#!/bin/sh
# reflash
#  ensure the flash disk is not mounted
#  save configuration files
#  update the kernel
#  update the flashdisk
#  restore the saved configuration files
# the set of configuration files is described by
# /etc/default/conffiles.
#
# /etc/default/functions contains useful utility functions
. /etc/default/functions
#
# CHECKING THE ENVIRONMENT
# ------------------------
# basic setup.  This could be parameterised to use different partitions!
ffspart=Flashdisk
kpart=Kernel
#
ffsdev="$(mtblockdev $ffspart)"
test -n "$ffsdev" -a -b "$ffsdev" || {
	echo "reflash: $ffspart($ffsdev): cannot find $ffspart mtd partition." >&2
	echo "  check /proc/mtd, either the partition does not exist or there is no" >&2
	echo "  corresponding block device." >&2
	exit 1
}
ffssize="$(devio "<<$ffsdev" 'pr$')"
#
kdev="$(mtblockdev $kpart)"
test -n "$kdev" -a -b "$kdev" || {
	echo "reflash: $kpart($kdev): cannot find $kpart mtd partition." >&2
	echo "  check /proc/mtd, either the partition does not exist or there is no" >&2
	echo "  corresponding block device." >&2
	exit 1
}
ksize="$(devio "<<$kdev" 'pr$')"
#
# find the device number of the flash partition then make sure it isn't
# mounted anywhere.
ffsno="$(devio "<<$ffsdev" prd)"
test -n "$ffsno" -a "$ffsno" -ge 0 || {
	echo "reflash: $ffsdev: device number $ffsno is not valid, cannot continue." >&2
	exit 1
}
#
# Make sure that Flashdisk isn't mounted on /
if test "$(devio "<</etc/init.d/sysconfsetup" prd)" -eq "$ffsno"
then
	echo "reflash: $ffsdev is mounted on /, use turnup ram to reflash" >&2
	exit 1
fi
#
# CHECKING FOR INPUT (ARGUMENTS ETC)
# ----------------------------------
#
# find the kernel and the new flash file system, they default to /boot/zImage
# and /boot/rootfs.jffs2, an image file can be used to specify both images.
ffsfile=/boot/rootfs.jffs2
kfile=/boot/zImage
imgfile=
while test $# -gt 0
do
	case "$1" in
	-k)	shift
		test $# -gt 0 || {
			echo "reflash: -k: give the file containing the kernel image" >&2
			exit 1
		}
		kfile="$1"
		imgfile=
		shift;;
	-j)	shift
		test $# -gt 0 || {
			echo "reflash: -j: give the file containing the root jffs2 image" >&2
			exit 1
		}
		ffsfile="$1"
		imgfile=
		shift;;
	-i)	shift
		test $# -gt 0 || {
			echo "reflash: -i: give the file containing the complete flash image" >&2
			exit 1
		}
		imgfile="$1"
		shift;;
	*)	echo "reflash: usage: $0 [-k kernel -j rootfs] | -i image" >&2
		echo "  -k [$kfile]: the new compressed kernel image ('zImage')" >&2
		echo "  -j [$ffsfile]: the new root file system (jffs2)" >&2
		echo "  -i image: a complete flash image (gives both kernel and jffs2)" >&2
		echo " The current jffs2 will be umounted if mounted." >&2
		exit 1;;
	esac
done
#
# Perform basic checks on the input (must exist, size must be ok).
if test -n "$imgfile"
then
	kfile=
	ffsfile=
	if test -r "$imgfile"
