Re: sigaltstack breaks swapcontext()

From: Andy Lutomirski
Date: Thu Jan 07 2016 - 12:23:27 EST


On Thu, Jan 7, 2016 at 7:33 AM, Stas Sergeev <stsp@xxxxxxx> wrote:
> 06.01.2016 22:53, Andy Lutomirski ÐÐÑÐÑ:
>>
>> On Wed, Jan 6, 2016 at 11:31 AM, Stas Sergeev <stsp@xxxxxxx> wrote:
>>>
>>> Exactly.
>>> Do you think this can be ignored?
>>> A man page should then be corrected with EPERM and the
>>> above note removed, right?
>>>
>> I think it can be ignored. I'd go the SS_FORCE route, though, to
>> maintain POSIX compliance.
>
> I think such a flag would be a wrong thing to do.
> Allowing only SS_DISABLE (without any new flags) keeps
> you still "compatible with posix", and anything beyond
> SS_DISABLE in a sighandler is not needed.
>
> So I think we only have the following options:
> 1. Remove the check and forget (if anything, glibc can
> add the EPERM check to stay compatible with crap).
> 2. Allow only SS_DISABLE. This will mean a large patch,
> touching all arches, but the bonus is the compatibility
> with posix, that no one needs in this particular case.

Why does allowing SS_DISABLE require touching all arches?

--Andy

--
Andy Lutomirski
AMA Capital Management, LLC
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