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From: allbery@ncoast.UUCP (Brandon Allbery)
Newsgroups: comp.unix.wizards
Subject: Re: signals like interrupts?
Message-ID: <3664@ncoast.UUCP>
Date: Mon, 27-Jul-87 21:21:35 EDT
Article-I.D.: ncoast.3664
Posted: Mon Jul 27 21:21:35 1987
Date-Received: Sat, 1-Aug-87 09:19:49 EDT
References: <17691@cmcl2.NYU.EDU> <3254@ncoast.UUCP> <17925@cmcl2.NYU.EDU> <2267@cheviot.newcastle.ac.uk>
Reply-To: allbery@ncoast.UUCP (Brandon Allbery)
Followup-To: comp.unix.wizards
Organization: Cleveland Public Access UN*X, Cleveland, Oh
Lines: 26

As quoted from <2267@cheviot.newcastle.ac.uk> by amh@cheviot.newcastle.ac.uk (Andrew Hilborne):
+---------------
| > In article <3254@ncoast.UUCP> allbery@ncoast.UUCP (Brandon Allbery) writes:
| > I often send SIGBUS to a process which traps SIGQUIT and then goes into
| > an infinite loop.  I want the core dump, else I would use SIGKILL.  Remember:
| >
| > Perhaps what is needed is a non-catchable terminate-with-coredump signal.
| >
| Programs should not normally trap SIGQUIT - this was originally
| designed to do just what you want.  Unfortunately a bug in one version
| of UN*X meant that a SETUID program owned by root could core-dump a
| file owned by root and writeable to another.  This was a security flaw
| and programs took to trapping SIGQUIT as well.
+---------------

Actually, I was trapping SIGQUIT because I needed two keyboard signals to
trigger various actions.  (This is System III, System V, and Xenix; don't
tell me about SIGIO, and _especially_ not about that hog of hogs, O_NDELAY
(or select() or FIONREAD-driven, for BSD) reads!)  The usual arrangement was
terminate on SIGINT and write a log file on SIGQUIT.  Needless to say, this
makes catching a runaway looper difficult unless one can kill -11 the program.
-- 
 Brandon S. Allbery, moderator of comp.sources.misc and comp.binaries.ibm.pc
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