Date: Thu, 5 Mar 2020 19:19:59 +0100 From: Dimitry Andric <dim@FreeBSD.org> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: Slawa Olhovchenkov <slw@zxy.spb.ru>, svn-src-head <svn-src-head@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, src-committers@freebsd.org Subject: Re: svn commit: r358655 - head/sbin/mount_nfs Message-ID: <1A13B93C-7D87-4210-AD3D-2B198C166CE1@FreeBSD.org> In-Reply-To: <20200305174411.GV5741@FreeBSD.org> References: <202003042227.024MRGsW072613@repo.freebsd.org> <244e28ea-1217-cefc-354e-02ecb201637a@FreeBSD.org> <20200305163350.GU5741@FreeBSD.org> <20200305172454.GJ8028@zxy.spb.ru> <20200305173515.GK8028@zxy.spb.ru> <20200305174411.GV5741@FreeBSD.org>
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[-- Attachment #1 --] On 5 Mar 2020, at 18:44, Gleb Smirnoff <glebius@FreeBSD.org> wrote: > > On Thu, Mar 05, 2020 at 08:35:15PM +0300, Slawa Olhovchenkov wrote: > S> > > D> sbin/mount_nfs/mount_nfs.c:549:10: error: cast from 'char *' to 'struct > S> > > D> if_msghdr *' increases required alignment from 1 to 4 > S> > > D> [-Werror,-Wcast-align] > S> > > D> ifm = (struct if_msghdr *)buf; > S> > > D> ^~~~~~~~~~~~~~~~~~~~~~~ > S> > > D> 1 error generated. > S> > > D> > S> > > D> In practice I don't think the buffer can ever get misaligned, so can you > S> > > D> please add a NO_WCAST_ALIGN= to the Makefile? > S> > > > S> > > route(8) handles the same problem via intermediate (void *) cast. What is > S> > > preferred way to solve the problem? Change compiler flags file wide, or > S> > > just through (void *) cast? > S> > > S> > Copy to aligned buffer or got SIGBUS on some architectures? > S> > S> char buf[2048] __aligned(__alignof(struct if_msghdr)); > S> > S> resolve this watning. > > Thanks, Slawa! I think this is the most elegant solution. Why don't just declare the buffer as: struct if_msghdr buf; and then do: nread = read(s, &buf, sizeof buf); ? You are never reading more than one if_msghdr anyway, and then there is no need to cast anything. -Dimitry [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.2 iF0EARECAB0WIQR6tGLSzjX8bUI5T82wXqMKLiCWowUCXmFCzwAKCRCwXqMKLiCW o+ZEAJwLg7kEAdqiUVSNjAK2vAzAeqZ1CACeOlYaTkNlVV9/9u4Hz8rthtlJdm8= =jHHx -----END PGP SIGNATURE-----home | help
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