[ovs-git] [openvswitch/ovs] f0e307: vlog: Better handle syslog handler exceptions.

[Ben Pfaff]

  Branch: refs/heads/master
  Home:   https://github.com/openvswitch/ovs
  Commit: f0e3075ff0d13a10f0605d4508d0dc72d605b5cc
      https://github.com/openvswitch/ovs/commit/f0e3075ff0d13a10f0605d4508d0dc72d605b5cc
  Author: Ilya Maximets <i.maximets at samsung.com>
  Date:   2019-02-25 (Mon, 25 Feb 2019)

  Changed paths:
    M python/ovs/vlog.py

  Log Message:
  -----------
  vlog: Better handle syslog handler exceptions.

'set_levels_from_string' doesn't check for exceptions that could
happen while opening syslog files or connecting to syslog sockets.

For example, if rsyslog stopped on a system:

  $ test-unixctl.py -vFACILITY:daemon --detach
  Traceback (most recent call last):
    File "../../../../tests/test-unixctl.py", line 90, in <module>
      main()
    File "../../../../tests/test-unixctl.py", line 61, in main
      ovs.vlog.handle_args(args)
    File "python/ovs/vlog.py", line 463, in handle_args
      msg = Vlog.set_levels_from_string(verbose)
    File "python/ovs/vlog.py", line 345, in set_levels_from_string
      Vlog.add_syslog_handler(words[1])
    File "python/ovs/vlog.py", line 321, in add_syslog_handler
      facility=syslog_facility)
    File "/python2.7/logging/handlers.py", line 759, in __init__
      self._connect_unixsocket(address)
    File "/python2.7/logging/handlers.py", line 787, in _connect_unixsocket
      self.socket.connect(address)
    File "/python2.7/socket.py", line 224, in meth
      return getattr(self._sock,name)(*args)
  socket.error: [Errno 111] Connection refused

In this case "/dev/log" file exists, so the check inside
'add_syslog_handler' doesn't help.

We need to catch the exceptions in 'set_levels_from_string' same way
as it done in 'init' function.
Also, we don't really need to check for '/dev/log' existence, because
exception will be catched on the upper layer and properly handled by
disabling the corresponding logger.

Fixes: d69d61c7c175 ("vlog: Ability to override the default log facility.")
Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
Signed-off-by: Ben Pfaff <blp at ovn.org>