add_preseeds_to_iso.sh

#!/bin/bash

# We follow these methods:
# https://wiki.debian.org/DebianInstaller/Preseed/EditIso
# https://wiki.debian.org/DebianInstaller/Modify/CD

# ------------------------------------------------

check_prerequisites() {
	if ! which 7z &> /dev/null; then
		echo "We need to have 7z installed (from package \"7z\")." >&2
		exit 1
	fi

	if ! which xorriso &> /dev/null; then
		echo "We need to have xorriso installed (from package \"xorriso\")." >&2
		exit 1
	fi

	if ! which isoinfo &> /dev/null; then
		echo "We need to have isoinfo installed (from package \"genisoimage\")." >&2
		exit 1
	fi
}

search_isolinux() {
	# Search for an isolinux isohdpfx.bin image
	# in the default locations and the content of
	# ISOLINUX_HINT.
	# If none is found at the usual locations
	# return 1

	for path in "$ISOLINUX_HINT" /usr/lib/ISOLINUX; do
		if [ -f "$path/isohdpfx.bin" ]; then
			ISOLINUX_BIN="$path/isohdpfx.bin"
			return 0
		fi
	done
	return 1
}

ask_for_locale() {
	# Ask user for the locale and keyboard layout he wishes to use
	#
	# Stores values in $LOCALE and $LAYOUT

	local QUERY
	if ! QUERY=$(setxkbmap -query); then
		LAYOUT="en"
	else
		LAYOUT="$(echo "$QUERY" | awk '
				/^layout:/ { printf $2 }
				# As far as I know the installer does not recognise this
				# /^variant:/ { printf "(" $2 ")" }
				END { print "" }
			')"
	fi

	read -p "Enter locale to use:           " -e -i "$LANG" LOCALE
	read -p "Enter keyboard layout to use:  " -e -i "$LAYOUT" LAYOUT
}

ask_for_authorised_keys() {
	# Ask user for the authorised keys to include as login keys for
	# the root user.
	#
	# Stores the concatinated content in AUTHORISED_KEYS


	echo "   You may store a number of ssh keys on the installation medium, "
	echo "   which may be used as the inital authorized_keys for root. "
	echo "   Enter them as a colon(:) separated list."

	local LINE

	for key in $HOME/.ssh/id_*.pub $HOME/.ssh/authorized_keys; do
		[ ! -f "$key" ] && continue
		if [ -z "$LINE" ]; then
			LINE="$key"
		else
			LINE="$LINE:$key"
		fi
	done

	read -p "Enter ssh key files:           " -e -i "$LINE" LINE

	AUTHORISED_KEYS=$(
		IFS=":"
		for key in $LINE; do
			if [ -r "$key" ]; then
				cat "$key"
			else
				echo "Key file not readable: $key" >&2
				return 1
			fi
		done
	)
}

find_firmware_file() {
	FIRMWARE="firmware.tar.gz"
	if [ ! -f "$FIRMWARE" ]; then
		echo "   No non-free firmware found. "
		echo "   Check 'http://github.com/mfherbst/debian-preansible' for details."
		FIRMWARE=""
		return 0
	fi

	echo "   Found debian non-free firmware file '$FIRMWARE'"
	read -p "Do you wish to add this file to the iso?  (Y/n)" RES
	if [ "$RES" == "n" -o "$RES" == "N" ]; then
		FIRMWARE=""
	fi
}

extract_info() {
	# $1: isofile
	# fills the variables
	#  ORIG_VOLUMEID       original volume id of the iso

	local INFO=$(isoinfo  -d -i "$1")
	ORIG_VOLUMEID=$(echo "$INFO" | awk -F ": " '/^Volume id:/ { print $2 }')
}

copy_iso() {
	#$1: isofile
	# echos the dir where the extracted copy can be found
	# returns 1 if problems

	local ISO="$1"
	local EXTRACTDIR=$(mktemp -d)

	if ! 7z -o"$EXTRACTDIR" x "$ISO" >/dev/null; then
		echo "Error extracting iso file" >&2
		return 1
	fi

	# delete the [BOOT] folder
	rm -rf "$EXTRACTDIR/[BOOT]"

	echo "$EXTRACTDIR"
	return 0
}

add_preseed() {
	#$1 dir where extracted iso files are located.
	#
	# dumps the contents of the variable AUTHORISED_KEYS
	# for installation as the initial authorized keys for
	# root.

	local EXTRACTDIR="$1"
	if [ ! -d "$EXTRACTDIR" ] ; then
		echo "Loopdir does not exist: $EXTRACTDIR" >&2
		return 1
	fi

