Re: How many wide characters may mbstowcs store?

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c
Subject	Re: How many wide characters may mbstowcs store?
Date	2020-05-23 07:51 -0700
Organization	A noiseless patient Spider
Message-ID	<86k112u2kx.fsf@linuxsc.com> (permalink)
References	(1 earlier) <r9bobp$fg5$1@news.albasani.net> <r9boue$25k$2@solani.org> <86mu6exxpw.fsf@linuxsc.com> <r9c0kj$8on$3@solani.org> <r9c1fg$9pu$1@solani.org>

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Philipp Klaus Krause <pkk@spth.de> writes:

> Am 11.05.20 um 19:05 schrieb Philipp Klaus Krause:
>
>> Am 11.05.20 um 18:06 schrieb Tim Rentsch:
>>
>>> Philipp Klaus Krause <pkk@spth.de> writes:
>>>
>>>> Am 11.05.20 um 16:44 schrieb Bonita Montero:
>>>>
>>>>> There's a POSIX-extension that if you pass nullptr for s, you get
>>>>> the size of the buffer needed for s.  Maybe this will help you.
>>>>> Otherwise: multibyte-characters are usually UTF-8-characters and
>>>>> it should be easy to find code to convert these charaters into
>>>>> wide-characters; but it should be also easy to write this yourself
>>>>> in 20min.
>>>>
>>>> At the moment I want to figure out what to do about the problem.  File a
>>>> bug against GCC in Ubuntu?  File a defect report / clarification request
>>>> with WG14?
>>>
>>> File a gcc bug report.  The gnu/gcc folks have misunderstood the
>>> standard, and they are shooting their users in the foot.  Your
>>> support/regression tests deserve thanks, and have provided a
>>> public service.
>>
>> However, with GCC having the bug on Ubuntu, but not on Debian, I wonder
>> if the GCC developers are really the source of the bug.  Maybe the bug is
>> in some patches Ubuntu adds to the upstream debian packages?
>
> I don't really undestand the patches Ubuntu applies to upstream Debian
> GCC packages, but there is something about
>
> + __interceptor_mbstowcs@Base 4.9
>
> so maybe Ubuntu enables some experimental optimization, that upstream
> Debian and GCC considered to not be ready yet to rill out to all users?

Looking at other messages I think you have identified what is
going on.  Doing some web searches, it does seem like what is
happening is triggered, at least partially, by the Ubuntu
choice to check the arguments more strictly than the Standard
allows.  Incidentally, there was some indication that the same
issue exists in Android, in case you care about that.

Even so, I think it would be good to file a bug report against
gcc.  It is gcc that chooses to call the overly strict, and also
non-standard, interface that does the wrong thing.  If gcc had
simply called the standard interface wcstombs then everything
would be fine.  There should at least be an option on gcc that
prevents it from using the non-standard and not conforming
interface.

