Re: Fread problem

From	Keith Thompson <kst-u@mib.org>
Newsgroups	comp.lang.c
Subject	Re: Fread problem
Date	2011-07-18 13:28 -0700
Organization	None to speak of
Message-ID	<lnoc0rmiyl.fsf@nuthaus.mib.org> (permalink)
References	(2 earlier) <ivrl7v$3gb$1@speranza.aioe.org> <87d3har2zu.fsf@temporary-address.org.uk> <ivss0p$ulb$1@speranza.aioe.org> <ln7h7foaac.fsf@nuthaus.mib.org> <j024e0$jl7$1@reader1.panix.com>

Show all headers | View raw

John Gordon <gordon@panix.com> writes:
> In <ln7h7foaac.fsf@nuthaus.mib.org> Keith Thompson <kst-u@mib.org> writes:
>> Then, rather than copying the saved contents of fback back into
>> *fp, I'd compare them.
>
>> With just a little work, you should be able to determine exactly
>> where the real problem is.
>
> Is this really true?  I thought memory corruption errors were quite
> difficult to track down precisely because the true error can be far
> upstream from the code which finally exhibits the broken behavior.

Maybe.  It should at least provide *some* useful information.

We know that the ugly hack of saving and restoring the contents
of the FILE object avoided the crash.  Assuming that the contents
of the FILE object are valid at point A (when they're saved),
and invalid at point B (when they're restored), and that nothing
between points A and B *should* be modifying it, then determining
the earliest point between A and B where the FILE object is actually
modified is likely to tell us something useful.

Of course it's also possible that the code that corrupts the FILE
object does so because something else was corrupted earlier, and
that could be much more difficult to track down.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Nokia
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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

csiph-web