slugos-init: add init script to handle USB device moving in 0.10

 - the init.d script fixfstab uses blkid to build a partition/uuid
   mapping table and compares this to the version from the previous
   boot, if anything changes /etc/fstab is updated

4 files changed, 120 insertions, 3 deletions

diff --git a/packages/slugos-init/files/functions b/packages/slugos-init/files/functions
index d631579966..ef10d65fb2 100644
--- a/packages/slugos-init/files/functions
+++ b/packages/slugos-init/files/functions
@@ -372,3 +372,17 @@ umountflash(){
 
 	return 0
 }
+
+#
+# uuid_by_partition
+#  output a list of partitions and their UUIDs
+uuid_by_partition() {
+	blkid -c /dev/null -s UUID | sed -n 's/^\([^:]*\): .*UUID="\([^"]*\)".*$/\1 \2/p'
+}
+
+#
+# partition_of uuid
+#  return the partition corresponding to the UUID
+partition_of() {
+	sed -n 's/^\([^ ]*\) '"$1"'$/\1/p'
+}
diff --git a/packages/slugos-init/files/initscripts/fixfstab b/packages/slugos-init/files/initscripts/fixfstab
new file mode 100644
index 0000000000..67116a12fd
--- /dev/null
+++ b/packages/slugos-init/files/initscripts/fixfstab
@@ -0,0 +1,91 @@
+#!/bin/sh
+# validate /etc/fstab against the current UUID list in
+# /etc/uuid_by_partition
+#
+. /etc/default/functions
+pfile=/etc/uuid_by_partition
+
+#
+# use debug to find out what is going on
+test "$1" = start -o "$1" = debug || exit 0
+
+#
+# obtain the current list of parititions with UUIDs
+newlist="$(uuid_by_partition)"
+
+if test -r "$pfile"
+then
+	# read the old list
+	oldlist="$(cat "$pfile")"
+	#
+	# if it hasn't changed nothing need be done
+	test "$newlist" = "$oldlist" && exit 0
+	#
+	# it has changed, but this only matters if
+	# a previously existing uuid has moved, build
+	# a list of old device vs new device for every
+	# uuid which has moved
+	changedlist="$(
+		{	echo "$oldlist"
+			echo "$newlist"
+		} | awk 'device[$2] == ""{device[$2] = $1}
+			device[$2] != $1{print device[$2], $1}')"
+
+	if test -n "$changedlist"
+	then
+		# at least one partition has moved, scan the
+		# current fstab to see if it has a reference
+		# to this partition
+		changedfstab="$(
+			{	echo "$changedlist"
+				echo '#fstab'
+				cat /etc/fstab
+			} | awk 'BEGIN{list=1}
+				list==1 && $0=="#fstab"{list=0; continue}
+				list==1{new[$1] = $2; continue}
+				new[$1] != ""{print $1, new[$1]}')"
+
+		# if this list is not empty edit the fstab
+		if test -n "$changedfstab"
+		then
+			rm -f /tmp/fstab.$$
+			# if the edit fails then do not overwrite the old
+			# partition list - just exit with an error
+			{	echo "$changedlist"
+				echo '#fstab'
+				cat /etc/fstab
+			} | awk 'BEGIN{list=1}
+				list==1 && $0=="#fstab"{list=0; continue}
+				list==1{new[$1] = $2; continue}
+				new[$1] != ""{$1 = new[$1]}
+				{print}' >/tmp/fstab.$$ || {
+				if test "$1" = start
+				then
+					logger -s "/etc/init.d/fixfstab: /tmp/fstab.$$: awk failed"
+				else
+					echo "debug: awk script failed with:" >&2
+					echo "$changedlist" >&2
+					echo "output in /tmp/fstab.$$" >&2
+				fi
+				exit 1
+			}
+
+			if test "$1" = start
+			then
+				mv /tmp/fstab.$$ /etc/fstab || {
+					logger -s "/etc/init.d/fixfstab: /tmp/fstab.$$: update failed"
+					exit 1
+				}
+			else
+				echo "debug: fstab changed:"
+				diff -u /etc/fstab /tmp/fstab.$$
+			fi
+		fi
+	fi
+fi
+
+# write the new list to the file, only if we
+# are doing something...
+test "$1" = start && echo "$newlist" >"$pfile"
+
+exit 0
diff --git a/packages/slugos-init/files/turnup b/packages/slugos-init/files/turnup
index d27648680f..f7fe0e7960 100644
--- a/packages/slugos-init/files/turnup
+++ b/packages/slugos-init/files/turnup
@@ -17,6 +17,10 @@ INRAM_DISK=""
 force=
 
