convert mount service to trigger

Good: this means it's not hanging holding the s6 dataase lock.

Bad: it's the ugliest implementation and doesn't deserve to be preserved

(tbf the ugliness is not new)

modules/ifwait/ifwait.nix

@@ -9,6 +9,7 @@ let
 in longrun {
   name = "ifwait.${interface.name}";
   buildInputs = [ service ];
+  isTrigger = true;
   run = ''
     ${ifwait}/bin/ifwait -s ${service.name}  $(output ${interface} ifname) ${state}
   '';

modules/mount/service.nix

@@ -4,15 +4,28 @@
 }:
 { device, mountpoint, options, fstype }:
 let
-  inherit (liminix.services) oneshot;
-in oneshot {
-  name = "mount.${lib.escapeURL mountpoint}";
-  up = ''
+  inherit (liminix.services) longrun oneshot;
+  options_string =
+    if options == [] then "" else "-o ${lib.concatStringsSep "," options}";
+  mount_service = oneshot {
+    name = "mount.${lib.escapeURL mountpoint}";
+    timeout-up = 3600;
+    up = "mount -t ${fstype} ${options_string} ${device} ${mountpoint}";
+    down = "umount ${mountpoint}";
+  };
+in longrun {
+  name = "watch-mount.${lib.strings.sanitizeDerivationName mountpoint}";
+  isTrigger = true;
+  buildInputs = [ mount_service ];
+
+  # This accommodates bringing the service up when the device appears.
+  # It doesn't bring it down on unplug because unmount will probably
+  # fail anyway (so don't do that)
+  run = ''
     while ! findfs ${device}; do
       echo waiting for device ${device}
       sleep 1
     done
-    mount -t ${fstype} -o ${lib.concatStringsSep "," options} ${device} ${mountpoint}
+    s6-rc -b -u change ${mount_service.name}
   '';
-  down = "umount ${mountpoint}";
 }

pkgs/liminix-tools/services/builder.sh

@@ -11,7 +11,7 @@ test -n "$contents" && for d in $contents; do
     touch $out/${name}/contents.d/$d
 done
 
-for i in timeout-up timeout-down run notification-fd up down consumer-for producer-for pipeline-name ; do
+for i in timeout-up timeout-down run notification-fd up down consumer-for producer-for pipeline-name restart-on-upgrade; do
     test -n "$(printenv $i)" && (echo "$(printenv $i)" > $out/${name}/$i)
 done
 

pkgs/liminix-tools/services/default.nix

@@ -36,12 +36,14 @@ let
     , dependencies ? []
     , contents ? []
     , buildInputs ? []
+    , isTrigger ? false
   } @ args:
     stdenvNoCC.mkDerivation {
       # we use stdenvNoCC to avoid generating derivations with names
       # like foo.service-mips-linux-musl
       inherit name serviceType up down run notification-fd
         producer-for consumer-for pipeline-name timeout-up timeout-down;
+      restart-on-upgrade = isTrigger;
       buildInputs = buildInputs ++ dependencies ++ contents;
       dependencies = builtins.map (d: d.name) dependencies;
       contents = builtins.map (d: d.name) contents;

pkgs/s6-rc-database/default.nix

@@ -21,11 +21,16 @@ in stdenvNoCC.mkDerivation  {
       if test -d $i; then
         for j in $i/* ; do
           if test -f $j/type ; then
+            if test -e $j/restart-on-upgrade; then
+              flag=force-restart
+            else
+              unset flag
+            fi
             case $(cat $j/type) in
               longrun|oneshot)
-                # s6-rc-update only wants oneshots in its
+                # s6-rc-update only wants atomics in its
                 # restarts file
-                echo $(basename $j) " " $i >>  $out/hashes
+                echo $(basename $j) " " ''${flag-$i} >>  $out/hashes
                 ;;
               *)
                 ;;

pkgs/systemconfig/restart-services.fnl

@@ -12,8 +12,11 @@
         new-hashes (hashes-from-file new)]
     (with-open [f (io.open "/tmp/restarts" :w)]
       (each [n h (pairs old-hashes)]
-        (when (not (= h (. new-hashes n)))
-          (f:write (.. n " restart\n")))))))
+        (let [new (. new-hashes n)]
+          (when (or (= h "force-restart")
+                    (= new "force-restart")
+                    (not (= h new)))
+            (f:write (.. n " restart\n"))))))))
 
