From 26963cfc2dfd8ba6bce927535317d799dda15102 Mon Sep 17 00:00:00 2001
From: aszlig <aszlig@redmoonstudios.org>
Date: Thu, 22 Oct 2015 19:40:00 +0200
Subject: [PATCH 1/2] switch-to-configuration: Fix unit name quoting.

Clearly it would be the best if we'd directly generate mount units
instead of converting /etc/fstab. But in order to do that we need to
test it throughly so this approach is for the next stable release.

This fix however is intended for inclusion into release-14.12 and
release-15.09.

Using a simple regular expression unfortunately isn't sufficient for
proper mount unit name quoting/escaping and there is a utility in
systemd called systemd-escape which does nothing less than that.

Of course, using an external program to escape the unit name is way more
expensive and causes us to fork for each mount point.

But given that we already do quite a lot of forks just for unit starting
and stopping, I think it doesn't matter that much. Well, except if you
have a whole bunch of mount points.

However, if the latter is the case and you have thousands of mount
points, you probably have stumbled over this already if your mount point
contains a dash.

As for my motivation to fix this: I've stumbled on this while trying to
fix the "none" backend test for NixOps (see NixOS/nixops#350), where the
target machines use /nix/.ro-store and /nix/.rw-store as mount points.

The implementation we had so far did improperly escape it so those mount
points got the following unit files:

 * nix-.ro-store.mount
 * nix-.rw-store.mount

The correct names for these units are however:

 * nix-.ro\x2dstore.mount
 * nix-.rw\x2dstore.mount

So using systemd-escape now properly generates these names.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
---
 .../system/activation/switch-to-configuration.pl   | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/nixos/modules/system/activation/switch-to-configuration.pl b/nixos/modules/system/activation/switch-to-configuration.pl
index 655fbab2a843..747de89905dc 100644
--- a/nixos/modules/system/activation/switch-to-configuration.pl
+++ b/nixos/modules/system/activation/switch-to-configuration.pl
@@ -261,12 +261,12 @@ while (my ($unit, $state) = each %{$activePrev}) {
 
 sub pathToUnitName {
     my ($path) = @_;
-    die unless substr($path, 0, 1) eq "/";
-    return "-" if $path eq "/";
-    $path = substr($path, 1);
-    $path =~ s/\//-/g;
-    # FIXME: handle - and unprintable characters.
-    return $path;
+    open my $cmd, "-|", "systemd-escape", "--suffix=mount", "-p", $path
+        or die "Unable to escape $path!\n";
+    my $escaped = join "", <$cmd>;
+    chomp $escaped;
+    close $cmd or die;
+    return $escaped;
 }
 
 sub unique {
@@ -290,7 +290,7 @@ my ($newFss, $newSwaps) = parseFstab "$out/etc/fstab";
 foreach my $mountPoint (keys %$prevFss) {
     my $prev = $prevFss->{$mountPoint};
     my $new = $newFss->{$mountPoint};
-    my $unit = pathToUnitName($mountPoint) . ".mount";
+    my $unit = pathToUnitName($mountPoint);
     if (!defined $new) {
         # Filesystem entry disappeared, so unmount it.
         $unitsToStop{$unit} = 1;

From 80fb17b251d163345ddf8aa14be283dd2f9cbcc5 Mon Sep 17 00:00:00 2001
From: aszlig <aszlig@redmoonstudios.org>
Date: Thu, 22 Oct 2015 19:50:12 +0200
Subject: [PATCH 2/2] nixos/nix-daemon: Require .mount for /nix/store.

Also related to NixOS/nixops#350, because while switching to the new
configuration, depending on /nix/store also propagates to the mount
points for /nix/.ro-store and /nix/.rw-store and we don't get an error
while trying to unmount them (because nix-daemon needs to be stopped for
unmounting these paths).

While Nix does have the option to set a different store path, I've found
only hardcoded references in nix-daemon.nix, so I'm using a hardcoded
reference here as well, because after all customizing the store path
will probably only make sense on non-NixOS systems.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
---
 nixos/modules/services/misc/nix-daemon.nix | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/nixos/modules/services/misc/nix-daemon.nix b/nixos/modules/services/misc/nix-daemon.nix
index 4aed91c34978..5f73191c639f 100644
--- a/nixos/modules/services/misc/nix-daemon.nix
+++ b/nixos/modules/services/misc/nix-daemon.nix
@@ -366,6 +366,8 @@ in
           // { CURL_CA_BUNDLE = "/etc/ssl/certs/ca-bundle.crt"; }
           // config.networking.proxy.envVars;
 
+        unitConfig.RequiresMountsFor = "/nix/store";
+
         serviceConfig =
           { Nice = cfg.daemonNiceLevel;
             IOSchedulingPriority = cfg.daemonIONiceLevel;