 #
+# pfile: the uuid/partition file
+pfile=/etc/uuid_by_partition
+
+#
 # fstype new
 #  The type of the file system mounted on "new"  Outputs the last
 #  piece of information found, which should be the one for the
@@ -312,7 +316,7 @@ setup_rootfs() {
 # setup_fstab new fsdev fstype fsoptions
 #  Alters the /etc/fstab entry for / to refer to the correct device and
 #  have the correct type and options.  Essential for checkroot to remount
-#  / with the correct options.
+#  / with the correct options.  Writes the initial uuid file.
 #  bad, since sed won't fail even if it changes nothing.
 setup_fstab() {
 	sed -i '\@^[^ 	]*[ 	][ 	]*/[ 	]@s@^.*$@'"$2	/	$3	$4	1  1"'@' "$1"/etc/fstab
@@ -322,6 +326,11 @@ setup_fstab() {
 		echo "  to ensure that the root partition is mounted correctly" >&2
 		return 1
 	}
+	#
+	# build $pfile
+	uuid_by_partition >"$1""$pfile" ||
+		echo "turnup: $pfile: blkid failed (ignored)" >&2
+	return 0
 }
 
 #
diff --git a/packages/slugos-init/slugos-init_0.10.bb b/packages/slugos-init/slugos-init_0.10.bb
index 179e5a735e..6a31fca367 100644
--- a/packages/slugos-init/slugos-init_0.10.bb
+++ b/packages/slugos-init/slugos-init_0.10.bb
@@ -4,7 +4,7 @@ PRIORITY = "required"
 LICENSE = "GPL"
 DEPENDS = "base-files devio"
 RDEPENDS = "busybox devio"
-PR = "r51"
+PR = "r52"
 
 SRC_URI = "file://boot/flash \
 	   file://boot/disk \
@@ -12,6 +12,7 @@ SRC_URI = "file://boot/flash \
 	   file://boot/ram \
 	   file://boot/network \
 	   file://boot/udhcpc.script \
+	   file://initscripts/fixfstab \
 	   file://initscripts/syslog.buffer \
 	   file://initscripts/syslog.file \
 	   file://initscripts/syslog.network \
@@ -35,7 +36,8 @@ CPROGS = "${USRSBINPROGS} ${SBINPROGS}"
 SCRIPTS = "turnup reflash leds sysconf"
 BOOTSCRIPTS = "flash disk nfs ram network udhcpc.script"
 INITSCRIPTS = "syslog.buffer syslog.file syslog.network zleds\
-	leds_startup rmrecovery sysconfsetup umountinitrd.sh"
+	leds_startup rmrecovery sysconfsetup umountinitrd.sh\
+	fixfstab"
 
 # This just makes things easier...
 S="${WORKDIR}"
@@ -120,6 +122,7 @@ pkg_postinst_slugos-init() {
 	test -n "$D" && opt="-r $D"
 	update-rc.d $opt hwclock.sh		start  8 S . start 45 0 6 .
 	update-rc.d $opt umountinitrd.sh	start  9 S .
+	update-rc.d $opt fixfstab		start 10 S .
 	update-rc.d $opt syslog.buffer		start 11 S . start 49 0 6 .
 	update-rc.d $opt sysconfsetup		start 12 S .
 	update-rc.d $opt syslog.file		start 39 S . start 47 0 6 .