Fix crash in runtime if PSK secret is missing

./Beremiz_service.py -s $PWD/psk2.txt -n beremiz /tmp/beremiz
Beremiz_service: 1.2-1378c18402c3+

Traceback (most recent call last):
File "./Beremiz_service.py", line 511, in <module>
ensurePSK(servicename, PSKpath)
File "/home/developer/WorkData/PLC/beremiz/beremiz/runtime/Stunnel.py", line 32, in ensurePSK
PSKgen(ID, PSKpath)
File "/home/developer/WorkData/PLC/beremiz/beremiz/runtime/Stunnel.py", line 23, in PSKgen
call(restart_stunnel_cmdline)
File "/home/developer/WorkData/PLC/beremiz/beremiz/runtime/spawn_subprocess.py", line 116, in call
pid = posix_spawn.posix_spawnp(cmd[0], cmd)
File "/home/developer/.local/lib/python2.7/site-packages/posix_spawn/_impl.py", line 120, in posix_spawnp
return _posix_spawn(lib.posix_spawnp, *args, **kwargs)
File "/home/developer/.local/lib/python2.7/site-packages/posix_spawn/_impl.py", line 111, in _posix_spawn
_check_error(res, path)
File "/home/developer/.local/lib/python2.7/site-packages/posix_spawn/_impl.py", line 10, in _check_error
raise OSError(errno, os.strerror(errno), path)
OSError: [Errno 2] No such file or directory: '/etc/init.d/S50stunnel'

     1

#!/usr/bin/env python

     2

# -*- coding: utf-8 -*-

     3

     4

# This file is part of Beremiz, a Integrated Development Environment for

     5

# programming IEC 61131-3 automates supporting plcopen standard and CanFestival.

     6

#

     7

# Copyright (c) 2016 Mario de Sousa (msousa@fe.up.pt)

     8

#

     9

# This program is free software: you can redistribute it and/or modify

    10

# it under the terms of the GNU General Public License as published by

    11

# the Free Software Foundation, either version 2 of the License, or

    12

# (at your option) any later version.

    13

#

    14

# This program is distributed in the hope that it will be useful,

    15

# but WITHOUT ANY WARRANTY; without even the implied warranty of

    16

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    17

# GNU General Public License for more details.

    18

#

    19

# You should have received a copy of the GNU General Public License

    20

# along with this program.  If not, see <http://www.gnu.org/licenses/>.

    21

#

    22

# This code is made available on the understanding that it will not be

    23

# used in safety-critical situations without a full and competent review.