From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58470) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gZJKG-0007cC-H1 for qemu-devel@nongnu.org; Tue, 18 Dec 2018 12:38:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gZJKF-0000YK-Cj for qemu-devel@nongnu.org; Tue, 18 Dec 2018 12:38:36 -0500 Date: Tue, 18 Dec 2018 17:38:01 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20181218173801.GG4807@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20181218110333.22558-1-philmd@redhat.com> <20181218092648-mutt-send-email-mst@kernel.org> <028f1498-d0bc-e920-1c7c-9a1f0bdded58@redhat.com> <20181218095334-mutt-send-email-mst@kernel.org> <42bc04b0-71b7-c9aa-554e-a337351b1e7e@redhat.com> <20181218120201-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181218120201-mutt-send-email-mst@kernel.org> Subject: Re: [Qemu-devel] [PATCH v2 0/3] Fix strncpy() warnings for GCC8 new -Wstringop-truncation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Paolo Bonzini , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org, Ben Pye , Stefan Weil , Howard Spoelstra , Jeff Cody , =?utf-8?Q?C=C3=A9dric?= Le Goater , Thomas Huth , Liu Yuan , Igor Mammedov , Max Reitz , Kevin Wolf , Eric Blake , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , David Hildenbrand , David Gibson , Markus Armbruster , qemu-block@nongnu.org, "Dr. David Alan Gilbert" , 1803872@bugs.launchpad.net, Juan Quintela On Tue, Dec 18, 2018 at 12:03:34PM -0500, Michael S. Tsirkin wrote: > On Tue, Dec 18, 2018 at 05:38:17PM +0100, Paolo Bonzini wrote: > > On 18/12/18 15:54, Michael S. Tsirkin wrote: > > > On Tue, Dec 18, 2018 at 03:45:08PM +0100, Paolo Bonzini wrote: > > >> On 18/12/18 15:31, Michael S. Tsirkin wrote: > > >>> Do you happen to know why does it build fine with > > >>> Gcc 8.2.1? > > >>> > > >>> Reading the GCC manual it seems that > > >>> there is a "nostring" attribute that means > > >>> "might not be 0 terminated". > > >>> I think we should switch to that which fixes the warning > > >>> but also warns if someone tries to misuse these > > >>> as C-strings. > > >>> > > >>> Seems to be a better option, does it not? > > >>> > > >>> > > >> > > >> Using strpadcpy is clever and self-documenting, though. We have it > > >> already, so why not use it. > > >> > > >> Paolo > > > > > > The advantage of nonstring is that it will catch attempts to > > > use these fields with functions that expect a 0 terminated string. > > > > > > strpadcpy will instead just silence the warning. > > > > Ah, I see. We could also do both, that's a matter of taste. > > > > Paolo > > Do you happen to know how to make gcc check the buffer size > for strpadcpy? Is the name strncpy just hard-coded? GCC provides strncpy as a builtin function and its warning only checks its builtin. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|