Re: C is not a low level language

From	Richard Heathfield <rjh@cpax.org.uk>
Newsgroups	comp.lang.c, comp.programming, comp.sys.raspberry-pi
Subject	Re: C is not a low level language
Date	2019-02-25 12:24 +0000
Organization	Fix this later
Message-ID	<q50mp7$gvu$1@dont-email.me> (permalink)
References	(11 earlier) <q4upp6$5k2$1@gioia.aioe.org> <q4ur5a$v7v$1@dont-email.me> <q4uv8j$v0m$1@gioia.aioe.org> <q4uvt3$trh$1@dont-email.me> <q5059c$12g$1@gioia.aioe.org>

Cross-posted to 3 groups.

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On 25/02/2019 07:25, R.Wieser wrote:
> Richard,
> 
>> It has rightly been said that threading is for people who don't understand
>> state machines, and state machines are for people who don't understand
>> threading. I am in the latter camp!
> 
> You're only strengthening my position you know. :-)

Hence the next sentence in my reply, which you've snipped:

"In the more general case, however, your point is taken."

> /Especially/ when you do not know what could happen it is a good idea to be
> defensive about what you're doing.

But I do know what could happen. Someone could use my code in a 
multi-threaded environment. Equally, someone could use my code and 
replace all instances of sin() with cos(), cos() with tan(), and tan() 
with sin(). Or they could change all the #defines. Or they could use the 
code in an environment where CHAR_BIT is not 8 (a restriction I regret, 
but not as much as I'd regret static arrays of, say, 16 giga-octets). Or 
they could flip a few random bits in the object code. Or they could use 
a compiler that assumes one calling convention and a linker that assumes 
a different one.

If they do any of those things, that really is their problem.

> But, do me a favour: think about the ammount of effort you would need to do
> to follow my suggestion, and the amount of fall-out you could be facing when
> the string doesn't get terminated (regardless of by mistake or by an attack)
> and compare those two.  What do you say, which of the two would "win" ?

It would have to be a mistake - that of using, in a multi-threaded 
environment, code designed for use in a single-threaded environment.

A *deliberate* single-threaded attempt to stop my code from 
null-terminating a copy of a string would fail. (If an attack is likely, 
the place to guard against it is after the length caching but before the 
malloc.)

And a deliberate *multi*-threaded attempt to attack the code would 
entail the mistake of using my code in a multi-threaded environment.

-- 
Richard Heathfield
Email: rjh at cpax dot org dot uk
"Usenet is a strange place" - dmr 29 July 1999
Sig line 4 vacant - apply within

