beremiz

Proper fix for error 'object has no attribute 'getSlave' in EtherCAT extension

2018-08-24, Andrey Skvortsov
96ca6b056c55
file isExecutable
Proper fix for error 'object has no attribute 'getSlave' in EtherCAT extension

traceback:
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1433, in OnPouSelectedChanged
window.RefreshView()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 837, in RefreshView
self.RefreshProcessVariables()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 886, in RefreshProcessVariables
slaves = self.Controler.GetSlaves(**self.CurrentNodesFilter)
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/EthercatMaster.py", line 341, in GetSlaves
for slave in self.Config.getConfig().getSlave():
:_'lxml.etree._Element'_object_has_no_attribute_'getSlave'

Steps to reproduce problem:

- Add new EtherCAT master
- Add new EthercatNode to the master
- double click on


Revert commit "Dirty fix for error '_object_has_no_attribute_'getSlave' in EtherCAT extension"
[a3ac46366b86a0b237dac93be6b2281ac70b98a8].

The problem was that XML elements (proxy object) in some cases were created using custom XML
classes constructors and lxml.etree.Element() call and live python
patching. This causes that lxml backend doesn't know that custom python class
should be used for these XML elements.
Proxy object can be move/deleted and recreated by lxml
backend at any point in time or this can be done in python by copy/deepcopy operations.
If this happens, then newly created
proxy elements are using default class lxml.etree._Element. And all
custom functionality is lost.

All created XML elements should be always created through corresponding
parser and class lookup callback done by lxml backend.
It's described in more details in lxml documentation:
https://lxml.de/element_classes.html
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# This file is part of Beremiz, a Integrated Development Environment for
# programming IEC 61131-3 automates supporting plcopen standard and CanFestival.
#
# Copyright (C) 2007: Edouard TISSERANT and Laurent BESSARD
#
# See COPYING file for copyrights details.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
from __future__ import absolute_import
from __future__ import print_function
import traceback
from time import sleep
import copy
import socket
import os.path
import Pyro
import Pyro.core
import Pyro.util
from Pyro.errors import PyroError
service_type = '_PYRO._tcp.local.'
# this module attribute contains a list of DNS-SD (Zeroconf) service types
# supported by this connector confnode.
#
# for connectors that do not support DNS-SD, this attribute can be omitted
# or set to an empty list.
def PYRO_connector_factory(uri, confnodesroot):
"""
This returns the connector to Pyro style PLCobject
"""
confnodesroot.logger.write(_("PYRO connecting to URI : %s\n") % uri)
servicetype, location = uri.split("://")
if servicetype == "PYROS":
schemename = "PYROLOCSSL"
# Protect against name->IP substitution in Pyro3
Pyro.config.PYRO_DNS_URI = True
# Beware Pyro lib need str path, not unicode
# don't rely on PYRO_STORAGE ! see documentation
Pyro.config.PYROSSL_CERTDIR = os.path.abspath(str(confnodesroot.ProjectPath) + '/certs')
if not os.path.exists(Pyro.config.PYROSSL_CERTDIR):
confnodesroot.logger.write_error(
'Error : the directory %s is missing for SSL certificates (certs_dir).'
'Please fix it in your project.\n' % Pyro.config.PYROSSL_CERTDIR)
return None
else:
confnodesroot.logger.write(_("PYRO using certificates in '%s' \n")
% (Pyro.config.PYROSSL_CERTDIR))
Pyro.config.PYROSSL_CERT = "client.crt"
Pyro.config.PYROSSL_KEY = "client.key"
# Ugly Monkey Patching
def _gettimeout(self):
return self.timeout
def _settimeout(self, timeout):
self.timeout = timeout
from M2Crypto.SSL import Connection # pylint: disable=import-error
Connection.timeout = None
Connection.gettimeout = _gettimeout
Connection.settimeout = _settimeout
# M2Crypto.SSL.Checker.WrongHost: Peer certificate commonName does not
# match host, expected 127.0.0.1, got server
Connection.clientPostConnectionCheck = None
else:
schemename = "PYROLOC"
if location.find(service_type) != -1:
try:
from zeroconf import Zeroconf
r = Zeroconf()
i = r.get_service_info(service_type, location)
if i is None:
raise Exception("'%s' not found" % location)
ip = str(socket.inet_ntoa(i.address))
port = str(i.port)
newlocation = ip + ':' + port
confnodesroot.logger.write(_("'{a1}' is located at {a2}\n").format(a1=location, a2=newlocation))
location = newlocation
r.close()
except Exception:
confnodesroot.logger.write_error(_("MDNS resolution failure for '%s'\n") % location)
confnodesroot.logger.write_error(traceback.format_exc())
return None
# Try to get the proxy object
try:
RemotePLCObjectProxy = Pyro.core.getAttrProxyForURI(schemename + "://" + location + "/PLCObject")
except Exception:
confnodesroot.logger.write_error(_("Connection to '%s' failed.\n") % location)
confnodesroot.logger.write_error(traceback.format_exc())
return None
def PyroCatcher(func, default=None):
"""
A function that catch a Pyro exceptions, write error to logger
and return default value when it happen
"""
def catcher_func(*args, **kwargs):
try:
return func(*args, **kwargs)
except Pyro.errors.ConnectionClosedError, e:
confnodesroot.logger.write_error(_("Connection lost!\n"))
confnodesroot._SetConnector(None)
except Pyro.errors.ProtocolError, e:
confnodesroot.logger.write_error(_("Pyro exception: %s\n") % e)
except Exception, e:
# confnodesroot.logger.write_error(traceback.format_exc())
errmess = ''.join(Pyro.util.getPyroTraceback(e))
confnodesroot.logger.write_error(errmess + "\n")
print(errmess)
confnodesroot._SetConnector(None)
return default
return catcher_func
# Check connection is effective.
# lambda is for getattr of GetPLCstatus to happen inside catcher
if PyroCatcher(RemotePLCObjectProxy.GetPLCstatus)() is None:
confnodesroot.logger.write_error(_("Cannot get PLC status - connection failed.\n"))
return None
_special_return_funcs = {
"StartPLC": False,
"GetTraceVariables": ("Broken", None),
"GetPLCstatus": ("Broken", None),
"RemoteExec": (-1, "RemoteExec script failed!")
}
class PyroProxyProxy(object):
"""
A proxy proxy class to handle Beremiz Pyro interface specific behavior.
And to put Pyro exception catcher in between caller and Pyro proxy
"""
def __getattr__(self, attrName):
member = self.__dict__.get(attrName, None)
if member is None:
def my_local_func(*args, **kwargs):
return RemotePLCObjectProxy.__getattr__(attrName)(*args, **kwargs)
member = PyroCatcher(my_local_func, _special_return_funcs.get(attrName, None))
self.__dict__[attrName] = member
return member
return PyroProxyProxy()