add GCS support to docs server

third_party/google_appengine_cloudstorage/cloudstorage/errors.py

+# Copyright 2012 Google Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+# either express or implied. See the License for the specific
+# language governing permissions and limitations under the License.
+
+"""Google Cloud Storage specific Files API calls."""
+
+
+
+
+
+__all__ = ['AuthorizationError',
+           'check_status',
+           'Error',
+           'FatalError',
+           'FileClosedError',
+           'ForbiddenError',
+           'NotFoundError',
+           'ServerError',
+           'TimeoutError',
+           'TransientError',
+          ]
+
+import httplib
+
+
+class Error(Exception):
+  """Base error for all gcs operations.
+
+  Error can happen on GAE side or GCS server side.
+  For details on a particular GCS HTTP response code, see
+  https://developers.google.com/storage/docs/reference-status#standardcodes
+  """
+
+
+class TransientError(Error):
+  """TransientError could be retried."""
+
+
+class TimeoutError(TransientError):
+  """HTTP 408 timeout."""
+
+
+class FatalError(Error):
+  """FatalError shouldn't be retried."""
+
+
+class FileClosedError(FatalError):
+  """File is already closed.
+
+  This can happen when the upload has finished but 'write' is called on
+  a stale upload handle.
+  """
+
+
+class NotFoundError(FatalError):
+  """HTTP 404 resource not found."""
+
+
+class ForbiddenError(FatalError):
+  """HTTP 403 Forbidden.
+
+  While GCS replies with a 403 error for many reasons, the most common one
+  is due to bucket permission not correctly setup for your app to access.
+  """
+
+
+class AuthorizationError(FatalError):
+  """HTTP 401 authentication required.
+
+  Unauthorized request has been received by GCS.
+
+  This error is mostly handled by GCS client. GCS client will request
+  a new access token and retry the request.
+  """
+
+
+class InvalidRange(FatalError):
+  """HTTP 416 RequestRangeNotSatifiable."""
+
+
+class ServerError(TransientError):
+  """HTTP >= 500 server side error."""
+
+
+def check_status(status, expected, path, headers=None,
+                 resp_headers=None, extras=None):
+  """Check HTTP response status is expected.
+
+  Args:
+    status: HTTP response status. int.
+    expected: a list of expected statuses. A list of ints.
+    path: filename or a path prefix.
+    headers: HTTP request headers.
+    resp_headers: HTTP response headers.
+    extras: extra info to be logged verbatim if error occurs.
+
+  Raises:
+    AuthorizationError: if authorization failed.
+    NotFoundError: if an object that's expected to exist doesn't.
+    TimeoutError: if HTTP request timed out.
+    ServerError: if server experienced some errors.
+    FatalError: if any other unexpected errors occurred.
+  """
+  if status in expected:
+    return
+
+  msg = ('Expect status %r from Google Storage. But got status %d.\n'
+         'Path: %r.\n'
+         'Request headers: %r.\n'
+         'Response headers: %r.\n'
+         'Extra info: %r.\n' %
+         (expected, status, path, headers, resp_headers, extras))
+
+  if status == httplib.UNAUTHORIZED:
+    raise AuthorizationError(msg)
+  elif status == httplib.FORBIDDEN:
+    raise ForbiddenError(msg)
+  elif status == httplib.NOT_FOUND:
+    raise NotFoundError(msg)
+  elif status == httplib.REQUEST_TIMEOUT:
+    raise TimeoutError(msg)
+  elif status == httplib.REQUESTED_RANGE_NOT_SATISFIABLE:
+    raise InvalidRange(msg)
+  elif (status == httplib.OK and 308 in expected and
+        httplib.OK not in expected):
+    raise FileClosedError(msg)
+  elif status >= 500:
+    raise ServerError(msg)
+  else:
+    raise FatalError(msg)