From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kurt Van Dijck Subject: Re: [PATCH] Use strcmp instead of strncmp Date: Wed, 14 Nov 2012 09:55:37 +0100 Message-ID: <20121114085537.GB82180@airbook.eia.lan> References: <1352821642-18791-1-git-send-email-alexander.stein@systec-electronic.com> <50A2AD0A.6040005@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from mailrelay002.isp.belgacom.be ([195.238.6.175]:40326 "EHLO mailrelay002.isp.belgacom.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751458Ab2KNIzn (ORCPT ); Wed, 14 Nov 2012 03:55:43 -0500 Content-Disposition: inline In-Reply-To: <50A2AD0A.6040005@pengutronix.de> Sender: linux-can-owner@vger.kernel.org List-ID: To: Marc Kleine-Budde Cc: Alexander Stein , linux-can@vger.kernel.org On Tue, Nov 13, 2012 at 09:26:50PM +0100, Marc Kleine-Budde wrote: > On 11/13/2012 04:47 PM, Alexander Stein wrote: > > This bug was detected by the clang warning: > > libsocketcan.c:384:16: warning: argument to 'sizeof' in 'strncmp' call > > is the same expression as the source; did you mean to provide an > > explicit length? [-Wsizeof-pointer-memaccess] > > sizeof(name)) != 0) > > ~~~~~~~^~~~~~ strlen() requires a null terminator. Is that always present? Unfortunately, I've no access to the libsocketcan code today... > > > > Signed-off-by: Alexander Stein > > --- > > src/libsocketcan.c | 3 ++- > > 1 files changed, 2 insertions(+), 1 deletions(-) > > > > diff --git a/src/libsocketcan.c b/src/libsocketcan.c > > index fedcbdc..3ad2a6c 100644 > > --- a/src/libsocketcan.c > > +++ b/src/libsocketcan.c > > @@ -364,6 +364,7 @@ static int do_get_nl_link(int fd, __u8 acquire, const char *name, void *res) > > nl_msg = NLMSG_NEXT(nl_msg, u_msglen)) { > > int type = nl_msg->nlmsg_type; > > int len; > > + int namelen = strlen(name); > > > > if (type == NLMSG_DONE) { > > done++; > > @@ -381,7 +382,7 @@ static int do_get_nl_link(int fd, __u8 acquire, const char *name, void *res) > > > > if (strncmp > > ((char *)RTA_DATA(tb[IFLA_IFNAME]), name, > > - sizeof(name)) != 0) > > + namelen) != 0) > > What about using strcmp() instead. AFAIK it will compare until it finds > the end of the string in one of the strings, so it should be no > difference here? if name contains a null terminator, using strcmp() is even better. > > > continue; > > > > if (tb[IFLA_LINKINFO]) > > > > Marc > > -- > Pengutronix e.K. | Marc Kleine-Budde | > Industrial Linux Solutions | Phone: +49-231-2826-924 | > Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | > Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | >