From 0ad3bedf9880b51e40459df4e33547bf234eeb4f Mon Sep 17 00:00:00 2001
From: Filippos Karapetis <bluegr@gmail.com>
Date: Tue, 15 Jun 2010 08:25:51 +0000
Subject: [PATCH] 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
---
 engines/sci/engine/savegame.cpp | 35 +++++++++++++++++++++++++++++++--
 engines/sci/engine/savegame.h   |  4 +++-
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/engines/sci/engine/savegame.cpp b/engines/sci/engine/savegame.cpp
index 89bfa5302da..155c5fad86c 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 e7e8fff9991..c8c7738fdf9 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;
 };