[chroot.inc] major improvements

-do not remove directories on startup/exit, instead check for existing
mounts.
-after remounting / to read-only, check if it worked.

1 files changed, 86 insertions, 25 deletions

diff --git a/remote/includes/chroot.inc b/remote/includes/chroot.inc
index 3485ce63..f0940bba 100644
--- a/remote/includes/chroot.inc
+++ b/remote/includes/chroot.inc
@@ -11,7 +11,7 @@
 # General information about OpenSLX can be found at http://openslx.org/
 # -----------------------------------------------------------------------------
 #
-#					Common functions for chrooting
+#			Common functions for chrooting
 #
 # -----------------------------------------------------------------------------
 
@@ -23,8 +23,20 @@ CHROOT_BINDMOUNTS="/dev /proc /sys /run"
 
 # Helper function to setup the directory structure
 chroot_prepare_dirs() {
-	# first the dir structure
-	[ -d "${CHROOT_TEMPDIR}" ] && rm -rf "${CHROOT_TEMPDIR}"
+	# first check if CHROOT_TEMPDIR exists
+	if [ -d "${CHROOT_TEMPDIR}" ]; then
+		# try to umount and rmdir CHROOT_MOUNTDIR
+		umount "${CHROOT_MOUNTDIR}" 2>/dev/null
+		rmdir "${CHROOT_MOUNTDIR}" || perror "Could not remove '${CHROOT_MOUNTDIR}', meaning it has stuff in it. Aborting..."
+
+		# try to umount and rmdir CHROOT_BINDDIR
+		umount "${CHROOT_BINDDIR}" 2>/dev/null
+		rmdir "${CHROOT_BINDDIR}" || perror "Could not remove '${CHROOT_BINDDIR}', meaning it has stuff in it. Aborting..."
+
+		# try to rmdir CHROOT_TEMPDIR
+		rmdir "${CHROOT_TEMPDIR}" || perror "Could not remove '${CHROOT_TEMPDIR}', meaning it has stuff in it. Aborting..."
+	fi
+
 	mkdir -p "${CHROOT_TEMPDIR}"	|| perror "Could not create base directory for mount directories $CHROOT_TEMPDIR."
 	for DIR in "${CHROOT_BINDDIR}" "${CHROOT_MOUNTDIR}"; do
 		mkdir -p "${DIR}"			|| perror "Could not create directory for mount directory $DIR."
@@ -36,31 +48,25 @@ chroot_prepare_dirs() {
 #	- make an overlay from CHROOT_LOWERDIR CHROOT_UPPERDIR
 #	- bind mount additional pseudo-fs (as given in CHROOT_BINDMOUNTS)
 chroot_prepare_mounts() {
-	# now the mounts
+
+	# first mount / on CHROOT_BINDDIR and remount read-only
 	mount -o bind "${CHROOT_LOWERDIR}" "${CHROOT_BINDDIR}"    || perror "Could not bind-mount '$CHROOT_LOWERDIR' to '$CHROOT_BINDDIR'."
 	mount -o remount,ro "${CHROOT_BINDDIR}"      		|| perror "Could not remount '$CHROOT_BINDDIR' read-only."
+
+	# check that it really is read-only
+	[ "x$(mount | grep -E "^/ on ${CHROOT_BINDDIR}" | grep -v '\(.*ro.*\)')" != "x" ] && perror "'${CHROOT_BINDDIR}' is not read-only! Aborting..."
+
+	# safe, go on to make the overlay
 	mount -t overlayfs overlayfs -o lowerdir="${CHROOT_BINDDIR}",upperdir="${CHROOT_UPPERDIR}" "${CHROOT_MOUNTDIR}"  \
 		|| perror "Could not mount (overlayfs) $CHROOT_LOWERDIR, $CHROOT_UPPERDIR to $CHROOT_BINDDIR."
+
+	# mount pseudo-filesystems
 	for DIR in $CHROOT_BINDMOUNTS; do
 		mount -o bind "${DIR}" "${CHROOT_MOUNTDIR}/${DIR}" \
 			|| perror "Could not bind mount '$DIR' into '$CHROOT_MOUNTDIR/$DIR'."
 	done
 }
 
