Do not report an error in websocket_log when closing a VNC connection

[skateman]

When closing a VNC console, the transmission block (1) can throw an IO::WaitWritable or with an even higher probability an IO::WaitReadable exception. These are not inherited from the IOError, so the cleanup will not treat this a closed exception (2) but as an error (3).

begin
  # transmission (1)
rescue IOError
  # clean up closed connection (2)
rescue StandardError => ex
  # clean up error (3)
end

The cleanup function is the same for both (2) and (3), the only difference is the way how we report them into the websocket log, That's the problem I'm trying to fix here by adding the 2 exception classes into (2).

@miq-bot add_label bug, providers/console, hammer/no
@miq-bot add_reviewer @djberg96, @kbrock @jrafanie

[miq-bot]

@skateman 'djberg96, kbrock jrafanie' is an invalid reviewer, ignoring...

[skateman]

EAGAIN
@miq-bot add_reviewer @kbrock
@miq-bot add_reviewer @jrafanie
@miq-bot add_reviewer @djberg96

[miq-bot]

Checked commit skateman@2d1204f with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
1 file checked, 0 offenses detected
Everything looks fine. ⭐

[djberg96]

Looking at the exception hierarchy, those are subclasses of Errno::EAGAIN, but even with your changes it would still not pickup Errno::EINPROGRESS errors. Are those possible? If so, I would suggest being even more generic and rescuing SystemCallError instead.

[skateman]

@djberg96 where are you looking at the hierarchy? Just because:

IO::WaitReadable < Errno::EAGAIN
=> nil

I think the SystemCallError is a little too much, originally I got an IO::EAGAINWaitReadable exception.

[jrafanie]

Looking at IO select docs, ( I believe that's what you're doing here, right?), the two additional exceptions seems appropriate.

[skateman]

@jrafanie we're not really calling IO.select anymore (except for OSX), but the code snippet in that comment seems just right. But if you send me a C code, I read it 😆 here are the related lines:

• https://github.com/ruby/ruby/blob/v2_4_5/io.c#L2680
• https://github.com/ruby/ruby/blob/v2_4_5/io.c#L2723

All the transmissions for any protocol combination eventually end up calling those two methods.