#!/bin/bash

# The currect work dir contains a dir named ./chroot (which can be
# a symlink to a partition as in my case) and is where we are going
# to build the system.
#
# ./embedded_packages contains packages built using:
#    emerge -B <package_name>
#
# The packages are then placed inside /usr/portage/packages/
# I moved them to a dir named embedded_packages in the current
# work dir for easy access and so they dont get mixed with the host's
# packages.

# Next we untar the packages into the chroot.

# - baselayout is the standard gentoo baselayout with all the bells
#   and whisltes.
#
# - tinylogin gives us a getty and some other usefull stuff such as 
#   passwd and su. We will symlink the names of the tools later.
#
# - busybox gives us pretty much the rest of the necessary standard
#   unix tools. We will symlink the names of the tools later.
#
# - standard glibc. Overkill but I still havent tried with uClibc.
# and rest of the stuff to comply with baselayout.
#
# Please note that the bare minimum is extracted from all the following
# packages apart from glibc and baselayout. In these two cases everything is
# dumped into the chroot without looking any further.
#
# Note regarding devfsd: The system works without devfsd but since it didnt
# fill much space I thought of including it.
#
# Note regarding bash: we have busybox, but many baselayout rc scripts require
# bash and since I didnt want to touch baselayout I was forced to include
# bash.
#
# Note regarding e2fsprogs: baselayout uses fsck and also fsck.ext3 in my case
# since I use ext3. So I only extract these from the package.
#
# Note regarding net-tools and coreutils: baselayout uses hostname and install
# so I only extract these files from these packages.
#
# gawk and grep are also used by baselayout so they are included although in
# the case of gawk the bare minimum is extracted.

# Here is a brief list of the packages you need to create using emerge -B
#   baselayout, tinylogin, busybox, glibc, grep, devfsd, bash, gawk,
#   e2fsprogs, net-tootls and coreutils.
#
# Remember once you create these move them to ./embedded_packages (or change
# the path below). 

tar xjpf ./embedded_packages/baselayout-* -C ./chroot/
tar xjpf ./embedded_packages/tinylogin-* -C ./chroot/
tar xjpf ./embedded_packages/busybox-* -C ./chroot/
tar xjpf ./embedded_packages/glibc-* -C ./chroot/
tar xjpf ./embedded_packages/grep-* -C ./chroot/
tar xjpf ./embedded_packages/devfsd-* -C ./chroot/

tar xjpf ./embedded_packages/bash-* -C ./chroot/ ./bin/bash

ln -s /bin/bash ./chroot/bin/sh

tar xvjpf ./embedded_packages/gawk-* -C ./chroot/ \
  ./lib/rcscripts/* ./usr/bin/awk ./usr/bin/gawk \
  ./usr/share/awk/* ./usr/lib/awk/* ./bin/gawk ./bin/gawk-* ./bin/awk \

tar xjpvf ./embedded_packages/e2fsprogs-* -C ./chroot/ \
  ./lib/libuuid.so.1 ./lib/libblkid.so.1.0 ./lib/libblkid.so.1 \
  ./lib/libuuid.so.1.2 ./sbin/fsck ./sbin/fsck.ext3 ./sbin/e2fsck \
  ./lib/libext2fs.so.2 ./lib/libext2fs.so.2.4 ./lib/libcom_err.so*

tar xvjpf ./embedded_packages/net-tools-* -C ./chroot/ \
  ./bin/hostname

tar xvjpf ./embedded_packages/coreutils-* -C ./chroot/ \
  ./bin/install



# I dont know where to get /dev so I just copy it from my host system. If you
# know a better way let me know. I could use a stage file, but I preferred
# this method since while building the embedded system it is more plausible
# the user has a /dev than a stage file at hand.

