Merge pull request #32 from jamesfe/invalid_signature_db_issue_26

Issue 26: Check and handle errors loading signature db

.travis.yml

@@ -8,6 +8,7 @@ sudo: false
 env:
 install:
     - pip install . coveralls
+    - pip install nbformat[test]
 script:
     - nosetests --with-coverage --cover-package=nbformat nbformat
 after_success:

nbformat/sign.py

@@ -123,8 +123,19 @@ def _db_default(self):
             self.log.warn("Missing SQLite3, all notebooks will be untrusted!")
             return
         kwargs = dict(detect_types=sqlite3.PARSE_DECLTYPES|sqlite3.PARSE_COLNAMES)
-        db = sqlite3.connect(self.db_file, **kwargs)
-        self.init_db(db)
+        try:
+            db = sqlite3.connect(self.db_file, **kwargs)
+            self.init_db(db)
+        except sqlite3.DatabaseError:
+            old_db_location = os.path.join(self.data_dir, self.db_file + ".bak")
+            self.log.warn("""The signatures database cannot be opened; maybe it is corrupted or encrypted.  You may need to rerun your notebooks to ensure that they are trusted to run Javascript.  The old signatures database has been renamed to %s and a new one has been created.""",
+                old_db_location)
+            if self.db_file != ':memory:':
+                os.rename(self.db_file, self.db_file + u'.bak')
+                db = sqlite3.connect(self.db_file, **kwargs)
+                self.init_db(db)
+            else:
+                raise
         return db
 
     def init_db(self, db):

nbformat/tests/test_sign.py

@@ -4,9 +4,11 @@
 # Distributed under the terms of the Modified BSD License.
 
 import copy
+import os
 import shutil
 import time
 import tempfile
+import testpath
 
 from .base import TestsBase
 
@@ -28,6 +30,20 @@ def setUp(self):
 
     def tearDown(self):
         shutil.rmtree(self.data_dir)
+
+    def test_invalid_db_file(self):
+        invalid_sql_file = os.path.join(self.data_dir, 'invalid_db_file.db')
+        with open(invalid_sql_file, 'w') as tempfile:
+            tempfile.write(u'[invalid data]')
+
+        invalid_notary = sign.NotebookNotary(
+            db_file=invalid_sql_file,
+            secret=b'secret',
+        )
+        invalid_notary.sign(self.nb)
+
+        testpath.assert_isfile(os.path.join(self.data_dir, invalid_sql_file))
+        testpath.assert_isfile(os.path.join(self.data_dir, invalid_sql_file + '.bak'))
 
     def test_algorithms(self):
         last_sig = ''
@@ -191,5 +207,4 @@ def test_check_cells_v3(self):
         self.assertFalse(self.notary.check_cells(nb))
         for cell in cells:
             self.assertNotIn('trusted', cell)
-
 

setup.py

@@ -95,6 +95,7 @@
 ]
 
 extras_require = setuptools_args['extras_require'] = {
+    'test': ['testpath'],
 }
 
 if 'setuptools' in sys.modules: