libnetlink: dump extack string in done message

Print any extack message that has been appended to a NLMSG_DONE message.
To avoid duplication, move the existing print code to a new helper.

Signed-off-by: David Ahern <dsahern@gmail.com>

diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 954571097ea8dd90a1ec3461da84865a4655f1be..e28e1ab6da5e96fa65c9e0b8cc78a62a510f71be 100644 (file)
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -67,6 +67,14 @@ static int err_attr_cb(const struct nlattr *attr, void *data)
        return MNL_CB_OK;
 }
 
+static void print_ext_ack_msg(bool is_err, const char *msg)
+{
+       fprintf(stderr, "%s: %s", is_err ? "Error" : "Warning", msg);
+       if (msg[strlen(msg) - 1] != '.')
+               fprintf(stderr, ".");
+       fprintf(stderr, "\n");
+}
+
 /* dump netlink extended ack error message */
 int nl_dump_ext_ack(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)
 {
@@ -108,12 +116,29 @@ int nl_dump_ext_ack(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)
        if (msg && *msg != '\0') {
                bool is_err = !!err->error;
 
-               fprintf(stderr, "%s: %s",
-                       is_err ? "Error" : "Warning", msg);
-               if (msg[strlen(msg) - 1] != '.')
-                       fprintf(stderr, ".");
-               fprintf(stderr, "\n");
+               print_ext_ack_msg(is_err, msg);
+               return is_err ? 1 : 0;
+       }
 
+       return 0;
+}
+
+static int nl_dump_ext_ack_done(const struct nlmsghdr *nlh, int error)
+{
+       struct nlattr *tb[NLMSGERR_ATTR_MAX + 1] = {};
+       unsigned int hlen = sizeof(int);
+       const char *msg = NULL;
+
+       if (mnl_attr_parse(nlh, hlen, err_attr_cb, tb) != MNL_CB_OK)
+               return 0;
+
+       if (tb[NLMSGERR_ATTR_MSG])
+               msg = mnl_attr_get_str(tb[NLMSGERR_ATTR_MSG]);
+
+       if (msg && *msg != '\0') {
+               bool is_err = !!error;
+
+               print_ext_ack_msg(is_err, msg);
                return is_err ? 1 : 0;
        }
 
@@ -127,6 +152,11 @@ int nl_dump_ext_ack(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)
 {
        return 0;
 }
+
+static int nl_dump_ext_ack_done(const struct nlmsghdr *nlh, int error)
+{
+       return 0;
+}
 #endif
 
 void rtnl_close(struct rtnl_handle *rth)
@@ -512,6 +542,10 @@ static int rtnl_dump_done(struct nlmsghdr *h)
        }
 
        if (len < 0) {
+               /* check for any messages returned from kernel */
+               if (nl_dump_ext_ack_done(h, len))
+                       return len;
+
                errno = -len;
                switch (errno) {
                case ENOENT: