Added a signature of the game itself inside saved games (the size of script 0, as well as the offset of the game object, which are unique for each game), to prevent users from loading saved games across different versions of the same game. In the cases where we can't load a saved game, throw a nice GUI dialog instead of a console warning

svn-id: r49687

2 files changed, 36 insertions, 3 deletions

diff --git a/engines/sci/engine/savegame.cpp b/engines/sci/engine/savegame.cpp
index 89bfa5302d..155c5fad86 100644
--- a/engines/sci/engine/savegame.cpp
+++ b/engines/sci/engine/savegame.cpp
@@ -53,6 +53,8 @@
 #include "sci/graphics/gui32.h"
 #endif
 
+#include "gui/message.h"
+
 namespace Sci {
 
 
@@ -307,6 +309,13 @@ static void sync_SavegameMetadata(Common::Serializer &s, SavegameMetadata &obj)
 	s.skip(4, VER(9), VER(9));	// obsolete: used to be game version
 	s.syncAsSint32LE(obj.savegame_date);
 	s.syncAsSint32LE(obj.savegame_time);
+	if (s.getVersion() < 22) {
+		obj.game_object_offset = 0;
+		obj.script0_size = 0;
+	} else {
+		s.syncAsUint16LE(obj.game_object_offset);
+		s.syncAsUint16LE(obj.script0_size);
+	}
 }
 
 void EngineState::saveLoadWithSerializer(Common::Serializer &s) {
@@ -862,6 +871,10 @@ int gamestate_save(EngineState *s, Common::WriteStream *fh, const char* savename
 	meta.savegame_date = ((curTime.tm_mday & 0xFF) << 24) | (((curTime.tm_mon + 1) & 0xFF) << 16) | ((curTime.tm_year + 1900) & 0xFFFF);
 	meta.savegame_time = ((curTime.tm_hour & 0xFF) << 16) | (((curTime.tm_min) & 0xFF) << 8) | ((curTime.tm_sec) & 0xFF);
 
+	Resource *script0 = g_sci->getResMan()->findResource(ResourceId(kResourceTypeScript, 0), false);
+	meta.script0_size = script0->size;
+	meta.game_object_offset = g_sci->getGameObject().offset;
+
 	if (s->executionStackBase) {
 		warning("Cannot save from below kernel function");
 		return 1;
@@ -892,15 +905,33 @@ void gamestate_restore(EngineState *s, Common::SeekableReadStream *fh) {
 
 	if ((meta.savegame_version < MINIMUM_SAVEGAME_VERSION) ||
 	    (meta.savegame_version > CURRENT_SAVEGAME_VERSION)) {
+		/*
 		if (meta.savegame_version < MINIMUM_SAVEGAME_VERSION)
-			warning("Old savegame version detected- can't load");
+			warning("Old savegame version detected, unable to load it");
 		else
-			warning("Savegame version is %d- maximum supported is %0d", meta.savegame_version, CURRENT_SAVEGAME_VERSION);
+			warning("Savegame version is %d, maximum supported is %0d", meta.savegame_version, CURRENT_SAVEGAME_VERSION);
+		*/
+
+		GUI::MessageDialog dialog("The format of this saved game is obsolete, unable to load it", "OK");
+		dialog.runModal();
 
 		s->r_acc = make_reg(0, 1);	// signal failure
 		return;
 	}
 
+	if (meta.game_object_offset > 0 && meta.script0_size > 0) {
+		Resource *script0 = g_sci->getResMan()->findResource(ResourceId(kResourceTypeScript, 0), false);
+		if (script0->size != meta.script0_size || g_sci->getGameObject().offset != meta.game_object_offset) {
+			//warning("This saved game was created with a different version of the game, unable to load it");
+
+			GUI::MessageDialog dialog("This saved game was created with a different version of the game, unable to load it", "OK");
+			dialog.runModal();
+
+			s->r_acc = make_reg(0, 1);	// signal failure
+			return;
+		}
+	}
+
 	if (meta.savegame_version >= 12) {
 		// We don't need the thumbnail here, so just read it and discard it
 		Graphics::Surface *thumbnail = new Graphics::Surface();
diff --git a/engines/sci/engine/savegame.h b/engines/sci/engine/savegame.h
index e7e8fff999..c8c7738fdf 100644
--- a/engines/sci/engine/savegame.h
+++ b/engines/sci/engine/savegame.h
@@ -36,7 +36,7 @@ namespace Sci {
 struct EngineState;
 
 enum {
-	CURRENT_SAVEGAME_VERSION = 21,
+	CURRENT_SAVEGAME_VERSION = 22,
 	MINIMUM_SAVEGAME_VERSION = 9
 };
 
@@ -47,6 +47,8 @@ struct SavegameMetadata {
 	Common::String game_version;
 	int savegame_date;
 	int savegame_time;
+	uint16 game_object_offset;
+	uint16 script0_size;
 };