Stage 7: command-line helpers dsv, duser, dfw, dsys (0.5.0)

- das-helpers replaces the dsv package and adds shared functions in
  /usr/lib/das/helpers.sh (bilingual messages, sudo re-exec, prompts).
- dsv new creates a runit service (command, user, directory, environment,
  svlogd log) and checks it stays up; dsv rm deletes one not from a package.
- duser: list, add (installer groups, --admin, key, password), del, passwd,
  lock/unlock (key logins too), key add|list|rm, groups +/-.
- dfw: allow/deny/status/reload for the tcp_ports and udp_ports sets of the
  inet das table, kept in /etc/nftables.d/dfw.nft and checked with nft -c.
- dsys: info, hostname, timezone, locale, keymap.
- xtools-minimal on both images.
- nftables.conf no longer suggests restarting the nftables service: its
  finish script flushes the whole ruleset, fail2ban's and Docker's included.
- das-server-install 0.2.0 mentions the helpers when it finishes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

srcpkgs/das-helpers/files/helpers.sh

@@ -0,0 +1,75 @@
+# Shared functions of the Das OS helpers (dsv, duser, dfw, dsys).
+# Sourced, not run: each helper sets "set -euo pipefail" itself.
+# shellcheck shell=bash
+
+self=${0##*/}
+
+if [[ ${LC_ALL:-} == uk* || ${LC_MESSAGES:-} == uk* || ${LANG:-} == uk* ]]; then
+  uk=1
+else
+  uk=""
+fi
+
+# say UKRAINIAN ENGLISH: prints the message in the user's language
+say() {
+  if [[ -n $uk ]]; then echo "$1"; else echo "$2"; fi
+}
+
+warn() {
+  say "$self: $1" "$self: $2" >&2
+}
+
+die() {
+  warn "$1" "$2"
+  exit 1
+}
+
+# need_root ARGS...: runs the helper again through sudo with the same arguments
+need_root() {
+  if [[ $EUID -ne 0 ]]; then
+    exec sudo "$0" "$@"
+  fi
+}
+
+# Questions are only asked on a terminal; scripts must pass every argument
+interactive() {
+  [[ -t 0 ]]
+}
+
+# ask VAR UKRAINIAN ENGLISH [DEFAULT]: reads a line into VAR; the prompt shows
+# the default, which an empty answer keeps
+ask() {
+  local -n _answer=$1
+  local prompt
+  prompt=$(say "$2" "$3")
+  if [[ -n ${4:-} ]]; then
+    prompt+=" [$4]"
+  fi
+  read -r -e -p "$prompt: " _answer || exit 1
+  [[ -n $_answer ]] || _answer=${4:-}
+}
+
+# confirm UKRAINIAN ENGLISH: a yes/no question, "no" by default
+confirm() {
+  local reply
+  read -r -p "$(say "$1 [т/Н]" "$2 [y/N]") " reply || return 1
+  [[ ${reply,,} == @(y|yes|т|так) ]]
+}
+
+# pad TEXT WIDTH: TEXT padded with spaces to WIDTH characters. printf pads by
+# bytes, ${#s} counts characters, so Cyrillic columns stay aligned.
+pad() {
+  local width=$(($2 - ${#1}))
+  ((width > 0)) || width=0
+  printf '%s%*s ' "$1" "$width" ''
+}
+
+# set_rc VAR VALUE: sets VAR in /etc/rc.conf, uncommenting Void's example line
+set_rc() {
+  local rc=${RC_CONF:-/etc/rc.conf}
+  if grep -q "^#\?$1=" "$rc"; then
+    sed -i "s|^#\?$1=.*|$1=\"$2\"|" "$rc"
+  else
+    echo "$1=\"$2\"" >>"$rc"
+  fi
+}