From: "René Scharfe" <l.s.r@web.de>
To: "Johannes Sixt" <j6t@kdbg.org>, "Martin Liška" <mliska@suse.cz>
Cc: Jeff King <peff@peff.net>, git@vger.kernel.org
Subject: Re: [PATCH v3 1/2] Fix nonnull errors reported by UBSAN with GCC 7.
Date: Thu, 6 Apr 2017 19:31:38 +0200 [thread overview]
Message-ID: <e392e05c-2815-8cfa-eed0-bd990f8ce954@web.de> (raw)
In-Reply-To: <587b0cb9-bd66-ddf7-5cca-023df3470883@kdbg.org>
Am 06.04.2017 um 18:33 schrieb Johannes Sixt:
> Am 06.04.2017 um 17:42 schrieb Martin Liška:
>> +static inline void *sane_memmove(void *dest, const void *src, size_t n)
>> +{
>> + if (n > 0)
>> + return memmove(dest, src, n);
>> + else
>> + return dest;
>> +}
>
> Huh? memmove with n == 0 is well-defined. This wrapper is pointless.
memmove(3) with NULL pointers is undefined. From string.h on Debian:
extern void *memmove (void *__dest, const void *__src, size_t __n)
__THROW __nonnull ((1, 2));
Sometimes we use a NULL pointer and a size of zero to represent arrays
with no members. That convention is incompatible with memmove(3), but
the wrapper above would support it. Checking the size instead of the
pointer is preferable because a positive length with NULL pointers
should still result in a segfault instead of a silent no-op.
(I'd still prefer a MOVE_ARRAY macro which also infers the element
size).
René
next prev parent reply other threads:[~2017-04-06 17:32 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-06 8:02 [PATCH 1/2] Fix nonnull errors reported by UBSAN with GCC 7 Martin Liška
2017-04-06 8:34 ` Jeff King
2017-04-06 9:52 ` [PATCH v2 " Martin Liška
2017-04-06 12:26 ` René Scharfe
2017-04-06 15:42 ` [PATCH v3 " Martin Liška
2017-04-06 16:33 ` Johannes Sixt
2017-04-06 17:31 ` René Scharfe [this message]
2017-04-06 20:49 ` Johannes Sixt
2017-04-07 14:23 ` Martin Liška
2017-04-07 15:25 ` René Scharfe
2017-04-07 15:25 ` [PATCH 1/2] add MOVE_ARRAY René Scharfe
2017-04-07 15:25 ` [PATCH 2/2] use MOVE_ARRAY René Scharfe
2017-04-17 1:49 ` [PATCH v3 1/2] Fix nonnull errors reported by UBSAN with GCC 7 Junio C Hamano
2017-04-17 7:59 ` Johannes Sixt
2017-04-06 8:57 ` [PATCH " Johannes Schindelin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=e392e05c-2815-8cfa-eed0-bd990f8ce954@web.de \
--to=l.s.r@web.de \
--cc=git@vger.kernel.org \
--cc=j6t@kdbg.org \
--cc=mliska@suse.cz \
--cc=peff@peff.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).