	then
		# read the partition table and from this find the offset
		# and size of Kernel and Flashdisk partitions.  The following
		# devio command just dumps the partition table in a format
		# similar to /proc/mtd (but it outputs decimal values!)
		#NOTE: this uses a here document because this allows the while
		# loop to set the variables, a pipe would put the while in
		# a sub-shell and the variable settings would be lost.  This
		# works in ash, no guarantees about other shells!
		while read size base name
		do
			case "$name" in
			Kernel)	imgksize="$size"
				imgkoffset="$base";;
			Flashdisk)
				imgffssize="$size"
				imgffsoffset="$base";;
			esac
		done <<EOI
$(devio "<<$imgfile" '
	<= $ 0x20000 -
	$( 1
		# 0xff byte in name[0] ends the partition table
		$? @ 255 =
		# output size base name
		<= f15+
		.= b 0xfffffff &
		<= f4+
		.= b
		pf "%lu %lu "
		<= f28-
		cp 16
		pn
		<= f240+
	$) 1')
EOI
		# check the result
		test -n "$imgksize" -a "$imgksize" -gt 0 -a "$imgksize" -le "$ksize" || {
			echo "reflash: $imgfile: bad kernel size ($imgksize, max $ksize)" >&2
			exit 1
		}
		test -n "$imgffssize" -a "$imgffssize" -gt 0 -a "$imgffssize" -le "$ffssize" || {
			echo "reflash: $imgfile: bad flashdisk size ($imgffssize, max $ffssize)" >&2
			exit 1
		}
	else
		echo "reflash: $imgfile: image file not found" >&2
		exit 1
	fi
else
	if test -r "$kfile"
	then
		# check the size
		s="$(devio "<<$kfile" 'pr$')"
		test -n "$s" -a "$s" -gt 0 -a "$s" -le "$ksize" || {
			echo "reflash: $kfile: bad size ($s, max $ksize)" >&2
			exit 1
		}
	else
		echo "reflash: $kfile: kernel file not found" >&2
		exit 1
	fi
	if test -r "$ffsfile"
	then
		s="$(devio "<<$ffsfile" 'pr$')"
		test -n "$s" -a "$s" -gt 0 -a "$s" -le "$ffssize" || {
			echo "reflash: $ffsfile: bad size ($s, max $ffssize)" >&2
			exit 1
		}
	else
		echo "reflash: $ffsfile: root file system image file not found" >&2
		exit 1
	fi
fi
#
# INPUTS OK, UMOUNT ANY EXISTING MOUNT OF THE FLASHDISK
# ----------------------------------------------------
echo "reflash: umounting any existing mount of $ffsdev" >&2
#
# check each mount point, do this last first because otherwise nested
# mounts of ffsdev cannot be umounted.
ffs_umount() {
	local device mp type options stuff

	read device mp type options stuff
	test -z "$device" && return 0

	# handle following entries first
	ffs_umount || return 1

	# handle this entry
	case "$type" in
	jffs2)	test "$(devio "<<$mp/etc/init.d/sysconfsetup" prd)" -ne "$ffsno" ||
		umount "$mp" || {
			echo "reflash: $mp: unable to umount $ffsdev" >&2
			return 1
		};;
	esac

	return 0
}
#
ffs_umount </proc/mounts || {
	echo "reflash: umount $ffsdev from all mount points then re-run reflash" >&2
	exit 1
}
#
# Everything is umounted, now remount on a temporary directory.
ffsdir="/tmp/flashdisk.$$"
mkdir "$ffsdir" || {
	echo "reflash: $ffsdir: failed to create temporary directory" >&2
	exit 1
}
#
mountflash "$ffsdir" -o ro || {
	rmdir "$ffsdir"
	exit 1
}
#
# this is a utility function to make the cleanup easier
errorexit() {
	umount "$ffsdir" && rmdir "$ffsdir" ||
		echo "reflash: $ffsdir: temporary directory cleanup failed" >&2
	exit 1
}
#
test -r "$ffsdir/etc/default/conffiles" || {
	echo "reflash: [/initrd]/etc/default/conffiles: file not found" >&2
	errorexit
}
#
# PRESERVE EXISTING CONFIGURATION
# -------------------------------
echo "reflash: preserving existing configuration file" >&2
#
# This step produces /tmp/preserve.$$ and /tmp/cpio.$$, the former is
# a list of the preserved configuration files together with the processing
# option, the latter is a directory tree of the preserved files (a directory
# tree makes the restore step easier.)
saved=/tmp/cpio.$$
list=/tmp/preserve.$$
mkdir "$saved" || {
	echo "reflash: $saved: could not create save directory" >&2
	errorexit
}
#
(	cd "$ffsdir"
	find etc/*.conf $(sed 's!^/!!' usr/lib/ipkg/info/*.conffiles) ! -type d -newer etc/.configured -print |
		sed 's/^/diff /'
	exec sed 's/#.*$//;/^[ 	]*$/d' etc/default/conffiles
) | sed 's!^/*!!' | awk '{ op=$1; $1=""; file[$0]=op }
	END{ for (f in file) if (file[f] != "ignore") print file[f] f }' |
while read op file
do
	if test -e "$ffsdir/$file"
	then
		echo "$op $file" >&3
		echo "$file"
	fi
done 3>"$list" | (cd "$ffsdir"; exec cpio -p -d -m -u "$saved") || {
	echo "reflash: $saved: copy of saved configuration files failed" >&2
	rm -rf "$saved"
	rm "$list"
	errorexit
}
#
# If this umount fails do not try to continue...
umount "$ffsdir" || {
	echo "reflash: $ffsdir: temporary mount point umount failed" >&2
	echo "  No changes have been made." >&2
	rm -rf "$saved"
	rm "$list"
