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/.#README

@@ -0,0 +1 @@
+dan@noetbook.911352349782478447

pkgs/ifwait/default.nix

@@ -0,0 +1,32 @@
+{
+  lua5_3
+, netlink-lua
+, stdenv
+, makeWrapper
+}:
+let
+  lua = lua5_3;
+  netlink = netlink-lua.override {inherit lua;};
+  fennel = lua.pkgs.fennel;
+in stdenv.mkDerivation rec {
+  pname = "ifwait";
+  version = "1";
+  phases = [ "installPhase" ];
+
+  buildInputs = [ lua netlink ];
+  nativeBuildInputs = [ makeWrapper fennel ];
+
+  LUA_CPATH = "${netlink}/lib/lua/${lua.luaversion}/\?.so"; # for nix-shell
+
+  installPhase = ''
+    mkdir -p $out/bin $out/lib
+    fennel --compile  ${./ifwait.fnl} > $out/lib/${pname}.lua
+
+    makeWrapper ${lua}/bin/lua $out/bin/${pname} \
+      --prefix LUA_CPATH ";" ${netlink}/lib/lua/${lua.luaversion}/\?.so \
+      --add-flags $out/lib/${pname}.lua
+  '';
+}
+
+# to use fennel.view,
+#  --prefix LUA_PATH ";" ${fennel}/share/lua/5.2/\?.lua \

pkgs/ifwait/ifwait.fnl

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+(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)))

pkgs/ifwait/waitup.fnl

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+(local netlink (require :netlink))
+(local sock (netlink.socket))
+
+(when  (< (# arg) 2)
+  (print "usage: waitup ifname fd")
+  (os.exit 1))
+
+(local ifname (. arg 1))
+(local fd (tonumber (. arg 2)))
+(local stream (io.open (.. "/proc/self/fd/" fd) "w"))
+
+(fn notify-ready []
+  (when (= "file" (io.type stream))
+    (stream:write "\n")
+    (stream:close))
+  (print (.. (. arg 0) ": received netlink operstate up for " ifname)))
+
+
+(fn run-events [evs]
+  (each [_ v (ipairs evs)]
+    (print :event v.event v.name)
+
+    (match v
+      ;; - up: Reflects the administrative state of the interface (IFF_UP)
+      ;; - running: Reflects the operational state (IFF_RUNNING).
+      {:event "newlink" :name ifname :up :yes :running :yes}
+      (notify-ready)
+
+      {:event "newlink" :name ifname :up :no}
+      (os.exit 0))))
+
+(run-events (sock:query {:link true}))
+
+(print (.. (. arg 0) ": waiting for netlink NEWLINK " ifname))
+
+(while (sock:poll)
+  (let [ev (sock:event)]
+    (run-events ev)))