convert inout test to use uevent-watch

following the upstream example, it republishes uevent messages
using multicast group 4 instead of group 2 as used by udev.

modules/all-modules.nix

@@ -19,6 +19,7 @@
    ./kernel
    ./outputs/kexecboot.nix
    ./mount
+   ./mdevd.nix
    ./network
    ./ntp
    ./outputs.nix

modules/mdevd.nix

@@ -0,0 +1,17 @@
+{ config, pkgs, lib, ...} :
+let inherit (pkgs.liminix.services) oneshot longrun bundle target;
+in {
+  config = {
+    services = rec {
+      mdevd = longrun {
+        name = "mdevd";
+        notification-fd = 3;
+        run = "${pkgs.mdevd}/bin/mdevd -D 3 -b 200000 -O4";
+      };
+      mdevd-coldplug = oneshot {
+        name ="mdev-coldplug";
+        up = "${pkgs.mdevd}/bin/mdevd-coldplug";
+      };
+    };
+  };
+}

pkgs/anoia/fs.fnl

@@ -33,4 +33,5 @@
  : mktree
  : rmtree
  : directory?
+ :symlink (fn [from to] (lfs.link from to true))
  }

pkgs/default.nix

@@ -82,6 +82,7 @@ in {
   zyxel-bootconfig = callPackage ./zyxel-bootconfig {};
   min-collect-garbage = callPackage ./min-collect-garbage {};
   min-copy-closure = callPackage ./min-copy-closure {};
+  nellie = callPackage ./nellie {};
   netlink-lua = callPackage ./netlink-lua {};
   odhcp-script = callPackage ./odhcp-script {};
   odhcp6c = callPackage ./odhcp6c {};
@@ -105,6 +106,7 @@ in {
   swconfig = callPackage ./swconfig {};
   systemconfig = callPackage ./systemconfig {};
   tufted = callPackage ./tufted {};
+  uevent-watch = callPackage ./uevent-watch {};
   writeAshScript = callPackage ./write-ash-script {};
   writeFennel = callPackage ./write-fennel {};
   writeFennelScript = callPackage ./write-fennel-script {};

pkgs/nellie/default.nix

@@ -0,0 +1,28 @@
+{ lua, lib, fetchpatch, fetchFromGitHub, stdenv }:
+
+let pname = "nellie";
+in lua.pkgs.buildLuaPackage {
+  inherit pname;
+  version = "0.1.1-1";
+
+  src = ./.;
+
+  buildPhase = "$CC -shared -l lua -o nellie.so nellie.c";
+
+  # for the checks to work you need to
+  # nix-build--option sandbox false
+  # otherwise the sandbox doesn't see any uevent messages
+
+  # doCheck = stdenv.hostPlatform == stdenv.buildPlatform;
+
+  checkPhase = ''
+    export LUA_CPATH=./?.so
+    lua test.lua
+  '';
+
+  installPhase = ''
+    mkdir -p "$out/lib/lua/${lua.luaversion}"
+    cp  nellie.so "$out/lib/lua/${lua.luaversion}/"
+  '';
+
+}

