openwrtv4/target/linux/x86/base-files/lib/upgrade/platform.sh
Jo-Philipp Wich 4aeeead303 x86: preserve partition table on sysupgrade
With this patch sysupgrade will write directly to the partitions
instead of to the main disk.  The UUID is copied from the image
to the MBR as well.  This prevents the mbr from being completely
overwritten and losing the partition table.  The -p option has
been added to maintain the original behavior and overwite the
entire disk with the new image.  Tests have been added to ensure
that the image partitions match up with the active partitions.

Signed-off-by: Rob Mosher <nyt-openwrt@countercultured.net>

SVN-Revision: 48682
2016-02-09 12:33:17 +00:00

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platform_export_bootpart() {
local cmdline uuid disk
if read cmdline < /proc/cmdline; then
case "$cmdline" in
*block2mtd=*)
disk="${cmdline##*block2mtd=}"
disk="${disk%%,*}"
;;
*root=*)
disk="${cmdline##*root=}"
disk="${disk%% *}"
;;
esac
case "$disk" in
PARTUUID=[a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]-02)
uuid="${disk#PARTUUID=}"
uuid="${uuid%-02}"
for disk in /dev/[hsv]d[a-z]; do
set -- $(dd if=$disk bs=1 skip=440 count=4 2>/dev/null | hexdump -v -e '4/1 "%02x "')
if [ "$4$3$2$1" = "$uuid" ]; then
export BOOTPART="${disk}1"
return 0
fi
done
;;
/dev/*)
export BOOTPART="${disk%[0-9]}1"
return 0
;;
esac
fi
return 1
}
platform_check_image() {
[ "$#" -gt 1 ] && return 1
case "$(get_magic_word "$1")" in
eb48|eb63) return 0;;
*)
echo "Invalid image type"
return 1
;;
esac
}
platform_copy_config() {
if [ -b "$BOOTPART" ]; then
mount -t ext4 -o rw,noatime "$BOOTPART" /mnt
cp -af "$CONF_TAR" /mnt/
umount /mnt
fi
}
get_partitions() { # <device> <filename>
local disk="$1"
local filename="$2"
if [ -b "$disk" -o -f "$disk" ]; then
echo "Reading partition table from $filename..."
partx -r "$disk" -gbo NR,START,SECTORS > "/tmp/partx.$filename"
fi
}
platform_do_upgrade() {
platform_export_bootpart
disk="${BOOTPART%[0-9]}"
if [ -b "$disk" ]; then
sync
if [ "$SAVE_PARTITIONS" = "1" ]; then
get_partitions "$disk" bootdisk
#get block size
sectors="$(partx -r $disk -gbo SECTORS --nr 1:1)"
size="$(partx -r $disk -gbo SIZE --nr 1:1)"
ibs="$(($size / $sectors))"
#extract the boot sector from the image
get_image "$@" | dd of=/tmp/image.bs count=1 bs=512b
get_partitions /tmp/image.bs image
#compare tables
diff="$(grep -F -x -v -f /tmp/partx.bootdisk /tmp/partx.image)"
if [ -n "$diff" ]; then
echo "Partition layout is changed. Full image will be written."
ask_bool 0 "Abort" && exit
get_image "$@" | dd of="$disk" bs=4096 conv=fsync
return 0
fi
#iterate over each partition from the image and write it to the boot disk
while read part start size; do
echo "Writing image to $disk$part..."
get_image "$@" | dd of="$disk$part" ibs="$ibs" obs=1M skip="$start" count="$size" conv=fsync
done < /tmp/partx.image
#copy partition uuid
echo "Writing new UUID to $disk$part..."
get_image "$@" | dd of="$disk" bs=1 skip=440 count=4 seek=440 conv=fsync
else
get_image "$@" | dd of="$disk" bs=4096 conv=fsync
fi
sleep 1
fi
}