[PATCH iproute2-next v4 3/4] iplink: Follow documented behaviour when "index" is given

[Serhey Popovych <serhe.popovych@gmail.com>]

Both ip-link(8) and error message when "index" parameter is given for
set/delete case says that index can only be given during network
device creation.

Follow this documented behaviour and get rid of ambiguous behaviour in
case of both "dev" and "index" specified for ip link delete scenario
(actually "index" being ignored in favor to "dev").

Prohibit "index" when configuring/deleting group of network devices.

Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
---
 ip/iplink.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/ip/iplink.c b/ip/iplink.c
index b4307ab..6d3ebde 100644
--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -964,6 +964,12 @@ static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv)
 	argc -= ret;
 	argv += ret;
 
+	if (!(flags & NLM_F_CREATE) && index) {
+		fprintf(stderr,
+			"index can be used only when creating devices.\n");
+		exit(-1);
+	}
+
 	if (group != -1) {
 		if (dev)
 			addattr_l(&req.n, sizeof(req), IFLA_GROUP,
@@ -994,11 +1000,6 @@ static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv)
 				"Not enough information: \"dev\" argument is required.\n");
 			exit(-1);
 		}
-		if (cmd == RTM_NEWLINK && index) {
-			fprintf(stderr,
-				"index can be used only when creating devices.\n");
-			exit(-1);
-		}
 
 		req.i.ifi_index = ll_name_to_index(dev);
 		if (!req.i.ifi_index)
-- 
1.7.10.4