Add custom impermanence module

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

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

@@ -0,0 +1,19 @@
+echo "Starting 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/$part"
+
+  if [ ! -d "$source_current" ]; 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"
+done

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"

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

@@ -0,0 +1,25 @@
+delete_subvolume_recursively() {
+  IFS=$'\n'
+  for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
+    delete_subvolume_recursively "/mnt/btrfs/$i"
+  done
+  btrfs subvolume delete "$1"
+}
+
+mkdir -p /mnt/btrfs
+mount /dev/mapper/luks /mnt/btrfs
+
+if [[ -e /mnt/btrfs/@ ]]; then
+  mkdir -p /mnt/btrfs/@.bak
+  timestamp=$(date --date="@$(stat -c %Y /mnt/btrfs/@)" "+%Y-%m-%d_%H:%M:%S")
+  mv /mnt/btrfs/@ "/mnt/btrfs/@.bak/$timestamp"
+fi
+
+find /mnt/btrfs/@.bak/ -maxdepth 1 -mtime +14 | while IFS= read -r i; do
+  delete_subvolume_recursively "$i"
+done
+
+btrfs subvolume create /mnt/btrfs/@
+
+umount /mnt/btrfs
+rmdir /mnt/btrfs