[tor-bugs] #10047 [Pluggable transport]: PTs could self-shutdown when they detect their stdout is closed

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#10047: PTs could self-shutdown when they detect their stdout is closed
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     Reporter:  infinity0            |      Owner:  asn
         Type:  enhancement          |     Status:  new
     Priority:  normal               |  Milestone:
    Component:  Pluggable transport  |    Version:
   Resolution:                       |   Keywords:
Actual Points:                       |  Parent ID:
       Points:                       |
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Description changed by infinity0:

Old description:

> In [#9330] we were exploring solutions to signal a PT to do clean
> shutdown on Windows. In [#10006] dcf suggested a workaround using
> JobObjects, which has the nice property that the children shutdown even
> when their parent crashes or is killed (SIGKILL or TerminateProcess).
>
> This raises the valid point, why don't we try to achieve this for all
> platforms? Since all PTs must already communicate via stdout back to Tor
> (or any parent process, such as a PT chainer), one way of detecting
> parent death is to check that stdout is still open.
>
> Example: [http://compgroups.net/comp.unix.programmer/how-to-kill-all-
> child-when-parent-exits/36841]
>
> We'll need to research whether we must write to the stream to detect it's
> closed, or if we can get away with doing something like poll or select.

New description:

 In [ticket:9330] we were exploring solutions to signal a PT to do clean
 shutdown on Windows. In [ticket:10006] dcf suggested a workaround using
 JobObjects, which has the nice property that the children shutdown even
 when their parent crashes or is killed (SIGKILL or TerminateProcess).

 This raises the valid point, why don't we try to achieve this for all
 platforms? Since all PTs must already communicate via stdout back to Tor
 (or any parent process, such as a PT chainer), one way of detecting parent
 death is to check that stdout is still open.

 Example: [http://compgroups.net/comp.unix.programmer/how-to-kill-all-
 child-when-parent-exits/36841]

 We'll need to research whether we must write to the stream to detect it's
 closed, or if we can get away with doing something like poll or select.

--

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/10047#comment:1>
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