5368: Loading familytree with downgraded Berkeley db should generate expressive error

svn: r18467

src/gen/db/dbconst.py

@@ -38,7 +38,8 @@ Declare constants used by database modules
 __all__ = (
             ('DBPAGE', 'DBMODE', 'DBCACHE', 'DBLOCKS', 'DBOBJECTS', 'DBUNDO',
              'DBEXT', 'DBMODE_R', 'DBMODE_W', 'DBUNDOFN', 'DBLOCKFN',
-             'DBRECOVFN', 'DBLOGNAME', 'DBFLAGS_O',  'DBFLAGS_R', 'DBFLAGS_D',
+             'DBRECOVFN','BDBVERSFN', 'DBLOGNAME', 'DBFLAGS_O',  'DBFLAGS_R',
+             'DBFLAGS_D',
             ) +
             
             ('PERSON_KEY', 'FAMILY_KEY', 'SOURCE_KEY', 'EVENT_KEY',
@@ -53,6 +54,7 @@ DBEXT     = ".db"           # File extension to be used for database files
 DBUNDOFN  = "undo.db"       # File name of 'undo' database
 DBLOCKFN  = "lock"          # File name of lock file
 DBRECOVFN = "need_recover"  # File name of recovery file
+BDBVERSFN = "bdbversion.txt"# File name of Berkeley DB version file
 DBLOGNAME = ".Db"           # Name of logger
 DBMODE_R  = "r"             # Read-only access
 DBMODE_W  = "w"             # Full Reaw/Write access

src/gen/db/exceptions.py

@@ -79,6 +79,30 @@ class DbVersionError(Exception):
                  "Gramps.\nPlease upgrade to the corresponding version or use "
                  "XML for porting data between different database versions.")
     
+class BsddbDowngradeError(Exception):
+    """
+    Error used to report that the Berkeley database used to create the family
+    tree is of a version that is too new to be supported by the current version.
+    """
+    def __init__(self, env_version, bdb_version):
+        Exception.__init__(self)
+        self.env_version = str(env_version)
+        self.bdb_version = str(bdb_version)
+
+    def __str__(self):
+        return _('Gramps stores its data in a Berkeley Database. '
+                 'The family tree you try to load was created with version '
+                 '%(env_version)s of the Berkeley DB. However, the Gramps '
+                 'version in use right now employs version %(bdb_version)s '
+                 'of the Berkeley DB. So you are trying to load data created '
+                 'in a newer format into an older program; this is bound to '
+                 'fail. The right approach in this case is to use XML export '
+                 'and import. So try to open the family tree on that computer '
+                 'with that software that created the family tree, export it '
+                 'to XML and load that XML into the version of Gramps you '
+                 'intend to use.') % {'env_version': self.env_version,
+                 'bdb_version': self.bdb_version}
+
 class DbEnvironmentError(Exception):
     """
     Error used to report that the database 'environment' could not be opened.

src/gen/db/write.py

@@ -56,9 +56,9 @@ else:
 from gen.lib import (GenderStats, Person, Family, Event, Place, Source, 
                      MediaObject, Repository, Note, Tag)
 from gen.db import (DbBsddbRead, DbWriteBase, BSDDBTxn, 
-                    DbTxn, BsddbBaseCursor, DbVersionError, DbEnvironmentError, 
-                    DbUpgradeRequiredError, find_surname, find_surname_name,
-                    DbUndoBSDDB as DbUndo)
+                    DbTxn, BsddbBaseCursor, BsddbDowngradeError, DbVersionError,
+                    DbEnvironmentError, DbUpgradeRequiredError, find_surname,
+                    find_surname_name, DbUndoBSDDB as DbUndo)
 from gen.db.dbconst import *
 from gen.utils.callback import Callback
 from gen.updatecallback import UpdateCallback
@@ -224,6 +224,7 @@ class DbBsddb(DbBsddbRead, DbWriteBase, UpdateCallback):
         self.secondary_connected = False
         self.has_changed = False
         self.brief_name = None
+        self.update_env_version = False
 
     def catch_db_error(func):
         """
@@ -349,6 +350,27 @@ class DbBsddb(DbBsddbRead, DbWriteBase, UpdateCallback):
             with BSDDBTxn(self.env, self.metadata) as txn:
                 txn.put('mediapath', path)            
 
+    def __check_bdb_version(self, name):
+        """Older version of Berkeley DB can't read data created by a newer
+        version."""
+        bdb_version = db.version()
+        env_version = (0, 0, 0)
+        versionpath = os.path.join(self.path, BDBVERSFN)
+        try:
+            with open(versionpath, "r") as version_file:
+                env_version = version_file.read().strip()
+                env_version = tuple(map(int, env_version[1:-1].split(', ')))
+        except:
+            # Just assume that the Berkeley DB version is OK.
+            pass
+        if (env_version[0] > bdb_version[0]) or \
+            (env_version[0] == bdb_version[0] and
+             env_version[1] > bdb_version[1]):
+            clear_lock_file(name)
+            raise BsddbDowngradeError(env_version, bdb_version)
+        elif env_version != bdb_version and not self.readonly:
+            self.update_env_version = True
+
     @catch_db_error
     def version_supported(self):
         dbversion = self.metadata.get('version', default=0)
@@ -400,6 +422,8 @@ class DbBsddb(DbBsddbRead, DbWriteBase, UpdateCallback):
         self.path = self.full_name
         self.brief_name = os.path.basename(name)
 
+        self.__check_bdb_version(name)
+
         # Set up database environment
         self.env = db.DBEnv()
         self.env.set_cachesize(0, DBCACHE)
@@ -1099,6 +1123,15 @@ class DbBsddb(DbBsddbRead, DbWriteBase, UpdateCallback):
         self.undo_history_callback = None
         self.undodb = None
 
+        if self.update_env_version:
+            versionpath = os.path.join(self.path, BDBVERSFN)
+            try:
+                with open(versionpath, "w") as version_file:
+                    version_file.write(str(db.version()))
+            except:
+                # Storing the version of Berkeley Db is not really vital.
+                pass
+
         try:
             clear_lock_file(self.get_save_path())
         except IOError:

src/gui/dbloader.py

@@ -309,6 +309,9 @@ class DbLoader(CLIDbLoader):
                     self.dbstate.db.set_save_path(filename)
                 else:
                     self.dbstate.no_database()
+        except gen.db.exceptions.BsddbDowngradeError, msg:
+            self.dbstate.no_database()
+            self._errordialog( _("Cannot open database"), str(msg))
         except gen.db.exceptions.DbVersionError, msg:
             self.dbstate.no_database()
             self._errordialog( _("Cannot open database"), str(msg))