	# dir containing this file:
	local SOURCEPREFIX="$(dirname "${BASH_SOURCE[0]}" )"

	# dirname of the preseeds top level folder.
	local PRESEEDSDIR="preseeds"

	# check if we can find the preseeds:
	if [ ! -d "$SOURCEPREFIX/$PRESEEDSDIR" ]; then
		echo "Could not find preseed files at the expected location">&2
		echo "   (\"$SOURCEPREFIX/$PRESEEDSDIR\")" >&2
		return 1
	fi

	# sanity check: is the "menu begin advanced" there
	if ! < "$EXTRACTDIR/isolinux/menu.cfg" grep -q 'menu begin advanced'; then
		echo "\"$EXTRACTDIR/isolinux/main.cfg\" has an unknown format." >&2
		return 1
	fi

	# copy the preseedsdir over
	if ! rsync -a -H "$SOURCEPREFIX/$PRESEEDSDIR" "$EXTRACTDIR/"; then
		echo "Error copying the preseeds dir \"$SOURCEPREFIX/$PRESEEDSDIR\"" >&2
		return 1
	fi

	# copy the authorized_keys for root
	echo "$AUTHORISED_KEYS" > "$EXTRACTDIR/$PRESEEDSDIR/root_keys"

	# drop the locale.cfg
	{
		echo "d-i  debian-installer/locale string $LOCALE"
		echo "d-i  keyboard-configuration/xkb-keymap select $LAYOUT"
	} > "$EXTRACTDIR/$PRESEEDSDIR/parts/locale.cfg"

	# Determine linux kernel and initrd to use:
	local BOOTVMLINUZ="/install.amd/vmlinuz"
	local INITRD="/install.amd/initrd.gz"
	if [ ! -f "$EXTRACTDIR/install.amd/vmlinuz" ]; then
		echo "No amd64 linux kernel found. Falling back to i386" >&2
		BOOTVMLINUZ="/install/vmlinuz"
		INITRD="/install/initrd.gz"
	fi

	#
	# Extra menu for isolinux boot
	#
	local MENUFILE="menu_extra.cfg" # menu files
	if ! cp "$SOURCEPREFIX/$MENUFILE" "$EXTRACTDIR/isolinux/preseed.cfg"; then
		echo "Error copying the preseed menu: \"$SOURCEPREFIX/$MENUFILE\"" >&2
		return 1
	fi

	local SUBFILE="$EXTRACTDIR/isolinux/preseedsub.cfg"
	for preseedfile in $SOURCEPREFIX/$PRESEEDSDIR/*.cfg; do
		[ ! -f "$preseedfile" ] && continue

		NAME=$(echo "$preseedfile" | sed "s/\.cfg$//; s#^$SOURCEPREFIX/$PRESEEDSDIR/##; s/[^a-zA-Z0-9]/_/g")
		cat <<-EOF
			label $NAME
			    menu label Preseed with $(basename "$preseedfile")
			    kernel $BOOTVMLINUZ
			    append auto=true file=/cdrom/$PRESEEDSDIR/$(basename "$preseedfile") preseed-md5=$(md5sum "$preseedfile" | cut -f 1 -d " ") priority=critical vga=788 initrd=$INITRD --- quiet
		EOF
	done > "$SUBFILE"

	# finally enable the preseed stuff:
	sed --in-place "/^menu begin advanced/iinclude preseed.cfg" "$EXTRACTDIR/isolinux/menu.cfg"

	#
	# Extra menu for grub (efi) boot
	#
	local GRUBCFG="$EXTRACTDIR/boot/grub/grub.cfg"
	local GRUBCFG_EXTRA=$({
		cat <<-EOF
		submenu 'Preansible Debian automatic install ...' {
		    set menu_color_normal=cyan/blue
		    set menu_color_highlight=white/blue
		    set theme=/boot/grub/theme/1-1
		EOF
		for preseedfile in $SOURCEPREFIX/$PRESEEDSDIR/*.cfg; do
			[ ! -f "$preseedfile" ] && continue

			NAME=$(echo "$preseedfile" | sed "s/\.cfg$//; s#^$SOURCEPREFIX/$PRESEEDSDIR/##; s/[^a-zA-Z0-9]/_/g")
			cat <<-EOF
			    menuentry 'Preseeded with $(basename "$preseedfile")' {
			        set background_color=black
			        linux $BOOTVMLINUZ auto=true file=/cdrom/$PRESEEDSDIR/$(basename "$preseedfile") preseed-md5=$(md5sum "$preseedfile" | cut -f 1 -d " ") priority=critical vga=788 --- quiet
			        initrd $INITRD
			    }
			EOF
		done
		echo "}"
	})
	< "$GRUBCFG" awk -v "extra=$GRUBCFG_EXTRA" '
		/^submenu (--hotkey=a )?.Advanced options/ { print extra }
		{print}
	' > "$GRUBCFG.new"

	if diff "$GRUBCFG.new" "$GRUBCFG" &> /dev/null; then
		echo "Error: No replacement occurred in $GRUBCFG, where one was exepected." >&2
		exit 1
	fi

	mv  "$GRUBCFG.new" "$GRUBCFG"

