base-files: merge /etc/passwd et al at sysupgrade config restore

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

package/base-files/Makefile

@@ -12,7 +12,7 @@ include $(INCLUDE_DIR)/version.mk
 include $(INCLUDE_DIR)/feeds.mk
 
 PKG_NAME:=base-files
-PKG_RELEASE:=232
+PKG_RELEASE:=233
 PKG_FLAGS:=nonshared
 
 PKG_FILE_DEPENDS:=$(PLATFORM_DIR)/ $(GENERIC_PLATFORM_DIR)/base-files/

package/base-files/files/lib/preinit/80_mount_root

@@ -2,6 +2,19 @@
 # Copyright (C) 2006 OpenWrt.org
 # Copyright (C) 2010 Vertical Communications
 
+missing_lines() {
+	local file1 file2 line
+	file1="$1"
+	file2="$2"
+	oIFS="$IFS"
+	IFS=":"
+	while read line; do
+		set -- $line
+		grep -q "^$1:" "$file2" || echo "$*"
+	done < "$file1"
+	IFS="$oIFS"
+}
+
 do_mount_root() {
 	mount_root
 	boot_run_hook preinit_mount_root
@@ -9,6 +22,9 @@ do_mount_root() {
 		echo "- config restore -"
 		cd /
 		tar xzf /sysupgrade.tgz
+		missing_lines /rom/etc/passwd /etc/passwd >> /etc/passwd
+		missing_lines /rom/etc/group /etc/group >> /etc/group
+		missing_lines /rom/etc/shadow /etc/shadow >> /etc/shadow
 		# Prevent configuration corruption on a power loss
 		sync
 	}