GNU pth + cygwin + fork [Was: Re: fork failure?]

[Charles Wilson <cygwin at cwilson dot fastmail dot fm>]

Charles Wilson wrote:

> Ach, the purist in me just wants to get pth working...

Hmm...it appears the right way to do this is NOT to add another special
case in pth: "no, on cygwin THIS is the way you poke around in the
jmp_buf" + extra cygwin TLC in pth_fork().  Instead, cygwin pth should
use the standard posix sigstack/sigaltstack approach.

But that'll have to wait until after cygwin-1.7.1:
http://cygwin.com/ml/cygwin/2009-07/msg00859.html
> Let me add a new data point: I'll implement sigaltstack after 1.7.1 is
> released.

And, of course, cgf's statement above doesn't mean that sigaltstack will
be available the day after 1.7.1 is released, either. I'm sure it will
be devilishly tricky to get right, and will take a lot of time and effort.

In the short-to-medium term, it looks like converting libassuan and
gnupg to use pthreads instead of pth won't be terribly difficult.  Once
once sig[alt]stack is available I can modify cygwin-pth to use the
sig[alt]stack "Machine Context Implementation" instead of the current
"sjlj/sjljw32/none" one, and then restore libassuan and gnupg to the pth
status quo ante.

I think that pretty much ends this nightmare thread -- but chalk another
vote up there for "pretty please, cgf, implement sigaltstack soonish".

--
Chuck

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