Re: malloc and maximum size

From	James Kuyper <jameskuyper@verizon.net>
Newsgroups	comp.lang.c
Subject	Re: malloc and maximum size
Date	2011-10-15 21:38 -0400
Organization	A noiseless patient Spider
Message-ID	<j7dcin$eik$1@dont-email.me> (permalink)
References	(7 earlier) <4E989DDC.8040900@verizon.net> <44pqhztcty.fsf@lowell-desk.lan> <lnaa93rw5t.fsf@nuthaus.mib.org> <j7asgb$nmk$1@dont-email.me> <j7ca3q$u1a$1@dont-email.me>

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On 10/15/2011 11:50 AM, Richard Damon wrote:
> On 10/14/11 10:51 PM, James Kuyper wrote:
...
>> As I'm sure you're already aware, 5.2.4.1 is one of my least favorite
>> clauses in the standard. Taking it's words literally, what it fails to
>> promise renders virtually the entire rest of the standard meaningless;
>> this is just one example of that fact. Except when I'm arguing against
>> someone who disagrees on that point, I generally prefer to pretend that
>> 5.2.4.1 says something that allows the rest of the standard to be
>> meaningful.
>>
> 
> One interesting thing to note, is that in reading 5.2.4.1, the standard 
> does NOT give the implementation any right to fail to translate a 
> program that exceeds the limits.

The standard requires acceptance of strictly conforming programs;
without defining what "accept" means. In ordinary English, I can accept
a gift without even opening it; and I can discard it after it accepting
it. Whether or not something else was actually intended, the failure to
provide any alternative to the common English defining of "accept"
renders that requirement toothless.

Note that, in any event, a program which exceeds the minimum
implementation limits in 5.2.4.1 is not strictly conforming.

5.2.4.1 is the ONLY clause that mandates that a conforming
implementation of C be able to translate and execute any program; and
that requirement only applies to the "one program"; which is pretty
unlikely to be any program I ever care to execute. YMMV :-)

> ... It can NOT be claimed to be undefined
> or unspecified behavior, as the standard's definition of conformance is 
> NOT limited to these limits (the only restriction I find is that a 
> strictly conforming program can not violate those limits). The standard 
> requires that the compiler must be able to succeed on one given program, 
> but grants no permission to fail.

It also imposes no requirement that it succeed, with one worthless
exception.

> I suppose that this is really a defect in the standard, and the standard 
> needs some language to allow the implementation to establish limits, and 
> to generate a diagnostic and reject a program that exceeds these limits.
> 
> Exceeding implementation limits must NOT be considered undefined 
> behavior, (unless the definition of implementation limits is vastly 
> improved) as currently you can not know if a given program exceeds the 
> implementation limits, so considering it undefined behavior, and not 
> requiring a diagnostic, means it is impossible to show any given 
> implementation as "non-conforming", as any non-conforming behavior can 
> be blamed on exceeding some implementation limit.

While I agree that that exceeding an implementation limit does not
render the behavior undefined, it does cancel the ONLY requirement that
an implementation even "accept" the program, much less translate and
execute it.

Oddly enough, the one program that an implementation is required to be
able to translate and execute is one that happens to be permitted to
exceed the minimum implementation limits.
-- 
James Kuyper

Thread

malloc and maximum size "V.Subramanian, India" <subramanian100in@yahoo.com> - 2011-10-14 06:31 -0700
  Re: malloc and maximum size gordonb.pey1d@burditt.org (Gordon Burditt) - 2011-10-14 09:45 -0500
    Re: malloc and maximum size Lowell Gilbert <lgusenet@be-well.ilk.org> - 2011-10-14 11:10 -0400
      Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 11:40 -0400
        Re: malloc and maximum size Lowell Gilbert <lgusenet@be-well.ilk.org> - 2011-10-14 15:00 -0400
          Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 15:17 -0400
            Re: malloc and maximum size Lowell Gilbert <lgusenet@be-well.ilk.org> - 2011-10-14 15:46 -0400
              Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 16:38 -0400
                Re: malloc and maximum size Ike Naar <ike@iceland.freeshell.org> - 2011-10-14 21:59 +0000
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 18:26 -0400
                Re: malloc and maximum size Lowell Gilbert <lgusenet@be-well.ilk.org> - 2011-10-14 18:42 -0400
                Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 16:27 -0700
                Re: malloc and maximum size Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-14 20:41 -0400
                Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 18:31 -0700
                Re: malloc and maximum size Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-15 02:58 +0100
                Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 22:11 -0700
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 22:59 -0400
                Re: malloc and maximum size Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-14 23:44 -0400
                Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 22:56 -0700
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-15 07:52 -0400
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:54 -0800
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:51 -0800
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 22:51 -0400
                Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 22:48 -0700
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-15 07:54 -0400
                Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-15 11:25 -0700
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-15 21:21 -0400
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 17:41 -0800
                Re: malloc and maximum size Kaz Kylheku <kaz@kylheku.com> - 2012-01-25 02:11 +0000
                Re: malloc and maximum size Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-15 11:50 -0400
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-15 21:38 -0400
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 17:33 -0800
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 17:06 -0800
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:58 -0800
                Re: malloc and maximum size Kaz Kylheku <kaz@kylheku.com> - 2012-01-25 01:23 +0000
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 16:31 -0800
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 22:20 -0400
                Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 16:03 -0700
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 23:01 -0400
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 17:35 -0800
                Re: malloc and maximum size Kaz Kylheku <kaz@kylheku.com> - 2012-01-25 02:33 +0000
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 17:14 -0800
              Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:45 -0800
            Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:32 -0800
              Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2012-01-25 02:40 -0800
                Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 17:27 -0800
          Re: malloc and maximum size Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-14 16:17 -0400
            Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 16:52 -0400
              Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 16:12 -0700
                Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 23:04 -0400
          Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:36 -0800
    Re: malloc and maximum size Ike Naar <ike@iceland.freeshell.org> - 2011-10-14 16:49 +0000
  Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 11:05 -0400
  Re: malloc and maximum size Nobody <nobody@nowhere.com> - 2011-10-14 16:11 +0100
  Re: malloc and maximum size Kenneth Brody <kenbrody@spamcop.net> - 2011-10-14 12:24 -0400
  Re: malloc and maximum size jt@toerring.de (Jens Thoms Toerring) - 2011-10-14 17:10 +0000
  Re: malloc and maximum size Stephen Sprunk <stephen@sprunk.org> - 2011-10-14 13:43 -0500
    Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 12:03 -0700
      Re: malloc and maximum size jt@toerring.de (Jens Thoms Toerring) - 2011-10-14 20:36 +0000
    Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:26 -0800
  Re: malloc and maximum size Seebs <usenet-nospam@seebs.net> - 2011-10-17 17:21 +0000
  Re: malloc and maximum size Shao Miller <sha0.miller@gmail.com> - 2012-01-24 23:49 -0500
    Re: malloc and maximum size Shao Miller <sha0.miller@gmail.com> - 2012-01-24 23:55 -0500

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