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From: wls@astrovax.UUCP (William L. Sebok)
Newsgroups: net.unix-wizards
Subject: Re: don't do long jumps in signal handlers
Message-ID: <562@astrovax.UUCP>
Date: Fri, 22-Mar-85 20:40:09 EST
Article-I.D.: astrovax.562
Posted: Fri Mar 22 20:40:09 1985
Date-Received: Sat, 23-Mar-85 04:26:02 EST
References: <312@calgary.UUCP> <2175@wateng.UUCP> <542@utcs.UUCP>
Organization: Princeton Univ. Astrophysics
Lines: 15

> I think the real problem is that UNIX allows one to catch signals at all.
> Given that we don't have cheap processes a la Thoth, catching signals is a
> necessary evil but signal handlers should be kept simple and in particular
> should avoid using longjmp (if you have ever read and understood the source,
> you won't want to use longjmp).

Unfortunately if you wan't to interrupt a 4.2 read() from a terminal you
have to do longjmp (or worse).

In my opinion, if they didn't want signals to abort terminal reads they should
have provided an explicit i/o abort function that could be called from the
signal handler.
-- 
Bill Sebok			Princeton University, Astrophysics
{allegra,akgua,burl,cbosgd,decvax,ihnp4,noao,princeton,vax135}!astrovax!wls