pkgs/nellie/nellie.c

@@ -0,0 +1,90 @@
+#include <lua.h>
+#include <lualib.h>
+#include <lauxlib.h>
+
+#include <linux/netlink.h>
+#include <sys/socket.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static int l_close_socket(lua_State *L) {
+    lua_getfield(L, 1, "fileno");
+    int fd = (int) lua_tointeger(L, -1);
+    close(fd);
+    return 0;
+}
+
+static int l_read_from_socket(lua_State *L) {
+    int length = 32;
+
+    if(lua_isnumber(L, 2))
+	length = lua_tointeger(L, 2);
+
+    lua_getfield(L, 1, "fileno");
+    int fd = (int) lua_tointeger(L, -1);
+    char *buf = (char *) malloc(length);
+    int bytes = recv(fd, buf, length, 0);
+
+    if(bytes > 0) {
+	lua_pushlstring(L, buf, bytes);
+	free(buf);
+	return 1;
+    } else {
+	free(buf);
+	return 0;
+    }
+}
+
+static int l_open_socket(lua_State *L) {
+    int netlink_fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_KOBJECT_UEVENT);
+
+    struct sockaddr_nl sa;
+    memset(&sa, 0, sizeof(sa));
+    sa.nl_family = AF_NETLINK;
+    sa.nl_pid = getpid();
+
+    if(lua_isnumber(L, 1)) {
+	sa.nl_groups = lua_tointeger(L, 1);
+	lua_pop(L, 1);
+    }
+    else {
+	sa.nl_groups = 4; 		/* group 4 is rebroadcasts from mdevd */
+    }
+
+    if(bind(netlink_fd, (struct sockaddr *) &sa, sizeof(sa))==0) {
+	lua_newtable(L);
+
+	lua_pushliteral(L, "fileno");
+	lua_pushinteger(L, netlink_fd);
+	lua_settable(L, 1);
+
+	lua_pushliteral(L, "read");
+	lua_pushcfunction(L, l_read_from_socket);
+	lua_settable(L, 1);
+
+	lua_pushliteral(L, "close");
+	lua_pushcfunction(L, l_close_socket);
+	lua_settable(L, 1);
+
+	return 1;
+    } else {
+	return 0;
+    }
+}
+
+
+static const struct luaL_Reg funcs [] = {
+    {"open", l_open_socket},
+    {NULL, NULL}  /* sentinel */
+};
+
+
+/* "luaopen_" prefix is magic and tells lua to run this function
+ * when it dlopens the library
+ */
+
+int luaopen_nellie (lua_State *L) {
+    luaL_newlib(L, funcs);
+    return 1;
+}

pkgs/nellie/test.lua

@@ -0,0 +1,6 @@
+local nellie = require('nellie')
+print('dfg')
+local f = nellie.open(2)
+
+print(string.byte(f:read(1000), 0, 60))
+print("CLOSED", f:close())

pkgs/uevent-watch/default.nix

@@ -0,0 +1,23 @@
+{
+  lua
+, nellie
+, writeFennelScript
+, runCommand
+, anoia
+, fennel
+, stdenv
+, fennelrepl
+}:
+stdenv.mkDerivation {
+  name = "uevent-watch";
+  src = ./.;
+  nativeBuildInputs = [ fennelrepl ];
+  installPhase = ''
+    mkdir -p $out/bin
+    cp -p ${writeFennelScript "uevent-watch" [fennel anoia nellie lua.pkgs.luafilesystem] ./watch.fnl} $out/bin/uevent-watch
+  '';
+  checkPhase = ''
+    fennelrepl ./test.fnl
+  '';
+  doCheck = true;
+}

