Incus: make prompts visible for end-user

core/core.func

@@ -718,12 +718,13 @@ arch_check() {
     echo -e "${TAB}If you try it, please report the outcome - success or failure:"
     echo -e "${TAB}${BGN}https://github.com/community-scripts/ProxmoxVED/issues${CL}"
     echo ""
-    if [[ ! -t 0 ]]; then
+    local arm64_src
+    if ! arm64_src="$(_cs_stdin_source)"; then
       msg_error "Not running interactively - refusing to guess on arm64. Set var_arm64=yes to override."
       sleep 2
       exit 106
     fi
-    read -r -p "${TAB}Continue anyway? (y/N): " arm64_prompt </dev/tty
+    read -r -p "${TAB}Continue anyway? (y/N): " arm64_prompt <"$arm64_src"
     if [[ "${arm64_prompt,,}" =~ ^(y|yes)$ ]]; then
       msg_ok "Continuing on arm64 - thanks for testing"
       return 0
@@ -1640,6 +1641,17 @@ show_missing_values_warning() {
   return 0
 }
 
+# Where to read an answer from, or failure when nobody can answer. Incus has no /dev/tty.
+_cs_stdin_source() {
+  if : 2>/dev/null </dev/tty; then
+    printf '/dev/tty'
+  elif [[ -t 0 || "${CS_STDIN_OK:-0}" == "1" ]]; then
+    printf '/dev/stdin'
+  else
+    return 1
+  fi
+}
+
 # ------------------------------------------------------------------------------
 # prompt_confirm()
 #
@@ -1693,9 +1705,8 @@ prompt_confirm() {
     fi
   fi
 
-  # Check if running in a TTY
-  if [[ ! -t 0 ]]; then
-    # Not a TTY, use default
+  local prompt_src
+  if ! prompt_src="$(_cs_stdin_source)"; then
     if [[ "$default" == "y" ]]; then
       return 0
     else
@@ -1706,7 +1717,7 @@ prompt_confirm() {
   # Interactive prompt with timeout
   echo -en "${YW}${message} ${hint} (auto-${default} in ${timeout}s): ${CL}"
 
-  if read -t "$timeout" -r response </dev/tty; then
+  if read -t "$timeout" -r response <"$prompt_src"; then
     # User provided input
     response="${response,,}" # lowercase
     case "$response" in

incus/backend.func

@@ -1054,23 +1054,15 @@ INNEREOF" >>"${LOGFILE:-$INCUS_BUILD_LOG}" 2>&1 || { msg_error "Failed to push f
   _install_script="$(_cs_fetch_text "install/${var_install}.sh")"
   _run_env="$(_incus_build_install_env)"
   _run_env+=$'\nsource /dev/stdin <<<"$(cat /tmp/incus-functions)"'
+  _run_env+=$'\n'"$(_incus_prompt_shim)"
 
-  # Deliberately NO pty here. Forcing one with `incus exec -t` looks like the
-  # fix for install scripts that prompt, but apt saves and restores stdin's
-  # terminal attributes around every dpkg call: on that pty tcsetattr returned
-  # EIO ("Setting in Stop via TCSAFLUSH for stdin failed"), killing the shell
-  # mid-install. It died before silent() could record anything, so the run was
-  # reported as a success against an empty container.
+  # No pty on purpose: under `incus exec -t` apt's tcsetattr fails with EIO and kills the shell.
   set +Eeuo pipefail
   trap - ERR
-  # stdin from /dev/null: without a pty `read -p` prints no prompt at all, so a
-  # script that asks a question waited on input nobody could see or answer.
-  # The trailing touch is a completion sentinel: all 552 install scripts run to
-  # cleanup_lxc/customize and none exits early, so the marker appears if and
-  # only if the script reached its end.
+  # The trailing touch is a completion sentinel: no install script exits early.
   incus exec "${CT_NAME}" -- bash -c "${_run_env}
 ${_install_script}
-touch /root/.install-${SESSION_ID}.done" </dev/null 2>&1 |
+touch /root/.install-${SESSION_ID}.done" 2>&1 |
     tee >(sed -u 's/.*\r//' >>"${LOGFILE:-$INCUS_BUILD_LOG}")
   # PIPESTATUS, not $?: the line above turns pipefail off, so $? is tee's
   # status - always 0. Every non-zero exit from the container was discarded
@@ -1403,9 +1395,44 @@ export REPO_SOURCE='${REPO_SOURCE:-}'
 export REPO_SLUG='${REPO_SLUG:-}'
 export TELEMETRY_PLATFORM='incus'
 export CS_ANIMATION_OK='$([ -t 1 ] && echo 1 || echo 0)'
+export CS_STDIN_OK='$([ -t 0 ] && echo 1 || echo 0)'
 EOF
 }
 
+# bash shows a `read -p` prompt only on a terminal, so without a pty the question was invisible.
+_incus_prompt_shim() {
+  cat <<'SHIMEOF'
+read() {
+  local -a _args=()
+  local _prompt="" _flags
+  while (($#)); do
+    if [[ "$1" == -*p && "$1" != --* && $# -ge 2 ]]; then
+      _flags="${1%p}"
+      [[ "$_flags" != "-" ]] && _args+=("$_flags")
+      _prompt="$2"
+      shift 2
+      continue
+    fi
+    _args+=("$1")
+    shift
+  done
+  [[ -n "$_prompt" ]] || {
+    builtin read "${_args[@]}"
+    return
+  }
+  printf '%s' "$_prompt" >&2
+  if [[ "${CS_STDIN_OK:-0}" != "1" ]]; then
+    printf '%s\n' "(no input available - using the default)" >&2
+    return 0
+  fi
+  builtin read "${_args[@]}" || {
+    printf '\n' >&2
+    return 0
+  }
+}
+SHIMEOF
+}
+
 incus_build_container() {
   _incus_sync_from_pve_settings
   _incus_prepare_install_exports

lxc/install.func

@@ -589,12 +589,11 @@ pkg_update() {
         else
           msg_warn "Find Debian mirrors at: https://www.debian.org/mirror/list"
         fi
-        # Only ask when there is someone to answer. Headless, /dev/tty does not
-        # exist, the read fails instantly, custom_mirror stays empty and the
-        # `continue` below spins the loop forever instead of prompting. Falling
-        # through leaves apt_ok=false, which the caller reports properly.
+        # Only ask when there is someone to answer: otherwise the loop spins forever.
+        local mirror_src
         while ! is_unattended; do
-          read -rp "  Enter a mirror hostname (or 'skip' to abort): " custom_mirror </dev/tty || break
+          mirror_src="$(_cs_stdin_source)" || break
+          read -rp "  Enter a mirror hostname (or 'skip' to abort): " custom_mirror <"$mirror_src" || break
           [[ -z "$custom_mirror" ]] && continue
           [[ "$custom_mirror" == "skip" ]] && break
           [[ ! "$custom_mirror" =~ ^[a-zA-Z0-9._-]+$ ]] && {

ui/API.txt

@@ -12,6 +12,7 @@ _cs_run_os_section
 _cs_run_update
 _cs_runtime_cache_dir
 _cs_scripts_ref_line
+_cs_stdin_source
 _dev_step_end
 _dev_step_key
 _dev_step_start