"bad format char passed to Py_BuildValue" exception with the python bindings

[glpatcern]

After upgrading our servers to xrootd 4.8.0, a python exception started to be thrown as per the title, whereas the same client code did not throw any exceptions with xrootd 4.7 and earlier versions.

A way to reproduce the issue is:

from XRootD import client as XrdClient
fs = XrdClient.FileSystem('root://your-favourite-xrootd-server')
status, resp = fs.query(QueryCode.OPAQUE, "/boguspath")

And the output is:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python2.6/site-packages/XRootD/client/filesystem.py", line 141, in query
    status, response = self.__fs.query(querycode, arg, timeout)
SystemError: bad format char passed to Py_BuildValue

(while it should be "The server answered with an error")

With @simonmichal we tried some combinations and it appears as the bug was there already before 4.8, but it is somehow exposed only now. The reason for this is that if a valid path (e.g. "/tmp") is passed to fs.query(), then the same exception is thrown also by an older xrootd server.

To be noted that we see this on CASTOR by issuing a query handled by fsctl() on the server side.
(For reference, the CASTOR Jira issue is at https://its.cern.ch/jira/browse/CASTOR-5501, but a CERN account is needed to see it. All relevant information has been reported here though).

[simonmichal]

This has been (potentially) fixed in b3419d2

Can we close it?

[glpatcern]

...which made it to release 4.8.1, right? I have deployed it and I don't see the issue any longer, so I'm OK to close this.

[simonmichal]

Perfect :-)