cp -a /dev ./chroot/


# Now the symlinks for tinylogin and busybox
#
# NOTE: If you see any errors while linking dont worry and ignore them.

ln -s /bin/busybox ./chroot/bin/basename
ln -s /bin/busybox ./chroot/bin/cat
ln -s /bin/busybox ./chroot/bin/chgrp
ln -s /bin/busybox ./chroot/bin/chmod
ln -s /bin/busybox ./chroot/bin/chown
ln -s /bin/busybox ./chroot/bin/chroot
ln -s /bin/busybox ./chroot/bin/cp
ln -s /bin/busybox ./chroot/bin/cut
ln -s /bin/busybox ./chroot/bin/date
ln -s /bin/busybox ./chroot/bin/dd
ln -s /bin/busybox ./chroot/bin/df
ln -s /bin/busybox ./chroot/bin/dirname
ln -s /bin/busybox ./chroot/bin/dmesg
ln -s /bin/busybox ./chroot/bin/du
ln -s /bin/busybox ./chroot/bin/echo
ln -s /bin/busybox ./chroot/bin/env
ln -s /bin/busybox ./chroot/bin/false
ln -s /bin/busybox ./chroot/bin/grep
ln -s /bin/busybox ./chroot/bin/gunzip
ln -s /bin/busybox ./chroot/bin/gzip
ln -s /bin/busybox ./chroot/bin/head
ln -s /bin/busybox ./chroot/bin/kill
ln -s /bin/busybox ./chroot/bin/killall
ln -s /bin/busybox ./chroot/bin/ln
ln -s /bin/busybox ./chroot/bin/ls
ln -s /bin/busybox ./chroot/bin/lsmod
ln -s /bin/busybox ./chroot/bin/mkdir
ln -s /bin/busybox ./chroot/bin/mknod
ln -s /bin/busybox ./chroot/bin/more
ln -s /bin/busybox ./chroot/bin/mount
ln -s /bin/busybox ./chroot/bin/mv
ln -s /bin/busybox ./chroot/bin/pidof
ln -s /bin/busybox ./chroot/bin/ping
ln -s /bin/busybox ./chroot/bin/ps
ln -s /bin/busybox ./chroot/bin/pwd
ln -s /bin/busybox ./chroot/bin/readlink
ln -s /bin/busybox ./chroot/bin/rm
ln -s /bin/busybox ./chroot/bin/rmdir
ln -s /bin/busybox ./chroot/bin/sed
ln -s /bin/busybox ./chroot/bin/sleep
ln -s /bin/busybox ./chroot/bin/sort
ln -s /bin/busybox ./chroot/bin/sync
ln -s /bin/busybox ./chroot/bin/tail
ln -s /bin/busybox ./chroot/bin/tar
ln -s /bin/busybox ./chroot/bin/test
ln -s /bin/busybox ./chroot/bin/touch
ln -s /bin/busybox ./chroot/bin/true
ln -s /bin/busybox ./chroot/bin/umount
ln -s /bin/busybox ./chroot/bin/uname
ln -s /bin/busybox ./chroot/bin/uniq
ln -s /bin/busybox ./chroot/bin/wc
ln -s /bin/busybox ./chroot/bin/whoami
ln -s /bin/busybox ./chroot/bin/yes
ln -s /bin/busybox ./chroot/bin/zcat
ln -s /bin/busybox ./chroot/sbin/halt
ln -s /bin/busybox ./chroot/sbin/ifconfig
ln -s /bin/busybox ./chroot/sbin/init
ln -s /bin/busybox ./chroot/sbin/losetup
ln -s /bin/busybox ./chroot/sbin/lsmod
ln -s /bin/busybox ./chroot/sbin/mkswap
ln -s /bin/busybox ./chroot/sbin/modprobe
ln -s /bin/busybox ./chroot/sbin/pidof
ln -s /bin/busybox ./chroot/sbin/pivot_root
ln -s /bin/busybox ./chroot/sbin/poweroff
ln -s /bin/busybox ./chroot/sbin/reboot
ln -s /bin/busybox ./chroot/sbin/route
ln -s /bin/busybox ./chroot/sbin/swapoff
ln -s /bin/busybox ./chroot/sbin/swapon
ln -s /bin/busybox ./chroot/usr/bin/basename
ln -s /bin/busybox ./chroot/usr/bin/cat
ln -s /bin/busybox ./chroot/usr/bin/chgrp
ln -s /bin/busybox ./chroot/usr/bin/chmod
ln -s /bin/busybox ./chroot/usr/bin/chown
ln -s /bin/busybox ./chroot/usr/bin/chroot
ln -s /bin/busybox ./chroot/usr/bin/chvt
ln -s /bin/busybox ./chroot/usr/bin/clear
ln -s /bin/busybox ./chroot/usr/bin/cmp
ln -s /bin/busybox ./chroot/usr/bin/cp
ln -s /bin/busybox ./chroot/usr/bin/cut
ln -s /bin/busybox ./chroot/usr/bin/date
ln -s /bin/busybox ./chroot/usr/bin/dd
ln -s /bin/busybox ./chroot/usr/bin/df
ln -s /bin/busybox ./chroot/usr/bin/dirname
ln -s /bin/busybox ./chroot/usr/bin/du
ln -s /bin/busybox ./chroot/usr/bin/echo
ln -s /bin/busybox ./chroot/usr/bin/env
ln -s /bin/busybox ./chroot/usr/bin/false
ln -s /bin/busybox ./chroot/usr/bin/fbset
ln -s /bin/busybox ./chroot/usr/bin/find
ln -s /bin/busybox ./chroot/usr/bin/free
ln -s /bin/busybox ./chroot/usr/bin/head
ln -s /bin/busybox ./chroot/usr/bin/kill
ln -s /bin/busybox ./chroot/usr/bin/killall
ln -s /bin/busybox ./chroot/usr/bin/ln
ln -s /bin/busybox ./chroot/usr/bin/ls
ln -s /bin/busybox ./chroot/usr/bin/mkdir
ln -s /bin/busybox ./chroot/usr/bin/mknod
ln -s /bin/busybox ./chroot/usr/bin/mv
ln -s /bin/busybox ./chroot/usr/bin/pidof
ln -s /bin/busybox ./chroot/usr/bin/pwd
ln -s /bin/busybox ./chroot/usr/bin/readlink
ln -s /bin/busybox ./chroot/usr/bin/reset
ln -s /bin/busybox ./chroot/usr/bin/rm
ln -s /bin/busybox ./chroot/usr/bin/rmdir
ln -s /bin/busybox ./chroot/usr/bin/sed
ln -s /bin/busybox ./chroot/usr/bin/sleep
ln -s /bin/busybox ./chroot/usr/bin/sort
ln -s /bin/busybox ./chroot/usr/bin/sync
ln -s /bin/busybox ./chroot/usr/bin/tail
ln -s /bin/busybox ./chroot/usr/bin/telnet
ln -s /bin/busybox ./chroot/usr/bin/test
ln -s /bin/busybox ./chroot/usr/bin/touch
ln -s /bin/busybox ./chroot/usr/bin/true
ln -s /bin/busybox ./chroot/usr/bin/uname
ln -s /bin/busybox ./chroot/usr/bin/uniq
ln -s /bin/busybox ./chroot/usr/bin/uptime
ln -s /bin/busybox ./chroot/usr/bin/vi
ln -s /bin/busybox ./chroot/usr/bin/wc
ln -s /bin/busybox ./chroot/usr/bin/wget
ln -s /bin/busybox ./chroot/usr/bin/which
ln -s /bin/busybox ./chroot/usr/bin/whoami
ln -s /bin/busybox ./chroot/usr/bin/xargs
ln -s /bin/busybox ./chroot/usr/bin/yes
ln -s /bin/busybox ./chroot/usr/sbin/klogd
ln -s /bin/busybox ./chroot/usr/sbin/syslogd