pkgs/uevent-watch/events.txt

@@ -0,0 +1,154 @@
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1
+SUBSYSTEM=usb
+MAJOR=189
+MINOR=1
+DEVNAME=bus/usb/001/002
+DEVTYPE=usb_device
+PRODUCT=46f4/1/0
+TYPE=0/0/0
+BUSNUM=001
+DEVNUM=002
+SEQNUM=1513
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0
+SUBSYSTEM=usb
+DEVTYPE=usb_interface
+PRODUCT=46f4/1/0
+TYPE=0/0/0
+INTERFACE=8/6/80
+MODALIAS=usb:v46F4p0001d0000dc00dsc00dp00ic08isc06ip50in00
+SEQNUM=1514
+
+add@/devices/virtual/workqueue/scsi_tmf_0
+ACTION=add
+DEVPATH=/devices/virtual/workqueue/scsi_tmf_0
+SUBSYSTEM=workqueue
+SEQNUM=1515
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0
+SUBSYSTEM=scsi
+DEVTYPE=scsi_host
+SEQNUM=1516
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/scsi_host/host0
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/scsi_host/host0
+SUBSYSTEM=scsi_host
+SEQNUM=1517
+
+bind@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0
+ACTION=bind
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0
+SUBSYSTEM=usb
+DEVTYPE=usb_interface
+DRIVER=usb-storage
+PRODUCT=46f4/1/0
+TYPE=0/0/0
+INTERFACE=8/6/80
+MODALIAS=usb:v46F4p0001d0000dc00dsc00dp00ic08isc06ip50in00
+SEQNUM=1518
+
+bind@/devices/pci0000:00/0000:00:13.0/usb1/1-1
+ACTION=bind
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1
+SUBSYSTEM=usb
+MAJOR=189
+MINOR=1
+DEVNAME=bus/usb/001/002
+DEVTYPE=usb_device
+DRIVER=usb
+PRODUCT=46f4/1/0
+TYPE=0/0/0
+BUSNUM=001
+DEVNUM=002
+SEQNUM=1519
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0
+SUBSYSTEM=scsi
+DEVTYPE=scsi_target
+SEQNUM=1520
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0
+SUBSYSTEM=scsi
+DEVTYPE=scsi_device
+MODALIAS=scsi:t-0x00
+SEQNUM=1521
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/scsi_device/0:0:0:0
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/scsi_device/0:0:0:0
+SUBSYSTEM=scsi_device
+SEQNUM=1522
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/scsi_disk/0:0:0:0
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/scsi_disk/0:0:0:0
+SUBSYSTEM=scsi_disk
+SEQNUM=1523
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/bsg/0:0:0:0
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/bsg/0:0:0:0
+SUBSYSTEM=bsg
+MAJOR=252
+MINOR=0
+DEVNAME=bsg/0:0:0:0
+SEQNUM=1524
+
+change@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0
+ACTION=change
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0
+SUBSYSTEM=scsi
+SDEV_UA=POWER_ON_RESET_OCCURRED
+DEVTYPE=scsi_device
+DRIVER=sd
+MODALIAS=scsi:t-0x00
+SEQNUM=1525
+
+add@/devices/virtual/bdi/8:0
+ACTION=add
+DEVPATH=/devices/virtual/bdi/8:0
+SUBSYSTEM=bdi
+SEQNUM=1526
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/block/sda
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/block/sda
+SUBSYSTEM=block
+MAJOR=8
+MINOR=0
+DEVNAME=sda
+DEVTYPE=disk
+DISKSEQ=2
+SEQNUM=1527
+
+add@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/block/sda/sda1
+ACTION=add
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0/block/sda/sda1
+SUBSYSTEM=block
+MAJOR=8
+MINOR=1
+DEVNAME=sda1
+DEVTYPE=partition
+DISKSEQ=2
+PARTN=1
+SEQNUM=1528
+
+bind@/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0
+ACTION=bind
+DEVPATH=/devices/pci0000:00/0000:00:13.0/usb1/1-1/1-1:1.0/host0/target0:0:0/0:0:0:0
+SUBSYSTEM=scsi
+DEVTYPE=scsi_device
+DRIVER=sd
+MODALIAS=scsi:t-0x00
+SEQNUM=1529

