#!/bin/bash

set -e
set -x

VER=$(uname -r)
NAME=$(basename $0)

rm -fr root
mkdir root
cp -a $0 root/
pushd root

mkdir -p dev bin etc/udhcpc etc/init.d lib/modules
mknod dev/console c 5 1
mknod dev/tty2 c 4 2
mknod dev/tty3 c 4 3
mknod dev/tty4 c 4 4

wget http://www.busybox.net/downloads/binaries/latest/busybox-i686 -O bin/busybox
chmod +x bin/busybox
ln -s bin/busybox init
ln -s busybox bin/sh

wget -q http://git.busybox.net/busybox/plain/examples/udhcp/simple.script -O etc/udhcpc/default.script
chmod +x etc/udhcpc/default.script

cat > etc/init.d/rcS <<EOF
#!/bin/sh
/bin/busybox mkdir -p root dev bin sbin usr/bin usr/sbin proc sys dev/pts
/bin/busybox --install -s
mount -t proc proc /proc
mount -t sysfs sysfs /sys
mount -t devpts devpts /dev/pts
mdev -s
echo /sbin/mdev >/proc/sys/kernel/hotplug
find /sys -name 'modalias' -type f -exec sort -u {} \; | sort | uniq | grep -v ^acpi | xargs -n 1 /sbin/modprobe
echo root::0:0:root:/root:/bin/sh > /etc/passwd
ifconfig lo up
ifconfig eth0 up
udhcpc -i eth0 -R -b -s /etc/udhcpc/default.script
hostname ${NAME}
EOF
chmod +x etc/init.d/rcS

cat > etc/inittab <<EOF
::sysinit:/etc/init.d/rcS
#::askfirst:/bin/sh
::ctrlaltdel:/sbin/reboot
::shutdown:/sbin/swapoff -a
::shutdown:/bin/umount -a -r
::restart:/sbin/init
::respawn:/usr/sbin/telnetd -F
tty2::respawn:/sbin/getty 115200 tty2
tty3::respawn:/sbin/getty 115200 tty3
tty4::respawn:/sbin/getty 115200 tty4
EOF

cp -a /lib/modules/${VER} lib/modules/

popd
find . |  cpio -o -H newc | gzip > initrd.cpio.gz