* Start of the installer: copy the closure of Nix to the target device

so we can then do nix-env operations in a chroot to do the actual
  installation.

svn path=/nixu/trunk/; revision=6977

test/installer.nix

@@ -0,0 +1,15 @@
+{ stdenv, genericSubstituter, shell, nix
+}:
+
+genericSubstituter {
+  src = ./installer.sh;
+  isExecutable = true;
+  inherit shell nix;
+  
+  nixClosure = stdenv.mkDerivation {
+    name = "closure";
+    builder = builtins.toFile "builder.sh"
+      "source $stdenv/setup; /nix/bin/nix-store -qR $nix > $out";
+    inherit nix;
+  };
+}

test/installer.sh

@@ -0,0 +1,41 @@
+#! @shell@
+
+# Syntax: installer.sh <DEVICE> <NIX-EXPR>
+# (e.g., installer.sh /dev/hda1 ./my-machine.nix)
+
+# - mount target device
+# - make Nix store etc.
+# - copy closure of rescue env to target device
+# - register validity
+# - start the "target" installer in a chroot to the target device
+#   * do a nix-pull
+#   * nix-env -p system-profile -i <nix-expr for the configuration>
+#   * run hook scripts provided by packages in the configuration?
+# - install/update grub
+
+targetDevice="$1"
+
+if test -z "$targetDevice"; then
+    echo "syntax: installer.sh <targetDevice>"
+    exit 1
+fi
+
+
+# Make sure that the target device isn't mounted.
+umount "$targetDevice" 2> /dev/null
+
+
+# Check it.
+fsck "$targetDevice" || exit 1
+
+
+# Mount the target device.
+mountPoint=/tmp/inst-mnt
+mkdir -p $mountPoint
+mount "$targetDevice" $mountPoint || exit 1
+
+
+# Copy Nix to the Nix store on the target device.
+mkdir -p $mountPoint/nix/store/
+cp -prd $(cat @nixClosure@) $mountPoint/nix/store/ || exit 1
+

test/rescue-system.nix

@@ -98,6 +98,13 @@ rec {
   };
 
 
+  # The installer.
+  nixosInstaller = import ./installer.nix {
+    inherit (pkgs) stdenv genericSubstituter nix;
+    shell = pkgs.bash + "/bin/sh";
+  };
+
+
   # Since the CD is read-only, the mount points must be on disk.
   cdMountPoints = pkgs.stdenv.mkDerivation {
     name = "mount-points";