	exit 1
}
#
# FLASH THE NEW IMAGES
# --------------------
echo "reflash: about to flash new images" >&2
#
# If the images are in separate files do this in two steps, kernel then
# rootfs (this seems like it might be safer if the first fails).  For an
# image file use one step but still write the kernel first.
do_devio() {
	if test -r "$imgfile"
	then
		# image file case - copy the whole of the image partition,
		# which already includes headers (etc).
		devio "$@" "<<$imgfile" ">>$ffsdev" ">>$kdev" '
			# kernel is at imgkoffset[imgksize]
			' "<= $imgkoffset" "cp $imgksize" '
			fb #t-,255
			' "<>$kdev" ">>$ffsdev" '
			# rootfs is at imgffsoffset[imgffssize]
			' "<= $imgffsoffset" "cp $imgffssize" '
			fb #t-,255'
	elif test -r "$kfile" -a -r "$ffsfile"
	then
		# use separate files, do this in one command to be sure
		# that everything can be opened at the start
		devio "$@" "<<$ffsfile" ">>$ffsdev" "<<$kfile" ">>$kdev" '
			# kernel write length+16,0,0,0 header, then fill
			wb $16+,4
			fb 12,0
			cp $
			fb #t-,255
			' "<>$kfile" "<>$kdev" "<<$ffsfile" ">>$ffsdev" '
			# rootfs, write the whole image, fill if necessary
			cp $
			fb #t-,255'
	else
		# oops, my checking was wrong...
		echo "reflash: internal error: image files not found!" >&2
		echo "  No changes have been made." >&2
		exit 2
	fi
}
#
echo "reflash: writing kernel to $kdev and rootfs to $ffsdev..." >&2
do_devio
st=$?
case "$st" in
0)	;;
1)	echo "reflash: flash of new images failed, no changes have been made" >&2
	rm -rf "$saved"
	rm "$list"
	exit 1;;
3)	echo "reflash: WARNING: partial flash, the system is unbootable" >&2
	echo "  Reflash from RedBoot or correct the problem here." >&2
	exit 3;;
*)	echo "reflash($st): internal error" >&2
	exit $st;;
esac
echo "  ... done" >&2
#
# verify - this just produces a warning
echo "reflash: verifying new flash image..." >&2
do_devio -v || {
	echo "reflash: WARNING: flash image verification failed" >&2
	echo "  The system is probably unbootable." >&2
	echo "  System configuration files will be restored but this may fail" >&2
	echo "  Starting a shell for user recovery (exit to continue)" >&2
	PS1='badflash$ ' sh -i <>/dev/tty >&0 2>&0
}
echo "  ... done" >&2
#
# RESTORE THE OLD CONFIGURATION
# -----------------------------
echo "reflash: restoring saved configuration files" >&2
#
# the file /etc/.configured is the datestamp file used to ensure that
# changed configuration files can be recognised.  It is created by
# /etc/rcS.d/S99finish on first boot (if it does not exist).  We need
# a timestamp earlier than any files we create so touch it here, this
# also acts as a test on the mounted file system
mountflash "$ffsdir" && :>"$ffsdir/etc/.configured" || {
	rmdir "$ffsdir"
	echo "reflash: mount of new flash root file system failed" >&2
	if test -d "$ffsdir/etc"
	then
		echo "    The file system does not seem to be writeable." >&2
		echo "    The mounted file system is in $ffsdir" >&2
	fi
	echo "  WARNING: the kernel and root file system have been reflashed," >&2
	echo "  HOWEVER the new root file system seems to be unuseable." >&2
	echo "  Saved configuration files are in $saved" >&2
	echo "  The list of saved configuration files is in $list" >&2
	echo " You should determine the reason for the failed mount, mount the new" >&2
	echo " file system and restore the configuration from $saved - it's just a" >&2
	echo " matter of copying the saved files where required." >&2
	exit 1
}
#
# verify file
#  this is called with the name of a 'diff' file which is, indeed,
#  different and with all the std streams connected to the tty.  It
#  returns a status code to say whether (0) or not (1) to copy the
#  file over.
#
verify_help() {
	echo "Please specify how to handle this file or link, the options are as follows,"
	echo "two character abbreviations may be used:"
	echo
	echo " keep:    retain the old file, overwrite the new flash image file"
	echo " upgrade: retain the new file, the old (saved) file is not used"
	echo " diff:    display the differences between the old and the new using diff -u"
	echo " shell:   temporarily start an interactive shell (sh -i), exit to continue"
	echo " skip:    ignore this file for the moment.  The file is left in the directory"
	echo "          $saved and many be handled after this script has completed"
}
#
verify() {
	local command file

	file="$1"
	echo "reflash: $file: configuration file changed."
