Merge lp:~crosser/duplicity/dpbx-fix-file-listing into lp:~duplicity-team/duplicity/0.8-series

[Eugene Crosser]

dpbxbackend: do not crash when remote directory is empty (always empty on first run).

[edso (ed.so)]

hi,

that workaround looks fishy to me. it will also mask other ListFolderErrors, even ones with a proper cause, that the user needs to see to take appropriate action.

can you dig into the error and find out the detailed error, so you might only ignore this specific error?

another less invasive workaround would be placing a dummy file in the new folder during creation.

probably the correct solution would be raising a bug ticket over at
  https://github.com/dropbox/dropbox-sdk-python/issues

thanks!.. ede/duply.net

review: Needs Fixing

[Eugene Crosser (crosser)]

Dropbox API probably works as designed: apparently it's actually not and 'empty folder' but 'non-existent folder':

```
ApiError('331ae42f2ac881f10caefc800e59e35b', ListFolderError(u'path', LookupError(u'not_found', None)))
```

It is non-trivial to check the contents of `ListFolderError`: it is a subcluss of `Union` which is a subclass of `Composite` which is a subclass of `Validator` which is much deeper than I am ready do dig.

My goal was to make duplicity work (for me), not to learn Dropbox API. Sorry.

[Kenneth Loafman (kenneth-loafman)]

There is already a bug report: https://github.com/dropbox/dropbox-sdk-python/issues/35

The third comment has a code snippet for handling the error. Maybe adopt that?

Unmerged revisions

=== modified file 'duplicity/backends/dpbxbackend.py'
--- duplicity/backends/dpbxbackend.py	2017-07-11 14:55:38 +0000
+++ duplicity/backends/dpbxbackend.py	2017-11-25 12:19:19 +0000
@@ -41,7 +41,7 @@
 from dropbox import Dropbox
 from dropbox.exceptions import AuthError, BadInputError, ApiError
 from dropbox.files import UploadSessionCursor, CommitInfo, WriteMode, \
-    GetMetadataError, DeleteError, UploadSessionLookupError
+    GetMetadataError, DeleteError, UploadSessionLookupError, ListFolderError
 from dropbox.oauth import DropboxOAuth2FlowNoRedirect
 from requests.exceptions import ConnectionError
 import time
@@ -383,15 +383,19 @@
         remote_dir = '/' + urllib.unquote(self.parsed_url.path.lstrip('/')).rstrip()
 
         log.Debug('dpbx.files_list_folder(%s)' % remote_dir)
-        resp = self.api_client.files_list_folder(remote_dir)
-        log.Debug('dpbx.list(%s): %s' % (remote_dir, resp))
-
         res = []
-        while True:
-            res.extend([entry.name for entry in resp.entries])
-            if not resp.has_more:
-                break
-            resp = self.api_client.files_list_folder_continue(resp.cursor)
+        try:
+            resp = self.api_client.files_list_folder(remote_dir)
+            log.Debug('dpbx.list(%s): %s' % (remote_dir, resp))
+
+            while True:
+                res.extend([entry.name for entry in resp.entries])
+                if not resp.has_more:
+                    break
+                resp = self.api_client.files_list_folder_continue(resp.cursor)
+        except ApiError as e:
+            if not isinstance(e.error, ListFolderError):
+                raise
 
         # Warn users of old version dpbx about automatically renamed files
         self.check_renamed_files(res)