add support for exposedroot option for live-helper

diff --git a/scripts/live b/scripts/live
index b4254e1..8f84ed2 100755 (executable)
--- a/scripts/live
+++ b/scripts/live
@@ -371,6 +371,11 @@ Arguments ()
                                export TORAM MODULETORAM
                                ;;
 
+                       exposedroot)
+                               EXPOSED_ROOT="Yes"
+                               export EXPOSED_ROOT
+                               ;;
+
                        union=*)
                                UNIONTYPE="${ARGUMENT#union=}"
                                export UNIONTYPE
@@ -961,9 +966,40 @@ setup_unionfs ()
                fi
        fi
 
-       mount ${cowdevice} -t ${cow_fstype} -o rw,noatime /cow || panic "Can not mount ${cowdevice} on /cow"
+       rofscount=$(echo ${rofslist} |wc -w)
+
+       if [ -n "${EXPOSED_ROOT}" ]
+       then
+               if [ ${rofscount} -ne 1 ]
+               then
+                       panic "only one RO file system supported with exposedroot: ${rofslist}"
+               fi
+               exposedrootfs=${rofslist%% }
+
+               mount --bind ${exposedrootfs} ${rootmnt} || \
+                       panic "bind mount of ${exposedrootfs} failed"
+
+               mount ${cowdevice} -t ${cow_fstype} -o rw,noatime /cow || \
+                       panic "Can not mount ${cowdevice} on /cow"
+
+               cow_dirs='/tmp /var/tmp /var/lock /var/run /var/log /var/spool
+                       /home /live /var/lib/live'
 
-       mount -t ${UNIONTYPE} -o noatime,dirs=/cow=rw:${rofsstring} ${UNIONTYPE} "${rootmnt}" || panic "${UNIONTYPE} mount failed"
+               for dir in ${cow_dirs}; do
+                       mkdir -p /cow${dir}
+                       mount -t ${UNIONTYPE} \
+                               -o rw,noatime,dirs=/cow${dir}=rw:${exposedrootfs}${dir}=ro \
+                               ${UNIONTYPE} "${rootmnt}${dir}" || \
+                               panic "mount ${UNIONTYPE} on ${rootmnt}${dir} failed with option \
+                                       rw,noatime,dirs=/cow${dir}=rw:${exposedrootfs}${dir}=ro"
+               done
+       else
+               mount ${cowdevice} -t ${cow_fstype} -o rw,noatime /cow || \
+                       panic "Can not mount ${cowdevice} on /cow"
+               mount -t ${UNIONTYPE} -o noatime,dirs=/cow=rw:${rofsstring} \
+                       ${UNIONTYPE} "${rootmnt}" || panic "mount ${UNIONTYPE} on \
+                       ${rootmnt} failed with option noatime,dirs=/cow=rw:${rofsstring}"
+       fi
 
        # Adding other custom mounts
        if [ -n "${PERSISTENT}" ]