[PATCH] Fix strict-aliasing warning in resolv/res_hconf.c

[Pedro Alves]

On 05/20/2015 05:27 PM, Steve Ellcey wrote:

> diff --git a/resolv/res_hconf.c b/resolv/res_hconf.c
> index 73942e8..3b05287 100644
> --- a/resolv/res_hconf.c
> +++ b/resolv/res_hconf.c
> @@ -444,13 +444,13 @@ _res_hconf_reorder_addrs (struct hostent *hp)
>  
>  	      ifaddrs[new_num_ifs].addrtype = AF_INET;
>  	      ifaddrs[new_num_ifs].u.ipv4.addr =
> -		((struct sockaddr_in *) &cur_ifr->ifr_addr)->sin_addr.s_addr;
> +		cur_ifr->ifr_addr_in.sin_addr.s_addr;

Without adding a new union member, isn't the simplest to just take a
copy step?  The interface already clearly assumes that a sockaddr_in
fits in a sockaddr.  Something like:

              union
                {
                  struct sockaddr sa;
                  struct sockaddr_in sin;
                } ss;

-  	      ifaddrs[new_num_ifs].u.ipv4.addr =
-		((struct sockaddr_in *) &cur_ifr->ifr_addr)->sin_addr.s_addr;
+             ss.sa = cur_ifr->ifr_addr;
+	      ifaddrs[new_num_ifs].u.ipv4.addr = ss.sin.sin_addr.s_addr;

etc.  Maybe the compiler even elides the copying.  (And if it doesn't,
would it matter here?)

Thanks,
Pedro Alves