[PATCH iproute2-next v2] ip: error out if iplink does not consume all options

[Jakub Kicinski <kuba@kernel.org>]

dummy does not define .parse_opt, which make ip ignore all
trailing arguments, for example:

 # ip link add type dummy a b c d e f name cheese

will work just fine (and won't call the device "cheese").
Error out in this case with a clear error message:

 # ip link add type dummy a b c d e f name cheese
 Garbage instead of arguments "a ...". Try "ip link help".

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
v2:
 - remove the ->parse_opt check later
v1: https://lore.kernel.org/all/20230728183329.2193688-1-kuba@kernel.org/
---
 ip/iplink.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/ip/iplink.c b/ip/iplink.c
index 6c5d13d53a84..9a548dd35f54 100644
--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -1112,13 +1112,12 @@ static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv)
 		argc -= ret;
 		argv += ret;
 
-		if (lu && argc) {
+		if (lu && lu->parse_opt && argc) {
 			struct rtattr *data;
 
 			data = addattr_nest(&req.n, sizeof(req), iflatype);
 
-			if (lu->parse_opt &&
-			    lu->parse_opt(lu, argc, argv, &req.n))
+			if (lu->parse_opt(lu, argc, argv, &req.n))
 				return -1;
 
 			addattr_nest_end(&req.n, data);
-- 
2.41.0