-# Helper to cleanup the temporary mounts
-chroot_cleanup_mounts() {
-	for DIR in $CHROOT_BINDMOUNTS; do
-		umount -l "${CHROOT_MOUNTDIR}/${DIR}"	|| pwarning "Could not unmount '$CHROOT_MOUNTDIR/$DIR'!"
-	done
-	umount -l "${CHROOT_MOUNTDIR}"				|| pwarning "Could not unmount '$CHROOT_MOUNTDIR'!"
-	umount -l "${CHROOT_BINDDIR}"				|| pwarning "Could not unmount '$CHROOT_BINDDIR'!"
-}
-
-# Helper to clean the temporary directories
-chroot_cleanup_dirs() {
-	rm -rf "${CHROOT_TEMPDIR}" || perror "Could not clean/delete temp directory '$CHROOT_TEMPDIR'."
-}
-
 # Helper to generate the mighty autoexec.bat
 chroot_gen_autoexec() {
 	# create the script to be automatically executed.
@@ -72,8 +78,7 @@ chroot_gen_autoexec() {
 	# dump the piped input to it
 	cat >> "${CHROOT_MOUNTDIR}/autoexec.bat"
 
-	# finish with an exit
-	echo "exit 0" >> "${CHROOT_MOUNTDIR}/autoexec.bat"
+	# make it executable
 	chmod +x "${CHROOT_MOUNTDIR}/autoexec.bat"
 }
 
@@ -87,9 +92,13 @@ chroot_handle_whiteouts() {
 		echo "/./${WHITEOUT#$CHROOT_UPPERDIR}" >> "$WHITEOUT_LIST"
 		rm -f -- "$WHITEOUT" || perror "Could not delete whiteout $WHITEOUT!"
 	done
-	pinfo "Whitelist dumped to '${CHROOT_UPPERDIR}/overlay.whiteout.list'"
+	pinfo "Whiteout list dumped to '${CHROOT_UPPERDIR}/overlay.whiteout.list'"
 }
 
+###############################################################################
+#
+#				MAIN FUNCTION
+#
 # Main function to be called from the outside
 # Usage:
 #	chroot_run <build_dir> < <code_to_exec_in_chroot>
@@ -124,13 +133,65 @@ chroot_run() {
 	if [ "$RET" -eq 0 ]; then
 		pinfo "chroot executed '${CHROOT_MOUNTDIR}/autoexec.bat' succeeded."
 	else
-		perror "Failed to chroot to '$CHROOT_MOUNTDIR' with error code: $RET"
+		perror "Failed to run '$CHROOT_MOUNTDIR/autoexec.bat' inside the chroot to '$CHROOT_MOUNTDIR' with error code: $RET"
 	fi
 
 	# handle whiteouts
 	chroot_handle_whiteouts || perror "'chroot_handle_whiteouts' failed with error code: $?"
 
-	# finally cleanup all the stuff we did previously
-	chroot_cleanup_mounts					|| perror "'chroot_cleanup_mounts' failed with $?."
-	chroot_cleanup_dirs						|| perror "'chroot_cleanup_dir' failed with $?."
+	# finally cleanup all the mounting stuff we did previously
+	chroot_cleanup_mounts			|| perror "'chroot_cleanup' failed with $?."
+}
+
+###############################################################################
+#
+#				CLEANUP FUNCTIONS
+#
+# Helper to check if the given path is mounted
+chroot_check_mount_point() {
+	[ "$#" -eq 1 ] || perror "'chroot_check_mount_point' called with $# arguements, only 1 accepted."
+	local MOUNT="$1"	
+	if [ "x$(mount | grep "$(readlink -f $MOUNT)")" != "x" ]; then
+		# still mounted
+		pdebug "'$MOUNT' is mounted!"
+		return 1
+	else
+		pdebug "'$MOUNT' is not mounted."
+		return 0
+	fi
+}
+
+# Helper to umount the given path
+chroot_umount() {
+	[ "$#" -eq 1 ] || perror "'chroot_umount' called with $# arguments, only 1 accepted."
+	local MOUNT="$1"
+
+	# check if MOUNT is mounted
+	if ! chroot_check_mount_point "${MOUNT}"; then
+		# still mounted
+		if umount -l "${MOUNT}"; then
+			pdebug "Successfully umounted '${MOUNT}'."
+		else
+			pwarning "Could not umount '${MOUNT}'! Trying again..."
+			# now it gets ugly
+			for i in `seq 1 5`; do
+				umount -l "${MOUNT}" && return 0
+			done
+			perror "Could not umount '${MOUNT}' after 5 tries! This shouldn't happen. Check your scripts."
+		fi
+	else
+		pdebug "'${MOUNT}' is not mounted."
+	fi
+
+	# better be safe than sorry
+	chroot_check_mount_point "$MOUNT" || perror "'$MOUNT' is still mounted, exiting before something bad happens..."
+}
+
+# Helper to cleanup the temporary mounts
+chroot_cleanup_mounts() {
+	for DIR in $CHROOT_BINDMOUNTS; do
+		chroot_umount "${CHROOT_MOUNTDIR}/${DIR}"
+	done
+	chroot_umount "${CHROOT_MOUNTDIR}"
+	chroot_umount "${CHROOT_BINDDIR}"
 }