Fix #2086. This changes the current behaviour.

Only games are loaded which have an higher revision
than the related value stored in the constants. Old behaviour
was to load everything and hope it works.

doc/CHANGELOG.md

@@ -1,6 +1,20 @@
 CHANGELOG Unknown Horizons
 ==========================
 
+| Release | Current savegame revision |
+|---|---|
+| 2014.1 | 74 |
+| 2013.3 | 73 |
+| 2013.2 | 71 |
+| 2013.1 | 70 |
+| 2012.1a | 56 |
+| 2012.1 | 56 |
+| 2011.3 | 43 |
+| 2011.2 | 15 |
+| 2011.1a | 12 |
+| 2011.1 | 12 |
+| 2010.1 | 8 |
+
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 2014-12-31: Milestone 2014.1

horizons/constants.py

@@ -73,6 +73,7 @@ def _get_git_version():
 
 	## +=1 this if you changed the savegame "api"
 	SAVEGAMEREVISION = 74
+	SAVEGAME_LEAST_UPGRADABLE_REVISION = 48
 
 	@staticmethod
 	def string():

horizons/main.py

@@ -373,12 +373,13 @@ def start_singleplayer(options):
 
 	from horizons.scenario import InvalidScenarioFileFormat # would create import loop at top
 	from horizons.util.savegameaccessor import MapFileNotFound
+	from horizons.util.savegameupgrader import SavegameTooOld
 	try:
 		_modules.session.load(options)
 		_modules.gui.close_all()
 	except InvalidScenarioFileFormat:
 		raise
-	except MapFileNotFound, Exception:
+	except (MapFileNotFound, SavegameTooOld, Exception):
 		_modules.gui.close_all()
 		# don't catch errors when we should fail fast (used by tests)
 		if os.environ.get('FAIL_FAST', False):

horizons/util/savegameupgrader.py

@@ -37,6 +37,13 @@
 from horizons.util.shapes import Rect
 from horizons.util.yamlcache import YamlCache
 
+class SavegameTooOld(Exception):
+	def __init__(self, msg=None, revision=None):
+		if msg is None:
+			msg = "The savegame is too old!"
+		if revision is not None:
+			msg += " Revision: " + str(revision)
+		super(SavegameTooOld, self).__init__(msg)
 
 class SavegameUpgrader(object):
 	"""The class that prepares saved games to be loaded by the current version."""
@@ -395,10 +402,9 @@ def _upgrade(self):
 		from horizons.savegamemanager import SavegameManager
 		metadata = SavegameManager.get_metadata(self.original_path)
 		rev = metadata['savegamerev']
-		if rev == 0: # not a regular savegame, usually a map
-			self.final_path = self.original_path
-		elif rev == VERSION.SAVEGAMEREVISION: # the current version
-			self.final_path = self.original_path
+
+		if not SavegameUpgrader.can_upgrade(rev):
+			raise SavegameTooOld(revision=rev)
 		else: # upgrade
 			self.log.warning('Discovered old savegame file, auto-upgrading: %s -> %s' % \
 						     (rev, VERSION.SAVEGAMEREVISION))
@@ -467,12 +473,11 @@ def _upgrade(self):
 
 	@classmethod
 	def can_upgrade(cls, from_savegame_version):
-		"""Calculates whether a savegame can be upgraded from the current version"""
-		for i in xrange(from_savegame_version+1, VERSION.SAVEGAMEREVISION+1, 1):
-			if not hasattr(cls, "_upgrade_to_rev" + str(i)):
-				return False
-		return True
-
+		"""Checks whether a savegame can be upgraded from the current version"""
+		if from_savegame_version >= VERSION.SAVEGAME_LEAST_UPGRADABLE_REVISION:
+			return True
+		else:
+			return False
 
 	def get_path(self):
 		"""Return the path to the up-to-date version of the saved game."""