Separate OSError with ValueError

OSError will only be raised, if file path is not readable because of permission issue.
With this change we will get correct error msg.

Change-Id: Iad3b0f2ab3e6eafd9f6c98477edfa35c4cd46ee8

nova/cmd/manage.py

@@ -3208,12 +3208,15 @@ class VolumeAttachmentCommands(object):
         ) as e:
             print(str(e))
             return 4
-        except (ValueError, OSError):
+        except ValueError as e:
             print(
                 f'Failed to open {connector_path}. Does it contain valid '
-                f'connector_info data?'
+                f'connector_info data?\nError: {str(e)}'
             )
             return 3
+        except OSError as e:
+            print(str(e))
+            return 3
         except exception.InvalidInput as e:
             print(str(e))
             return 2

nova/tests/unit/cmd/test_manage.py

@@ -3488,6 +3488,18 @@ class VolumeAttachmentCommandsTestCase(test.NoDBTestCase):
             output = self.output.getvalue().strip()
             self.assertIn('Failed to open fake_path', output)
 
+    @mock.patch('os.path.exists')
+    def test_refresh_connector_file_oserr(self, mock_exists):
+        """Test refresh with connector file having no read permission.
+        """
+        mock_exists.return_value = True
+        with self.patch_open('fake_path', b'invalid json') as mock_file:
+            mock_file.side_effect = OSError("Permission denied")
+            ret = self.commands.refresh(
+                uuidsentinel.volume, uuidsentinel.instance, 'fake_path'
+            )
+            self.assertEqual(3, ret)
+
     @mock.patch('os.path.exists')
     def _test_refresh(self, mock_exists):
         ctxt = context.get_admin_context()