nixos/stage-2-init: Clean up legacy commands

We can perform most of the mkdir/ln/rm using systemd-tmpfiles
instead which cleans up the script.

/bin and /home are created by their activation script snippets

usbfs is deprecated and unused.

hwclock seems to be automatically executed by systemd on startup.

The mkswap to prevent hibernation cycles seems to be executed by systemd
as well since the provided regression tests succeeds.

nixos/modules/system/boot/stage-2-init.sh

@@ -12,10 +12,6 @@ for o in $(</proc/cmdline); do
             # Show each command.
             set -x
             ;;
-        resume=*)
-            set -- $(IFS==; echo $o)
-            resumeDevice=$2
-            ;;
     esac
 done
 
@@ -72,46 +68,12 @@ if [ -n "@readOnlyStore@" ]; then
 fi
 
 
-# Provide a /etc/mtab.
-install -m 0755 -d /etc
-test -e /etc/fstab || touch /etc/fstab # to shut up mount
-rm -f /etc/mtab* # not that we care about stale locks
-ln -s /proc/mounts /etc/mtab
-
-
-# More special file systems, initialise required directories.
-[ -e /proc/bus/usb ] && mount -t usbfs usbfs /proc/bus/usb # UML doesn't have USB by default
-install -m 01777 -d /tmp
-install -m 0755 -d /var/{log,lib,db} /nix/var /etc/nixos/ \
-    /run/lock /home /bin # for the /bin/sh symlink
-
-
-# Miscellaneous boot time cleanup.
-rm -rf /var/run /var/lock
-rm -f /etc/{group,passwd,shadow}.lock
-
-
-# Also get rid of temporary GC roots.
-rm -rf /nix/var/nix/gcroots/tmp /nix/var/nix/temproots
-
-
-# For backwards compatibility, symlink /var/run to /run, and /var/lock
-# to /run/lock.
-ln -s /run /var/run
-ln -s /run/lock /var/lock
-
-
-# Clear the resume device.
-if test -n "$resumeDevice"; then
-    mkswap "$resumeDevice" || echo 'Failed to clear saved image.'
-fi
-
-
 # Use /etc/resolv.conf supplied by systemd-nspawn, if applicable.
 if [ -n "@useHostResolvConf@" ] && [ -e /etc/resolv.conf ]; then
     resolvconf -m 1000 -a host </etc/resolv.conf
 fi
 
+
 # Log the script output to /dev/kmsg or /run/log/stage-2-init.log.
 # Only at this point are all the necessary prerequisites ready for these commands.
 exec {logOutFd}>&1 {logErrFd}>&2
@@ -133,22 +95,9 @@ echo "running activation script..."
 $systemConfig/activate
 
 
-# Restore the system time from the hardware clock.  We do this after
-# running the activation script to be sure that /etc/localtime points
-# at the current time zone.
-if [ -e /dev/rtc ]; then
-    hwclock --hctosys
-fi
-
-
 # Record the boot configuration.
 ln -sfn "$systemConfig" /run/booted-system
 
-# Prevent the booted system from being garbage-collected. If it weren't
-# a gcroot, if we were running a different kernel, switched system,
-# and garbage collected all, we could not load kernel modules anymore.
-ln -sfn /run/booted-system /nix/var/nix/gcroots/booted-system
-
 
 # Run any user-specified commands.
 @shell@ @postBootCommands@

nixos/modules/system/boot/systemd/tmpfiles.nix

@@ -100,5 +100,22 @@ in
         '';
       })
     ];
+
+    systemd.tmpfiles.rules = [
+      "d  /etc/nixos                         0755 root root - -"
+      "d  /nix/var                           0755 root root - -"
+      "L+ /nix/var/nix/gcroots/booted-system 0755 root root - /run/booted-system"
+      "d  /run/lock                          0755 root root - -"
+      "d  /var/db                            0755 root root - -"
+      "L  /etc/mtab                          -    -    -    - ../proc/mounts"
+      "L  /var/lock                          -    -    -    - ../run/lock"
+      # Boot-time cleanup
+      "R! /etc/group.lock                    -    -    -    - -"
+      "R! /etc/passwd.lock                   -    -    -    - -"
+      "R! /etc/shadow.lock                   -    -    -    - -"
+      "R! /etc/mtab*                         -    -    -    - -"
+      "R! /nix/var/nix/gcroots/tmp           -    -    -    - -"
+      "R! /nix/var/nix/temproots             -    -    -    - -"
+    ];
   };
 }

nixos/tests/hibernate.nix

@@ -117,6 +117,11 @@ in makeTest {
       resume = create_named_machine("resume")
       resume.start()
       resume.succeed("grep 'not persisted to disk' /run/test/suspended")
+
+      # Ensure we don't restore from hibernation when booting again
+      resume.crash()
+      resume.wait_for_unit("default.target")
+      resume.fail("grep 'not persisted to disk' /run/test/suspended")
     '';
 
 }