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Groups > comp.lang.c > #21393

Re: Open letter to Ian Collins

From Ian Collins <ian-news@hotmail.com>
Newsgroups comp.lang.c
Subject Re: Open letter to Ian Collins
Date 2012-05-27 15:16 +1200
Message-ID <a2dkjvF7faU2@mid.individual.net> (permalink)
References <jprl29$ifd$1@speranza.aioe.org>

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On 05/27/12 10:22 AM, jacob navia wrote:
> Hi Ian
>
> In the c++ newsgroup you asked me for an example of the ccl performance
> It was something with building a huge list, then sorting it, if I
> remember correctly...
>
> I have built this example code:
>
<snip>

I get a segv when I run the example.  Running in dbx with access 
checking enabled shows:

Write to unallocated (wua):
Attempting to write 1 byte at address 0x8091d88
     which is just past heap block of size 800 bytes at 0x8091a68
This block was allocated from:
         newHeapObject<-NewLink<-Add_nd<-Add<-main
Location of error: heap.c, line 75, newHeapObject()

The offending code appears to be here in heap.c:

      /* The array of block pointers is full. Allocate CHUNK_SIZE blocks 
more */
       siz = (l->BlockCount+CHUNK_SIZE)*sizeof(ListElement *);
       result = l->Allocator->realloc(l->Heap,siz);
       if (result == NULL) {
         return NULL;
       }
       l->MemoryUsed+= siz;
       l->Heap = (char **)result;
       /* Position pointer at the start of the new area */
       result += l->BlockCount*sizeof(ListElement *);
       /* Zero the new pointers */
       memset(result,0,siz);

It looks like you are allocating siz byes, incrementing part (half) way 
through the bock then zeroing the next siz bytes.

-- 
Ian Collins

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Thread

Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-05-27 00:22 +0200
  Re: Open letter to Ian Collins Ike Naar <ike@sverige.freeshell.org> - 2012-05-26 22:36 +0000
    Re: Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-05-27 01:13 +0200
      Re: Open letter to Ian Collins Barry Schwarz <schwarzb@dqel.com> - 2012-05-26 16:53 -0700
    Re: Open letter to Ian Collins Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-05-26 16:41 -0700
      Re: Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-05-26 22:43 -0400
  Re: Open letter to Ian Collins Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-05-26 15:41 -0700
    Re: Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-05-27 01:14 +0200
  Re: Open letter to Ian Collins MelissA <melis@a.com> - 2012-05-27 00:52 +0200
  Re: Open letter to Ian Collins Stephen Sprunk <stephen@sprunk.org> - 2012-05-26 20:40 -0500
    Re: Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-05-27 09:32 +0200
      Re: Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-05-27 07:18 -0400
  Re: Open letter to Ian Collins Ian Collins <ian-news@hotmail.com> - 2012-05-27 14:24 +1200
    Re: Open letter to Ian Collins "BartC" <bc@freeuk.com> - 2012-05-27 10:36 +0100
      Re: Open letter to Ian Collins Ian Collins <ian-news@hotmail.com> - 2012-05-27 22:33 +1200
        Re: Open letter to Ian Collins "BartC" <bc@freeuk.com> - 2012-05-27 12:25 +0100
          Re: Open letter to Ian Collins Ian Collins <ian-news@hotmail.com> - 2012-05-28 07:17 +1200
      Re: Open letter to Ian Collins Ike Naar <ike@sverige.freeshell.org> - 2012-05-27 13:03 +0000
  Re: Open letter to Ian Collins Ian Collins <ian-news@hotmail.com> - 2012-05-27 15:16 +1200
    Re: Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-05-27 09:30 +0200
      Re: Open letter to Ian Collins Ian Collins <ian-news@hotmail.com> - 2012-05-27 20:56 +1200
        Re: Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-05-27 11:12 +0200
          Re: Open letter to Ian Collins Ian Collins <ian-news@hotmail.com> - 2012-05-27 21:22 +1200
            Re: Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-05-27 07:15 -0400
            Re: Open letter to Ian Collins Keith Thompson <kst-u@mib.org> - 2012-05-27 07:49 -0700
              Re: Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-05-27 13:55 -0400
                Re: Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-05-27 22:24 +0200
                Re: Open letter to Ian Collins "BartC" <bc@freeuk.com> - 2012-05-27 22:09 +0100
                Re: Open letter to Ian Collins Keith Thompson <kst-u@mib.org> - 2012-05-27 14:33 -0700
                Re: Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-05-27 17:49 -0400
                Re: Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-05-27 17:31 -0400
                Re: Open letter to Ian Collins Philip Lantz <prl@canterey.us> - 2012-05-28 01:38 -0700
                Re: Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-05-28 08:18 -0400
        Re: Open letter to Ian Collins "BartC" <bc@freeuk.com> - 2012-05-27 15:46 +0100
        Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-06-13 21:25 -0400
          Re: Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-06-13 21:52 -0400
          Re: Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-06-14 04:00 +0200
            Re: Open letter to Ian Collins pete <pfiland@mindspring.com> - 2012-06-14 00:04 -0400
  Re: Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-05-27 09:42 +0200
  Re: Open letter to Ian Collins "io_x" <a@b.c.invalid> - 2012-05-28 12:39 +0200
    Re: Open letter to Ian Collins "io_x" <a@b.c.invalid> - 2012-05-28 21:44 +0200
      Re: Open letter to Ian Collins jacob navia <jacob@spamsink.net> - 2012-05-29 09:46 +0200
        Re: Open letter to Ian Collins "io_x" <a@b.c.invalid> - 2012-05-29 10:06 +0200
          Re: Open letter to Ian Collins "io_x" <a@b.c.invalid> - 2012-05-29 10:37 +0200
            Re: Open letter to Ian Collins "io_x" <a@b.c.invalid> - 2012-05-29 10:58 +0200
              Re: Open letter to Ian Collins "Joachim Schmitz" <nospam.jojo@schmitz-digital.de> - 2012-05-29 11:34 +0200
              Re: Open letter to Ian Collins Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-05-29 03:02 -0700
      Re: Open letter to Ian Collins "io_x" <a@b.c.invalid> - 2012-05-29 09:59 +0200
      Re: Open letter to Ian Collins "io_x" <a@b.c.invalid> - 2012-05-29 20:09 +0200
  Re: Open letter to Ian Collins "Sarah Wren" <swreb@ameritech.net> - 2012-05-29 01:40 -0600

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