switch to s6-linux-init and s6-rc

This is at the point where it runs a getty and a pile of s6-supervise
processes, though it doesn't seem to run the things being supervised

tests/pseudofiles/result.expected

@@ -0,0 +1,13 @@
+/service/s6-linux-init-runleveld/notification-fd f 0644 0 0 echo -n "3" |qprint -d
+/service/s6-linux-init-runleveld/run f 0755 0 0 echo -n "       hello=0A	      newline=0A" |qprint -d
+/service/s6-linux-init-runleveld d 0755 0 0
+/service/s6-linux-init-shutdownd/fifo i 0600 0 0 f
+/service/s6-linux-init-shutdownd/run f 0755 0 0 echo -n "s6-linux-init/bin/s6-linux-init-shutdownd -c  =22/etc/s6-linux-init/current=22 -g 3000=0A" |qprint -d
+/service/s6-linux-init-shutdownd d 0755 0 0
+/service/s6-svscan-log/fifo i 0600 0 0 f
+/service/s6-svscan-log/notification-fd f 0644 0 0 echo -n "3" |qprint -d
+/service/s6-svscan-log/run f 0644 0 0 echo -n "gdsgdfgsdgf=0A" |qprint -d
+/service/s6-svscan-log d 0755 0 0
+/service d 0755 0 0
+
+/uncaught-logs d 2750 0 0

tests/pseudofiles/run.sh

@@ -0,0 +1,17 @@
+set -e
+
+expr=$(cat <<"EXPR"
+let
+  overlay = import ./overlay.nix;
+  nixpkgs = import <nixpkgs> (  {overlays = [overlay]; });
+  structure = import ./tests/pseudofiles/structure.nix;
+in nixpkgs.pkgs.pseudofile "pseudo.s6-init" structure
+EXPR
+       )
+
+NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build -E "${expr}" -o tests/pseudofiles/result $*
+diff tests/pseudofiles/result tests/pseudofiles/result.expected
+test -f  /tmp/out.squashfs && rm /tmp/out.squashfs
+nix-shell -p squashfsTools -p qprint --run "mksquashfs - /tmp/out.squashfs -p '/ d 755 0 0' -pf tests/pseudofiles/result -quiet -no-progress"
+foo="$(nix-shell -p squashfsTools --run 'unsquashfs -cat /tmp/out.squashfs service/s6-linux-init-runleveld/run')"
+test "$foo" = "$(printf "hello\nworld")"

tests/pseudofiles/structure.nix

@@ -0,0 +1,45 @@
+let
+  dir = contents: { type = "d"; inherit contents; };
+  structure = {
+    service = dir {
+      s6-linux-init-runleveld = dir {
+        notification-fd = { file = "3"; };
+        run = {
+          file = ''
+           hello
+           world
+          '';
+          mode = "0755";
+        };
+      };
+      s6-linux-init-shutdownd = dir {
+        fifo = {
+          type = "i";
+          subtype = "f";
+          mode = "0600";
+        };
+        run = {
+          file = ''
+              s6-linux-init/bin/s6-linux-init-shutdownd -c  "/etc/s6-linux-init/current" -g 3000
+            '';
+          mode = "0755";
+        };
+
+      };
+      s6-svscan-log = dir {
+        fifo = {
+          type = "i";
+          subtype = "f";
+          mode = "0600";
+        };
+        notification-fd = { file = "3"; };
+        run = {
+          file = ''
+              gdsgdfgsdgf
+          '';
+        };
+      };
+    };
+    uncaught-logs = (dir {}) // {mode = "2750";};
+  };
+in structure