pkgs/uevent-watch/test.fnl

@@ -0,0 +1,48 @@
+(local { : view} (require :fennel))
+
+(set _G.arg (doto [] (tset 0 "test")))
+(local subject (require :watch))
+
+(macro expect= [actual expected]
+  `(let [ve# (view ,expected)
+         va# (view ,actual)]
+     (when (not (= ve# va#))
+       (assert false
+               (.. "\nexpected " ve# "\ngot " va#)
+               ))))
+
+(let [params
+      {:matches {:devname "foo" :partname "my-usbstick"}}]
+  (expect= (subject.event-matches? params {}) false)
+  (expect= (subject.event-matches? params {:devname "bill"}) false)
+  (expect= (subject.event-matches? params {:devname "foo" :partname "my-usbstick"}) true)
+  (expect= (subject.event-matches? params {:devname "foo" :otherthing "bar" :partname "my-usbstick"}) true)
+  )
+
+
+;; Events come from the netlink socket as an initial summary line
+;; followed by a NUL character followed by newline-separated key=value
+;; pairs. For ease of editing we don't have NULs in events.txt,
+;; so we need to massage it into shape here
+
+(local events
+       (with-open [f (io.open "./events.txt" :r)]
+         (let [text (string.gsub (f:read "*a") "\n\n" "\0")  ]
+           (icollect [n (string.gmatch text "([^\0]+)")]
+             (string.gsub n "\n" "\0" 1)))))
+
+
+(fn next-event []
+  (var i 0)
+  (fn []
+    (let [i_ (+ 1 i)
+          e (. events i_)]
+      (set i i_)
+      e)))
+
+;; this tests event parsing but not whether anything
+;; happens as a result of processing them
+(subject.run
+ ["-s" "foo" "-n" (os.getenv "TMPDIR") "partname=backup-disk" ]
+ { :read (next-event) }
+ )

pkgs/uevent-watch/watch.fnl

@@ -0,0 +1,70 @@
+(local { : assoc : system : dirname } (require :anoia))
+(local { : mktree : rmtree : symlink } (require :anoia.fs))
+
+(fn parse-match [s]  (string.match s "(.-)=(.+)"))
+
+(fn parse-args [args]
+  (match args
+    ["-s" service & rest] (assoc (parse-args rest) :service service)
+    ["-n" path & rest] (assoc (parse-args rest) :linkname path)
+    matches { :matches (collect [_ m (ipairs matches)] (parse-match m)) }
+    _  nil))
+
+(fn %% [fmt ...] (string.format fmt ...))
+
+(fn event-matches? [params e]
+  (and
+   e
+   (accumulate [match? true
+                name value (pairs params.matches)]
+     (and match? (= value (. e name))))))
+
+
+(var up :unknown)
+
+(fn start-service [devname linkname service]
+  (match (symlink (.. "/dev/" devname ) linkname)
+    ok (pcall system (%% "s6-rc -b -u change %q" service))
+    (nil err) false))
+
+(fn stop-service [linkname service]
+  (match (pcall system (%% "s6-rc -b -d change %q" linkname service))
+    ok (os.remove linkname)
+    (nil err) false))
+
+(fn toggle-service [devname linkname service wanted?]
+  (when (not (= up wanted?))
+    (set up
+         (if wanted?
+             (start-service devname linkname service)
+             (not (stop-service linkname service))))))
+
+(fn parse-uevent [s]
+  (when s
+    (let [(nl nxt) (string.find s "\0" 1 true)]
+      (collect [k v (string.gmatch
+                     (string.sub s (+ 1 nxt))
+                     "(%g-)=(%g+)")]
+        (k:lower) v))))
+
+(fn run [args fh]
+  (set up :unknown)
+  (let [parameters
+        (assert (parse-args args) (.. "can't parse args: " (table.concat args " ")))]
+    (mktree (dirname parameters.linkname))
+    (var finished? false)
+
+    (while (not finished?)
+      (let [e (parse-uevent (fh:read 5000))]
+        (when (event-matches? parameters e)
+          (let [wanted? (. {:add true :change true} e.action)]
+            (toggle-service e.devname parameters.linkname parameters.service wanted?)))
+        (set finished? (= e nil))
+        ))))
+
+(when (not (= (. arg 0) "test"))
+  (let [nellie (require :nellie)
+        netlink (nellie.open 4)]
+    (run arg netlink)))
+
+{ : run  : event-matches? }

tests/inout/configuration.nix

@@ -15,6 +15,7 @@ in rec {
     "${modulesPath}/network"
     "${modulesPath}/ssh"
     "${modulesPath}/mount"
+    "${modulesPath}/mdevd.nix"
   ];
 
   filesystem = dir { srv = dir {}; };
@@ -46,16 +47,20 @@ in rec {
   rootfsType = "jffs2";
   hostname = "inout";
 
