Re: Fread problem

From	blmblm@myrealbox.com <blmblm.myrealbox@gmail.com>
Newsgroups	comp.lang.c
Subject	Re: Fread problem
Date	2011-07-19 17:19 +0000
Organization	None
Message-ID	<98lsl8FgvmU2@mid.individual.net> (permalink)
References	<ivq9i7$841$1@speranza.aioe.org> <ivss0p$ulb$1@speranza.aioe.org> <1b62n23pw6.fsf@snowball.wb.pfeifferfamily.net> <ivvhlc$148$1@speranza.aioe.org>

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In article <ivvhlc$148$1@speranza.aioe.org>,
Jack  <spamtrap@trashcan.invalid> wrote:
> On Sat, 16 Jul 2011 14:57:13 -0600, Joe Pfeiffer wrote:
> 
> > Jack <spamtrap@trashcan.invalid> writes:
> > 
> >> On Sat, 16 Jul 2011 10:25:41 +0100, Dr Nick wrote:
> >>
> >>> Jack <spamtrap@trashcan.invalid> writes:

[ snip ]

> >>>> Actually, I think it's a memory error somewhere that causes really
> >>>> indirectly this bug.

[ snip ]

> >> Thanks for your help. I think I've now found a solution.
> >>
> >> After the file is first Fopen'd, I make a backup of the internal
> >> buffers. fp=Fopen(...);
> >> FILE fback;
> >> memcpy(&fback,fp,sizeof(FILE));
> >>
> >> then before the fread I restore this buffer,
> >> memcpy(fp,&fback,sizeof(FILE));
> >> Fread(...,fp);
> >>
> >> Now there is no segmentation fault, job done.
> > 
> > That's not a fix.  Your underlying bug is still present; your code is
> > still broken.  Anything from adding a new line of code to a new compiler
> > version to a new version of libc to slightly different input than what
> > you've tested on so far could make it manifest again at any time.
> 
> I sure do understand the point everyone's making, and in an ideal world 
> I'd get right to the heart of this bug. BUT... the customer pays for 
> their support contract annually in advance, any time we have to spend on 
> maintenance from that contract is just a cost to our company, so we get 
> strong pressure from management to get quick 'n' easy fixes out the door.
> 
> Anyways, if the problem reoccurs in future, with any luck it'll end up on 
> some other maintenance programmer's books not mine. :)

One wonders how/whether your "fix" will complicate the job of that
other maintenance programmer.  At least you put in a comment, right?
though really, it might be tricky to word a comment in a way that
would be helpful to other programmers without being something you
would not want repeated to your boss.

I've been a maintenance programmer, and it's likely that in that
capacity I came up with my share of ugly hacks (hard to remember
given that it was many years ago), but this one is -- memorable.

-- 
B. L. Massingill
ObDisclaimer:  I don't speak for my employers; they return the favor.

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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