Add impermanence create option

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

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

@@ -1,22 +1,49 @@
 # shellcheck shell=bash
 
 # shellcheck disable=SC2154
-echo "Starting impermanence mount with source: $source, target: $target, path: $path."
+echo "Starting impermanence mount with source: $source, target: $target, path: $path, create: $create"
 
 source_current="$source"
 target_current="$target"
 
-IFS='/' read -ra path_parts <<< "$path"
-unset "path_parts[-1]"
+IFS='/' read -ra parts <<< "$path"
+leaf="${parts[-1]}"
 
-for part in "${path_parts[@]}"; do
-  source_current="$source_current/$part"
-  target_current="$target_current/$part"
+for part in "${parts[@]}"; do
+  source_current+="/$part"
+  target_current+="/$part"
 
-  if [[ ! -d "$source_current" ]]; then
+  if [[ -e "$source_current" ]]; then
+    read -r mode owner group <<< "$(stat -c '%a %u %g' "$source_current")"
+
+    if [[ -d "$source_current" ]]; then
+      install -d -m "$mode" -o "$owner" -g "$group" "$target_current"
+      continue
+    fi
+
+    if [[ "$part" != "$leaf" ]]; then
+      echo "Error: $source_current is not a directory, persistence for $path can not be applied."
+      exit 1
+    fi
+
+    install -m "$mode" -o "$owner" -g "$group" /dev/null "$target_current"
+  fi
+
+  if [[ "$create" == "none" ]]; then
     break
   fi
 
-  read -r mode owner group <<< "$(stat -c '%a %u %g' "$source_current")"
-  install -d -m "$mode" -o "$owner" -g "$group" "$target_current"
+  if [[ -e "$target_current" ]]; then
+    template="$target_current"
+  else
+    template="${source_current%/*}"
+  fi
+
+  read -r mode owner group <<< "$(stat -c '%a %u %g' "$template")"
+
+  if [[ "$part" == "$leaf" && "$create" == "file" ]]; then
+    install -m "$mode" -o "$owner" -g "$group" /dev/null "$source_current"
+  else
+    install -d -m "$mode" -o "$owner" -g "$group" "$source_current"
+  fi
 done