generate a mips squashfs with some s6-rc services

haven't even tried booting it but I don't expect it to work. Needs

- s6-linux-init or some other pid 1 program
- a kernel

tools/builder.sh

@@ -0,0 +1,16 @@
+source $stdenv/setup
+mkdir -p $out/${name}
+echo $type > $out/${name}/type
+mkdir -p $out/${name}/dependencies.d
+echo $buildInputs > $out/buildInputs
+test -n "$dependencies" && for d in "$dependencies"; do
+    touch $out/${name}/dependencies.d/$d
+done
+test -n "$contents" && for d in "$contents"; do
+    mkdir -p $out/${name}/contents.d
+    touch $out/${name}/contents.d/$d
+done
+test -n "$run" && (echo "$run" > $out/${name}/run)
+test -n "$up" && (echo "$up" > $out/${name}/up)
+test -n "$down" && (echo "$down" > $out/${name}/down)
+(echo  $out/${name} && cd $out/${name} && find . -ls)

tools/default.nix

@@ -0,0 +1,80 @@
+{
+  stdenvNoCC
+, s6-rc
+} :let
+  inherit (builtins) concatStringsSep;
+  longrun = {
+    name
+    , run
+    , outputs ? []
+    , dependencies ? []
+  } @ args: stdenvNoCC.mkDerivation {
+    name = "${name}.service";
+    type = "longrun";
+    buildInputs = dependencies;
+    dependencies = builtins.map (d: d.name) dependencies;
+    inherit run;
+    builder = ./builder.sh;
+  };
+  oneshot = {
+    name
+    , up
+    , down
+    , outputs ? []
+    , dependencies ? []
+    , ...
+  } @ args: stdenvNoCC.mkDerivation {
+    # stdenvNoCC is to avoid generating derivations with names
+    # like foo.service-mips-linux-musl
+    name = "${name}.service";
+    type = "oneshot";
+    # does this suffice to make sure dependencies are included
+    # even though the built output has no references to their
+    # store directories?
+    buildInputs = dependencies;
+    inherit up down;
+    dependencies = builtins.map (d: d.name) dependencies;
+    builder = ./builder.sh;
+  };
+  bundle = {
+    name
+    , contents ? []
+    , dependencies ? []
+    , ...
+  }: stdenvNoCC.mkDerivation {
+    name = "${name}.bundle";
+    type = "bundle";
+    contents = builtins.map (d: d.name) contents;
+    buildInputs = dependencies ++ contents;
+    dependencies = builtins.map (d: d.name) dependencies;
+    builder = ./builder.sh;
+  };
+in {
+  networking = {
+    interface = { type, device }  @ args: oneshot {
+      name = "${device}.link";
+      up = "ip link set up dev ${device}";
+      down = "ip link set down dev ${device}";
+    } // {
+      inherit device;
+    };
+    address = interface: { family, addr } @ args: oneshot {
+      dependencies = [ interface ];
+      name = "${interface.device}.addr.${addr}";
+      up = "ip address add ${addr} dev ${interface.device} ";
+      down = "ip address del ${addr} dev ${interface.device} ";
+    };
+    udhcpc = interface: { ... } @ args: longrun {
+      name = "${interface.device}.udhcp";
+      run = "udhchpcd ${interface.device}";
+    };
+    odhcpc = interface: { ... } @ args: longrun {
+      name = "${interface.device}.odhcp";
+      run = "odhcpcd ${interface.device}";
+    };
+  };
+  services = {
+    inherit longrun oneshot bundle;
+    output = service: name: "/run/services/outputs/${service.name}/${name}";
+  };
+}