];
     game.options[opt] = newval;

Engine/game/savegame.cpp

@@ -368,6 +368,7 @@ void DoBeforeRestore(PreservedParams &pp)
 {
     pp.SpeechVOX = play.voice_avail;
     pp.MusicVOX = play.separate_music_lib;
+    memcpy(pp.GameOptions, game.options, GameSetupStruct::MAX_OPTIONS * sizeof(int));
 
     unload_old_room();
     raw_saved_screen = nullptr;
@@ -459,6 +460,14 @@ void RestoreViewportsAndCameras(const RestoredData &r_data)
     play.InvalidateViewportZOrder();
 }
 
+// Resets a number of options that are not supposed to be changed at runtime
+static void CopyPreservedGameOptions(GameSetupStructBase &gs, const PreservedParams &pp)
+{
+    const auto restricted_opts = GameSetupStructBase::GetRestrictedOptions();
+    for (auto opt : restricted_opts)
+        gs.options[opt] = pp.GameOptions[opt];
+}
+
 // Final processing after successfully restoring from save
 HSaveError DoAfterRestore(const PreservedParams &pp, RestoredData &r_data)
 {
@@ -471,6 +480,9 @@ HSaveError DoAfterRestore(const PreservedParams &pp, RestoredData &r_data)
     play.voice_avail = pp.SpeechVOX;
     play.separate_music_lib = pp.MusicVOX;
 
+    // Restore particular game options that must not change at runtime
+    CopyPreservedGameOptions(game, pp);
+
     // Restore debug flags
     if (debug_flags & DBG_DEBUGMODE)
         play.debug_mode = 1;

Engine/game/savegame_internal.h

@@ -38,10 +38,12 @@ typedef std::shared_ptr<Bitmap> PBitmap;
 struct PreservedParams
 {
     // Whether speech and audio packages available
-    bool SpeechVOX;
-    bool MusicVOX;
+    bool SpeechVOX = false;
+    bool MusicVOX = false;
+    // Game options, to preserve ones that must not change at runtime
+    int GameOptions[GameSetupStructBase::MAX_OPTIONS]{};
     // Script global data sizes
-    size_t GlScDataSize;
+    size_t GlScDataSize = 0u;
     std::vector<size_t> ScMdDataSize;
 
     PreservedParams();