writing to data store broken due to permissions issue

[sascha_silbe]

Writing data store entries fails inside the data store:

Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.6/dbus/service.py", line 702, in _message_cb
    retval = candidate_method(self, *args, **keywords)
  File "/usr/lib/python2.6/dist-packages/carquinyol/datastore.py", line 271, in get_filename
    return self._file_store.retrieve(uid, user_id, extension)
  File "/usr/lib/python2.6/dist-packages/carquinyol/filestore.py", line 134, in retrieve
    os.chmod(file_path, 0440)
OSError: [Errno 1] Operation not permitted: '/home/sascha.silbe/.sugar/default/datastore/2b/2bd396fa-ddb2-43e6-b8ae-680f475488ce/data'

That's because the submitted files are owned by the isolation user and moved (not copied) into the data store:

sascha.silbe@xo15-sascha:~/sugar-jhbuild/source/sugar-datastore$ ls -l /home/sascha.silbe/.sugar/default/datastore/2b/2bd396fa-ddb2-43e6-b8ae-680f475488ce/data
-rw-rw-rw- 1 10046 sascha.silbe 232 Oct 17 22:22 /home/sascha.silbe/.sugar/default/datastore/2b/2bd396fa-ddb2-43e6-b8ae-680f475488ce/data

Not sure what the best solution is:

• Copying would be wasteful (especially for large entries)
• For changing ownership after moving we'd need some helper running as root.
• Leaving the permissions as-is would lead to the same issues I encountered with ​Backup / ​Restore: other activities cannot read or overwrite existing entries from an activity that set restrictive permissions.

​DBus 1.3.0 apparently has support for fd passing. Maybe the next generation of sugar-datastore and sugar-toolkit should use that to transfer the entries? Most activities wouldn't need to create an on-disk copy first.

[sascha_silbe]

Sorry Michael, forgot to add you to CC.