Re: [PATCH iproute2 2/2] lib/libnetlink: update rtnl_talk to support malloc buff at run time

[Hangbin Liu <liuhangbin@gmail.com>]

On Fri, Sep 08, 2017 at 01:06:52PM +0200, Phil Sutter wrote:
> Hi Hangbin,
> 
> On Fri, Sep 08, 2017 at 06:14:57PM +0800, Hangbin Liu wrote:
> [...]
> > diff --git a/genl/ctrl.c b/genl/ctrl.c
> > index 448988e..699657b 100644
> > --- a/genl/ctrl.c
> > +++ b/genl/ctrl.c
> > @@ -55,6 +55,7 @@ int genl_ctrl_resolve_family(const char *family)
> >  	};
> >  	struct nlmsghdr *nlh = &req.n;
> >  	struct genlmsghdr *ghdr = &req.g;
> > +	struct nlmsghdr *answer = NULL;
> 
> I don't think it's necessary to assign NULL here or in any of the other
> cases.

OK
> 
> >  	if (rtnl_open_byproto(&rth, 0, NETLINK_GENERIC) < 0) {
> >  		fprintf(stderr, "Cannot open generic netlink socket\n");
> > @@ -63,19 +64,19 @@ int genl_ctrl_resolve_family(const char *family)
> >  
> >  	addattr_l(nlh, 128, CTRL_ATTR_FAMILY_NAME, family, strlen(family) + 1);
> >  
> > -	if (rtnl_talk(&rth, nlh, nlh, sizeof(req)) < 0) {
> > +	if (rtnl_talk(&rth, nlh, &answer) < 0) {
> 
> I didn't check, but it's likely that at least in some cases 'nlh'
> contains some buffer space to hold the answer (if it will be larger than
> the input). If so, this could be dropped since the buffer is no longer
> reused.

Yes, I will remove the buffer.

Thanks
Hangbin