[tor-bugs] #17946 [Stem]: launch_tor should kill process on exception while bootstrapping (for example, on KeyboardInterrupt)

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#17946: launch_tor should kill process on exception while bootstrapping (for
example, on KeyboardInterrupt)
------------------------+-----------------------------------
     Reporter:  germn   |      Owner:  atagar
         Type:  defect  |     Status:  new
     Priority:  Medium  |  Milestone:
    Component:  Stem    |    Version:
     Severity:  Normal  |   Keywords:  launch_tor, bootstrap
Actual Points:          |  Parent ID:
       Points:          |    Sponsor:
------------------------+-----------------------------------
 What will happen if we will call
 {{{
 stem.process.launch_tor_with_config(config, timeout=None)
 }}}
 and CTRL+C some time after?

 KeyboardInterrupt exception would be raised somewhere inside launch_tor,
 and we will have one of following situations:
 1) KeyboardInterrupt raised before or while subprocess.Popen - everything
 is ok
 2) KeyboardInterrupt raised after subprocess.Popen, inside bootstrapping,
 but before launch_tor finished - we will have hanging tor process with no
 ability to terminate it manually.

 This issue is about to fix second case. All we need is to add handling of
 second situation inside launch_tor function. Here's example of code that
 should be added before line 165 inside stem.process:


 {{{
 except:  # on any exception while bootstrapping
     tor_process.kill()  # kill existing process
     raise  # reraise exception
 }}}

 But note, you should also fix "finally" block to prevent closing stdout,
 stderr of terminated process.

 Note, this issue is not only about KeyboardInterrupt, but also for any
 other exception that can be raised suddenly everyehere, like
 asyncio.CancelledError

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17946>
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