x86: generalize partition discovery for sysupgrade

Generalize the partition discovery in sysupgrade in order to fix sysupgrade
and config backup/recovery on MMC block devices which use a different naming
scheme compared to mtdblock or sd* devices.

The change also adds the find applet to the ramdisk utilities so that upgrade
code can rely on it.

The commit is based on the initial submission by Russell Senior at
http://patchwork.ozlabs.org/patch/625440/ .

Signed-off-by: Russell Senior <russell@personaltelco.net>
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

package/base-files/files/lib/upgrade/common.sh

@@ -53,7 +53,7 @@ run_ramfs() { # <command> [...]
 		/bin/vi /bin/ls /bin/cat /usr/bin/awk /usr/bin/hexdump		\
 		/bin/sleep /bin/zcat /usr/bin/bzcat /usr/bin/printf /usr/bin/wc \
 		/bin/cut /usr/bin/printf /bin/sync /bin/mkdir /bin/rmdir	\
-		/bin/rm /usr/bin/basename /bin/kill /bin/chmod
+		/bin/rm /usr/bin/basename /bin/kill /bin/chmod /usr/bin/find
 
 	install_bin /bin/uclient-fetch /bin/wget
 	install_bin /sbin/mtd

target/linux/x86/base-files/lib/preinit/79_move_config

@@ -2,10 +2,12 @@
 # Copyright (C) 2012-2015 OpenWrt.org
 
 move_config() {
+	local partdev
+
 	. /lib/upgrade/platform.sh
 
-	if platform_export_bootpart; then
-		mount -t ext4 -o rw,noatime "$BOOTPART" /mnt
+	if platform_export_bootdevice && platform_export_partdevice partdev 1; then
+		mount -t ext4 -o rw,noatime "/dev/$partdev" /mnt
 		mv -f /mnt/sysupgrade.tgz /
 		umount /mnt
 	fi

target/linux/x86/base-files/lib/upgrade/platform.sh

@@ -1,5 +1,21 @@
-platform_export_bootpart() {
-	local cmdline uuid disk
+platform_export_partdevice() {
+	local var="$1" offset="$2"
+	local uevent MAJOR MINOR DEVNAME DEVTYPE
+
+	for uevent in /sys/class/block/*/uevent; do
+		. "$uevent"
+		if [ $BOOTDEV_MAJOR = $MAJOR -a $(($BOOTDEV_MINOR + $offset)) = $MINOR -a -b "/dev/$DEVNAME" ]; then
+			export "$var=$DEVNAME"
+			return 0
+		fi
+	done
+
+	return 1
+}
+
+platform_export_bootdevice() {
+	local cmdline uuid disk uevent
+	local MAJOR MINOR DEVNAME DEVTYPE
 
 	if read cmdline < /proc/cmdline; then
 		case "$cmdline" in
@@ -17,20 +33,27 @@ platform_export_bootpart() {
 			PARTUUID=[a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]-02)
 				uuid="${disk#PARTUUID=}"
 				uuid="${uuid%-02}"
-				for disk in /dev/*; do
-					[ -b "$disk" ] || continue
+				for disk in $(find /dev -type b); 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="${disk}1"
-						return 0
+						uevent="/sys/class/block/${disk##*/}/uevent"
+						break
 					fi
 				done
 			;;
 			/dev/*)
-				export BOOTPART="${disk%[0-9]}1"
-				return 0
+				uevent="/sys/class/block/${disk##*/}/uevent"
 			;;
 		esac
+
+		if [ -e "$uevent" ]; then
+			. "$uevent"
+
+			export BOOTDEV_MAJOR=$MAJOR
+			export BOOTDEV_MINOR=$MINOR
+
+			return 0
+		fi
 	fi
 
 	return 1
@@ -49,8 +72,10 @@ platform_check_image() {
 }
 
 platform_copy_config() {
-	if [ -b "$BOOTPART" ]; then
-		mount -t ext4 -o rw,noatime "$BOOTPART" /mnt
+	local partdev
+
+	if platform_export_partdevice partdev 1; then
+		mount -t ext4 -o rw,noatime "/dev/$partdev" /mnt
 		cp -af "$CONF_TAR" /mnt/
 		umount /mnt
 	fi
@@ -87,18 +112,16 @@ get_partitions() { # <device> <filename>
 }
 
 platform_do_upgrade() {
-	platform_export_bootpart
-	disk="${BOOTPART%[0-9]}"
+	local diskdev partdev ibs diff
 
-	if [ -b "$disk" ]; then
+	if platform_export_bootdevice && platform_export_partdevice diskdev 0; then
 		sync
 		if [ "$SAVE_PARTITIONS" = "1" ]; then
-			get_partitions "$disk" bootdisk
-
+			get_partitions "/dev/$diskdev" bootdisk
 
 			#get block size
-			if [ -f "/sys/block/${disk##*/}/queue/physical_block_size" ]; then
-				ibs="$(cat "/sys/block/${disk##*/}/queue/physical_block_size")"
+			if [ -f "/sys/block/$diskdev/queue/physical_block_size" ]; then
+				ibs="$(cat "/sys/block/$diskdev/queue/physical_block_size")"
 			else
 				ibs=512
 			fi
@@ -114,21 +137,25 @@ platform_do_upgrade() {
 				echo "Partition layout is changed.  Full image will be written."
 				ask_bool 0 "Abort" && exit
 
-				get_image "$@" | dd of="$disk" bs=4096 conv=fsync
+				get_image "$@" | dd of="/dev/$diskdev" 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
+				if platform_export_partdevice partdev $part; then
+					echo "Writing image to /dev/$partdev..."
+					get_image "$@" | dd of="/dev/$partdev" ibs="$ibs" obs=1M skip="$start" count="$size" conv=fsync
+				else
+					echo "Unable to find partition $part device, skipped."
+				fi
 			done < /tmp/partmap.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
+			echo "Writing new UUID to /dev/$diskdev..."
+			get_image "$@" | dd of="/dev/$diskdev" bs=1 skip=440 count=4 seek=440 conv=fsync
 		else
-			get_image "$@" | dd of="$disk" bs=4096 conv=fsync
+			get_image "$@" | dd of="/dev/$diskdev" bs=4096 conv=fsync
 		fi
 
 		sleep 1