[s3] Re-raise non-404 errors in .exists() (jschneier#1085)

storages/backends/s3boto3.py

@@ -469,18 +469,15 @@ def exists(self, name):
  self.connection.meta.client.head_object(Bucket=self.bucket_name, Key=name)
  return True
  except ClientError as error:
- if error.response.get('Error', {}).get('Code') == '404':
+ if error.response['ResponseMetadata']['HTTPStatusCode'] == 404:
  return False
 
- # Some other error was encountered. As `get_available_name` calls this,
- # we have to assume the filename is unavailable. If we return true due to some
- # other error, we'd overwrite a file.
- return True
+ # Some other error was encountered. Re-raise it.
+ raise
 
  def listdir(self, name):
  path = self._normalize_name(self._clean_name(name))
- # The path needs to end with a slash, but if the root is empty, leave
- # it.
+ # The path needs to end with a slash, but if the root is empty, leave it.
  if path and not path.endswith('/'):
  path += '/'
 

tests/test_s3boto3.py

@@ -488,15 +488,25 @@ def test_storage_exists(self):
 
  def test_storage_exists_false(self):
  self.storage.connection.meta.client.head_object.side_effect = ClientError(
- {'Error': {'Code': '404', 'Message': 'Not Found'}},
+ {'Error': {}, 'ResponseMetadata': {'HTTPStatusCode': 404}},
  'HeadObject',
  )
- self.assertFalse(self.storage.exists("file.txt"))
+ self.assertFalse(self.storage.exists('file.txt'))
  self.storage.connection.meta.client.head_object.assert_called_with(
  Bucket=self.storage.bucket_name,
  Key='file.txt',
  )
 
+ def test_storage_exists_other_error_reraise(self):
+ self.storage.connection.meta.client.head_object.side_effect = ClientError(
+ {'Error': {}, 'ResponseMetadata': {'HTTPStatusCode': 403}},
+ 'HeadObject',
+ )
+ with self.assertRaises(ClientError) as cm:
+ self.storage.exists('file.txt')
+
+ self.assertEqual(cm.exception.response['ResponseMetadata']['HTTPStatusCode'], 403)
+
  def test_storage_delete(self):
  self.storage.delete("path/to/file.txt")
  self.storage.bucket.Object.assert_called_with('path/to/file.txt')