-  services.mount_external_disk = svc.mount.build {
-    device = "LABEL=backup-disk";
-    mountpoint = "/srv";
-    fstype = "ext4";
-  };
-
-  services.sshd = svc.ssh.build { };
-
-  defaultProfile.packages = with pkgs; [
-    min-collect-garbage
-    tcpdump
-  ];
+  services.watch_mount_srv =
+    let
+      node = "/dev/disk/by-partlabel/backup-disk";
+      mount = oneshot {
+        name = "mount-srv";
+        up = "mount -t ext2 ${node} /srv";
+        down = "umount /srv";
+      };
+    in longrun {
+      name = "mount_srv";
+      run = ''
+        ${pkgs.uevent-watch}/bin/uevent-watch -s ${mount.name} -n ${node} partname=backup-disk devtype=partition
+      '';
+      dependencies = [ config.services.mdevd ];
+      buildInputs = [ mount ];
+    };
 }

tests/inout/script.expect

@@ -9,21 +9,14 @@ proc chat {instr outstr} {
 spawn socat -,echo=0,icanon=1 unix-connect:vm/monitor
 set monitor_id $spawn_id
 
-# expect "(qemu)"
-# send "set_link virtio-net-pci.1 off\n"
-# expect "(qemu)"
-# send "set_link virtio-net-pci.0 off\n"
-# expect "(qemu)"
-# send "c\r\n"
-
 spawn socat unix-connect:vm/console -
 set console_id $spawn_id
 
 expect "BusyBox"
 chat "#" "PS1=RE\\ADY_\\ ; stty -echo \r"
-chat "READY_"  "s6-rc -b  -a list\r"
+chat "READY_"  "tail -f /run/uncaught-logs/current & \rs6-rc -b  -a list\r"
 
-chat "watch-mount" "\r"
+chat "mount" "\r"
 
 set spawn_id $monitor_id
 chat "QEMU" "device_add usb-storage,bus=xhci.0,drive=usbstick\n"
@@ -32,16 +25,15 @@ chat "(qemu)" "version\r"
 set spawn_id $console_id
 
 expect {
-  "mounted filesystem" { }
+  "sda: sda1" { }
   timeout { exit 1 }
 }
 
 
 send "\r"
-chat "READY_" "s6-rc -b -a list\r"
-chat "READY_" "cat /proc/mounts\r"
+chat "READY_" "sleep 3; grep /srv /proc/mounts && hostname\r"
 
 expect {
-  "/srv" { }
+  "inout" { }
   timeout { exit 1 }
 }

tests/inout/test.nix

@@ -13,13 +13,15 @@ in pkgs.runCommand "check" {
     socat
     e2fsprogs
     util-linux # for sfdisk, fallocate
+    parted
   ] ;
 } ''
 mkdir vm
 dd if=/dev/zero of=./vm/stick.e2fs bs=1M count=32
 mkfs.ext2 -L backup-disk ./vm/stick.e2fs
-cat <(dd if=/dev/zero bs=512 count=4)  ./vm/stick.e2fs > ./vm/stick.img
-echo '4,-,L,*' | sfdisk ./vm/stick.img
+dd if=/dev/zero of=./vm/stick.img bs=1M count=38
+dd if=./vm/stick.e2fs of=./vm/stick.img bs=512 seek=34 conv=notrunc
+parted -s ./vm/stick.img -- mklabel gpt mkpart backup-disk ext2 34s -0M
 
 ${img}/run.sh  --background ./vm --flag -device --flag usb-ehci,id=xhci --flag -drive  --flag if=none,id=usbstick,format=raw,file=$(pwd)/vm/stick.img
 expect ${./script.expect} | tee $out