Re: Fread problem

From	Jack <spamtrap@trashcan.invalid>
Newsgroups	comp.lang.c
Subject	Re: Fread problem
Date	2011-07-16 09:22 +0000
Organization	Aioe.org NNTP Server
Message-ID	<ivrl7v$3gb$1@speranza.aioe.org> (permalink)
References	<ivq9i7$841$1@speranza.aioe.org> <ivqcap$eqo$1@reader1.panix.com>

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On Fri, 15 Jul 2011 21:43:53 +0000, John Gordon wrote:
> In <ivq9i7$841$1@speranza.aioe.org> Jack <spamtrap@trashcan.invalid>
> writes:
> 
>> I got a strange problem with Fread:
> 
>> It crashes my program from time to time, in one of its internal memcpy
>> calls.
> 
> When things like this happen it is nearly always because of a memory
> corruption bug elsewhere in your program, not because of a bug in a
> library function like fread().
> 
> C is, unfortunately, a fragile language.  If you copy more to a buffer
> than it can hold, or call free() on a bad value, or call free() twice on
> the same value, you've just corrupted the memory space of your program
> and anything can happen from that point onward, including crashes in
> library functions such as fread().
> 
> If your program is a simple one, go over it again and try to identify
> any areas where you might have committed the above errors.  If it's a
> complex program, you might use a memory analyzer such as efence or
> valgrind.

Yes...
Actually, I think it's a memory error somewhere that causes really
indirectly this bug.
But I find it strange that even a memory error makes a fread with proper
parameters ( I do check this ) fail.

I've heard somewhere one can play with the file buffer, so I tried it,
and put MY file buffer, with the Setbuff() function. And it didn't crash
anymore, but the read couldn't read all the files. Some bytes in the
middle were missing (I think it is when I resume the reading, after
having processed the first part)...

Last thing, this Fread occurs in a big source file... Created by lex / 
yacc.

The file is big, not easy to understand, so difficult to debug
: (

Thread

Fread problem Jack <spamtrap@trashcan.invalid> - 2011-07-15 20:56 +0000
  Re: Fread problem Ian Collins <ian-news@hotmail.com> - 2011-07-16 09:05 +1200
    Re: Fread problem Noob <root@127.0.0.1> - 2011-07-19 13:41 +0200
  Re: Fread problem John Gordon <gordon@panix.com> - 2011-07-15 21:43 +0000
    Re: Fread problem Jack <spamtrap@trashcan.invalid> - 2011-07-16 09:22 +0000
      Re: Fread problem Dr Nick <3-nospam@temporary-address.org.uk> - 2011-07-16 10:25 +0100
        Re: Fread problem Jack <spamtrap@trashcan.invalid> - 2011-07-16 20:23 +0000
          Re: Fread problem Ian Collins <ian-news@hotmail.com> - 2011-07-17 08:37 +1200
          Re: Fread problem John Gordon <gordon@panix.com> - 2011-07-16 20:46 +0000
            Re: Fread problem James Kuyper <jameskuyper@verizon.net> - 2011-07-16 18:29 -0400
              Re: Fread problem John Gordon <gordon@panix.com> - 2011-07-16 23:14 +0000
          Re: Fread problem Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-07-16 16:55 -0400
            Re: Fread problem blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-19 17:17 +0000
              [OT] Re: Fread problem Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-07-19 20:11 -0400
                Re: [OT] Re: Fread problem Seebs <usenet-nospam@seebs.net> - 2011-07-20 02:27 +0000
          Re: Fread problem Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-07-16 14:57 -0600
            Re: Fread problem Jack <spamtrap@trashcan.invalid> - 2011-07-17 20:45 +0000
              Re: Fread problem Ian Collins <ian-news@hotmail.com> - 2011-07-18 08:50 +1200
              Re: Fread problem James Kuyper <jameskuyper@verizon.net> - 2011-07-17 17:06 -0400
                Re: Fread problem Ian Collins <ian-news@hotmail.com> - 2011-07-18 09:09 +1200
                Re: Fread problem Hans Vlems <hvlems@freenet.de> - 2011-07-18 13:01 -0700
              Re: Fread problem Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-07-17 16:06 -0600
              Re: Fread problem Geoff <geoff@invalid.invalid> - 2011-07-17 17:56 -0700
                Re: Fread problem Seebs <usenet-nospam@seebs.net> - 2011-07-18 04:08 +0000
                Re: Fread problem Geoff <geoff@invalid.invalid> - 2011-07-17 22:08 -0700
                Re: Fread problem Jack <spamtrap@trashcan.invalid> - 2011-07-18 20:20 +0000
                Re: Fread problem Ian Collins <ian-news@hotmail.com> - 2011-07-19 08:50 +1200
                Re: Fread problem Cat 22 <cat22@invalid.org> - 2011-07-18 18:34 -0700
                Re: Fread problem James Kuyper <jameskuyper@verizon.net> - 2011-07-19 07:19 -0400
                Re: Fread problem Stephen Sprunk <stephen@sprunk.org> - 2011-07-19 09:31 -0500
              Re: Fread problem Todd Carnes <toddcarnes@gmail.com> - 2011-07-18 04:23 +0000
              Re: Fread problem Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-07-18 01:15 -0700
              Re: Fread problem Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-07-18 07:22 -0400
                Re: Fread problem Kenneth Brody <kenbrody@spamcop.net> - 2011-07-18 13:56 -0400
              Re: Fread problem Kenneth Brody <kenbrody@spamcop.net> - 2011-07-18 13:49 -0400
                Re: Fread problem Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-07-18 20:31 -0400
                Re: Fread problem Squeamizh <squeamz@hotmail.com> - 2011-07-18 21:11 -0700
              Re: Fread problem blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-19 17:19 +0000
                Re: Fread problem Kenneth Brody <kenbrody@spamcop.net> - 2011-07-19 14:18 -0400
                Re: Fread problem pete <pfiland@mindspring.com> - 2011-07-19 15:19 -0400
                Re: Fread problem blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-19 21:33 +0000
          Re: Fread problem Geoff <geoff@invalid.invalid> - 2011-07-16 14:27 -0700
            Re: Fread problem John Gordon <gordon@panix.com> - 2011-07-16 22:22 +0000
          Re: Fread problem "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-07-16 23:28 -0700
          Re: Fread problem "J. J. Farrell" <jjf@bcs.org.uk> - 2011-07-18 04:58 +0100
          Re: Fread problem Keith Thompson <kst-u@mib.org> - 2011-07-18 08:53 -0700
            Re: Fread problem Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-07-18 18:07 +0100
              Re: Fread problem Keith Thompson <kst-u@mib.org> - 2011-07-18 12:50 -0700
            Re: Fread problem Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-07-18 12:18 -0600
            Re: Fread problem John Gordon <gordon@panix.com> - 2011-07-18 20:18 +0000
              Re: Fread problem Keith Thompson <kst-u@mib.org> - 2011-07-18 13:28 -0700
                Re: Fread problem Lew Pitcher <lpitcher@teksavvy.com> - 2011-07-18 16:55 -0400
              Re: Fread problem Anders Wegge Keller <wegge@wegge.dk> - 2011-07-18 22:51 +0200
            Re: Fread problem blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-19 17:21 +0000
          Re: Fread problem Kenneth Brody <kenbrody@spamcop.net> - 2011-07-18 13:44 -0400
      Re: Fread problem Ian Collins <ian-news@hotmail.com> - 2011-07-16 21:39 +1200
      Re: Fread problem Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-07-16 12:18 -0600
      Re: Fread problem John Gordon <gordon@panix.com> - 2011-07-16 19:36 +0000

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