Thread

Re: C is not a low level language "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-02-24 12:40 +0800
  Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 05:16 +0000
    Re: C is not a low level language "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-02-24 13:20 +0800
      Re: C is not a low level language "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-02-24 13:24 +0800
      Re: C is not a low level language "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-02-24 19:45 +0800
      Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-24 13:09 +0000
        Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 14:38 +0000
          Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-24 15:18 +0000
            Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-24 17:21 +0100
              Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 17:43 +0000
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-24 20:17 +0100
              Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-24 18:19 +0000
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-24 20:02 +0100
                Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-24 19:26 +0000
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-24 21:36 +0100
                Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-24 20:47 +0000
                Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 21:10 +0000
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-25 08:25 +0100
                Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-25 12:24 +0000
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-25 17:04 +0100
                Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-25 16:52 +0000
                Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-24 17:59 -0800
                Re: C is not a low level language "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-02-25 08:46 +0100
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-25 09:36 +0100
                Re: C is not a low level language "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-02-25 10:13 +0100
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-26 09:56 +0100
                Re: C is not a low level language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-02-25 14:12 +0000
                Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 12:20 +0000
                Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-25 13:36 -0800
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-25 10:29 +0200
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-25 09:41 +0100
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-25 10:55 +0200
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-25 10:24 +0100
                Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 21:03 +0000
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-25 08:58 +0100
                Re: C is not a low level language "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-02-25 09:40 +0100
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-25 10:01 +0100
              Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-24 12:55 -0800
                Re: C is not a low level language "R.Wieser" <address@not.available> - 2019-02-25 08:31 +0100
            Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 17:42 +0000
              Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-24 18:19 +0000
            Re: C is not a low level language Bill Findlay <findlaybill@blueyonder.co.uk> - 2019-02-24 17:56 +0000
              Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-24 18:23 +0000
                Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 20:58 +0000
              Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 20:52 +0000
                Re: C is not a low level language Bill Findlay <findlaybill@blueyonder.co.uk> - 2019-02-25 16:31 +0000
              Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-25 14:01 -0800
                Re: C is not a low level language scott@slp53.sl.home (Scott Lurndal) - 2019-02-25 23:04 +0000
                Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-25 15:53 -0800
                Re: C is not a low level language Bill Findlay <findlaybill@blueyonder.co.uk> - 2019-02-28 16:07 +0000
              Re: C is not a low level language Björn Lundin <b.f.lundin@gmail.com> - 2019-02-25 20:50 +0100
                Re: C is not a low level language Bill Findlay <findlaybill@blueyonder.co.uk> - 2019-02-28 16:04 +0000
                Re: C is not a low level language "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> - 2019-02-28 16:25 +0000
                Re: C is not a low level language "Mayayana" <mayayana@invalid.nospam> - 2019-02-28 11:56 -0500
                Re: C is not a low level language "NY" <me@privacy.net> - 2019-02-28 19:45 +0000
              Re: C is not a low level language Bart <bc@freeuk.com> - 2019-02-25 17:55 +0000
                Re: C is not a low level language Bill Findlay <findlaybill@blueyonder.co.uk> - 2019-02-28 16:03 +0000
                Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-28 11:25 -0800
                Re: C is not a low level language Bart <bc@freeuk.com> - 2019-02-28 19:30 +0000
          Re: C is not a low level language Jasen Betts <jasen@xnet.co.nz> - 2019-02-24 20:47 +0000
            Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 21:29 +0000
              Re: C is not a low level language Jasen Betts <jasen@xnet.co.nz> - 2019-02-25 20:16 +0000
      Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-24 12:53 -0800
      Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-25 09:49 +0200
    Re: C is not a low level language Björn Lundin <b.f.lundin@gmail.com> - 2019-02-25 21:07 +0100
      Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 22:59 +0000
        Re: C is not a low level language Björn Lundin <b.f.lundin@gmail.com> - 2019-02-26 09:57 +0100
          Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-26 09:59 +0000
  Re: C is not a low level language Eric Stevens <eric.stevens@sum.co.nz> - 2019-02-24 19:54 +1300
    Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-24 07:56 +0000
      Re: C is not a low level language Eric Stevens <eric.stevens@sum.co.nz> - 2019-02-24 21:58 +1300
        Re: C is not a low level language "A. Dumas" <alexandre@dumas.fr.invalid> - 2019-02-24 10:57 +0100
        Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-24 10:13 +0000
        Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 10:47 +0000
          Re: C is not a low level language "Mayayana" <mayayana@invalid.nospam> - 2019-02-24 08:48 -0500
            Re: C is not a low level language The Natural Philosopher <tnp@invalid.invalid> - 2019-02-24 14:42 +0000
            Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 07:15 +0000
              Re: C is not a low level language "Mayayana" <mayayana@invalid.nospam> - 2019-02-25 09:25 -0500
                Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 15:03 +0000
                Re: C is not a low level language "Mayayana" <mayayana@invalid.nospam> - 2019-02-25 12:10 -0500
                Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 17:58 +0000
                Re: C is not a low level language Axel Berger <Spam@Berger-Odenthal.De> - 2019-02-25 17:44 +0100
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-25 19:18 +0200
            Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-25 10:35 +0200
              Re: C is not a low level language "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> - 2019-02-25 10:44 +0000
                Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-02-25 12:29 +0000
                Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 14:26 +0000
                Re: C is not a low level language "NY" <me@privacy.net> - 2019-02-25 17:08 +0000
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-25 20:08 +0200
                Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 18:00 +0000
                Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-27 22:37 -0800
                Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-28 02:25 -0800
                Re: C is not a low level language Diesel <nobody@haph.org> - 2019-03-05 04:29 +0000
              Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 12:27 +0000
              Re: C is not a low level language "Mayayana" <mayayana@invalid.nospam> - 2019-02-25 09:36 -0500
                Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 15:05 +0000
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-25 19:20 +0200
                Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-25 23:02 +0000
                Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-26 06:52 +0000
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-26 12:41 +0200
                Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-26 12:20 +0000
                Re: C is not a low level language David Brown <david.brown@hesbynett.no> - 2019-02-26 14:01 +0100
                Re: C is not a low level language "Mayayana" <mayayana@invalid.nospam> - 2019-02-26 08:48 -0500
                Re: C is not a low level language Björn Lundin <b.f.lundin@gmail.com> - 2019-02-26 19:20 +0100
              Re: C is not a low level language Wolf K <wolfmac@sympatico.ca> - 2019-02-25 10:04 -0500
        Re: C is not a low level language lonelydad <lonelydad58@gmail.com> - 2019-02-24 14:44 +0000
        Re: C is not a low level language "U-laptop\\Norah" <Norah@laptop.i-did-not-set--mail-host-address--so-tickle-me> - 2019-02-27 16:16 -0600
          Re: C is not a low level language Eric Stevens <eric.stevens@sum.co.nz> - 2019-03-01 12:12 +1300
            Re: C is not a low level language Richard Heathfield <rjh@cpax.org.uk> - 2019-03-01 00:19 +0000
      Re: C is not a low level language Gene Wirchenko <genew@telus.net> - 2019-02-24 19:59 -0800
        Re: C is not a low level language Bill Findlay <findlaybill@blueyonder.co.uk> - 2019-02-25 16:10 +0000
        Re: C is not a low level language Björn Lundin <b.f.lundin@gmail.com> - 2019-02-25 21:02 +0100
          Re: C is not a low level language Lars Enderin <lars.enderin@telia.com> - 2019-02-26 00:37 +0100
            Re: C is not a low level language Wolf K <wolfmac@sympatico.ca> - 2019-02-25 19:09 -0500
            Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-26 06:52 +0000
    Re: C is not a low level language T <T@invalid.invalid> - 2019-02-24 00:30 -0800
      Re: C is not a low level language T <T@invalid.invalid> - 2019-02-24 00:31 -0800
      Re: C is not a low level language Ahem A Rivet's Shot <steveo@eircom.net> - 2019-02-24 10:16 +0000
    Re: C is not a low level language "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> - 2019-02-24 11:22 +0000
      Re: C is not a low level language "Mayayana" <mayayana@invalid.nospam> - 2019-02-24 08:51 -0500
        Re: C is not a low level language pyotr filipivich <phamp@mindspring.com> - 2019-02-24 07:20 -0800
          Re: C is not a low level language "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> - 2019-02-24 15:35 +0000