	verify_help "$file"
	while :
	do
		echo -n "option: "
		read command
		case "$command" in
		ke*)	return 0;;
		up*)	rm "$saved/$file"
			return 1;;
		di*)	echo "DIFF OLD($saved) NEW($ffsdir)"
			diff -u "$saved/$file" "$ffsdir/$file";;
		sh*)	PS1="$file: " sh -i;;
		sk*)	return 1;;
		*)	verify_help "$file";;
		esac
	done
}
# the same, but for a link
verify_link() {
	local command link

	link="$1"
	echo "reflash: $link: configuration link changed."
	verify_help "$link"
	while :
	do
		echo -n "option: "
		read command
		case "$command" in
		ke*)	return 0;;
		up*)	rm "$saved/$link"
			return 1;;
		di*)	echo "DIFF:"
			echo "OLD($saved): $link -> $(readlink "$saved/$link")"
			echo "NEW($ffsdir): $link -> $(readlink "$ffsdir/$link")";;
		sh*)	PS1="$link: " sh -i;;
		sk*)	return 1;;
		*)	verify_help "$link";;
		esac
	done
}
#
while read op file
do
	# handle .configured specially (to preserve the original datestamp)
	if test "$file" = "etc/.configured"
	then
		# this should definately not fail because of the test above!
		if cp -a "$saved/$file" "$ffsdir/$file"
		then
			echo "$file" >&3
		else
			echo "reflash: $file: timestamp copy failed (ignored)" >&2
		fi
	elif test -h "$saved/file" -o -h "$ffsdir/$file"
	then
		# new or old symbolic link
		if test -h "$saved/$file" -a -h "$ffsdir/$file" &&
			test "$(readlink "$saved/$file")" = "$(readlink "$ffsdir/$file")"
		then
			# no change
			echo "$file" >&3
		else
			# assume a change regardless
			case "$op" in
			preserve)
				echo "$file"
				echo "$file" >&3;;
			diff)	# need user input
				if verify_link "$file" <>/dev/tty >&0 2>&0
				then
					echo "$file"
					echo "$file" >&3
				fi;;
			esac
		fi
	else
		# only overwrite if necessary
		if test -e "$ffsdir/$file" && cmp -s "$saved/$file" "$ffsdir/$file"
		then
			# do not overwrite
			echo "$file" >&3
		elif test ! -e "$ffsdir/$file"
		then
			# always preserve
			echo "$file"
			echo "$file" >&3
		else
			case "$op" in
			preserve)
				echo "$file"
				echo "$file" >&3;;
			diff)	# the files are different, get user input
				if verify "$file" <>/dev/tty >&0 2>&0
				then
					echo "$file"
					echo "$file" >&3
				fi;;
			esac
		fi
	fi
done <"$list" 3>/tmp/restore.$$ | (cd "$saved"; exec cpio -p -d -u "$ffsdir") || {
	echo "reflash: $saved: restore of saved configuration files failed" >&2
	echo "  The new flash file system is mounted on $ffsdir" >&2
	echo "  The saved files are in $saved and the list in $list, the list of" >&2
	echo "  files selected for restore is in /tmp/restore.$$" >&2
	echo "  You should restore any required configuration from $saved," >&2
	echo "  then umount $ffsdir and reboot." >&2
	exit 1
}
#
# remove the copied files (i.e. the ones which were preserved)
(	cd "$saved"
	exec rm $(cat /tmp/restore.$$)
)
rm /tmp/restore.$$
#
# clean up, files left in $saved need to be handled by the user
files="$(find "$saved" ! -type d -print)"
if test -n "$files"
then
	echo "reflash: the following saved configuration files remain:" >&2
	echo "$files" >&2
	echo "The full list of preserved files is in $list.  To alter the" >&2
	echo "new root file system use the command:" >&2
	echo "" >&2
	echo "  mount -t jffs2 $ffsdev /mnt" >&2
	echo "" >&2
	echo "The saved files are in the temporary directory, they will not" >&2
	echo "be retained across a system boot.  Copy them elsewhere if you" >&2
	echo "are unsure whether they are needed" >&2
else
	rm -rf "$saved"
	rm "$list"
fi
#
# now the final umount
if umount "$ffsdir"
then
	rmdir "$ffsdir"
	echo "reflash: system upgrade complete.  Reboot to continue." >&2
	exit 0
else
	echo "reflash: $ffsdir: temporary mount point umount failed" >&2
	echo "  ALL changes have been made successfully, however the umount of" >&2
	echo "  the new root file system has failed.  You should determine the" >&2
	echo "  cause of the failure, umount $ffsdir, then reboot the system (this" >&2
	echo "  will use the upgraded kernel and root file system)" >&2
	exit 1
fi