Support home-based mailboxes during automated upgrades

update.sh

@@ -15,6 +15,8 @@ UP_INSTALL_DEPS=false
 UP_GITEA=''
 UP_RCLONE=''
 UP_CRON=''
+UP_MAIL_DIR=''
+UP_MAIL_HOMES=false
 UP_STATE=''
 UP_WORKER=false
 while (( $# )); do
@@ -26,11 +28,14 @@ while (( $# )); do
     --no-gitea) UP_GITEA=false; shift ;;
     --rclone-config) UP_RCLONE=${2:?Missing rclone configuration}; shift 2 ;;
     --cron-services) UP_CRON=${2:?Missing comma-separated systemd units}; shift 2 ;;
+    --mail-dir) UP_MAIL_DIR=${2:?Missing mailbox directory}; shift 2 ;;
+    --mail-homes-only) UP_MAIL_HOMES=true; shift ;;
     --worker) UP_WORKER=true; UP_STATE=${2:?Missing state}; shift 2 ;;
-    --help) echo 'Usage: sudo bash update.sh [--foreground] [--config FILE] [--rclone-config FILE] [--enable-gitea | --no-gitea] [--cron-services UNIT,...] [--install-deps]'; exit 0 ;;
+    --help) echo 'Usage: sudo bash update.sh [--foreground] [--config FILE] [--rclone-config FILE] [--enable-gitea | --no-gitea] [--cron-services UNIT,...] [--mail-dir DIR | --mail-homes-only] [--install-deps]'; exit 0 ;;
     *) die "Unknown argument: $1" ;;
   esac
 done
+[[ -z $UP_MAIL_DIR || $UP_MAIL_HOMES == false ]] || die 'Choose --mail-dir OR --mail-homes-only'
 [[ $EUID == 0 ]] || die 'Run with sudo bash'
 need systemctl; need flock
 # This lock excludes two coordinators, independently from ordinary backup jobs.
@@ -46,6 +51,51 @@ prompt() {
 append_setting() { printf '%s=%q\n' "$1" "$2" >> "$UP_STATE/candidate.conf"; }
 discover() { python3 "$LIB_DIR/update-discover.py" "$@"; }
 
+# Do not infer mailbox coverage from an existing directory. In particular,
+# creating an empty /var/vmail would make preflight pass without saving mail.
+prepare_mail() {
+  local choice home
+  if [[ $ENABLE_MAIL != true ]]; then
+    [[ -z $UP_MAIL_DIR && $UP_MAIL_HOMES == false ]] || die 'Mail options require ENABLE_MAIL=true'
+    return 0
+  fi
+  if [[ -n $UP_MAIL_DIR ]]; then
+    MAIL_DIR=$UP_MAIL_DIR
+    ENABLE_MAIL_STORE=true
+  elif [[ $UP_MAIL_HOMES == true ]]; then
+    ENABLE_MAIL_STORE=false
+  elif [[ $ENABLE_MAIL_STORE == true && ! -d $MAIL_DIR ]]; then
+    echo "Konfiguriertes zentrales Mailverzeichnis fehlt: $MAIL_DIR"
+    printf 'Konfigurierte Mail-Homes: '; printf '%q ' "${MAIL_HOME_DIRS[@]}"; echo
+    echo 'Absoluten Pfad zur tatsaechlichen zentralen Mailablage angeben.'
+    echo 'Nur wenn ALLE Mailboxen in den konfigurierten Homes liegen: homes eingeben.'
+    echo 'Bei unbekannter Ablage abbrechen; kein leeres Ersatzverzeichnis anlegen.'
+    [[ -t 0 ]] || die 'Missing mail source: supply --mail-dir DIR or explicitly confirm coverage with --mail-homes-only'
+    read -r -p 'Mailverzeichnis / homes / Enter zum Abbrechen: ' choice
+    [[ -n $choice ]] || die 'Mail storage unresolved; installed package/config/timer unchanged'
+    if [[ $choice == homes ]]; then
+      printf 'Home-Excludes: '; printf '%q ' "${MAIL_HOME_EXCLUDES[@]}"; echo
+      prompt 'Alle Mailboxen liegen in diesen Homes, ohne ausgeschlossene Pfade oder weitere Mounts? [j/N]' || die 'Mail coverage not confirmed'
+      ENABLE_MAIL_STORE=false
+    else MAIL_DIR=$choice; fi
+  fi
+  if [[ $ENABLE_MAIL_STORE == true ]]; then
+    [[ $MAIL_DIR == /* ]] || die 'MAIL_DIR must be absolute'
+    check_source_path "$MAIL_DIR"
+    append_setting MAIL_DIR "$MAIL_DIR"
+    echo "Zentrales Mailverzeichnis: $MAIL_DIR"
+  else
+    [[ $ENABLE_MAIL_HOME_DIRS == true && ${#MAIL_HOME_DIRS[@]} -gt 0 ]] || die 'Homes-only mail requires enabled, nonempty MAIL_HOME_DIRS'
+    for home in "${MAIL_HOME_DIRS[@]}"; do
+      [[ $home == /* ]] || die 'MAIL_HOME_DIRS must be absolute'
+      check_source_path "$home"
+    done
+    printf 'Mail ausschliesslich in Homes (Excludes und Mountgrenzen gelten): '
+    printf '%q ' "${MAIL_HOME_DIRS[@]}"; echo
+  fi
+  append_setting ENABLE_MAIL_STORE "$ENABLE_MAIL_STORE"
+}
+
 if [[ $UP_WORKER == false ]]; then
   systemctl is-active --quiet app-backup-upgrade.service && die 'Upgrade service is already running'
   # Only install missing, small prerequisites when requested. Never upgrade PHP,
@@ -87,6 +137,7 @@ if [[ $UP_WORKER == false ]]; then
   append_setting ENABLE_UPLOAD true
   append_setting ENABLE_NEXTCLOUD_MAINTENANCE true
   append_setting MAIL_BACKUP_MODE stop
+  prepare_mail
   if [[ $ENABLE_WORDPRESS == true || $ENABLE_NEXTCLOUD == true ]]; then
     for pair in "ENABLE_HTTPD_STOP:$HTTPD_SERVICE_NAME" "ENABLE_PHPFPM_STOP:$PHPFPM_SERVICE_NAME"; do
       name=${pair%%:*}; unit=${pair#*:}