dragora/stages/2/02-initramfs

# Build script for the single-purpose initramfs (liveCD).
#
# Copyright (c) 2017 Matias Fonzo, <selk@dragora.org>.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

mkdir -p -- "${rootdir}/initrd"

cat << "EOF" > "${rootdir}/initrd/init"
#! /bin/busybox ash

/bin/busybox sleep 7

/bin/busybox mkdir -p /dev /proc /sys /.UP

/bin/busybox mount -n -o nosuid,noexec,nodev -t proc proc /proc
/bin/busybox mount -n -o nosuid,noexec,nodev -t sysfs sysfs /sys
/bin/busybox mount -n -t devtmpfs devtmpfs /dev

/bin/busybox sleep 3

/bin/busybox mount -n -o rw,size=100% -t tmpfs tmpfs /.UP
/bin/busybox mkdir /.UP/cdrom /.UP/rw /.UP/squash /.UP/union

# Mount ISO and system image
/bin/busybox mount -n -t iso9660 LABEL=Dragora /.UP/cdrom
/bin/busybox mount -n -o loop -t squashfs /.UP/cdrom/dragora.sfs /.UP/squash

# Merge Squashfs with AUFS
/bin/busybox mount -o br=/.UP/rw:/.UP/squash -t aufs none /.UP/union

# Move virtual file systems prior to switch_root
/bin/busybox mount --move /dev   /.UP/union/dev
/bin/busybox mount --move /proc  /.UP/union/proc
/bin/busybox mount --move /sys   /.UP/union/sys

exec /bin/busybox switch_root /.UP/union /sbin/init

EOF

chmod 750 "${rootdir}/initrd/init"

# Make initramfs
cd -- "${rootdir}/initrd"
rm -f initrd.img

find . | sed 's!^./!!' | cpio -oC512 -H newc | \
 lzip -9c --dictionary-size=16 > initrd.img