base-files: functions: introduce new helper functions

Introduce cmdline_get_var() to /lib/function.sh and make use of it in
export_rootdev() in /lib/upgrade/common.sh, making the code more
simple and removing one level of indentation.
Introduce get_partition_by_name() to /lib/upgrade/common.sh which is
useful on non-EFI GPT platforms like mt7622.
Remove some dead-code while at it.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

2 files changed, 68 insertions, 63 deletions

diff --git a/package/base-files/files/lib/functions.sh b/package/base-files/files/lib/functions.sh
index 2bad45324f..d8604415cc 100644
--- a/package/base-files/files/lib/functions.sh
+++ b/package/base-files/files/lib/functions.sh
@@ -384,4 +384,14 @@ board_name() {
 	[ -e /tmp/sysinfo/board_name ] && cat /tmp/sysinfo/board_name || echo "generic"
 }
 
+cmdline_get_var() {
+	local var=$1
+	local cmdlinevar tmp
+
+	for cmdlinevar in $(cat /proc/cmdline); do
+		tmp=${cmdlinevar##${var}}
+		[ "=" = "${tmp:0:1}" ] && echo ${tmp:1}
+	done
+}
+
 [ -z "$IPKG_INSTROOT" ] && [ -f /lib/config/uci.sh ] && . /lib/config/uci.sh
diff --git a/package/base-files/files/lib/upgrade/common.sh b/package/base-files/files/lib/upgrade/common.sh
index 968893e226..b0a482821d 100644
--- a/package/base-files/files/lib/upgrade/common.sh
+++ b/package/base-files/files/lib/upgrade/common.sh
@@ -147,71 +147,57 @@ part_magic_fat() {
 }
 
 export_bootdevice() {
-	local cmdline bootdisk rootpart uuid blockdev uevent line class
+	local cmdline uuid blockdev uevent line class
 	local MAJOR MINOR DEVNAME DEVTYPE
+	local rootpart="$(cmdline_get_var root)"
+
+	case "$rootpart" 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]-[a-f0-9][a-f0-9])
+			uuid="${rootpart#PARTUUID=}"
+			uuid="${uuid%-[a-f0-9][a-f0-9]}"
+			for blockdev in $(find /dev -type b); do
+				set -- $(dd if=$blockdev bs=1 skip=440 count=4 2>/dev/null | hexdump -v -e '4/1 "%02x "')
+				if [ "$4$3$2$1" = "$uuid" ]; then
+					uevent="/sys/class/block/${blockdev##*/}/uevent"
+					break
+				fi
+			done
+		;;
+		PARTUUID=????????-????-????-????-??????????02)
+			uuid="${rootpart#PARTUUID=}"
+			uuid="${uuid%02}00"
+			for disk in $(find /dev -type b); do
+				set -- $(dd if=$disk bs=1 skip=568 count=16 2>/dev/null | hexdump -v -e '8/1 "%02x "" "2/1 "%02x""-"6/1 "%02x"')
+				if [ "$4$3$2$1-$6$5-$8$7-$9" = "$uuid" ]; then
+					uevent="/sys/class/block/${disk##*/}/uevent"
+					break
+				fi
+			done
+		;;
+		/dev/*)
+			uevent="/sys/class/block/${rootpart##*/}/../uevent"
+		;;
+		0x[a-f0-9][a-f0-9][a-f0-9] | 0x[a-f0-9][a-f0-9][a-f0-9][a-f0-9] | \
+		[a-f0-9][a-f0-9][a-f0-9] | [a-f0-9][a-f0-9][a-f0-9][a-f0-9])
+			rootpart=0x${rootpart#0x}
+			for class in /sys/class/block/*; do
+				while read line; do
+					export -n "$line"
+				done < "$class/uevent"
+				if [ $((rootpart/256)) = $MAJOR -a $((rootpart%256)) = $MINOR ]; then
+					uevent="$class/../uevent"
+				fi
+			done
+		;;
+	esac
 
-	if read cmdline < /proc/cmdline; then
-		case "$cmdline" in
-			*root=*)
-				rootpart="${cmdline##*root=}"
-				rootpart="${rootpart%% *}"
-			;;
-		esac
-
-		case "$bootdisk" in
-			/dev/*)
-				uevent="/sys/class/block/${bootdisk##*/}/uevent"
-			;;
-		esac
-
-		case "$rootpart" 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]-[a-f0-9][a-f0-9])
-				uuid="${rootpart#PARTUUID=}"
-				uuid="${uuid%-[a-f0-9][a-f0-9]}"
-				for blockdev in $(find /dev -type b); do
-					set -- $(dd if=$blockdev bs=1 skip=440 count=4 2>/dev/null | hexdump -v -e '4/1 "%02x "')
-					if [ "$4$3$2$1" = "$uuid" ]; then
-						uevent="/sys/class/block/${blockdev##*/}/uevent"
-						break
-					fi
-				done
-			;;
-			PARTUUID=????????-????-????-????-??????????02)
-				uuid="${rootpart#PARTUUID=}"
-				uuid="${uuid%02}00"
-				for disk in $(find /dev -type b); do
-					set -- $(dd if=$disk bs=1 skip=568 count=16 2>/dev/null | hexdump -v -e '8/1 "%02x "" "2/1 "%02x""-"6/1 "%02x"')
-					if [ "$4$3$2$1-$6$5-$8$7-$9" = "$uuid" ]; then
-						uevent="/sys/class/block/${disk##*/}/uevent"
-						break
-					fi
-				done
-			;;
-			/dev/*)
-				uevent="/sys/class/block/${rootpart##*/}/../uevent"
-			;;
-			0x[a-f0-9][a-f0-9][a-f0-9] | 0x[a-f0-9][a-f0-9][a-f0-9][a-f0-9] | \
-			[a-f0-9][a-f0-9][a-f0-9] | [a-f0-9][a-f0-9][a-f0-9][a-f0-9])
-				rootpart=0x${rootpart#0x}
-				for class in /sys/class/block/*; do
-					while read line; do
-						export -n "$line"
-					done < "$class/uevent"
-					if [ $((rootpart/256)) = $MAJOR -a $((rootpart%256)) = $MINOR ]; then
-						uevent="$class/../uevent"
-					fi
-				done
-			;;
-		esac
-
-		if [ -e "$uevent" ]; then
-			while read line; do
-				export -n "$line"
-			done < "$uevent"
-			export BOOTDEV_MAJOR=$MAJOR
-			export BOOTDEV_MINOR=$MINOR
-			return 0
-		fi
+	if [ -e "$uevent" ]; then
+		while read line; do
+			export -n "$line"
+		done < "$uevent"
+		export BOOTDEV_MAJOR=$MAJOR
+		export BOOTDEV_MINOR=$MINOR
+		return 0
 	fi
 
 	return 1
@@ -242,6 +228,15 @@ hex_le32_to_cpu() {
 	echo "$@"
 }
 
+get_partition_by_name() {
+	for partname in /sys/class/block/$1/*/name; do
+		[ "$(cat ${partname})" = "$2" ] && {
+			basename ${partname%%/name}
+			break
+		}
+	done
+}
+
 get_partitions() { # <device> <filename>
 	local disk="$1"
 	local filename="$2"