Re: capturing system shutdown signals?

systemd is able to execute commands in ExecStop=. A named pipe with a
thread reading from it is a strategy. With a fallback to handling signals.
With a fallback to making code unwind safe (at least the lisp parts,
foreign code is another story).

On Sat, Apr 27, 2024 at 2:07 AM Stas Boukarev <[email protected]> wrote:

> Probably the best bet is disabling signals where things are unwind-safe,
> and handling them from a dedicated thread. But there's no API for that.
> Barely anything is async unwind safe.
> Using sb-posix:pipe + sb-posix:write in an interrupt handler is safe,
> provided the function running involves no other lisp code.
>
> On Sat, Apr 27, 2024 at 1:55 AM Stas Boukarev <[email protected]> wrote:
>
>> Catching unix signals won't help programs that can't unwind cleanly.
>> Unless you just ignore them.
>>
>> On Sat, Apr 27, 2024 at 1:52 AM Grégory Vanuxem <[email protected]>
>> wrote:
>>
>>> I think the signal-handler stuff in the UNIX package should help you.
>>> Install one or more handler(s) I guess:
>>>
>>> https://github.com/sbcl/sbcl/blob/master/src/code/signal.lisp
>>>
>>> For Unix-like (POSIX)
>>> signals, see:
>>>
>>> https://sites.uclouvain.be/SystInfo/usr/include/asm-generic/signal.h.html
>>>
>>>
>>> You will first need to handle the SIGTERM, 15 , but eventually 9, hard
>>> kill. Eventually more since there are also some other terminaison
>>> mechanisms,  but I think the SBCL debugger is invoked there, for example
>>> floating-point exceptions (division by 0 for example). See man signal(s).
>>>
>>> https://pubs.opengroup.org/onlinepubs/7908799/xsh/signal.h.html
>>>
>>>
>>> - Greg
>>>
>>>
>>>
>>>
>>>
>>>
>>> Le sam. 27 avr. 2024 à 00:31, Stas Boukarev <[email protected]> a
>>> écrit :
>>>
>>>> My "man kill" doesn't contain the word "shutdown" and
>>>> kill -L
>>>> says
>>>> kill: unknown signal: SIGL
>>>>
>>>> On Sat, Apr 27, 2024 at 1:15 AM Jeff Cunningham <
>>>> [email protected]> wrote:
>>>>
>>>>> See "man kill" or "kill -L" for a list.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Fri, 26 Apr 2024 23:36:18 +0300
>>>>> Stas Boukarev <[email protected]> wrote:
>>>>>
>>>>> > What's a shutdown signal?
>>>>> >
>>>>> > On Fri, Apr 26, 2024 at 8:14 PM Jeff Cunningham <
>>>>> [email protected]>
>>>>> > wrote:
>>>>> >
>>>>> > > Is there a way to capture a general shutdown signal in a running
>>>>> > > sbcl-compiled program (Hunchentoot
>>>>> > > server) so it can gracefully do some house-keeping first? This is
>>>>> running
>>>>> > > on a Linux platform. I
>>>>> > > had a binary data file destroyed the other day from improper
>>>>> closure while
>>>>> > > writing.
>>>>> > >
>>>>> > > Best regards,
>>>>> > >
>>>>> > > -- Jeff
>>>>> > >
>>>>> > >
>>>>> > >
>>>>> > >
>>>>> > >
>>>>> > >
>>>>> > >
>>>>> > >
>>>>> > > _______________________________________________
>>>>> > > Sbcl-help mailing list
>>>>> > > [email protected]
>>>>> > > https://lists.sourceforge.net/lists/listinfo/sbcl-help
>>>>> > >
>>>>>
>>>>> _______________________________________________
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>>>>
>>>

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