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Groups > comp.lang.forth > #36045

Re: Counted string

Newsgroups comp.lang.forth
Date 2015-01-26 11:21 -0800
References <174b22de-2454-4e17-ac18-6a1333ec408f@googlegroups.com> <op.xsx0jbi0v6dtjm@localhost>
Message-ID <d55e2379-92cb-454c-bb04-059c86ab8eb6@googlegroups.com> (permalink)
Subject Re: Counted string
From Marek Brunda <marekb@phoenics.org>

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Dne sobota 24. ledna 2015 2:17:25 UTC+1 Rod Pemberton napsal(a):
> On Mon, 19 Jan 2015 02:54:49 -0500, Marek Brunda <marekb@phoenics.org>  
> wrote:
> 
> > Hi, can anyone explain me, what's wrong with counted strings? Maybe it's  
> > a stupid question, but I've never understood it. Thanks
> 
> This has been discussed many times here in the past.
> You can search the Google Groups archive of this Usenet group.
> 
> Nul-terminated strings replaced counted strings for the most part
> many decades ago in most programming languages, e.g., 1970's or 1980's.
> 
> The problem back then with counted strings was that the count could
> be changed, but the length of the string wouldn't be.  I.e., there
> is a mismatch in the size of the count and the actual length of the
> string.  If the count is too short, then the string is truncated.
> This isn't a problem.  If the count is too large, then you have a
> very serious issue.  More space for a new larger string wasn't
> allocated.  The string is the same size, but the count is larger.
> So, the oversized count value allows you to access data PAST the
> actual end-of-string.  I.e., you can read data you shouldn't have
> access to, or write to variables you shouldn't have access to.
> This is the same technique used by hackers for buffer overflow.
> 
> (FYI, to prevent flame war, there are those here who claim that
> can't actually happen in Forth ...)
> 
> Languages like C which use nul-terminated strings frequently
> only need to detect the end-of-string.  They generally don't
> need to know the string's length.  So, not counting the length
> of a string and just appending a nul-terminator to create a
> string increased code speed.  Of course, not terminating
> a string in C, which happens with some string functions under
> certain conditions, can cause overruns or unintended access too.
> 
> 
> Rod Pemberton

I read all the posts and I understand the arguments. So why not use NULL terminated strings in Forth?

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Thread

Counted string Marek Brunda <marekb@phoenics.org> - 2015-01-18 23:54 -0800
  Re: Counted string "Elizabeth D. Rather" <erather@forth.com> - 2015-01-18 22:08 -1000
    Re: Counted string anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-01-19 09:36 +0000
      Re: Counted string "HAA" <someone@microsoft.com> - 2015-01-20 00:21 +1100
        Re: Counted string Coos Haak <chforth@hccnet.nl> - 2015-01-19 14:44 +0100
      Re: Counted string Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-01-20 00:45 -0800
        Re: Counted string anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-01-20 13:12 +0000
          Re: Counted string Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-01-21 01:05 -0800
            Re: Counted string albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-01-21 10:54 +0000
    Re: Counted string lehs <skydda.barnen@gmail.com> - 2015-01-30 11:18 -0800
  Re: Counted string Matthias Koch <matthias.koch@hot.uni-hannover.de> - 2015-01-21 11:58 +0100
    Re: Counted string "HAA" <someone@microsoft.com> - 2015-01-22 11:49 +1100
  Re: Counted string "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-01-23 20:17 -0500
    Re: Counted string Marek Brunda <marekb@phoenics.org> - 2015-01-26 11:21 -0800
      Re: Counted string Mark Wills <markwills1970@gmail.com> - 2015-01-26 12:11 -0800
        Re: Counted string "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-01-26 21:55 -0500
          Re: Counted string Julian Fondren <julian.fondren@gmail.com> - 2015-01-26 19:46 -0800
            Re: Counted string albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-01-27 12:07 +0000
              Re: Counted string "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-01-28 20:13 -0500
            Re: Counted string anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-01-27 15:43 +0000
              Re: Counted string Marek Brunda <marekb@phoenics.org> - 2015-01-27 13:28 -0800
                Re: Counted string Elizabeth D Rather <erather@forth.com> - 2015-01-27 13:06 -1000
                Re: Counted string anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-01-30 17:33 +0000
            Re: Counted string "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-01-28 20:07 -0500
              Re: Counted string "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-01-28 20:16 -0500
              Re: Counted string Coos Haak <chforth@hccnet.nl> - 2015-01-29 03:14 +0100
      Re: Counted string Pablo Hugo Reda <pabloreda@gmail.com> - 2015-01-26 12:14 -0800
        Re: Counted string "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-01-26 21:55 -0500
        Re: Counted string Ron Aaron <rambamist@gmail.com> - 2015-01-27 06:55 +0200
          Re: Counted string "Alex McDonald" <blog@rivadpm.com> - 2015-01-27 14:46 +0000
      Re: Counted string "Elizabeth D. Rather" <erather@forth.com> - 2015-01-26 11:25 -1000

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