replace waitup with more generally useful ifwait

* wait for $interface present before ip link set up dev
* wait for wlan0 running before adding to bridge

pkgs/ifwait/ifwait.fnl

@@ -0,0 +1,52 @@
+(local netlink (require :netlink))
+(local sock (netlink.socket))
+
+; (local { : view} (require :fennel))
+
+(fn assoc [tbl k v]
+  (tset tbl k v)
+  tbl)
+
+(fn parse-args [args]
+  (match args
+    ["-v" & rest]  (assoc (parse-args rest) :verbose true)
+    ["-t" timeout & rest] (assoc (parse-args rest) :timeout (tonumber timeout))
+    [linkname "up"] {:link linkname :expecting "up"}
+    [linkname "running"] {:link linkname :expecting "running"}
+    [linkname "present"] {:link linkname :expecting "present"}
+    [linkname nil] {:link linkname :expecting "present"}
+    _  nil))
+
+(local parameters
+       (or
+        (parse-args arg)
+        (assert false (.. "Usage: " (. arg 0) " [-v] ifname [present|up|running]"))))
+
+(fn run-events [evs]
+  (each [_ v (ipairs evs)]
+    (let [got
+          (match v
+            ;; - up: Reflects the administrative state of the interface (IFF_UP)
+            ;; - running: Reflects the operational state (IFF_RUNNING).
+            {:event "newlink" :name parameters.link :up :yes :running :yes}
+            {:present true :up true :running true}
+
+            {:event "newlink" :name parameters.link :up :yes}
+            {:present :true :up true}
+
+            {:event "newlink" :name parameters.link}
+            {:present true }
+
+            _
+            {})]
+      (when (. got parameters.expecting)
+        (os.exit 0)))))
+
+
+(when parameters.verbose
+  (print (.. (. arg 0) ": waiting for "
+             parameters.link " to be " parameters.expecting)))
+
+(run-events (sock:query {:link true}))
+
+(while (sock:poll) (run-events (sock:event)))