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Groups > comp.lang.c > #94916

Re: UB of memcpy(NULL, NULL, 0)

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: UB of memcpy(NULL, NULL, 0)
Date 2016-10-16 11:20 +0100
Organization A noiseless patient Spider
Message-ID <87d1j04mu4.fsf@bsb.me.uk> (permalink)
References <ntnodu$p8o$1@dont-email.me> <nttu4o$1fuc$1@gioia.aioe.org> <87zim549aa.fsf@bsb.me.uk> <a2728f07-3a11-4b6b-8f1f-1c7592831506@googlegroups.com>

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Malcolm McLean <malcolm.mclean5@btinternet.com> writes:

> On Saturday, October 15, 2016 at 10:00:54 PM UTC+1, Ben Bacarisse wrote:
>> Lőrinczy Zsigmond <nospam@for.me> writes:
>> 
>
>>   inline
>>   void *nzmemcpy(void *restrict p1, const void *restrict p2, size_t len)
>>   {
>>       return len ? memcpy(p1, p2, len) : p1;
>>   }
>> 
>> Is this really making programmers' lives miserable?
>> 
> Yes, The logic is "copy the contents of p2 to p1". And it just gets
> buried in minutae
> if you manually inline that function, and makes functions non-leaf if you supply
> it. 
> Leaf functions ("Malcolm functions") with no dependencies at all are the most
> portable, most reusable C constructs you can have, and so you shouldn't surrender
> that characteristic lightly. Then dependencies only on malloc(), free(), dependencies
> only on other trivial, supplied subroutines, and dependencies only on the standard
> library are the next best.So nzmemcpy() is not a disaster. But it's
> still not desireable.

A C program that calls memcpy is no less portable (in 2016) than one
that does not, and may well be more efficient than one that uses a
portable copy function written in C.  Your own obsessions need not be
shared (and in my view should not be shared) by other C programmers.

-- 
Ben.

