enchantment: lib.chroot: refactor done + cleanup

Refactor the shared code in enchant_chroot_done and enchant_chroot_cleanup into
a separate, new function enchant_chroot_close. The usage of
enchant_chroot_close is potentially dangerous (whereas cleanup is guaranteed
dangerous), so it should be used carefully.

Additionally, rather than hardcoding the mountpoints or relying on a recursive
umount, which may not be available on the host system, get the list of mount
points to umount from the list of what's actually mounted in that chroot, but
sorted in reverse order (to guarantee that nested subdirs are unmounted before
their parents).

1 files changed, 51 insertions, 23 deletions

diff --git a/enchantment/lib/lib.chroot b/enchantment/lib/lib.chroot
index ab710e5..de61ff1 100644
--- a/enchantment/lib/lib.chroot
+++ b/enchantment/lib/lib.chroot
@@ -106,6 +106,55 @@ function enchant_chroot_init() {
 }
 
 #-------------------------------------------------------------------------------
+## @param chroot index (optional)
+## @param target chroot paths (optional)
+##
+## Unmounts required mount points in the chroot and unsets the related CHROOT
+## variables. If no target chroot is not provided, it will close ALL known
+## chroot paths.
+##
+#-------------------------------------------------------------------------------
+function enchant_chroot_close() {
+  local index="$1"
+  local chroot=
+  local target=
+
+  shift 1
+  chroot=( "$@" )
+  [[ -z "$chroot" ]] && chroot=( "${LIBCHROOT_PATHS[@]}" )
+
+  for target in "${chroot[@]}"
+  do
+    local mounts=( $(grep -o "$target[^[:space:]]*" | sort -r) )
+    [[ -n "$mounts" ]] || mounts=( sys run dev/pts dev proc )
+    cauldron_verbose "closing chroot mounts: ${mounts[@]}"
+
+    # unmount the chroot mount points
+    for mnt in "${mounts[@]}"
+    do
+      if grep -q "$mnt" "$target/proc/mounts"
+      then
+        "${CAULDRON_CMD_UNMOUNT[@]}" "$target/$mnt" ||
+          return $ERR_CHROOT_DONE
+      fi
+    done
+  done
+
+  # clear the chroot definitions
+  if [[ -n "$index" ]]
+  then
+    unset LIBCHROOT_USERS[index]
+    unset LIBCHROOT_PATHS[index]
+  else
+    unset LIBCHROOT_USERS
+    unset LIBCHROOT_PATHS
+  fi
+  unset CAULDRON_CHROOT
+
+  return $ERR_OK
+}
+
+#-------------------------------------------------------------------------------
 ## @param target dir to chroot into (optional)
 ##
 ## Cleans up the chroot environment after it is no longer needed
@@ -131,14 +180,7 @@ function enchant_chroot_done() {
       then
         LIBCHROOT_USERS[index]=$((LIBCHROOT_USERS[index]-1))
       else
-        # unmount the chroot mount points
-        "${ENCHANT_CMD_UNMOUNT_RECURSIVE[@]}" "$target"/* ||
-          return $ERR_CHROOT_DONE
-
-        # clear the chroot definitions
-        unset ENCHANT_CHROOT
-        unset LIBCHROOT_USERS[index]
-        unset LIBCHROOT_PATHS[index]
+        enchant_chroot_close "$index" "$target"
       fi
     fi
   done
@@ -153,21 +195,7 @@ function enchant_chroot_done() {
 ##
 #-------------------------------------------------------------------------------
 function enchant_chroot_cleanup() {
-  local target=
-
-  for target in "${LIBCHROOT_PATHS[@]}"
-  do
-    # unmount the chroot mount points
-    "${ENCHANT_CMD_UNMOUNT_RECURSIVE[@]}" "$target"/* ||
-      return $ERR_CHROOT_DONE
-  done
-
-  # clear the chroot definitions
-  unset LIBCHROOT_USERS
-  unset LIBCHROOT_PATHS
-  unset ENCHANT_CHROOT
-
-  return $ERR_OK
+  enchant_chroot_close
 }
 
 #-------------------------------------------------------------------------------