Re: Libc support for old BSD-style "sigcontext" signal handlers is broken, let's just kill it.

[christos%astron.com@localhost (Christos Zoulas)]

In article <141D1BEC-0F6D-4BB8-8B44-ABA98806CC9A%me.com@localhost>,
Jason Thorpe  <thorpej%me.com@localhost> wrote:
>
>> On Oct 26, 2021, at 6:56 AM, Jason Thorpe <thorpej%me.com@localhost> wrote:
>> 
>> Obviously, the practical impact of this is nil, since no one apparently
>noticed (and I guess we didnâ??t break any programs that people were
>using). We havenâ??t documented that style of handler for a VERY long time
>but presumably the intent was for it to continue to work because the code
>remained and was modified several times over the years. (it was certainly
>my original intent when I first added support for multiple signal
>trampolines in a single process ~20 years ago, and it did in fact work for
>the first few years that code existed).
>
>Oh, I suppose I should also point out that kernel support for the older
>trampoline is in the COMPAT_16 module (the new â??siginfoâ?? stuff was
>added in NetBSD 2.0).

I think we should do the minimal change and merge all the
__sigaction14_sigcontext.c files, as well as enable the ifdef'ed out code
to restore compatibility and add unit tests if we are going to keep the
code in the kernel so that we can test it.

christos