Re: PATCH: (2) Re: FreeBSD compatability feature request

[Peter Stephenson <pws@csr.com>]

Peter Stephenson wrote:
> However, that now gives us three different modes: the original zsh one,
> POSIX where all traps are deferred, and this mode where signals are
> delivered straight through.  So one option isn't enough.  Presumably
> TRAPS_ASYNC should be off for the standard zsh behaviour, on for the new
> behaviour, and we need another option for POSIX which will be overridden
> if TRAPS_ASYNC is set.  Yuk.

Actually (sorry to generate all the traffic) it's possible I was getting
confused...

Zsh will usually block other signals while waiting for SIGCHLD.  This
may be all that POSIX requires.  What it doesn't do (and why I was able
to get asynchronous traps working) is ensure that traps don't run if it
stops waiting, for example because a different process exited.  I
originally tested this by running a background functions which exited,
generating a SIGCHLD, which caused all queued signals to be delivered.

Hence it's possible that the queueing traps thing is a red herring, that
zsh is sufficiently POSIX compliant by default, and all we need is the
ability to receive signals other than SIGCHLD while waiting for a child.
(It's a bit late to back out now.)

If anybody actually knows anything about all this, their views would be
especially welcome.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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