netdev - [PATCH iproute2-next v4 2/4] iplink: Use "dev" and "name" parameters interchangeable when possible

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Date:   Wed,  7 Mar 2018 10:40:37 +0200
From:   Serhey Popovych <serhe.popovych@...il.com>
To:     netdev@...r.kernel.org
Cc:     dsahern@...il.com
Subject: [PATCH iproute2-next v4 2/4] iplink: Use "dev" and "name" parameters interchangeable when possible

Both of them accept network device name as argument, but have different
meaning:

  dev  - is a device by it's name,
  name - name for specific device.

The only case where they treated separately is network device rename
case where need to specify both ifindex and new name. In rest of the
cases we can assume that dev == name.

With this change we do following:

  1) Kill ambiguity with both "dev" and "name" parameters given the same
     name:

       ip link {add|set} dev veth100a name veth100a ...

  2) Make sure we do not accept "name" more than once.

  3) For VF and XDP treat "name" as "dev". Fail in case of "dev" is
     given after VF and/or XDP parsing.

  4) Make veth and vxcan to accept both "name" and "dev" as their peer
     parameters, effectively following general ip-link(8) utility
     behaviour on link create:

       ip link add {name|dev} veth1a type veth peer {name|dev} veth1b

Signed-off-by: Serhey Popovych <serhe.popovych@...il.com>
---
 ip/iplink.c |   34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/ip/iplink.c b/ip/iplink.c
index 5471626..b4307ab 100644
--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -597,9 +597,15 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
 			req->i.ifi_flags &= ~IFF_UP;
 		} else if (strcmp(*argv, "name") == 0) {
 			NEXT_ARG();
+			if (*name)
+				duparg("name", *argv);
 			if (check_ifname(*argv))
 				invarg("\"name\" not a valid ifname", *argv);
 			*name = *argv;
+			if (!*dev) {
+				*dev = *name;
+				dev_index = ll_name_to_index(*dev);
+			}
 		} else if (strcmp(*argv, "index") == 0) {
 			NEXT_ARG();
 			if (*index)
@@ -654,6 +660,9 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
 			if (xdp_parse(&argc, &argv, req, dev_index,
 				      generic, drv, offload))
 				exit(-1);
+
+			if (offload && *name == *dev)
+				*dev = NULL;
 		} else if (strcmp(*argv, "netns") == 0) {
 			NEXT_ARG();
 			if (netns != -1)
@@ -745,6 +754,9 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
 			if (len < 0)
 				return -1;
 			addattr_nest_end(&req->n, vflist);
+
+			if (*name == *dev)
+				*dev = NULL;
 		} else if (matches(*argv, "master") == 0) {
 			int ifindex;
 
@@ -895,7 +907,7 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
 
 			if (strcmp(*argv, "dev") == 0)
 				NEXT_ARG();
-			if (*dev)
+			if (*dev != *name)
 				duparg2("dev", *argv);
 			if (check_ifname(*argv))
 				invarg("\"dev\" not a valid ifname", *argv);
@@ -905,6 +917,14 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
 		argc--; argv++;
 	}
 
+	/* Allow "ip link add dev" and "ip link add name" */
+	if (!*name)
+		*name = *dev;
+	else if (!*dev)
+		*dev = *name;
+	else if (!strcmp(*name, *dev))
+		*name = *dev;
+
 	if (dev_index && addr_len) {
 		int halen = nl_get_ll_addr_len(dev_index);
 
@@ -983,10 +1003,16 @@ static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv)
 		req.i.ifi_index = ll_name_to_index(dev);
 		if (!req.i.ifi_index)
 			return nodev(dev);
+
+		/* Not renaming to the same name */
+		if (name == dev)
+			name = NULL;
 	} else {
-		/* Allow "ip link add dev" and "ip link add name" */
-		if (!name)
-			name = dev;
+		if (name != dev) {
+			fprintf(stderr,
+				"both \"name\" and \"dev\" cannot be used when creating devices.\n");
+			exit(-1);
+		}
 
 		if (link) {
 			int ifindex;
-- 
1.7.10.4