Message-ID: <3BB4E801.32F49852@cyberoptics.com> From: Eric Rudd Organization: CyberOptics X-Mailer: Mozilla 4.72 [en] (Win95; U) X-Accept-Language: en,pdf MIME-Version: 1.0 Newsgroups: comp.os.msdos.djgpp Subject: Re: Heap structure References: <3BA1292B DOT C593DFD8 AT cyberoptics DOT com> <9p25as$rra$1 AT milzis DOT latnet DOT lv> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 27 Date: Fri, 28 Sep 2001 16:13:37 -0500 NNTP-Posting-Host: 38.196.93.9 X-Trace: client 1001711620 38.196.93.9 (Fri, 28 Sep 2001 17:13:40 EDT) NNTP-Posting-Date: Fri, 28 Sep 2001 17:13:40 EDT To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Reply-To: djgpp AT delorie DOT com Antonijs Kipans wrote: > As I stumbled over this myself, there is one unexpected possibility - you > trie to fprintf() into UNOPEN file! My program had opened and closed the same file for appending several times before the bomb occurred, and the file contents were plausible, so I doubt that was the problem here. The debugging tools were not of much help because the side effects of the bug disappeared as soon as I enabled the debugging code. (Specifically, whenever I increased malloc_debug to 1 or higher to detect the bug, the program executed normally and malloc_verify() returned 1 -- how frustrating!) By inspection, I eventually did find some errors in my code, and after I fixed them the program didn't bomb anymore. Thanks to all who offered their help. -Eric > "Eric Rudd" wrote in message > news:3BA1292B DOT C593DFD8 AT cyberoptics DOT com... > > I have a DJGPP program that is bombing with a SIGSEGV error. I have > > reason to believe that the program has an array overflow that is > > corrupting the structure of the heap. (The program actually bombs in a > > malloc call inside fprintf, but at this point I have no convincing > > reason to believe that a system function bug is to blame.)