From f164f19d954cf41c763272db913850dbb12251ee Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Wed, 6 Mar 2024 23:18:28 +0000
Subject: [PATCH] service starts and stops

---
 pkgs/ifwait/ifwait.fnl      |  25 ++++++--
 pkgs/ifwait/test-ifwait.fnl | 115 ++++++++++++++++++++++++++++--------
 2 files changed, 110 insertions(+), 30 deletions(-)

diff --git a/pkgs/ifwait/ifwait.fnl b/pkgs/ifwait/ifwait.fnl
index 3677252..9af41f9 100644
--- a/pkgs/ifwait/ifwait.fnl
+++ b/pkgs/ifwait/ifwait.fnl
@@ -1,9 +1,8 @@
 (local nl (require :anoia.nl))
+(local { : assoc : system } (require :anoia))
 
 ; (local { : view} (require :fennel))
 
-(local { : assoc : system } (require :anoia))
-
 (fn parse-args [args]
   (match args
     ["-v" & rest]  (assoc (parse-args rest) :verbose true)
@@ -31,9 +30,19 @@
 
           _
           {})]
-    (. got params.expecting)))
+    (not (not (. got params.expecting)))))
+
+(var up :unknown)
+(fn toggle-service [service wanted?]
+  (when (not (= up wanted?))
+    (set up
+         (if wanted?
+             (pcall system (.. "s6-rc -u change " service))
+             (not (pcall system (.. "s6-rc -d change " service)))))
+    ))
 
 (fn run [args event-fn]
+  (set up :unknown)
   (let [parameters
         (assert (parse-args args)
                 (.. "Usage: ifwait [-v] ifname [present|up|running]"))]
@@ -41,9 +50,13 @@
       (print (.. "ifwait: waiting for "
                  parameters.link " to be " parameters.expecting)))
 
-    (each [e (event-fn)
-           &until (event-matches? parameters e)]
-      true)))
+    (if parameters.service
+        (each [e (event-fn)]
+          (if (= e.name parameters.link)
+              (toggle-service parameters.service (event-matches? parameters e))))
+        (each [e (event-fn)
+               &until (event-matches? parameters e)]
+          true))))
 
 (when (not (= (. arg 0) "test"))
   (run arg #(nl.events {:link true})))
diff --git a/pkgs/ifwait/test-ifwait.fnl b/pkgs/ifwait/test-ifwait.fnl
index eef6acd..3381b5a 100644
--- a/pkgs/ifwait/test-ifwait.fnl
+++ b/pkgs/ifwait/test-ifwait.fnl
@@ -4,6 +4,14 @@
 (var fake-system (fn [s] (print "executing " s)))
 (tset anoia :system #(fake-system $1))
 
+(macro expect= [actual expected]
+  `(let [ve# (view ,expected)
+         va# (view ,actual)]
+     (when (not (= ve# va#))
+       (assert false
+               (.. "\nexpected " ve# "\ngot " va#)
+               ))))
+
 (fn event-generator [events]
   (coroutine.wrap
    (fn []
@@ -19,34 +27,93 @@
 (local ifwait (require :ifwait))
 
 (let [gen (event-generator (file-events "events-fixture"))]
-  (ifwait.run ["-v" "dummy0" "up"] #gen)
+  (ifwait.run ["dummy0" "up"] #gen)
   (match (pcall gen)
     (true _) true
     (false msg) (error "didn't detect dummy0 up event")))
 
-(var succeeded? false)
+(var upsies [])
 (set fake-system
      (fn [s]
-       (print "exec" s)
-       (if (s:match "addmember") (set succeeded? true))))
+       (if (s:match "-u change addmember")
+           (table.insert upsies :u)
+           (s:match "-d change addmember")
+           (table.insert upsies :d))))
 
-(let [events
-      [{:event "newlink"
-        :hwaddr "b6:7d:5c:38:89:1d"
-        :index 21
-        :mtu 1500
-        :name "dummy0"
-        :running "no"
-        :stamp 857161382
-        :up "no"}
-       {:event "newlink"
-        :hwaddr "52:f0:46:da:0c:0c"
-        :index 22
-        :mtu 1500
-        :name "dummy0"
-        :running "no"
-        :stamp 857161383
-        :up "yes"}]
-      gen (event-generator events)]
-  (ifwait.run ["-v" "-s" "addmember" "dummy0" "up"] #gen)
-  (assert succeeded?))
+(fn newlink [name up running]
+  {:event "newlink"
+   :hwaddr "b6:7d:5c:38:89:1d"
+   :index (string.unpack ">i2" name)
+   :mtu 1500
+   : name
+   : running
+   :stamp 857161382
+   : up })
+
+"when it gets events that don't match the interface, nothing happens"
+
+(let [gen (-> [(newlink "eth1" "no" "no")] event-generator)]
+  (set upsies [])
+  (ifwait.run [ "-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies []))
+
+"when it gets an event that should start the service, the service starts"
+
+(let [gen (->
+           [(newlink "dummy0" "no" "no")
+            (newlink "dummy0" "yes" "no")
+            (newlink "eth1" "no" "no")]
+           event-generator)]
+  (set upsies [])
+  (ifwait.run ["-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies [:d :u]))
+
+"when it gets an event that should stop the service, the service stops"
+
+(let [gen (->
+           [(newlink "dummy0" "no" "no")
+            (newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "no" "no")
+            ]
+           event-generator)]
+  (set upsies [])
+  (ifwait.run ["-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies [:d :u :d]))
+
+"it does not call s6-rc again if the service is already in required state"
+
+(let [gen (->
+           [(newlink "dummy0" "no" "no")
+            (newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "yes" "yes")
+            (newlink "dummy0" "yes" "yes")
+            (newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "no" "no")
+            ]
+           event-generator)]
+  (set upsies [])
+  (ifwait.run ["-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies [:d :u :d]))
+
+"it handles an error return from s6-rc"
+
+(set fake-system
+     (fn [s]
+       (if (s:match "-u change addmember")
+           (table.insert upsies :u)
+           (s:match "-d change addmember")
+           (table.insert upsies :d))
+       (error "false")
+       ))
+
+(let [gen (->
+           [(newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "yes" "yes")
+            (newlink "dummy0" "yes" "yes")
+            (newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "no" "no")
+            ]
+           event-generator)]
+  (set upsies [])
+  (ifwait.run ["-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies [:u :u :u :u]))