* Scripts to set up and run the absolute minimal pure Nix

environment; that is, an operating system environment in which there
  is (essentially) only a store.

  The script `make-disk.sh' creates an ext2 disk image, creates a Nix
  store in it, and copies the closure of the bash package (from
  nixpkgs) to it.  The script `run.sh' then starts bash in a UML
  virtual machine.

  The contents of the image after creation look like this:

  $ ls -l
  drwxr-xr-x    2 root     root         1024 2004-02-14 19:13 dev
  lrwxrwxrwx    1 root     root           61 2004-02-14 23:34 init -> /nix/store/e40873ece7a010752ad72b4262b23d28-bash-2.05b/bin/sh
  drwx------    2 root     root        12288 2004-02-14 19:13 lost+found
  drwxr-xr-x    4 root     root         1024 2004-02-14 19:13 nix
  drwxr-xr-x    2 root     root         1024 2004-02-14 19:13 proc
  drwxrwxrwt    2 root     root         1024 2004-02-14 19:13 tmp

  The next step is to add all the other stuff that goes into a working
  system (coreutils, etc.).  BTW, if you don't have `ls' you can still
  list directories by doing `echo *' :-)

  Nix itself should also be Nixified so that it can be put into the
  store.

svn path=/nixu/trunk/; revision=783

bootstrap.nix

@@ -0,0 +1,4 @@
+let {
+  pkgs = import pkgs/system/i686-linux.nix;
+  body = pkgs.bash;
+}

fill-disk.sh

@@ -0,0 +1,64 @@
+#! /bin/sh -e
+
+initExpr=$1
+
+make_dir() {
+    mode=$1
+    name=$2
+    echo creating $name...
+    if ! test -d $root/$name; then mkdir $root/$name; fi
+    chmod $mode $root/$name
+}
+
+root=/tmp/mnt
+
+echo mounting...
+mount -t ext2 /dev/discs/disc0/disc $root
+
+make_dir 00755 /dev
+make_dir 00755 /proc
+make_dir 01777 /tmp
+make_dir 00755 /nix
+make_dir 00755 /nix/store
+make_dir 00755 /nix/var
+make_dir 00755 /nix/var/nix
+make_dir 00755 /nix/var/nix/db
+make_dir 00755 /nix/var/log
+make_dir 00755 /nix/var/log/nix
+
+export NIX_ROOT=$root
+
+echo initialising Nix DB...
+/nix/bin/nix-store --init
+
+echo verifying Nix DB...
+/nix/bin/nix-store --verify
+
+echo registering valid paths...
+(while read storepath; do
+    echo PATH $storepath
+    if ! /nix/bin/nix-store --isvalid $storepath 2> /dev/null; then
+        (unset NIX_ROOT; /nix/bin/nix-store --dump $storepath) | /nix/bin/nix-store --restore $storepath
+        /nix/bin/nix-store --validpath $storepath
+    fi
+done) < /tmp/storepaths
+
+echo registering successors...
+(while read line; do
+    echo SUCC $line
+    /nix/bin/nix-store --successor $line
+done) < /tmp/successors
+
+echo setting init symlink...
+initPath=$(/nix/bin/nix-store -qn $initExpr)
+rm -f $root/init
+ln -s $initPath/bin/sh $root/init
+
+echo unmounting...
+umount $root
+
+echo syncing...
+sync
+
+echo halting...
+/sbin/halt -d -f

make-disk.sh

@@ -0,0 +1,34 @@
+#! /bin/sh -e
+
+image=/tmp/disk.img
+size=$(expr 256 \* 1024 \* 1024)
+storepaths=/tmp/storepaths
+successors=/tmp/successors
+
+if ! test -f $image; then 
+
+    echo creating empty disk of $size bytes in $image...
+    # Note: this is a sparse file.
+    dd if=/dev/zero of=$image bs=1 seek=$(expr $size - 1) count=1
+
+    echo creating disk image in $image...
+    /sbin/mke2fs -F $image
+
+fi
+
+
+# What to copy?
+storeexpr=$(nix-instantiate ./bootstrap.nix)
+nix-store -rB $storeexpr
+nix-store -qn --requisites $storeexpr > $storepaths
+
+(while read storepath; do
+  nix-store -q --predecessors $storepath | (while read predecessor; do
+    echo $predecessor $storepath
+  done) 
+done) < $storepaths > $successors
+
+# Fill the disk with the minimal Nix store.
+if ! test -d /tmp/mnt; then mkdir /tmp/mnt; fi
+linux ubd0=$image root=/dev/root rootflags=/ rootfstype=hostfs init="$(pwd)/fill-disk.sh $storeexpr"
+

run.sh

@@ -0,0 +1,5 @@
+#! /bin/sh -e
+
+image=/tmp/disk.img
+
+linux ubd0=$image init="/init"