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How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 13:30 +0200
  Re: How many wide characters may mbstowcs store? Manfred <noname@add.invalid> - 2020-05-11 13:55 +0200
    Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 14:01 +0200
      Re: How many wide characters may mbstowcs store? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-05-11 09:08 -0400
        Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 15:19 +0200
        Re: How many wide characters may mbstowcs store? Manfred <noname@add.invalid> - 2020-05-11 18:32 +0200
        Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 18:59 +0200
          Re: How many wide characters may mbstowcs store? scott@slp53.sl.home (Scott Lurndal) - 2020-05-11 17:42 +0000
            Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 20:30 +0200
            Re: How many wide characters may mbstowcs store? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-05-12 00:29 -0400
              Re: How many wide characters may mbstowcs store? Manfred <noname@add.invalid> - 2020-05-12 14:41 +0200
              Re: How many wide characters may mbstowcs store? Bonita Montero <Bonita.Montero@gmail.com> - 2020-05-12 16:19 +0200
  Re: How many wide characters may mbstowcs store? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-05-11 13:03 +0100
    Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 14:07 +0200
  Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 15:20 +0200
    Re: How many wide characters may mbstowcs store? Bonita Montero <Bonita.Montero@gmail.com> - 2020-05-11 16:31 +0200
    Re: How many wide characters may mbstowcs store? Barry Schwarz <schwarzb@delq.com> - 2020-05-11 10:06 -0700
  Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 15:58 +0200
    Re: How many wide characters may mbstowcs store? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-05-11 10:24 -0400
    Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 16:52 +0200
      Re: How many wide characters may mbstowcs store? Manfred <noname@add.invalid> - 2020-05-11 18:55 +0200
    Re: How many wide characters may mbstowcs store? richard@cogsci.ed.ac.uk (Richard Tobin) - 2020-05-11 15:51 +0000
      Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 19:01 +0200
        Re: How many wide characters may mbstowcs store? scott@slp53.sl.home (Scott Lurndal) - 2020-05-11 17:33 +0000
          Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 20:57 +0200
            Re: How many wide characters may mbstowcs store? scott@slp53.sl.home (Scott Lurndal) - 2020-05-11 19:17 +0000
              Re: How many wide characters may mbstowcs store? richard@cogsci.ed.ac.uk (Richard Tobin) - 2020-05-11 19:41 +0000
                Re: How many wide characters may mbstowcs store? scott@slp53.sl.home (Scott Lurndal) - 2020-05-11 20:01 +0000
            Re: How many wide characters may mbstowcs store? scott@slp53.sl.home (Scott Lurndal) - 2020-05-11 19:19 +0000
    Re: How many wide characters may mbstowcs store? Florian Weimer <fw@deneb.enyo.de> - 2020-05-11 20:24 +0200
      Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 20:59 +0200
        Re: How many wide characters may mbstowcs store? scott@slp53.sl.home (Scott Lurndal) - 2020-05-11 19:17 +0000
          Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 21:24 +0200
        Re: How many wide characters may mbstowcs store? Florian Weimer <fw@deneb.enyo.de> - 2020-05-11 22:30 +0200
  Re: How many wide characters may mbstowcs store? Bonita Montero <Bonita.Montero@gmail.com> - 2020-05-11 16:44 +0200
    Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 16:54 +0200
      Re: How many wide characters may mbstowcs store? Bonita Montero <Bonita.Montero@gmail.com> - 2020-05-11 16:57 +0200
        Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 17:07 +0200
          Re: How many wide characters may mbstowcs store? Bonita Montero <Bonita.Montero@gmail.com> - 2020-05-11 17:08 +0200
          Re: How many wide characters may mbstowcs store? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-05-11 11:25 -0400
      Re: How many wide characters may mbstowcs store? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-11 09:06 -0700
        Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 19:05 +0200
          Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 19:19 +0200
            Re: How many wide characters may mbstowcs store? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-23 07:51 -0700
              Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-23 20:27 +0200
                Re: How many wide characters may mbstowcs store? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-05-23 14:25 -0700
                Re: How many wide characters may mbstowcs store? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-26 07:09 -0700
                Re: How many wide characters may mbstowcs store? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-26 07:14 -0700
                Re: How many wide characters may mbstowcs store? Spiros Bousbouras <spibou@gmail.com> - 2020-05-26 16:00 +0000
                Re: How many wide characters may mbstowcs store? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-29 21:23 -0700
                Re: How many wide characters may mbstowcs store? Spiros Bousbouras <spibou@gmail.com> - 2020-05-30 20:08 +0000
                Re: How many wide characters may mbstowcs store? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-06-03 08:46 -0700
                Re: How many wide characters may mbstowcs store? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-06-03 10:18 -0700
                Re: How many wide characters may mbstowcs store? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-06-23 05:35 -0700
                Re: How many wide characters may mbstowcs store? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-06-26 06:32 -0700
                Re: How many wide characters may mbstowcs store? raltbos@xs4all.nl (Richard Bos) - 2020-06-04 20:34 +0000
        Re: How many wide characters may mbstowcs store? scott@slp53.sl.home (Scott Lurndal) - 2020-05-11 17:39 +0000
          Re: How many wide characters may mbstowcs store? Autist <autist69@gmail.com> - 2020-05-11 19:42 +0200
          Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-11 20:28 +0200
            Re: How many wide characters may mbstowcs store? scott@slp53.sl.home (Scott Lurndal) - 2020-05-11 18:37 +0000
              Re: How many wide characters may mbstowcs store? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-05-11 11:50 -0700
                Re: How many wide characters may mbstowcs store? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-05-12 20:02 +0100
                Re: How many wide characters may mbstowcs store? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-05-12 13:12 -0700
          Re: How many wide characters may mbstowcs store? richard@cogsci.ed.ac.uk (Richard Tobin) - 2020-05-11 19:56 +0000
          Re: How many wide characters may mbstowcs store? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-24 16:49 -0700
      Re: How many wide characters may mbstowcs store? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-05-11 14:19 -0700
        Re: How many wide characters may mbstowcs store? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-05-11 14:22 -0700
          Re: How many wide characters may mbstowcs store? Philipp Klaus Krause <pkk@spth.de> - 2020-05-12 09:17 +0200
        Re: How many wide characters may mbstowcs store? raltbos@xs4all.nl (Richard Bos) - 2020-05-24 16:12 +0000
          Re: How many wide characters may mbstowcs store? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-05-24 15:10 -0700
          Re: How many wide characters may mbstowcs store? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-05-24 22:58 -0400
  Re: How many wide characters may mbstowcs store? richard@cogsci.ed.ac.uk (Richard Tobin) - 2020-05-11 20:07 +0000
  Re: How many wide characters may mbstowcs store? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2020-06-25 21:42 -0700

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