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add uevent-watch, which toggles services based on uevent msgs

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This commit is contained in:
Daniel Barlow 2024-04-15 21:15:07 +01:00
parent 5564cf0554
commit ea2b25168e
6 changed files with 297 additions and 0 deletions
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1
pkgs/anoia/fs.fnl
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@ -33,4 +33,5 @@
: mktree
: rmtree
: directory?
:symlink (fn [from to] (lfs.link from to true))
}

1
pkgs/default.nix
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@ -106,6 +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 {};

23
pkgs/uevent-watch/default.nix Normal file
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@ -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;
}

154
pkgs/uevent-watch/events.txt Normal file
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@ -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

48
pkgs/uevent-watch/test.fnl Normal file
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@ -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) }
)

70
pkgs/uevent-watch/watch.fnl Normal file
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@ -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? }