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| From | raltbos@xs4all.nl (Richard Bos) |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: UB of memcpy(NULL, NULL, 0) |
| Date | 2016-10-18 16:54 +0000 |
| Organization | Go wash your mouth. |
| Message-ID | <580652f9.3303000@news.xs4all.nl> (permalink) |
| References | <ntnodu$p8o$1@dont-email.me> <nttu4o$1fuc$1@gioia.aioe.org> <lnvawtgxb0.fsf@kst-u.example.com> <1b195986-62eb-4600-9723-1e45cafbc840@googlegroups.com> |
supercat@casperkitty.com wrote: > On Saturday, October 15, 2016 at 3:40:50 PM UTC-5, Keith Thompson wrote: > > As a programmer, how much of a burden is it to avoid calling memcpy() > > with a null pointer? > > It adds a wasted comparison when implementing an API that can accept > optional data given a pointer and length, and specifies that the pointer > is ignored if the length is zero. No, it doesn't, because if you arrange your code properly that comparison would have been done in any case, not just for memcpy() but for all the other code that uses that pointer. At least, I've never written code that allocates a pointer, memcpy()s to it, and immediately deallocates it; I've always done more with any single pointer, and therefore, have always had to check for null in any case. The test is not done specifically for the memcpy(); therefore, it is adding the test inside memcpy() which wastes a comparison. > For how many real-world implementations of memcpy Your favourite straw man again? Knock it off, already. Richard
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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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