Date: Wed, 17 Oct 2001 15:33:49 +1000 From: Gregory Bond <gnb@itga.com.au> To: Zero Sum <count@shalimar.net.au> Cc: Greg Black <gjb@gbch.net>, cjclark@alum.mit.edu, "Crist J. Clark" <cristjc@earthlink.net>, Heath Nielson <heath@cs.byu.edu>, Warner Losh <imp@harmony.village.org>, David Marker <marker_d@yahoo.com>, freebsd-stable@FreeBSD.ORG Subject: Re: setenv() cores with NULL value [was Re: Gdm proplem on 4.4] Message-ID: <200110170533.PAA22928@lightning.itga.com.au> In-Reply-To: Your message of Wed, 17 Oct 2001 14:56:44 %2B1000.
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> One particular compiler returned something like "^AT". As far as I
> am concerned that was a flaw both then and now. That was the
> manufacturer I was talking about.
This was probably the AT&T 3B series.
There was famous code in some of the AT&T Unix utilities (troff from memory)
that did
if (strcmp(ptr, "^AT") == 0) { ..... }
because whoever wrote the program had no idea about C.
Dereferencing NULL pointers has been illegal C since the day C was invented.
See if you can dig up K&R 1st edition (I've lost mine over the years...) That
it would work at all on some systems is at best an artfact of the
implementation, at worst a bug. On the 3B, they couldn't change what *0
returned if they wanted to (because page 0 contained IRQ vectors or some such).
When Sun was porting Unix to the original Sun 1, they made the wise decision
that page 0 (& hence NULL pointers) would raise SIGSEGV. They had to expend a
collossal effort to remove all the NULL-pointer derefs from AT&T and Berkeley
code in order to ship SunOs. They were still fixing NULL-pointer bugs in thing
s like troff & nroff as late as SunOs 3.4.
All of which is way OT for -stable.....
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