Re: Safer and more convenient strcpy()

Message-ID	<v5q8lf-saq.ln1@wilbur.25thandClement.com> (permalink)
From	William Ahern <william@25thandClement.com>
Subject	Re: Safer and more convenient strcpy()
Newsgroups	comp.lang.c
References	(4 earlier) <89bb4ef0-56cc-45fd-9dc9-04376ce0d29d@googlegroups.com> <DpbgE.6596$sw5.1011@fx21.iad> <8f69ad8b-a898-4423-8781-0df209e92782@googlegroups.com> <slrnq8374v.4jo.grahn+nntp@frailea.sa.invalid> <8dn8lf-9mt2.ln1@wilbur.25thandClement.com>
Date	2019-03-07 16:38 -0800

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William Ahern <william@25thandclement.com> wrote:
> Jorgen Grahn <grahn+nntp@snipabacken.se> wrote:
>> On Thu, 2019-03-07, Malcolm McLean wrote:
>>> On Thursday, 7 March 2019 16:12:28 UTC, Scott Lurndal  wrote:
>> ...
>>>> How is that better than
>>>> 
>>>>    size_t numbytes = snprintf(dst, sizeof(dst), "%s", src);
>>>> 
>>>> safe, nul-byte terminated and returns an indication of whether
>>>> src was larger than dst.
>>> ?
>>> Because if you want to make more than one call, to concatenate strings,
>>> you have to recalcuate the size parameter, which is where errors 
>>> could creep in.
>> 
>> On the other hand, snprintf() itself has good support for
>> concatenating strings.
> 
> snprintf has more complex error conditions, though. For example, in glibc
> snprintf is implemented using the stdio subsystem, effectively invoking
> something like fprintf through a specialized FILE handle. Initialization of
> the internal data structures can require dynamic allocation and so even a
> simple format string like "%s" can return ENOMEM. AFAIU, floating point
> specifiers can require dynamic allocation in most (all?) snprintf
> implementations.
> 
> And then there's the matter that snprintf takes an int parameter for the
> buffer size as well as returning an int, raising the spectre of unexpected
> and undefined conversions and overflows. Indeed, the two issues
> combined--integer conversions and managing error conditions--makes the above
> example snprintf usage poorly written code, IMO.

Correction: it only returns an int; it takes size_t. However, there's the
issue of the treatment of a buffer size value greater than INT_MAX.

Thread

Safer and more convenient strcpy() Howard Chu <highlandsun@gmail.com> - 2019-03-06 03:45 -0800
  Re: Safer and more convenient strcpy() Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-03-06 03:58 -0800
    Re: Safer and more convenient strcpy() Howard Chu <highlandsun@gmail.com> - 2019-03-06 04:31 -0800
      Re: Safer and more convenient strcpy() "I Set My Girlfriend's Pantyhose on Fire" <cdalten@gmail.com> - 2019-03-06 05:18 -0800
        Re: Safer and more convenient strcpy() Howard Chu <highlandsun@gmail.com> - 2019-03-06 13:03 -0800
          Re: Safer and more convenient strcpy() William Ahern <william@25thandClement.com> - 2019-03-06 16:51 -0800
            Re: Safer and more convenient strcpy() Howard Chu <highlandsun@gmail.com> - 2019-03-07 07:40 -0800
              Re: Safer and more convenient strcpy() scott@slp53.sl.home (Scott Lurndal) - 2019-03-07 16:12 +0000
                Re: Safer and more convenient strcpy() Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-03-07 08:28 -0800
                Re: Safer and more convenient strcpy() scott@slp53.sl.home (Scott Lurndal) - 2019-03-07 16:51 +0000
                Re: Safer and more convenient strcpy() Howard Chu <highlandsun@gmail.com> - 2019-03-07 09:31 -0800
                Re: Safer and more convenient strcpy() Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-03-07 11:17 -0800
                Re: Safer and more convenient strcpy() Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-03-07 22:35 +0000
                Re: Safer and more convenient strcpy() Howard Chu <highlandsun@gmail.com> - 2019-03-07 15:32 -0800
                Re: Safer and more convenient strcpy() scott@slp53.sl.home (Scott Lurndal) - 2019-03-08 14:29 +0000
                Re: Safer and more convenient strcpy() Howard Chu <highlandsun@gmail.com> - 2019-03-08 07:09 -0800
                Re: Safer and more convenient strcpy() Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-03-08 15:39 +0000
                Re: Safer and more convenient strcpy() Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-03-08 07:56 -0800
                Re: Safer and more convenient strcpy() Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-03-09 08:12 +0000
                Re: Safer and more convenient strcpy() William Ahern <william@25thandClement.com> - 2019-03-07 15:51 -0800
                Re: Safer and more convenient strcpy() William Ahern <william@25thandClement.com> - 2019-03-07 16:38 -0800
                Re: Safer and more convenient strcpy() Keith Thompson <kst-u@mib.org> - 2019-03-07 18:32 -0800
                Re: Safer and more convenient strcpy() William Ahern <william@25thandClement.com> - 2019-03-07 20:00 -0800
                Re: Safer and more convenient strcpy() Howard Chu <highlandsun@gmail.com> - 2019-03-08 04:15 -0800
            Re: Safer and more convenient strcpy() "I Set My Girlfriend's Pantyhose on Fire" <cdalten@gmail.com> - 2019-03-07 12:15 -0800
      Re: Safer and more convenient strcpy() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-03-06 09:12 -0800
  Re: Safer and more convenient strcpy() mark.bluemel@gmail.com - 2019-03-06 08:27 -0800
  Re: Safer and more convenient strcpy() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-03-06 09:22 -0800
  Re: Safer and more convenient strcpy() Rosario19 <Ros@invalid.invalid> - 2019-03-07 09:10 +0100
    Re: Safer and more convenient strcpy() Rosario19 <Ros@invalid.invalid> - 2019-03-07 09:12 +0100
      Re: Safer and more convenient strcpy() mark.bluemel@gmail.com - 2019-03-07 00:55 -0800
  Re: Safer and more convenient strcpy() William Ahern <william@25thandClement.com> - 2019-03-07 16:09 -0800
    Re: Safer and more convenient strcpy() Howard Chu <highlandsun@gmail.com> - 2019-03-08 04:04 -0800
    Re: Safer and more convenient strcpy() eric.sanchis@iut-rodez.fr - 2019-04-15 04:40 -0700
      Re: Safer and more convenient strcpy() nobody@example.org (Scott) - 2019-04-16 03:33 +0000
        Re: Safer and more convenient strcpy() eric.sanchis@iut-rodez.fr - 2019-04-16 05:35 -0700
          Re: Safer and more convenient strcpy() nobody@example.org (Scott) - 2019-04-17 01:19 +0000
            Re: Safer and more convenient strcpy() eric.sanchis@iut-rodez.fr - 2019-04-17 05:35 -0700
              Re: Safer and more convenient strcpy() nobody@example.org (Scott) - 2019-04-17 16:59 +0000
                Re: Safer and more convenient strcpy() eric.sanchis@iut-rodez.fr - 2019-04-17 23:40 -0700
  Re: Safer and more convenient strcpy() Philipp Klaus Krause <pkk@spth.de> - 2019-03-20 11:10 +0100
    Re: Safer and more convenient strcpy() Philipp Klaus Krause <pkk@spth.de> - 2019-03-20 11:13 +0100

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