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Re: Combination of sigwait() with sigaction()?

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Markus Elfring <Markus.Elfring@web.de> writes:
> I have found an interesting article about waiting for signals in a separate
> thread. A source code skeleton is shown.
> http://devcry.heiho.net/2009/05/pthreads-and-unix-signals.html
>
> The author suggested also to install an empty signal handler by the function
> "sigaction". How do you think about this suggestion?
> Is the mentioned indication of non-default signal actions useful here?

The author is somewhat confused here: sigwait returns "pending signals",
this means "signals which don't cause any 'action' because they're
blocked", hence, no "default actions" will happen. But the disposition
of a signal can be set to something other than "default action" or "signal
handler", namely, to "ignore this signals" and signals set to be ignored
don't become pending signals, they're just discarded (and hence, sigwait
will never return them). The main annoyance here is that the default
disposition of SIGCHLD is "ignore", hence, without setting that to
something else, sigwait (and similar routines) will never return a
SIGCHLD.

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Thread

Combination of sigwait() with sigaction()? Markus Elfring <Markus.Elfring@web.de> - 2013-11-21 17:50 +0100
  Re: Combination of sigwait() with sigaction()? Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2013-11-21 17:02 +0000
    Re: Combination of sigwait() with sigaction()? Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2013-11-21 17:32 +0000
    Re: Combination of sigwait() with sigaction()? Markus Elfring <Markus.Elfring@web.de> - 2013-11-21 18:38 +0100
  Re: Combination of sigwait() with sigaction()? "Chris M. Thomasson" <no@spam.invalid> - 2013-11-21 14:52 -0800

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