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Thread

UB of memcpy(NULL, NULL, 0) Noob <root@127.0.0.1> - 2016-10-13 12:42 +0200
  Re: UB of memcpy(NULL, NULL, 0) Richard Heathfield <rjh@cpax.org.uk> - 2016-10-13 11:55 +0100
    Re: UB of memcpy(NULL, NULL, 0) Noob <root@127.0.0.1> - 2016-10-13 13:09 +0200
      Re: UB of memcpy(NULL, NULL, 0) Richard Heathfield <rjh@cpax.org.uk> - 2016-10-13 12:22 +0100
        Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-13 12:22 -0700
          Re: UB of memcpy(NULL, NULL, 0) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-10-13 12:32 -0700
            Re: UB of memcpy(NULL, NULL, 0) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-10-13 12:34 -0700
    Re: UB of memcpy(NULL, NULL, 0) Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-10-13 08:24 -0600
      Re: UB of memcpy(NULL, NULL, 0) Richard Heathfield <rjh@cpax.org.uk> - 2016-10-13 16:22 +0100
      Re: UB of memcpy(NULL, NULL, 0) Noob <root@127.0.0.1> - 2016-10-13 17:49 +0200
        Re: UB of memcpy(NULL, NULL, 0) Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-10-13 12:02 -0600
  Re: UB of memcpy(NULL, NULL, 0) Lőrinczy Zsigmond <nospam@for.me> - 2016-10-15 20:56 +0200
    Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-15 12:52 -0700
    Re: UB of memcpy(NULL, NULL, 0) "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-15 15:55 -0400
    Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-15 13:41 -0700
      Re: UB of memcpy(NULL, NULL, 0) Lőrinczy Zsigmond <nospam@for.me> - 2016-10-16 11:17 +0200
        Re: UB of memcpy(NULL, NULL, 0) Richard Heathfield <rjh@cpax.org.uk> - 2016-10-16 10:26 +0100
        Re: UB of memcpy(NULL, NULL, 0) raltbos@xs4all.nl (Richard Bos) - 2016-10-16 09:55 +0000
          Re: UB of memcpy(NULL, NULL, 0) Jerry Stuckle <jstucklex@attglobal.net> - 2016-10-16 08:44 -0400
            Re: UB of memcpy(NULL, NULL, 0) David Brown <david.brown@hesbynett.no> - 2016-10-17 10:06 +0200
              Re: UB of memcpy(NULL, NULL, 0) Jerry Stuckle <jstucklex@attglobal.net> - 2016-10-17 09:06 -0400
                Re: UB of memcpy(NULL, NULL, 0) David Brown <david.brown@hesbynett.no> - 2016-10-17 16:29 +0200
                Re: UB of memcpy(NULL, NULL, 0) Jerry Stuckle <jstucklex@attglobal.net> - 2016-10-17 17:05 -0400
                Re: UB of memcpy(NULL, NULL, 0) David Brown <david.brown@hesbynett.no> - 2016-10-18 11:19 +0200
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-18 08:04 -0700
                Re: UB of memcpy(NULL, NULL, 0) Jerry Stuckle <jstucklex@attglobal.net> - 2016-10-18 16:27 -0400
            Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-17 08:59 -0700
              Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-17 11:21 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-17 13:42 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-17 14:46 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-17 15:52 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-17 16:43 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-18 08:00 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-18 09:14 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-18 09:43 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-18 11:31 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-18 12:49 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-18 12:03 -0700
              Re: UB of memcpy(NULL, NULL, 0) Jerry Stuckle <jstucklex@attglobal.net> - 2016-10-17 17:06 -0400
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-17 14:55 -0700
        Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-16 11:23 -0700
      Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-17 08:49 -0700
        Re: UB of memcpy(NULL, NULL, 0) raltbos@xs4all.nl (Richard Bos) - 2016-10-18 16:54 +0000
          Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-18 11:09 -0700
            Re: UB of memcpy(NULL, NULL, 0) raltbos@xs4all.nl (Richard Bos) - 2016-10-23 13:24 +0000
              Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-24 09:28 -0700
              Re: UB of memcpy(NULL, NULL, 0) <william@wilbur.25thandClement.com> - 2016-10-29 11:32 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-29 14:12 -0700
    Re: UB of memcpy(NULL, NULL, 0) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-15 22:00 +0100
      Re: UB of memcpy(NULL, NULL, 0) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-16 02:51 -0700
        Re: UB of memcpy(NULL, NULL, 0) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-16 11:20 +0100
          Re: UB of memcpy(NULL, NULL, 0) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-16 04:14 -0700
            Re: UB of memcpy(NULL, NULL, 0) BartC <bc@freeuk.com> - 2016-10-16 12:22 +0100
            Re: UB of memcpy(NULL, NULL, 0) Richard Heathfield <rjh@cpax.org.uk> - 2016-10-16 13:01 +0100
              Re: UB of memcpy(NULL, NULL, 0) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-16 05:29 -0700
                Re: UB of memcpy(NULL, NULL, 0) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-16 20:47 +0100
                Re: UB of memcpy(NULL, NULL, 0) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-17 02:08 -0700
                Re: UB of memcpy(NULL, NULL, 0) David Brown <david.brown@hesbynett.no> - 2016-10-17 10:24 +0200
                Re: UB of memcpy(NULL, NULL, 0) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-17 08:05 -0700
                Re: UB of memcpy(NULL, NULL, 0) David Brown <david.brown@hesbynett.no> - 2016-10-17 17:25 +0200
  Re: UB of memcpy(NULL, NULL, 0) Lőrinczy Zsigmond <nospam@for.me> - 2016-10-17 17:08 +0200
    Re: UB of memcpy(NULL, NULL, 0) Lorinczy Zsigmond <zsiga@nospam.for.me> - 2016-10-21 12:46 +0200
      Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-21 08:06 -0700
        Re: UB of memcpy(NULL, NULL, 0) Lőrinczy Zsigmond <nospam@for.me> - 2016-10-21 18:30 +0200
          Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-21 09:34 -0700
            Re: UB of memcpy(NULL, NULL, 0) Lőrinczy Zsigmond <nospam@for.me> - 2016-10-22 07:42 +0200
              Re: UB of memcpy(NULL, NULL, 0) James Kuyper <jameskuyper@verizon.net> - 2016-10-22 10:31 -0400
                Re: UB of memcpy(NULL, NULL, 0) Lőrinczy Zsigmond <nospam@for.me> - 2016-10-22 17:49 +0200
                Re: UB of memcpy(NULL, NULL, 0) Tim Rentsch <txr@alumni.caltech.edu> - 2016-10-22 13:43 -0700
                Re: UB of memcpy(NULL, NULL, 0) Lőrinczy Zsigmond <nospam@for.me> - 2016-10-23 07:47 +0200
                Re: UB of memcpy(NULL, NULL, 0) "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-23 11:07 -0400
                Re: UB of memcpy(NULL, NULL, 0) Lőrinczy Zsigmond <nospam@for.me> - 2016-10-23 17:45 +0200
                Re: UB of memcpy(NULL, NULL, 0) "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-23 12:16 -0400
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-24 07:38 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-24 08:38 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-24 09:44 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-23 12:22 -0700
                Re: UB of memcpy(NULL, NULL, 0) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-23 13:37 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-23 14:15 -0700
                Re: UB of memcpy(NULL, NULL, 0) Ike Naar <ike@iceland.freeshell.org> - 2016-10-24 06:11 +0000
                Re: UB of memcpy(NULL, NULL, 0) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-24 00:58 -0700
                Re: UB of memcpy(NULL, NULL, 0) Tim Rentsch <txr@alumni.caltech.edu> - 2016-10-23 14:07 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-24 07:48 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-24 08:40 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-24 10:03 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-24 12:06 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-24 13:36 -0700
                Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-24 13:57 -0700
                Re: UB of memcpy(NULL, NULL, 0) Tim Rentsch <txr@alumni.caltech.edu> - 2016-10-24 14:16 -0700
                Re: UB of memcpy(NULL, NULL, 0) supercat@casperkitty.com - 2016-10-24 17:23 -0700
                Re: UB of memcpy(NULL, NULL, 0) Tim Rentsch <txr@alumni.caltech.edu> - 2016-10-25 07:57 -0700
                Re: UB of memcpy(NULL, NULL, 0) James Kuyper <jameskuyper@verizon.net> - 2016-10-22 18:23 -0400
                Re: UB of memcpy(NULL, NULL, 0) "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-23 10:44 -0400
                Re: UB of memcpy(NULL, NULL, 0) Richard Heathfield <rjh@cpax.org.uk> - 2016-10-23 16:24 +0100
                Re: Verbing Noob <root@127.0.0.1> - 2016-10-23 18:02 +0200
        Re: UB of memcpy(NULL, NULL, 0) raltbos@xs4all.nl (Richard Bos) - 2016-10-23 13:26 +0000
          Re: UB of memcpy(NULL, NULL, 0) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-23 07:40 -0700
      Re: UB of memcpy(NULL, NULL, 0) asetofsymbols@gmail.com - 2016-10-21 23:56 -0700
        Re: UB of memcpy(NULL, NULL, 0) Lőrinczy Zsigmond <nospam@for.me> - 2016-10-22 12:21 +0200
          Re: UB of memcpy(NULL, NULL, 0) Keith Thompson <kst-u@mib.org> - 2016-10-22 16:33 -0700

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