Fix read-only support

semidbm/compat.py

@@ -16,8 +16,10 @@
 
 
 DATA_OPEN_FLAGS = os.O_RDWR | os.O_CREAT | os.O_APPEND
+DATA_OPENRO_FLAGS = os.O_RDONLY
 if sys.platform.startswith('win'):
     # On windows we need to specify that we should be
     # reading the file as a binary file so it doesn't
     # change any line ending characters.
     DATA_OPEN_FLAGS = DATA_OPEN_FLAGS | os.O_BINARY
+    DATA_OPENRO_FLAGS = DATA_OPENRO_FLAGS | os.O_BINARY

semidbm/db.py

@@ -237,6 +237,14 @@ def __delitem__(self, key):
     def __setitem__(self, key, value):
         self._method_not_allowed('setitem')
 
+    def _load_db(self):
+        self._index = self._load_index(self._data_filename)
+        self._data_fd = os.open(self._data_filename, compat.DATA_OPENRO_FLAGS)
+        self._current_offset = os.lseek(self._data_fd, 0, os.SEEK_END)
+
+    def _write_headers(self, filename):
+        pass
+
     def sync(self):
         self._method_not_allowed('sync')
 

test_semidbm.py

@@ -374,6 +374,11 @@ def test_remap_required(self):
 
 
 class TestReadOnlyMode(SemiDBMTest):
+    def setUp(self):
+        super(TestReadOnlyMode, self).setUp()
+        db = semidbm.open(self.dbdir, 'c')
+        db.close()
+
     def open_db_file(self, **kwargs):
         return semidbm.open(self.dbdir, 'r', **kwargs)