 (fn exec [text command]
   (io.write (.. text ": "))

tests/ci.nix

@@ -9,4 +9,5 @@
   fennel = import ./fennel/test.nix;
   tftpboot = import ./tftpboot/test.nix;
   updown = import ./updown/test.nix;
+  inout = import ./inout/test.nix;
 }

tests/inout/configuration.nix

@@ -0,0 +1,61 @@
+{ config, pkgs, lib, modulesPath, ... } :
+let
+  inherit (pkgs.liminix.services) bundle oneshot longrun;
+  inherit (pkgs.pseudofile) dir symlink;
+  inherit (pkgs) serviceFns;
+
+  svc = config.system.service;
+
+in rec {
+  imports = [
+    "${modulesPath}/dhcp6c"
+    "${modulesPath}/dnsmasq"
+    "${modulesPath}/firewall"
+    "${modulesPath}/hostapd"
+    "${modulesPath}/network"
+    "${modulesPath}/ssh"
+    "${modulesPath}/mount"
+  ];
+
+  filesystem = dir { srv = dir {}; };
+
+  kernel = {
+    config = {
+      USB = "y";
+      USB_EHCI_HCD = "y";
+      USB_EHCI_HCD_PLATFORM = "y";
+      USB_OHCI_HCD = "y";
+      USB_OHCI_HCD_PLATFORM = "y";
+      USB_SUPPORT = "y";
+      USB_COMMON = "y";
+      USB_STORAGE = "y";
+      USB_STORAGE_DEBUG = "n";
+      USB_UAS = "y";
+      USB_ANNOUNCE_NEW_DEVICES = "y";
+      SCSI = "y";
+      BLK_DEV_SD = "y";
+      USB_PRINTER = "y";
+      MSDOS_PARTITION = "y";
+      EFI_PARTITION = "y";
+      EXT4_FS = "y";
+      EXT4_USE_FOR_EXT2 = "y";
+      FS_ENCRYPTION = "y";
+    };
+  };
+
+  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
+  ];
+}

tests/inout/script.expect

@@ -0,0 +1,47 @@
+set timeout 10
+
+proc chat {instr outstr} {
+    expect {
+        $instr  { send $outstr }
+        timeout { exit 1 }
+    }
+}
+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 "watch-mount" "\r"
+
+set spawn_id $monitor_id
+chat "QEMU" "device_add usb-storage,bus=xhci.0,drive=usbstick\n"
+chat "(qemu)" "version\r"
+
+set spawn_id $console_id
+
+expect {
+  "mounted filesystem" { }
+  timeout { exit 1 }
+}
+
+
+send "\r"
+chat "READY_" "s6-rc -b -a list\r"
+chat "READY_" "cat /proc/mounts\r"
+
+expect {
+  "/srv" { }
+  timeout { exit 1 }
+}

tests/inout/test.nix

@@ -0,0 +1,26 @@
+{
+  liminix
+, nixpkgs
+}:
+let img = (import liminix {
+      device = import "${liminix}/devices/qemu/";
+      liminix-config = ./configuration.nix;
+    }).outputs.vmroot;
+    pkgs = import <nixpkgs> { overlays = [(import ../../overlay.nix)]; };
+in pkgs.runCommand "check" {
+  nativeBuildInputs = with pkgs; [
+    expect
+    socat
+    e2fsprogs
+    util-linux # for sfdisk, fallocate
+  ] ;
+} ''
+mkdir vm
+dd if=/dev/zero of=./vm/stick.e2fs bs=1M count=32
+mkfs.ext2 -L backup-disk ./vm/stick.e2fs
+cat <(dd if=/dev/zero bs=512 count=4)  ./vm/stick.e2fs > ./vm/stick.img
+echo '4,-,L,*' | sfdisk ./vm/stick.img
+
+${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
+''