platform/netlink: cleanup nla_parse*() code by using safer macros

- drop explicit MAX sizes like

      static const struct nla_policy policy[IFLA_INET6_MAX+1] = {

  The compiler will deduce that.

  It saves redundant information (which is possibly wrong). Also,
  the max define might be larger than we actually need it, so we
  just waste a few bytes of static memory and do unnecesary steps
  during validation.

  Also, the compiler will catch bugs, if the array size of policy/tb
  is too short for what we access later (-Warray-bounds).

- avoid redundant size specifiers like:

      static const struct nla_policy policy[IFLA_INET6_MAX+1] = {
      ...
      struct nlattr *tb[IFLA_INET6_MAX+1];
      ...
      err = nla_parse_nested (tb, IFLA_INET6_MAX, attr, policy);

- use the nla_parse*_arr() macros that determine the maxtype
  based on the argument types.

- move declaration of "static const struct nla_policy policy" variable
  to the beginning, before auto variables.

- drop unneeded temporay error variables.

1 files changed, 10 insertions, 8 deletions

diff --git a/src/platform/wpan/nm-wpan-utils.c b/src/platform/wpan/nm-wpan-utils.c
index 4ae1770ffe..b7a51e9bf2 100644
--- a/src/platform/wpan/nm-wpan-utils.c
+++ b/src/platform/wpan/nm-wpan-utils.c
@@ -153,17 +153,19 @@ struct nl802154_interface {
 static int
 nl802154_get_interface_handler (struct nl_msg *msg, void *arg)
 {
+	static const struct nla_policy nl802154_policy[] = {
+		[NL802154_ATTR_PAN_ID]     = { .type = NLA_U16 },
+		[NL802154_ATTR_SHORT_ADDR] = { .type = NLA_U16 },
+	};
+	struct nlattr *tb[G_N_ELEMENTS (nl802154_policy)];
 	struct nl802154_interface *info = arg;
 	struct genlmsghdr *gnlh = nlmsg_data (nlmsg_hdr (msg));
-	struct nlattr *tb[NL802154_ATTR_MAX + 1] = { 0, };
-	static const struct nla_policy nl802154_policy[NL802154_ATTR_MAX + 1] = {
-		[NL802154_ATTR_PAN_ID] =            { .type = NLA_U16 },
-		[NL802154_ATTR_SHORT_ADDR] =        { .type = NLA_U16 },
-	};
 
-	if (nla_parse (tb, NL802154_ATTR_MAX, genlmsg_attrdata (gnlh, 0),
-	               genlmsg_attrlen (gnlh, 0), nl802154_policy) < 0)
-	return NL_SKIP;
+	if (nla_parse_arr (tb,
+	                   genlmsg_attrdata (gnlh, 0),
+	                   genlmsg_attrlen (gnlh, 0),
+	                   nl802154_policy) < 0)
+		return NL_SKIP;
 
 	if (tb[NL802154_ATTR_PAN_ID])
 		info->pan_id = le16toh (nla_get_u16 (tb[NL802154_ATTR_PAN_ID]));