Re: [PATCH 1/2] sigaltstack: implement SS_AUTODISARM flag

From	Stas Sergeev <stsp@list.ru>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/2] sigaltstack: implement SS_AUTODISARM flag
Date	2016-03-05 08:50 +0100
Message-ID	<r9f8m-2Tl-1@gated-at.bofh.it> (permalink)
References	<r7DHQ-8rB-15@gated-at.bofh.it> <r7DHR-8rB-51@gated-at.bofh.it> <r96op-5cc-11@gated-at.bofh.it> <r9eYF-2Pv-1@gated-at.bofh.it>
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05.03.2016 10:39, Stas Sergeev пишет:
> 05.03.2016 01:22, Andy Lutomirski пишет:
>> On Mon, Feb 29, 2016 at 1:29 PM, Stas Sergeev <stsp@list.ru> wrote:
>>> This patch implements the SS_AUTODISARM flag that can be ORed with
>>> SS_ONSTACK when forming ss_flags.
>>> When this flag is set, sigaltstack will be disabled when entering
>>> the signal handler; more precisely, after saving sas to uc_stack.
>>> When leaving the signal handler, the sigaltstack is restored by
>>> uc_stack.
>>> When this flag is used, it is safe to switch from sighandler with
>>> swapcontext(). Without this flag, the subsequent signal will corrupt
>>> the state of the switched-away sighandler.
>>>
>> This looks reasonable to me with one exception: how does a user
>> program detect the presence of this feature?
> Compile-time detection:
> #ifdef SS_AUTODISARM
>   # I have this feature
>   ...
> #endif
>
> Run-time detection:
> int err = sigaltstack(SS_ONSTACK | SS_AUTODISARM);
> if (err == EINVAL) {
I guess I mean here
if (err && errno == EINVAL)

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Re: [PATCH 1/2] sigaltstack: implement SS_AUTODISARM flag Andy Lutomirski <luto@amacapital.net> - 2016-03-04 23:30 +0100
  Re: [PATCH 1/2] sigaltstack: implement SS_AUTODISARM flag Stas Sergeev <stsp@list.ru> - 2016-03-05 08:40 +0100
    Re: [PATCH 1/2] sigaltstack: implement SS_AUTODISARM flag Stas Sergeev <stsp@list.ru> - 2016-03-05 08:50 +0100

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