	# and adjust the md5sums:
	(
		cd $EXTRACTDIR
		md5sum `find ! -name "md5sum.txt" ! -path "./isolinux/*" -follow -type f` > md5sum.txt
	)

	return 0
}

add_firmware() {
	local FIRMWARE="$1"
	local EXTRACTDIR="$2"

	tar -C "$EXTRACTDIR/firmware" -xzf "$FIRMWARE"
}

make_new_iso() {
	# Reads the global variables
	#	ORIG_VOLUMEID	the original volume id
	#	ISOLINUX_BIN	the location of the isolinx binary to use
	#			or "" if no isolinux boot image should be
	#			available.


	local LOOPDIR="$1"
	local ISOIMAGE="$2"

	local MBR=()
	if [ "$ISOLINUX_BIN" ]; then
		MBR=(-isohybrid-mbr "$ISOLINUX_BIN")
	fi

	OPTIONS=(
		#
		# Generic options
		#
		# Output file
		-o "$ISOIMAGE"
		#
		# Volume ID
		-V "Preseeded $ORIG_VOLUMEID" -A ""
		#
		# Use long joliet (more than 64char filenames)
		# as well as Rock Ridge extension
		-J -r -joliet-long
		#
		# Copy an ISOLINUX mbr template, which executes the boot image from BIOS
		# Also announce it as a GPT partition for booting via EFI and as MBR partition
		${MBR[@]}
		#
		# First boot option
		#
		# an legacy iso image
		-b isolinux/isolinux.bin -c isolinux/boot.cat -boot-load-size 4 -boot-info-table -no-emul-boot
		#
		# have another:
		-eltorito-alt-boot
		#
		# an efi iso image
		-e boot/grub/efi.img -no-emul-boot -isohybrid-gpt-basdat
	)

	QUIET="-quiet"
	if [ "$DEBUG" == "y" ]; then
		QUIET=""
	fi
	xorriso -as mkisofs $QUIET "${OPTIONS[@]}" "$LOOPDIR"
}

usage() {
	cat <<-EOF
	$(basename "$0") [ -h | --help | --debug | -d ] <iso>

	Add preseeds to a debian iso file.

	--debug or -d causes debug files to be kept after the
	script has run.
	EOF
}

cleanup() {
	# delete temporary directory

	if [ "$DEBUG" == "y" ]; then
		echo "MODIFYDIR is $MODIFYDIR"
	else
		rm -r "$MODIFYDIR"
	fi
}

# ------------------------------------------------

check_prerequisites

DEBUG=n
while [ "$1" ]; do
	case "$1" in
		-h|--help)
			usage
			exit 0
			;;
		-d|--debug)
			DEBUG="y"
			;;
		*)
			break
			;;
	esac
	shift
done
ISOFILE="$1"

if [ ! -f "$ISOFILE" ]; then
	echo "The first argument \"$ISOFILE\" is not a valid debian iso" >&2
	exit 1
fi

NEWISO="$(basename "$ISOFILE" ".iso")-preseeded.iso"
if [ -f "$NEWISO" ]; then
	echo "Output iso: $NEWISO already exists" >&2
	exit 1
fi

if ! search_isolinux; then
	echo "WARNING: Could not find ISOLINUX on the system" >&2
	echo "         Either install \"isolinux\" package or set ISOLINUX_HINT to" >&2
	echo "         the isolinux directory (e.g. /usr/lib/ISOLINUX)" >&2
	echo "" >&2
	echo "         Proceeding without ISOLINUX MBR image. Perhaps iso is not bootable ...">&2
fi

ask_for_locale || exit 1
echo
ask_for_authorised_keys || exit 1
echo
find_firmware_file || exit 1
echo
echo Please wait ...

# extract some info from the iso file
extract_info "$ISOFILE"

if ! MODIFYDIR=$(copy_iso "$ISOFILE"); then
	echo "Error copying the iso: Is it a valid iso file?" >&2
	exit 1
fi

trap cleanup EXIT SIGTERM

if [ "$FIRMWARE" ]; then
	if ! add_firmware "$FIRMWARE" "$MODIFYDIR"; then
		echo "Adding $FIRMWARE failed" >&2
		exit 1
	fi
fi

if ! add_preseed "$MODIFYDIR"; then
	echo "Error adding the preseed stuff." >&2
	exit 1
fi

if ! make_new_iso "$MODIFYDIR" "$NEWISO"; then
	echo "Creating new iso failed" >&2
	exit 1
fi

echo "Preseeded iso can be found in \"$NEWISO\"."
exit 0