Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!helios!diamond!jdm5548
From: jdm5548@diamond.tamu.edu (James Darrell McCauley)
Newsgroups: comp.lang.c
Subject: data space address too high?
Keywords: malloc, dbx, high address
Message-ID: <7295@helios.TAMU.EDU>
Date: 9 Aug 90 20:21:52 GMT
Sender: usenet@helios.TAMU.EDU
Reply-To: jdm5548@diamond.tamu.edu (James Darrell McCauley)
Organization: Texas A&M University Agricultural Engineering Dept
Lines: 62

NOTE: Probably another novice question. Those easily irritated should skip
this message.

Thank you all for the responses to my last question. [I learned that you
don't ask questions unless you've had enough sleep to really think about
your problem ;-)]

This one (I don't think) is not as trivial as my last.

Here's what I get from 'dbxtool' when I try to print the value of a
variable at the point where my program crashes:

=]Reading symbolic information...
=]Read 2365 symbols
=](dbxtool) print table[k]
=]`fillab`fillab`table[`fillab`fillab`k] = 0x40a00000
=](dbxtool) print table[k][2]
=]warning: core file read error: data space address too high
=]bad data address
=](dbxtool)

Here's what I get when I print the address of array elements:

=] (lots of stuff deleted)
=]&table[15][3]=152048
=]&table[15][4]=152052
=]k = 16
=]&table[16][1]=1084227588
=]&table[16][2]=1084227592
=]&table[16][3]=1084227596
=]&table[16][4]=1084227600    <=== assignments begin to these addresses
after this
=]Bus error (core dumped)

Could someone explain to me what this may mean? I assume it has something to
do with extensive use (overuse) of malloc, but malloc didn't return any
errors. Just a guess, but could I be allocating memory that's not accessible?

I tried to isolate the problem in the infamous "test.c," but to no
avail. I didn't think it appropriate to include all 1870 lines. THEREFORE,
please don't flame for not including source.

BTW, 'lint *c' doesn't mention anything unusual. Sun OS 4.0.3 on Sun 3/60
with 12 MB of memory. When including /usr/lib/debug/malloc.o &
/usr/lib/debug/mallocmap.o at link time, I don't even get to the error
described above. It complains:
=]free: bad block size (1003204457) at 0x22d30
=]
=]IOT trap (core dumped)
I haven't tracked this one down yet.

Something tells me that I'm going to have a heck of a time porting this
to a PC (and it's only 30% complete) :-(

Sorry for all the verbage. Please e-mail responses unless you think it
would be more appropriate to post. Many thanks for your patience and 
suggestions.
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James Darrell McCauley                 jdm5548@diamond.tamu.edu
Dept of Ag. Engineering                          (409) 845-6484
Texas A&M University, College Station, Texas 77843-2117, USA
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