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Re: Trivial C11 threads.h wrapper (public domain)

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From	Jens Gustedt <jens.gustedt@loria.fr>
Newsgroups	comp.lang.c, comp.programming.threads
Subject	Re: Trivial C11 threads.h wrapper (public domain)
Date	Mon, 01 Oct 2012 08:26:30 +0200
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Am 01.10.2012 01:48, schrieb Eric Sosman:
> On 9/30/2012 6:44 PM, Jens Gustedt wrote:
>> [...]
>> Ah, thinking of it a bit more, it is actually not "(void)" which is
>> problematic but the fact that the function may result in errno being
>> set to a non-zero value. I'll replace by something like
>>
>> if (pthread_mutex_destroy(&P99_ENCP(p00_mtx))) errno = 0;
> 
>     This would be a very bad thing to do in an implementation
> that is supposed to imitate a Standard C library function.
> 
>     7.5p3: "The value of errno in the initial thread is zero
>     at program startup [...] but is never set to zero by any
>     library function. [...]"
> 

Right. The reason is that I thought that pthread_mutex_destroy could
set errno to some error value. But re-reading the manual page of that
I see that the error code is in the function return. So there is no
need to do that at all.

(Otherwise I would have had to capture errno before the call and to
restore it if the call to pthread_mutex_destroy failed. Expensive.)

Thanks

Jens

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Thread

Trivial C11 threads.h wrapper (public domain) John Tsiombikas <nuclear@member.fsf.org> - 2012-09-27 03:38 +0000
  Re: Trivial C11 threads.h wrapper (public domain) Keith Thompson <kst-u@mib.org> - 2012-09-26 20:50 -0700
    Re: Trivial C11 threads.h wrapper (public domain) John Tsiombikas <nuclear@member.fsf.org> - 2012-09-27 04:15 +0000
      Re: Trivial C11 threads.h wrapper (public domain) Lorenzo Beretta <lory.fulgi@infinito.it> - 2012-09-27 16:35 +0200
        Re: Trivial C11 threads.h wrapper (public domain) John Tsiombikas <nuclear@member.fsf.org> - 2012-09-27 15:58 +0000
          Re: Trivial C11 threads.h wrapper (public domain) Lorenzo Beretta <lory.fulgi@infinito.it> - 2012-09-27 18:27 +0200
          Re: Trivial C11 threads.h wrapper (public domain) William Ahern <william@wilbur.25thandClement.com> - 2012-09-28 12:08 -0700
          Re: Trivial C11 threads.h wrapper (public domain) Kaz Kylheku <kaz@kylheku.com> - 2012-09-28 19:38 +0000
          Re: Trivial C11 threads.h wrapper (public domain) Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-09-28 15:50 -0400
            Re: Trivial C11 threads.h wrapper (public domain) Lorenzo Beretta <lory.fulgi@infinito.it> - 2012-09-29 18:41 +0200
  Re: Trivial C11 threads.h wrapper (public domain) Markus Elfring <Markus.Elfring@web.de> - 2012-09-27 13:45 +0200
    Re: Trivial C11 threads.h wrapper (public domain) John Tsiombikas <nuclear@member.fsf.org> - 2012-09-27 16:14 +0000
      Re: Trivial C11 threads.h wrapper (public domain) Markus Elfring <Markus.Elfring@web.de> - 2012-09-28 12:05 +0200
        Re: Trivial C11 threads.h wrapper (public domain) Keith Thompson <kst-u@mib.org> - 2012-09-28 03:39 -0700
        Re: Trivial C11 threads.h wrapper (public domain) James Kuyper <jameskuyper@verizon.net> - 2012-09-28 08:23 -0400
          Re: Trivial C11 threads.h wrapper (public domain) John Tsiombikas <nuclear@member.fsf.org> - 2012-09-28 19:48 +0000
    Re: Trivial C11 threads.h wrapper (public domain) Toby Douglass <a@b.com> - 2012-10-01 20:19 +0200
      Re: Trivial C11 threads.h wrapper (public domain) James Kuyper <jameskuyper@verizon.net> - 2012-10-01 14:37 -0400
      Re: Trivial C11 threads.h wrapper (public domain) Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-10-01 14:38 -0400
      Re: Trivial C11 threads.h wrapper (public domain) Keith Thompson <kst-u@mib.org> - 2012-10-01 14:58 -0700
  Re: Trivial C11 threads.h wrapper (public domain) Jens Gustedt <jens.gustedt@loria.fr> - 2012-09-28 20:22 +0200
    Re: Trivial C11 threads.h wrapper (public domain) Markus Elfring <Markus.Elfring@web.de> - 2012-09-30 23:13 +0200
      Re: Trivial C11 threads.h wrapper (public domain) Keith Thompson <kst-u@mib.org> - 2012-09-30 14:28 -0700
        Re: Trivial C11 threads.h wrapper (public domain) Jens Gustedt <jens.gustedt@loria.fr> - 2012-10-01 00:37 +0200
          Re: Trivial C11 threads.h wrapper (public domain) Jens Gustedt <jens.gustedt@loria.fr> - 2012-10-01 00:44 +0200
            Re: Trivial C11 threads.h wrapper (public domain) Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-09-30 19:48 -0400
              Re: Trivial C11 threads.h wrapper (public domain) Jens Gustedt <jens.gustedt@loria.fr> - 2012-10-01 08:26 +0200
          Re: Trivial C11 threads.h wrapper (public domain) Markus Elfring <Markus.Elfring@web.de> - 2012-10-01 11:25 +0200
            Re: Trivial C11 threads.h wrapper (public domain) Jens Gustedt <jens.gustedt@loria.fr> - 2012-10-01 11:47 +0200
              Re: Trivial C11 threads.h wrapper (public domain) Markus Elfring <Markus.Elfring@web.de> - 2012-10-01 12:05 +0200
                Re: Trivial C11 threads.h wrapper (public domain) Jens Gustedt <jens.gustedt@loria.fr> - 2012-10-01 13:15 +0200
                Clarification for interface specification "C11 threads.h" Markus Elfring <Markus.Elfring@web.de> - 2012-10-03 11:02 +0200
                Re: Clarification for interface specification "C11 threads.h" Keith Thompson <kst-u@mib.org> - 2012-10-03 13:29 -0700
                Re: Clarification for interface specification "C11 threads.h" Jens Gustedt <jens.gustedt@loria.fr> - 2012-10-04 13:35 +0200
                Re: Clarification for interface specification "C11 threads.h" Markus Elfring <Markus.Elfring@web.de> - 2012-10-12 17:45 +0200
                Re: Trivial C11 threads.h wrapper (public domain) Noob <root@127.0.0.1> - 2012-10-01 18:10 +0200
              Re: Trivial C11 threads.h wrapper (public domain) Nick Bowler <nbowler@draconx.ca> - 2012-10-01 19:28 +0000
              Re: Trivial C11 threads.h wrapper (public domain) Keith Thompson <kst-u@mib.org> - 2012-10-01 15:19 -0700
                Re: Trivial C11 threads.h wrapper (public domain) Kaz Kylheku <kaz@kylheku.com> - 2012-10-01 23:57 +0000
      Re: Trivial C11 threads.h wrapper (public domain) Jens Gustedt <jens.gustedt@loria.fr> - 2012-10-02 14:48 +0200

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