Subject: Re: [PATCH iproute2 1/3] iplink: Improve index parameter handling

From: Stephen Hemminger <[email-masked]>
Date: Mon, 18 Dec 2017 13:22:31 -0800

On Mon, 18 Dec 2017 23:02:07 +0200
Serhey Popovich <[email-masked]> wrote:

> Stephen Hemminger wrote:
> > On Mon, 18 Dec 2017 20:54:06 +0200
> > Serhey Popovych <[email-masked]> wrote:
> >   
> >> diff --git a/ip/iplink.c b/ip/iplink.c
> >> index 1e685cc..4f9c169 100644
> >> --- a/ip/iplink.c
> >> +++ b/ip/iplink.c
> >> @@ -586,8 +586,10 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
> >>  			*name = *argv;
> >>  		} else if (strcmp(*argv, "index") == 0) {
> >>  			NEXT_ARG();
> >> +			if (*index)
> >> +				duparg("index", *argv);
> >>  			*index = atoi(*argv);
> >> -			if (*index < 0)
> >> +			if (*index <= 0)  
> > 
> > Why not use strtoul instead of atoi?  
> Do not see reason for strtoul() instead atoi():
> 
>   1) main arg: indexes in kernel represented as "int", which is
>      signed. <= 0 values are reserved for various special purposes
>      (see net/core/fib_rules.c on how device matching implemented).
> 
>      Configuring network device manually with index <= 0 is not correct
>      (however possible). Kernel itself never chooses ifindex <= 0.
> 
>      Having unsigned int > 0x7fffffff actually means index <= 0.
> 
>   2) this is not single place in iproute2 where it is used: not
>      going to remove last user.
> 
>   3) make changes clear and transparent for review.

I would rather all of iproute2 correctly handles unsigned values.
Too much code is old K&R style C "the world is an int" and "who needs
to check for negative".

There already is get_unsigned() in iproute2 util functions.
Why not use that?