SVGHMI: JsonTable now use intermediate variables again to address JSON data without duplicating code or referencing. Using intermediate variables also alows to check for availability of data and stop evaluating early if data is missing. Finally added complete roundtrip example to illustrate use of JSonTable to display "alarms" collected in python from changes on PLC boolean variables.
from __future__ import absolute_import
from __future__ import print_function
import os
from binascii import b2a_hqx
try:
from runtime.spawn_subprocess import call
except ImportError:
from subprocess import call
restart_stunnel_cmdline = ["/etc/init.d/S50stunnel", "restart"]
_PSKpath = None
def restartStunnel():
"""
Restart stunnel service using SysV init stript
to apply new generated credentials
"""
try:
call(restart_stunnel_cmdline)
except OSError:
print(_("Couldn't restart stunnel service"))
def PSKgen(ID, PSKpath):
# b2a_hqx output len is 4/3 input len
secret = os.urandom(192) # int(256/1.3333)
secretstring = b2a_hqx(secret)
PSKstring = ID+":"+secretstring
with open(PSKpath, 'w') as f:
f.write(PSKstring)
restartStunnel()
def ensurePSK(ID, PSKpath):
global _PSKpath
_PSKpath = PSKpath
# check if already there
if not os.path.exists(PSKpath):
# create if needed
PSKgen(ID, PSKpath)
def getPSKID(errorlog):
if _PSKpath is not None:
if not os.path.exists(_PSKpath):
errorlog(
'Error: Pre-Shared-Key Secret in %s is missing!\n' % _PSKpath)
return None
ID, _sep, PSK = open(_PSKpath).read().partition(':')
PSK = PSK.rstrip('\n\r')
return (ID, PSK)
return None