ln -s /bin/tinylogin ./chroot/bin/login
ln -s /bin/tinylogin ./chroot/bin/su
ln -s /bin/tinylogin ./chroot/bin/login
ln -s /bin/tinylogin ./chroot/sbin/getty
ln -s /bin/tinylogin ./chroot/usr/bin/passwd
ln -s /bin/tinylogin ./chroot/usr/sbin/adduser




# We need to substitute all occurances of agetty to getty in etc/inittab
#
# Note that this is the *only* modification we are going to do to baselayout.

cat ./chroot/etc/inittab  | sed s:agetty:getty:g > ./chroot/etc/inittab.new
mv ./chroot/etc/inittab.new ./chroot/etc/inittab




# Clean up doc, man, info, locales, zoneinfo, include (if you can think of
# more let me know)

rm -Rf ./chroot/usr/share/{doc,man,info,locale,i18n,zoneinfo}
rm -Rf ./chroot/usr/include
rm -Rf ./chroot/usr/lib/locale



# fix /etc/hostname and warn regarding /etc/fstab

echo "using an arbitary ./chroot/etc/hostname..."

echo tinytest.europeansoftware.com >./chroot/etc/hostname

echo "please fix your ./chroot/etc/fstab and set your bootloader and you are ready..."

# I kept an fstab in the current work dir.. so I dont have to modify it every
# time I recreate the chroot.
cp ./fstab ./chroot/etc/fstab