Re: What's new in C?

From	glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups	comp.lang.c
Subject	Re: What's new in C?
Date	2012-12-05 01:19 +0000
Organization	Aioe.org NNTP Server
Message-ID	<k9m7e8$m42$1@speranza.aioe.org> (permalink)
References	(7 earlier) <k9b6a7$lb4$1@dont-email.me> <MoCdnWbKR-yIJyDNnZ2dnUVZ_qidnZ2d@supernews.com> <k9kt3r$qjf$1@dont-email.me> <k9lpb4$mhi$1@speranza.aioe.org> <k9lvhe$ffd$1@dont-email.me>

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Eric Sosman <esosman@comcast-dot-net.invalid> wrote:

(snip)

>     On closer reading, it turns out that the intimacy isn't
> *required* at all: If you longjmp() past a VLA's release, the
> Standard allows the memory to leak.  So it's a QoI issue: A
> VLA-unaware longjmp() is permitted to leak the memory (just
> as it leaks other resources), or a VLA-aware longjmp() can
> play nice and clean things up.

That is interesting.

>     Either way, the first approach cannot possibly be purely
> a library matter: The compiler needs to arrange for the free()
> (or equivalent) on any "normal" block exit, including exits by
> way of return, break, continue, and goto.

>> Well, I suppose in some processors the stack operation might
>> be predefined well enough that there weren't any possible
>> variations.

>     Sorry; I don't understand this.

Is it, in general, possible to write a C library, including
longjmp(), that is independent of the compiler?

On many processors, there is more than one way to keep track
of stack pointers and frame pointers. There is even (still)
the question of caller or callee popping the arguments
off the stack. Then there are IBM mainframes with no stack.

-- glen

Thread

What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-11-28 19:41 -0700
  Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-11-28 19:15 -0800
    Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 02:43 -0700
      Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 07:45 -0500
  Re: What's new in C? Noob <root@127.0.0.1> - 2012-11-29 10:36 +0100
    Re: What's new in C? Weland <weland@sdf.lonestar.org> - 2012-11-29 10:17 +0000
    Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 01:45 -0700
  Re: What's new in C? Weland <weland@sdf.lonestar.org> - 2012-11-29 09:48 +0000
    Re: What's new in C? David Brown <david@westcontrol.removethisbit.com> - 2012-11-29 13:50 +0100
  Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-29 05:55 -0800
    Re: What's new in C? Les Cargill <lcargill99@comcast.com> - 2012-11-29 12:48 -0600
      Re: What's new in C? Rui Maciel <rui.maciel@gmail.com> - 2012-11-30 10:46 +0000
        Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-30 05:31 -0800
          Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-11-30 14:22 +0000
          Re: What's new in C? Rui Maciel <rui.maciel@gmail.com> - 2012-11-30 15:04 +0000
            Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-30 16:41 +0000
              Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-11-30 11:49 -0500
              Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-30 10:12 -0800
              Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-11-30 11:12 -0800
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-30 22:26 +0000
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-11-30 22:36 +0000
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-30 23:27 +0000
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 01:39 -0700
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-04 00:43 -0800
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 03:14 -0700
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-04 12:50 +0000
                Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-12-04 05:54 -0800
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-04 20:51 +0000
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 16:09 -0500
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-04 16:19 -0500
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-04 21:45 +0000
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-05 01:13 +0000
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-04 20:36 -0500
                Re: What's new in C? Robert Wessel <robertwessel2@yahoo.com> - 2012-12-04 20:26 -0600
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-04 18:48 -0800
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-05 02:57 +0000
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-05 01:42 +0000
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 02:06 -0700
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 07:50 -0500
                Re: What's new in C? JohnF <john@please.see.sig.for.email.com> - 2012-12-06 13:46 +0000
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 09:39 -0500
              Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-11-30 15:52 -0500
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 01:53 -0700
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 08:16 -0500
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-04 21:18 +0000
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 18:04 -0500
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-05 01:19 +0000
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 21:05 -0500
                Re: What's new in C? Noob <root@127.0.0.1> - 2012-12-05 16:45 +0100
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 01:45 -0700
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 08:12 -0500
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-06 21:13 +0000
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-06 09:15 -0500
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-12 18:28 -0700
        Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-11-30 11:22 -0800
          Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 03:04 -0700
  Re: What's new in C? Rui Maciel <rui.maciel@gmail.com> - 2012-11-29 18:19 +0000
    Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-29 11:41 -0800
  Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-11-30 20:50 +0000
    Re: What's new in C? Jens Gustedt <jens.gustedt@loria.fr> - 2012-11-30 23:35 +0100
      Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-05 03:26 +0000
        Re: What's new in C? gwowen <gwowen@gmail.com> - 2012-12-05 23:49 -0800
          Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 01:49 -0700
          Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 07:55 +0000
            Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 13:29 +0000
              Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 15:23 +0000
                Re: What's new in C? Martin Shobe <martin.shobe@yahoo.com> - 2012-12-08 17:46 +0000
                Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-12-08 10:45 -0800
                Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 19:32 +0000
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 18:55 +0000
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 08:26 +1300
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 20:12 +0000
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 09:18 +1300
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 21:21 +0000
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 10:27 +1300
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 13:36 -0800
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 12:59 -0800
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 22:10 +0000
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 16:15 -0800
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 14:23 +1300
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 14:20 +1300
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 11:32 -0800
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-09 02:52 +0000
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-09 02:53 +0000
                Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 20:08 +0000
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 20:25 +0000

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