Re: standard error messages in a std::string or in a const char *

From	Keith Thompson <kst-u@mib.org>
Newsgroups	comp.lang.c++
Subject	Re: standard error messages in a std::string or in a const char *
Date	2019-09-11 02:37 -0700
Organization	None to speak of
Message-ID	<lnzhjbcgx0.fsf@kst-u.example.com> (permalink)
References	<ql98g2$8tf$1@dont-email.me> <ql98je$8tf$2@dont-email.me> <slrnqnhc2b.cdo.grahn+nntp@frailea.sa.invalid> <qlacv3$1d1o$1@adenine.netfront.net>

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Juha Nieminen <nospam@thanks.invalid> writes:
> Jorgen Grahn <grahn+nntp@snipabacken.se> wrote:
>>> https://linux.die.net/man/3/strerror
>>>
>>> maybe will work ...
>> 
>> It will do what the documentation says, and lots of people use it.
>> Note its limitations, though.  It's not thread-safe, for example.
>
> What do you mean it's not thread-safe? AFAIK errno is thread-local
> according to the standard.

errno is thread-local.  That doesn't necessarily mean that strerror()
is thread-safe.  For example, a conforming implementation could
always return a pointer to the same static buffer, initialized
with the appropriate message before it returns.  And at least one
implementation (x86_64-w64-mingw32-gcc) appears to do exactly that.

N1570 7.24.6.2p3:

    The strerror function is not required to avoid data races with
    other calls to the strerror function. The implementation shall
    behave as if no library function calls the strerror function.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */

Thread

standard error messages in a std::string or in a const char * Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-11 00:35 +0200
  Re: standard error messages in a std::string or in a const char * Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-11 00:37 +0200
    Re: standard error messages in a std::string or in a const char * Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-09-11 08:28 +0000
      Re: standard error messages in a std::string or in a const char * Juha Nieminen <nospam@thanks.invalid> - 2019-09-11 08:58 +0000
        Re: standard error messages in a std::string or in a const char * Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-11 11:09 +0200
          Re: standard error messages in a std::string or in a const char * Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-11 11:37 +0200
        Re: standard error messages in a std::string or in a const char * Keith Thompson <kst-u@mib.org> - 2019-09-11 02:37 -0700
          Re: standard error messages in a std::string or in a const char * Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-11 11:47 +0200
            Re: standard error messages in a std::string or in a const char * Öö Tiib <ootiib@hot.ee> - 2019-09-11 04:43 -0700
              Re: standard error messages in a std::string or in a const char * James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-09-11 08:27 -0400
                Re: standard error messages in a std::string or in a const char * Manfred <noname@add.invalid> - 2019-09-11 14:56 +0200
                Re: standard error messages in a std::string or in a const char * Daniel <danielaparker@gmail.com> - 2019-09-11 07:00 -0700
          Re: standard error messages in a std::string or in a const char * Thiago Adams <thiago.adams@gmail.com> - 2019-09-11 09:44 -0700
          Re: standard error messages in a std::string or in a const char * Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-09-12 10:21 +0000
            Re: standard error messages in a std::string or in a const char * Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-12 13:05 +0200
        Re: standard error messages in a std::string or in a const char * Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-11 17:43 +0200
          Re: standard error messages in a std::string or in a const char * Paavo Helde <myfirstname@osa.pri.ee> - 2019-09-11 19:23 +0300
            Re: standard error messages in a std::string or in a const char * Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-11 19:19 +0200
              Re: standard error messages in a std::string or in a const char * Paavo Helde <myfirstname@osa.pri.ee> - 2019-09-11 20:32 +0300
                Re: standard error messages in a std::string or in a const char * Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-12 13:08 +0200
                Re: standard error messages in a std::string or in a const char * Thiago Adams <thiago.adams@gmail.com> - 2019-09-12 04:29 -0700
                Re: standard error messages in a std::string or in a const char * Keith Thompson <kst-u@mib.org> - 2019-09-12 14:41 -0700
              Re: standard error messages in a std::string or in a const char * Thiago Adams <thiago.adams@gmail.com> - 2019-09-11 10:39 -0700
              Re: standard error messages in a std::string or in a const char * James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-09-11 19:50 -0400
                Re: standard error messages in a std::string or in a const char * Keith Thompson <kst-u@mib.org> - 2019-09-11 17:11 -0700
                Re: standard error messages in a std::string or in a const char * James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-09-11 20:23 -0400
                Re: standard error messages in a std::string or in a const char * David Brown <david.brown@hesbynett.no> - 2019-09-12 11:21 +0200
                Re: standard error messages in a std::string or in a const char * James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-09-12 07:31 -0400
                Re: standard error messages in a std::string or in a const char * Manfred <noname@add.invalid> - 2019-09-12 15:44 +0200

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