make_initramfs

#!/bin/bash

ROOT=/boot
INITRAMFS="$ROOT/initramfs"
XZ_OPTS="--check=crc32 --lzma2=dict=512KiB"

if [ -z $1 ]
then
	CREATE=1
	INITRAM_DIR=`mktemp -d -t initramfs.XXX`
else
	CREATE=0
	INITRAM_DIR=$1
fi

DIRS="	sys
	proc
	dev
	etc
	newroot
	usr/lib
	usr/bin
	"

declare -A LINKS=(
	[bin]="usr/bin"
	[sbin]="usr/bin"
	[usr/sbin]="bin"
	[lib]="usr/lib"
	[lib64]="usr/lib"
	[usr/lib64]="lib"
)

BINS="	/sbin/zpool
	/sbin/mount.zfs
	/sbin/zfs
	/bin/busybox
	/lib/libgcc_s.so.1
	"

EXTRA=" /etc/hostid
	"
declare -A LIBS=()

resolve_libs() {
	for lib in `objdump -p $1 | grep NEEDED | sed 's/\s\+NEEDED\s\+//'`
	do
		if [[ ! -n "${LIBS[/lib/${lib}]}" ]]
		then
			LIBS[/lib/${lib}]=0;
		fi
	done
}

echo "composing initramfs in $INITRAM_DIR"

if [ $CREATE == 0 ]
then
	echo "Remove old initramfs in $INITRAM_DIR? (y/n)"
	read ANS
	if [ $ANS == "y" ]
	then
		rm -r $INITRAM_DIR
	fi
fi

for dir in $DIRS
do
	mkdir -p $INITRAM_DIR/$dir
done

for link in ${!LINKS[@]}
do
	ln -s ${LINKS[$link]} $INITRAM_DIR/${link}
done

for bin in ${BINS}
do
	echo "\tresolving $bin"
	cp $bin ${INITRAM_DIR}/$bin
	resolve_libs $bin
done

for i in {1..10}
do
	for lib in ${!LIBS[@]}
	do
		if [[ ${LIBS[${lib}]} == 0 ]]
		then
			echo "\tresolving $lib"
			cp -L $lib ${INITRAM_DIR}/$lib
			LIBS[${lib}]=1;
			resolve_libs $lib
		fi
	done
done

# add /dev/console
mknod $INITRAM_DIR/dev/console c 5 1 2>/dev/null

for bin in $EXTRA
do
	[ -e $bin ] || continue
	mkdir -p $INITRAM_DIR/`dirname $bin`
	cp -L $bin $INITRAM_DIR/$bin
done

# populate plymouth if available
if [ -x /usr/libexec/plymouth/plymouth-populate-initrd ]
then
	/usr/libexec/plymouth/plymouth-populate-initrd -t $INITRAM_DIR
fi

# init
cp /root/bin/init.tpl $INITRAM_DIR/init
chmod +x $INITRAM_DIR/init

cp /etc/zfs/*.cache $INITRAM_DIR/etc/

if [ $CREATE == 1 ]
then
	# backup
	echo "backing up $INITRAMFS"
	mv $INITRAMFS $INITRAMFS.old

	# create
	echo "creating new $INITRAMFS"
	cd $INITRAM_DIR
	find . | cpio --quiet -o -H newc | xz $XZ_OPTS > $INITRAMFS
	cd
	rm -r $INITRAM_DIR
fi