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Date: Thu, 29 Oct 2020 15:12:21 +0100
From: Florian Weimer <fweimer@...hat.com>
To: musl@...ts.openwall.com
Subject: Re: More thoughts on wrapping signal handling
* Alexander Monakov:
> On Thu, 29 Oct 2020, Alexander Monakov wrote:
>
>> On Thu, 29 Oct 2020, Rich Felker wrote:
>>
>> > Yes, I kinda hand-waved over this with the word "call", which I
>> > thought about annotating with (*). In the case of SA_ONSTACK you need
>> > a primitive to "call on new stack", and while the ucontext is mostly
>> > not meaningful/inspectable to the signal handler (because it's
>> > interrupting libc code), the saved signal mask is. You can have the
>> > caller restore it (in place of SYS_[rt_]sigreturn), but the natural
>> > common solution to all of these needs is having a sort of makecontext.
>>
>> Alternatively you could re-raise the signal to have the kernel re-deliver
>> it with the correctly regenerated ucontext (and on the right stack)?
>> Would that be undesirable for some reason?
>
> Ah, because there's no way to propagate siginfo struct. Sorry :)
Yes, and that's why I think copying it into TLS space will not work,
either.
Thanks,
Florian
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