From:	"Aleksey Kondratyev" <akondra AT no-spam-mv DOT ru>
Newsgroups:	comp.os.msdos.djgpp
Subject:	strange SIGSEGV
Date:	Sun, 14 Jun 1998 15:58:10 +0400
Organization:	Middle Volga Communication service
Lines:	35
Message-ID:	<6m0eh3$bv9$1@simtel.ru>
NNTP-Posting-Host:	ppp13.usr.mv.ru
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hello, All!

There is a strange bug in my symbolic algebra program
written on DJGPP.

It uses dynamic allocation and crashes on very complex
tasks (lots of small chunks are allocated) but under
Win95 only (giving memory protection fault). Everything
works perfectly and produces right result under plain DOS.
Also, no problems running from rhide or gdb invoked under
Win95. I studied stack dump (by symify) and saw that
dreferencing of a pointer to a heap allocated object
(I write on C++) causes the fault. I did try to put some
conditions verifing used pointers near the suspitious code
but they seem to be correct. Also, the error above is not
stable. Sometimes, everything works okey even under Win95
and even processing the same task. Probably, it is not
stack overflow because I tried to increase stack size and
nothing changed.

Could it be a bug in Win95 DPMI or memory allocation scheme?

There were many questions in this newsgroup about
memory faults under plain DOS while everything was OK
under Win95 but my situation seems to be the opposite.

----------------------------------------------------------------------
Aleksey Kondratyev
Ph.D. student of Ulyanovsk state University, Russia
http://www.mv.ru/~akondra
E-mail akondra AT mmf DOT univ DOT simbirsk DOT su
           akondra AT no-spam-mv DOT ru
           Remove "no-spam-" when replying

- Raw text -