#!/bin/bash
# Create an initrd image for opening an encrypted device

# Get the actual installed kernel version, not the running kernel, which might be different
KVER=`file /boot/vmlinuz | perl -pe 's|.* version (.*?) .*|\1|'`
OUTPUT_FILE=/boot/initramfs-$KVER.cpio.gz

# Possible to override the filename
[ ! -z $1 ] && OUTPUT_FILE=$1

echo -n "Creating $OUTPUT_FILE..."

# Binaries needed in the image
BINS="/bin/bash /bin/cat /bin/cp /bin/dd /bin/echo /bin/ln /bin/ls /bin/mknod /bin/killall /bin/mount /bin/rm /bin/sed /bin/uname /bin/mkdir /bin/sh /bin/sleep /bin/umount /bin/grep"
BINS="$BINS /usr/bin/stat /usr/bin/kbd_mode /usr/bin/setfont /usr/bin/loadkeys /usr/bin/dumpkeys"

SBINS="/sbin/dmsetup /sbin/udevd /sbin/udevadm /sbin/blkid /sbin/modprobe /sbin/insmod /sbin/switch_root"
SBINS="$SBINS /usr/sbin/cryptsetup"

# Create a temporrary working directory, the X chars are replace by a random number code
WDIR=$(mktemp -d /tmp/initrd-work.XXXXXXXXXX)
LIBS=$(mktemp /tmp/libs.XXXXXXXXXX)

# Create base directory structure
mkdir -p $WDIR/{bin,dev,lib/firmware,run,sbin,sys,proc,usr/lib}
mkdir -p $WDIR/etc/{modprobe.d,udev/rules.d}
touch $WDIR/etc/modprobe.d/modprobe.conf
ln -s lib $WDIR/lib64

# Create necessary device nodes
mknod -m 640 $WDIR/dev/console c 5 1
mknod -m 664 $WDIR/dev/null    c 1 3

# Install the init file, a custom script used to unlock the root device
install -m0755 /usr/bin/mkinitramfs.init $WDIR/init

# Install the binaries to the temporary dir, use ldd to find the linked libraries
for f in $BINS; do
  ldd $f | sed "s/\t//" | cut -d " " -f1 >> $LIBS
  cp $f $WDIR/bin
done

for sf in $SBINS; do
  ldd $sf | sed "s/\t//" | cut -d " " -f1 >> $LIBS
  cp $sf $WDIR/sbin
done

# Install libraries
sort $LIBS | uniq | while read lib; do
  if [ -e "/lib/$lib" ]; then cp "/lib/$lib" $WDIR/lib; fi
  if [ -e $lib ]; then cp "$lib" $WDIR/lib; fi
  if [ -e "/usr/lib/$lib" ]; then cp "/usr/lib/$lib" $WDIR/lib; fi
done

# Copy udev settings
if [ -d /lib/udev ]; then
  cp -a /lib/udev $WDIR/lib
fi

# Remove virtualbox rules, not needed during boot and causing errors about missing scripts
rm -f $WDIR/lib/udev/rules.d/*-vboxdrv.rules

# Fix systems where /sbin points to /usr/bin
if [ -L /sbin ]; then
  SBINTARGET=`readlink /sbin`
  mkdir -p $WDIR/$SBINTARGET
  mv $WDIR/sbin/* $WDIR/$SBINTARGET
  rmdir $WDIR/sbin
  ln -s $SBINTARGET $WDIR/sbin
fi
# Fix systems where /bin points to /usr/bin
if [ -L /bin ]; then
  BINTARGET=`readlink /bin`
  mkdir -p $WDIR/$BINTARGET
  mv $WDIR/bin/* $WDIR/$BINTARGET
  rmdir $WDIR/bin
  ln -s $BINTARGET $WDIR/bin
fi
# Fix systems where /lib points to /usr/lib
if [ -L /lib ]; then
  LIBTARGET=`readlink /lib`
  mkdir -p $WDIR/$LIBTARGET
  mv $WDIR/lib/* $WDIR/$LIBTARGET
  rmdir $WDIR/lib
  ln -s $LIBTARGET $WDIR/lib
fi

# Install any firmware present. Needed if the network module is included and firmware for it is required, increases image size significantly
#cp -a /lib/firmware $WDIR/lib

# Copy kernel modules. This is needed if the keyboard/USB/filesystem/etc drivers are compiled as modules
# Without these modules it would be impossible to load the rootfs or unlock (type in) the encrypted root password
find /lib/modules/$KVER/kernel/{crypto,fs,lib}                      \
     /lib/modules/$KVER/kernel/drivers/{block,ata,gpu,hid,input}    \
     /lib/modules/$KVER/kernel/drivers/{md,firewire,scsi,message}   \
     /lib/modules/$KVER/kernel/drivers/{pcmcia,virtio,usb}          \
     -type f 2> /dev/null | cpio --make-directories -p --quiet $WDIR
cp /lib/modules/$KVER/modules.{builtin,order} $WDIR/lib/modules/$KVER
depmod -b $WDIR $KVER

# Create the compressed ram image
cd $WDIR &&
find . | cpio -o -H newc | gzip -9 > $OUTPUT_FILE

# Clean up
rm -fr $WDIR $LIBS
echo "Done."