base-files: add sysupgrade -o to save all overlay files

Add sysupgrade '-o' option in order to include all overlay files in
backup, except for those that are from packages but including files
listed in conffiles, sysupgrade.conf or /lib/upgrade/keep.d.

With '-u' option, it will skip files equals to /rom and conffiles that
were not changed.

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>

package/base-files/files/sbin/sysupgrade

@@ -9,6 +9,7 @@ export INTERACTIVE=0
 export VERBOSE=1
 export SAVE_CONFIG=1
 export SAVE_OVERLAY=0
+export SAVE_OVERLAY_PATH=
 export SAVE_PARTITIONS=1
 export SKIP_UNCHANGED=0
 export CONF_IMAGE=
@@ -27,7 +28,8 @@ while [ -n "$1" ]; do
 		-v) export VERBOSE="$(($VERBOSE + 1))";;
 		-q) export VERBOSE="$(($VERBOSE - 1))";;
 		-n) export SAVE_CONFIG=0;;
-		-c) export SAVE_OVERLAY=1;;
+		-c) export SAVE_OVERLAY=1 SAVE_OVERLAY_PATH=/etc;;
+		-o) export SAVE_OVERLAY=1 SAVE_OVERLAY_PATH=/;;
 		-p) export SAVE_PARTITIONS=0;;
 		-u) export SKIP_UNCHANGED=1;;
 		-b|--create-backup) export CONF_BACKUP="$2" NEED_IMAGE=1; shift;;
@@ -54,12 +56,14 @@ IMAGE="$1"
 [ -z "$IMAGE" -a -z "$NEED_IMAGE" -a $CONF_BACKUP_LIST -eq 0 -o $HELP -gt 0 ] && {
 	cat <<EOF
 Usage: $0 [<upgrade-option>...] <image file or URL>
-       $0 [-q] [-i] [-c] [-u] <backup-command> <file>
+       $0 [-q] [-i] [-c] [-u] [-o] <backup-command> <file>
 
 upgrade-option:
 	-f <config>  restore configuration from .tar.gz (file or url)
 	-i           interactive mode
 	-c           attempt to preserve all changed files in /etc/
+	-o           attempt to preserve all changed files in /, except those
+	             from packages but including changed confs.
 	-u           skip from backup files that are equal to those in /rom
 	-n           do not save configuration over reflash
 	-p           do not attempt to restore the partition table after flash.
@@ -129,12 +133,52 @@ add_conffiles() {
 
 add_overlayfiles() {
 	local file="$1"
-	( cd /overlay/upper/; find ./etc \( -type f -o -type l \) $find_filter | sed \
+
+	local packagesfiles=$1.packagesfiles
+	touch "$packagesfiles"
+
+	if [ "$SAVE_OVERLAY_PATH" = / ]; then
+		local conffiles=$1.conffiles
+		local keepfiles=$1.keepfiles
+
+		list_conffiles | cut -f2 -d ' ' | sort -u > "$conffiles"
+
+		# backup files from /etc/sysupgrade.conf and /lib/upgrade/keep.d, but
+		# ignore those aready controlled by opkg conffiles
+		find $(sed -ne '/^[[:space:]]*$/d; /^#/d; p' \
+			/etc/sysupgrade.conf /lib/upgrade/keep.d/* 2>/dev/null) \
+			\( -type f -o -type l \) 2>/dev/null | sort -u |
+			grep -h -v -x -F -f $conffiles > "$keepfiles"
+
+		# backup conffiles, but only those changed if '-u'
+		[ $SKIP_UNCHANGED = 1 ] &&
+			list_changed_conffiles | sort -u > "$conffiles"
+
+		# do not backup files from packages, except those listed
+		# in conffiles and keep.d
+		{
+			find /usr/lib/opkg/info -type f -name "*.list" -exec cat {} \;
+			find /usr/lib/opkg/info -type f -name "*.control" -exec sed \
+				-ne '/^Alternatives/{s/^Alternatives: //;s/, /\n/g;p}' {} \; |
+				cut -f2 -d:
+		} |  grep -v -x -F -f $conffiles |
+		     grep -v -x -F -f $keepfiles | sort -u > "$packagesfiles"
+		rm -f "$keepfiles" "$conffiles"
+	fi
+
+	# busybox grep bug when file is empty
+	[ -s "$packagesfiles" ] || echo > $packagesfiles
+
+	( cd /overlay/upper/; find .$SAVE_OVERLAY_PATH \( -type f -o -type l \) $find_filter | sed \
 		-e 's,^\.,,' \
 		-e '\,^/etc/board.json$,d' \
 		-e '\,/[^/]*-opkg$,d' \
 		-e '\,^/etc/urandom.seed$,d' \
-	)> "$file"
+		-e '\,^/usr/lib/opkg/.*,d' \
+	) | grep -v -x -F -f $packagesfiles > "$file"
+
+	rm -f "$packagesfiles"
+
 	return 0
 }