Re: [PATCH] Use strcmp instead of strncmp

[Kurt Van Dijck <kurt.van.dijck@eia.be>]

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 <alexander.stein@systec-electronic.com>
> > ---
> >  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
> 
> -- 
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>