Xref: utzoo comp.sys.att:5022 unix-pc.general:1944
Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!ukma!rutgers!bpa!manta!brant
From: brant@manta.pha.pa.us (Brant Cheikes)
Newsgroups: comp.sys.att,unix-pc.general
Subject: Re: 3B1 problem: mysterious core files in /etc/lddrv
Summary: Dump the user structure out of the core file.
Message-ID: <460@manta.pha.pa.us>
Date: 24 Dec 88 16:25:21 GMT
References: <1988Dec23.021443.21872@ziebmef.uucp>
Reply-To: brant@manta.pha.pa.us (Brant Cheikes)
Organization: Soul of the Gnu Machine, Philadelphia
Lines: 39

[Although Chris wrote
> Thanks in advance; reply by mail if possible and I'll summarize.
he also wrote
>[The next hop on pathalias's preferred mail path to here just went
>away; please route mail manually until the January maps come out.]
I doubted the likelihood of mail to get thru with all the evil
rerouters out there.]

Chris Siebenmann writes:
>Every so often (once a day right now, it seems) *something* here is
>dumping core in /etc/lddrv. [...]
>Any ideas on what program might dump core in /etc/lddrv? Any ideas on
>how to identify what program produced a specific core dump? Is this
>information stored anywhere in the core file? 

No, yes, and yes.

If you know where to look, you can find the user structure, described in
<sys/user.h>, in the core file.  The user structure tells you all sorts
of neat things about the core-dumping process, including its name.
In C, first
  cfp = fopen(core_name, "r");
where core_name is the name of the core file you want to inspect.
Then you must jump past the stuff (kernel stack data?) at the start of
the core file:
  fseek(cfp, (long)U_OFFSET, 0);
where U_OFFSET is defined in <sys/param.h>.  Now you can just
  { struct user u; /* from <sys/user.h> */
    fread(&u, sizeof(u), 1, cfp);
    /* print out useful data in u */
  }

>Chris Siebenmann		uunet!utgpu!{ontmoh!moore,ncrcan}!ziebmef!cks
>cks@ziebmef.UUCP	     or	.....!utgpu!{,ontmoh!,ncrcan!brambo!}cks
-- 
Brant Cheikes
University of Pennsylvania
Department of Computer and Information Science
brant@manta.pha.pa.us, brant@linc.cis.upenn.edu, bpa!manta!brant