From e53603a1fcf2dc90c7f5d90b73965e5deff9fbd0 Mon Sep 17 00:00:00 2001
From: Nick Hall <nick-h@gramps-project.org>
Date: Wed, 28 Mar 2018 19:03:08 +0100
Subject: [PATCH] Check that backend exists before loading database

---
 gramps/cli/arghandler.py |  3 +++
 gramps/cli/clidbman.py   | 26 ++++++++++++--------------
 gramps/gen/db/utils.py   | 21 +++++++++++++--------
 3 files changed, 28 insertions(+), 22 deletions(-)

diff --git a/gramps/cli/arghandler.py b/gramps/cli/arghandler.py
index 5423e71ea..83788a6e0 100644
--- a/gramps/cli/arghandler.py
+++ b/gramps/cli/arghandler.py
@@ -554,6 +554,9 @@ class ArgHandler:
         if self.dbman.needs_recovery(dbpath):
             self.__error(_("Database needs recovery, cannot open it!"))
             return False
+        if self.dbman.backend_unavailable(dbpath):
+            self.__error(_("Database backend unavailable, cannot open it!"))
+            return False
         return True
 
     #-------------------------------------------------------------------------
diff --git a/gramps/cli/clidbman.py b/gramps/cli/clidbman.py
index 63335f1bd..7a110de82 100644
--- a/gramps/cli/clidbman.py
+++ b/gramps/cli/clidbman.py
@@ -48,8 +48,8 @@ import logging
 from gramps.gen.plug import BasePluginManager
 from gramps.gen.config import config
 from gramps.gen.constfunc import win
-from gramps.gen.db.dbconst import DBLOGNAME
-from gramps.gen.db.utils import make_database
+from gramps.gen.db.dbconst import DBLOGNAME, DBBACKEND
+from gramps.gen.db.utils import make_database, get_dbid_from_path
 from gramps.gen.const import GRAMPS_LOCALE as glocale
 _ = glocale.translation.gettext
 
@@ -68,7 +68,6 @@ _LOG = logging.getLogger(DBLOGNAME)
 #-------------------------------------------------------------------------
 DEFAULT_TITLE = _("Family Tree")
 NAME_FILE = "name.txt"
-BACKEND_FILE = "database.txt"
 META_NAME = "meta_data.db"
 UNAVAILABLE = _('Unavailable')
 
@@ -156,11 +155,7 @@ class CLIDbManager:
         _("Version")
         _("Schema version")
         """
-        dbid = "bsddb"
-        dbid_path = os.path.join(dirpath, "database.txt")
-        if os.path.isfile(dbid_path):
-            with open(dbid_path) as file:
-                dbid = file.read().strip()
+        dbid = get_dbid_from_path(dirpath)
         if not self.is_locked(dirpath):
             try:
                 database = make_database(dbid)
@@ -237,11 +232,7 @@ class CLIDbManager:
             for dpath in os.listdir(dbdir):
                 dirpath = os.path.join(dbdir, dpath)
                 path_name = os.path.join(dirpath, NAME_FILE)
-                try:
-                    with open(os.path.join(dirpath, "database.txt")) as file:
-                        backend_type = file.read()
-                except:
-                    backend_type = "bsddb"
+                backend_type = get_dbid_from_path(dirpath)
                 if os.path.isfile(path_name):
                     with open(path_name, 'r', encoding='utf8') as file:
                         name = file.readline().strip()
@@ -309,7 +300,7 @@ class CLIDbManager:
                 dbid = config.get('database.backend')
             newdb = make_database(dbid)
 
-        backend_path = os.path.join(new_path, BACKEND_FILE)
+        backend_path = os.path.join(new_path, DBBACKEND)
         with open(backend_path, "w", encoding='utf8') as backend_file:
             backend_file.write(dbid)
 
@@ -403,6 +394,13 @@ class CLIDbManager:
             return True
         return False
 
+    def backend_unavailable(self, dbpath):
+        """
+        Returns True if the database in dirpath has an unavailable backend
+        """
+        dbid = get_dbid_from_path(dbpath)
+        return self.get_backend_name_from_dbid(dbid) == UNAVAILABLE
+
     def remove_database(self, dbname, user=None):
         """
         Deletes a database folder given a pattenr that matches
diff --git a/gramps/gen/db/utils.py b/gramps/gen/db/utils.py
index 1fb639fba..8adedabc7 100644
--- a/gramps/gen/db/utils.py
+++ b/gramps/gen/db/utils.py
@@ -41,7 +41,7 @@ from ..plug import BasePluginManager
 from ..const import PLUGINS_DIR, USER_PLUGINS
 from ..constfunc import win, get_env_var
 from ..config import config
-from .dbconst import DBLOGNAME, DBLOCKFN
+from .dbconst import DBLOGNAME, DBLOCKFN, DBBACKEND
 
 #-------------------------------------------------------------------------
 #
@@ -109,13 +109,7 @@ def lookup_family_tree(dbname):
             if dbname == name:
                 locked = False
                 locked_by = None
-                backend = None
-                fname = os.path.join(dirpath, "database.txt")
-                if os.path.isfile(fname):
-                    with open(fname, 'r', encoding='utf8') as ifile:
-                        backend = ifile.read().strip()
-                else:
-                    backend = "bsddb"
+                backend = get_dbid_from_path(dirpath)
                 try:
                     fname = os.path.join(dirpath, "lock")
                     with open(fname, 'r', encoding='utf8') as ifile:
@@ -126,6 +120,17 @@ def lookup_family_tree(dbname):
                 return (dirpath, locked, locked_by, backend)
     return None
 
+def get_dbid_from_path(dirpath):
+    """
+    Return a database backend from a directory path.
+    """
+    dbid = "bsddb"
+    dbid_path = os.path.join(dirpath, DBBACKEND)
+    if os.path.isfile(dbid_path):
+        with open(dbid_path) as file:
+            dbid = file.read().strip()
+    return dbid
+
 def import_as_dict(filename, user, skp_imp_adds=True):
     """
     Import the filename into a InMemoryDB and return it.