cmd/snap-mgmt: replace use of /snap with SNAP_MOUNT_DIR

Cleanup remaining uses of /snap and replace them with SNAP_MOUNT_DIR

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

cmd/snap-mgmt/snap-mgmt.sh.in

@@ -42,16 +42,16 @@ purge() {
         # snap.mount.service is a trusty thing
         systemctl_stop snap.mount.service
     else
-        # undo any bind mount to /snap that resulted from LP:#1668659
+        # undo any bind mount to ${SNAP_MOUNT_DIR} that resulted from LP:#1668659
         # (that bug can't happen in trusty -- and doing this would mess up snap.mount.service there)
-        if grep -q "/snap /snap" /proc/self/mountinfo; then
-            umount -l /snap || true
+        if grep -q "${SNAP_MOUNT_DIR} ${SNAP_MOUNT_DIR}" /proc/self/mountinfo; then
+            umount -l "${SNAP_MOUNT_DIR}" || true
         fi
     fi
 
     units=$(systemctl list-unit-files --full | grep -vF snap.mount.service || true)
-    mounts=$(systemctl list-unit-files --full | grep "^${SNAP_UNIT_PREFIX}[-.].*\.mount" | cut -f1 -d ' ')
-    services=$(systemctl list-unit-files --full | grep "^${SNAP_UNIT_PREFIX}[-.].*\.service" | cut -f1 -d ' ')
+    mounts=$(echo "$units" | grep "^${SNAP_UNIT_PREFIX}[-.].*\.mount" | cut -f1 -d ' ')
+    services=$(echo "$units" | grep "^${SNAP_UNIT_PREFIX}[-.].*\.service" | cut -f1 -d ' ')
     for unit in $services $mounts; do
         # ensure its really a snap mount unit or systemd unit
         if ! grep -q 'What=/var/lib/snapd/snaps/' "/etc/systemd/system/$unit" && ! grep -q 'X-Snappy=yes' "/etc/systemd/system/$unit"; then
@@ -127,7 +127,8 @@ purge() {
 
     if test -d /etc/apparmor.d; then
         echo "Removing extra snap-confine apparmor rules"
-        rm -f /etc/apparmor.d/snap.core.*.usr.lib.snapd.snap-confine
+        # shellcheck disable=SC2046
+        rm -f /etc/apparmor.d/$(echo "$SNAP_UNIT_PREFIX" | tr '-' '.').core.*.usr.lib.snapd.snap-confine
     fi
 }