Re: [PATCH] scripts: environment: Properly handle SIGINT.

["Thompson, David" <dthompson2@worcester.edu>]

On Sun, Mar 27, 2016 at 1:35 PM, Ludovic Courtès <ludo@gnu.org> wrote:
> "Thompson, David" <dthompson2@worcester.edu> skribis:
>
>> On Sat, Mar 26, 2016 at 2:33 PM, Thompson, David
>> <dthompson2@worcester.edu> wrote:
>>> On Sat, Mar 26, 2016 at 2:23 PM, Ludovic Courtès <ludo@gnu.org> wrote:
>>>> David Thompson <dthompson2@worcester.edu> skribis:
>>>>
>>>>> * tests/guix-environment-container.sh: Remove obsolete test.
>>>>
>>>> [...]
>>>>
>>>>> -if guix environment --bootstrap --container \
>>>>> -     --ad-hoc bootstrap-binaries -- kill -SEGV 2
>>>>> -then false;
>>>>> -else
>>>>> -    test $? -gt 127
>>>>> -fi
>>>>
>>>> This test was added in light of <http://bugs.gnu.org/21958>.  We want to
>>>> make sure we don’t lose that property.
>>>>
>>>> What happens exactly when a signal is sent to PID 1?  I would expect
>>>> that its parent process, which is outside the container in a waitpid
>>>> call, would simply get its exit value in the normal way, and thus,
>>>> changing “2” to “1” in this test should do the trick.  Am I naïve?  :-)
>>>
>>> The problem is that a process within the container cannot just kill
>>> PID 1 since its the init process and the kernel protects it, so
>>> changing "2" to "1" doesn't work.  The exit status of the environment
>>> command is 0 in that case because PID 1 never received the signal and
>>> thus exits normally.
>>>
>>> I'll try to come up with a replacement test case, thanks for giving me
>>> the context in which it was added.  (I should've used 'git blame'
>>> first.)
>>
>> Coming up with a replacement test has proved very difficult.  Since
>> PID 1 is unkillable, I'm having a hell of time coming up with a clever
>> way to kill a Guile process via a signal.
>
> Would it help to change the test to:
>
>   guix environment --bootstrap --container \
>      --ad-hoc bootstrap-binaries -- sh -c 'exec kill -SEGV 2'
>
> essentially mimicking previous behavior?

This didn't work, but for the record Ludo and I figured out another
way on IRC that involves using the FFI to make Guile segfault.  Fun
times!

Pushed with that change.

- Dave