From mboxrd@z Thu Jan  1 00:00:00 1970
MIME-Version: 1.0
From: Giacomo Tesio <giacomo@tesio.it>
Date: Wed,  3 May 2017 17:15:30 +0200
Message-ID: <CAHL7psHr5CLwXcY3Mhner+6hAV4nh5Rf7_H7KVe2Chnm_==OgQ@mail.gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Content-Type: text/plain; charset=UTF-8
Subject: [9fans] NSAVE/NRSTR use case in libap
Topicbox-Message-UUID: bba942f8-ead9-11e9-9d60-3106f5b1d025

Reading notify(2) I've noticed that I do not understand POSIX signals
enough to grasp the problem NSAVE/NRSTR are designed to solve.

Initially I supposed they where supposed to allow nested signals, so
that a note occurred during the execution of a signal handler wont
need to wait for NCONT.

Thus I suppose that I'm missing something: I can't imagine a (non
real-time) program requiring to handle a signal while handling a
signal.

So my questions are:

- why Plan 9 needs NSAVE/NRSTR? Which ANSI/POSIX semantics are they
designed to help with?
- can you point me to an application actually using such semantics
(either ported to Plan9 or not).


Giacomo