Add custom impermanence module

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/common/system/configs/impermanence/scripts/stop.sh

@@ -0,0 +1,38 @@
+echo "Stopping impermanence mount with source: $source, target: $target, path: $path."
+
+source_current="$source"
+target_current="$target"
+
+IFS='/' read -ra path_parts <<< "$path"
+unset "path_parts[-1]"
+
+for part in "${path_parts[@]}"; do
+  source_current="$source_current/$part"
+  target_current="$target_current/$part"
+
+  if [ ! -d "$target_current" ]; then
+    break
+  fi
+
+  if [ -d "$source_current" ]; then
+    continue
+  fi
+
+  read -r mode owner group <<< "$(stat -c '%a %u %g' "$target_current")"
+  install -d -m "$mode" -o "$owner" -g "$group" "$source_current"
+done
+
+source=$(realpath -m "$source/$path")
+target=$(realpath -m "$target/$path")
+
+if [ ! -e "$target" ] || { [ -d "$target" ] && [ -z "$(ls -A "$target")" ]; } || { [ -f "$target" ] && [ ! -s "$target" ]; }; then
+  exit 0
+fi
+
+if [ -e "$source" ]; then
+  >&2 echo "Error: Source $source already exists. Cannot move $target to $source."
+  exit 1
+fi
+
+echo "Moving target $target to source $source."
+mv "$target" "$source"