Date: Thu, 4 Jun 1998 18:30:01 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: Don.Lewis@tsc.tdk.com (Don Lewis) Cc: dk+@ua.net, barry@lustig.com, freebsd-hackers@FreeBSD.ORG, serge@yahoo.com Subject: Re: Code Logic Question in 2.2 RELENG Message-ID: <199806041830.LAA02825@usr05.primenet.com> In-Reply-To: <199806040855.BAA06987@salsa.gv.tsc.tdk.com> from "Don Lewis" at Jun 4, 98 01:55:26 am
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> Well, there's a call to perror(). What does it say errno is? My
> suspicion is that it is ECHILD. My somewhat dated copy of portmap.c
> has the following code:
>
> void
> reap()
> {
> while (wait3((int *)NULL, WNOHANG, (struct rusage *)NULL) > 0);
> }
>
> If portmap receives two signals closely spaced in time, the first
> signal will interrupt the select() call, and if reap() is called
> after select() has set errno and returned, the wait3() call in reap()
> will stomp errno. I've fixed similar problems by saving errno at the
> beginning of a signal handler and restoring it at the end. I'm not
> sure what ANSI and POSIX have to say about this and I don't know if
> you can do this if you are using threads and have a per-thread errno,
> but it has worked for me.
Which reminds me. Someone needs to fix the "siginterrupt" man page.
I would, but I think it is FreeBSD that is broken, not the man page,
and that by default, system calls *should* be restarted after a
signal is caught. I find it utterly bogus that I have to springle
the bejesus out of my code for while()'s and tests for "EINTR" and
manually restart all of my system calls. Gruds, if I wanted that,
I load System V on my box instead of BSD.
In The Good Old Days(tm), it wasn't an option; if you wanted EINTR
type behaviour, you did a setjmp before the call you wanted the
behaviour on, and like a decent, God-fearing BSD'er, you called
longjmp from the signal handler to prevent the call from being
restarted.
Just think how much easier the POSIX threading would be; the user
space pthreads should default to restart behaviour for calls, and
have a seperate handler that queues signals to the schedluer.
[ ...the crusty old BSD hermit slinks back to his cave... ]
Terry Lambert
terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.
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