            Re: C is not a low level language "Mayayana" <mayayana@invalid.nospam> - 2019-02-24 11:05 -0500
            Re: C is not a low level language pyotr filipivich <phamp@mindspring.com> - 2019-02-24 14:39 -0800
              Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-24 19:11 -0800
              Re: C is not a low level language Wolf K <wolfmac@sympatico.ca> - 2019-02-25 09:41 -0500
                Re: C is not a low level language "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> - 2019-02-25 14:53 +0000
                Re: C is not a low level language Wolf K <wolfmac@sympatico.ca> - 2019-02-25 10:19 -0500
                Re: C is not a low level language David Brown <david.brown@hesbynett.no> - 2019-02-25 16:38 +0100
                Re: C is not a low level language Wolf K <wolfmac@sympatico.ca> - 2019-02-25 11:20 -0500
                Re: C is not a low level language "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> - 2019-02-25 17:49 +0000
                Re: C is not a low level language David Brown <david.brown@hesbynett.no> - 2019-02-26 09:18 +0100
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-25 12:17 -0500
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-25 20:25 +0200
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-25 13:40 -0500
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-26 12:45 +0200
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-26 08:02 -0500
                Re: C is not a low level language Wolf K <wolfmac@sympatico.ca> - 2019-02-26 09:11 -0500
                Re: C is not a low level language Diesel <nobody@haph.org> - 2019-03-05 04:29 +0000
                Re: C is not a low level language David Brown <david.brown@hesbynett.no> - 2019-02-26 09:23 +0100
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-26 08:02 -0500
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-26 17:57 +0200
                Re: C is not a low level language Diesel <nobody@haph.org> - 2019-03-05 04:29 +0000
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-25 17:42 -0500
                Re: C is not a low level language Bart <bc@freeuk.com> - 2019-02-25 22:33 +0000
                Re: C is not a low level language David Brown <david.brown@hesbynett.no> - 2019-02-26 09:30 +0100
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-25 12:17 -0500
                Re: C is not a low level language Keith Thompson <kst-u@mib.org> - 2019-02-25 13:52 -0800
                Re: C is not a low level language "NY" <me@privacy.net> - 2019-02-25 15:20 +0000
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-25 12:17 -0500
                Re: C is not a low level language Bart <bc@freeuk.com> - 2019-02-25 18:47 +0000
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-25 13:50 -0500
                Re: C is not a low level language Bart <bc@freeuk.com> - 2019-02-25 18:59 +0000
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-25 20:15 +0200
                Re: C is not a low level language scott@slp53.sl.home (Scott Lurndal) - 2019-02-25 18:38 +0000
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-26 12:49 +0200
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-25 13:40 -0500
                Re: C is not a low level language Wouter Verhelst <w@uter.be> - 2019-02-26 12:55 +0200
                Re: C is not a low level language scott@slp53.sl.home (Scott Lurndal) - 2019-02-26 16:29 +0000
                Re: C is not a low level language Diesel <nobody@haph.org> - 2019-03-05 04:29 +0000
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-03-04 23:43 -0500
                Re: C is not a low level language "NY" <me@privacy.net> - 2019-02-25 18:16 +0000
                Re: C is not a low level language "NY" <me@privacy.net> - 2019-02-25 17:44 +0000
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-25 13:05 -0500
                Re: C is not a low level language Robert Wessel <robertwessel2@yahoo.com> - 2019-02-26 00:51 -0600
                Re: C is not a low level language "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-02-26 10:58 +0100
                Re: C is not a low level language Robert Wessel <robertwessel2@yahoo.com> - 2019-02-26 10:53 -0600
                Re: C is not a low level language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-02-26 17:49 +0000
                Re: C is not a low level language scott@slp53.sl.home (Scott Lurndal) - 2019-02-26 18:11 +0000
                Re: C is not a low level language Bart <bc@freeuk.com> - 2019-02-26 18:24 +0000
                Re: C is not a low level language "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-02-26 19:24 +0100
                Re: C is not a low level language "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-02-26 19:44 +0100
                Re: C is not a low level language nobody@example.org (Scott) - 2019-02-26 06:33 +0000
                Re: C is not a low level language nospam <nospam@nospam.invalid> - 2019-02-25 12:17 -0500
        Re: C is not a low level language Gene Wirchenko <genew@telus.net> - 2019-02-24 20:03 -0800
      Re: C is not a low level language pyotr filipivich <phamp@mindspring.com> - 2019-02-24 14:56 -0800
  Re: C is not a low level language Jasen Betts <jasen@xnet.co.nz> - 2019-02-24 20:43 +0000
    Re: C is not a low level language "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-02-25 14:14 +0800
      Re: C is not a low level language "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> - 2019-02-25 10:45 +0000
        Re: C is not a low level language "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-02-25 19:04 +0800

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