fix: close the silent-EOF class at the two host/ gates it also reached (#111)

The first pass fixed #111 where it was reported — confirm() and
uninstall_confirm() in bin/box — and stopped there, while the same defect
sat at two more destructive gates in this repo:

  · host/revoke-user.sh:50 guards 'box revoke --purge', the prompt whose
    own text says "this cannot be undone";
  · host/teardown-host.sh:31 guards a full host teardown.

Both run under 'set -euo pipefail', so an unguarded 'read' returning
non-zero on EOF ends the run before the 'case' that names the abort —
exit 1, in silence, at the moment the script asked. Each now carries the
guard in its own script's wording rather than importing bin/box's die().

The three drill/ prompts are deliberately untouched: they run under
'set -u' only, so EOF falls through to the '*)' arm and already aborts
out loud. install.sh:65 was already guarded.

What keeps the class closed is a repo-wide sweep in test/cli.sh: every
statement-initial 'read' fed from stdin, in any file that turns on
errexit, must carry a '||' guard — 'while read' loops and '<<<'
herestrings excluded, since neither is a prompt. Removing any of the four
guards makes it fail and name the file:line; it flags nothing else across
the tree's fifteen shell files. The absence of exactly this check is why
the host/ pair was missed the first time.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -103,7 +103,24 @@ which records not just what changed but what each drill run proved.
   `script`: they were structurally untested before, because `[ -t 0 ]`
   sends a terminal-less suite to the refusal branch and every existing
   check stopped there — which is exactly how this survived four
-  releases.
+  releases. Review caught that the first pass fixed the bug where it was
+  reported and stopped there, while the same defect sat at two more
+  destructive gates in this repo: `host/revoke-user.sh:50`, the prompt
+  guarding `box revoke --purge` — the one whose own text says "this
+  cannot be undone" — and `host/teardown-host.sh:31`, guarding a full
+  host teardown. Both run under `set -euo pipefail`, both died mute on
+  EOF with their `aborted` line never reached; both now carry the guard
+  in their own script's wording. The three `drill/` prompts are
+  deliberately left alone — they run under `set -u` only, so EOF falls
+  through to the `*)` arm and already aborts out loud — and
+  `install.sh:65` was already guarded. What keeps the class closed is a
+  repo-wide sweep in `test/cli.sh`: every statement-initial `read` fed
+  from stdin, in any file that turns on errexit, must carry a `||`
+  guard, with `while read` loops and `<<<` herestrings excluded because
+  neither is a prompt. The sweep flags all four sites when their guards
+  are removed and nothing else across the tree's fifteen shell files —
+  the absence of exactly this check is why the `host/` pair was missed
+  in the first place.
 - **`box restore` asks before it destroys — and the confirmation prompt is
   now the row's, not rm's** (#105) — `restore` and `rm` both irreversibly
   discard user state, and only one of them asked. The table gave `restore`

host/revoke-user.sh

@@ -47,7 +47,11 @@ if [ "$purge" -eq 1 ]; then
   if [ -z "${BOX_YES:-}" ]; then
     if [ -t 0 ]; then
       printf 'box revoke: delete ALL of %s'\''s boxes, images and their project %s? this cannot be undone. [y/N] ' "$user" "$project"
-      read -r reply
+      # EOF (Ctrl-D) is an answer too, and it is a refusal. Unguarded, 'read'
+      # returns non-zero and errexit ends the run right here — before the
+      # 'case' below can name the abort, so the most destructive prompt box
+      # has would go silent at the moment it asked (#111).
+      read -r reply || { echo "box revoke: aborted." >&2; exit 1; }
       case "$reply" in y|Y|yes|YES|Yes) : ;; *) echo "box revoke: aborted." >&2; exit 1 ;; esac
     else
       echo "box revoke: refusing to --purge without a terminal to confirm on. BOX_YES=1 means yes." >&2

host/teardown-host.sh

@@ -28,7 +28,9 @@ $purge && echo "Incus itself will also be uninstalled (--purge-incus)."
 if [ "$yes" -eq 1 ]; then
   echo "(confirmed non-interactively: --yes/BOX_YES)"
 else
-  read -rp "Continue? [y/N] " a
+  # EOF (Ctrl-D) refuses, out loud: unguarded, errexit would end the run on
+  # this line and the 'aborted' below would never print (#111).
+  read -rp "Continue? [y/N] " a || { echo "aborted"; exit 1; }
   case "$a" in y|Y) ;; *) echo "aborted"; exit 1 ;; esac
 fi
 

test/cli.sh

@@ -938,6 +938,47 @@ else
   echo "skip: the interactive confirm answers (no util-linux 'script' here; CI has it)"
 fi
 
+# --- the sweep: no prompt-shaped 'read' under 'set -e' may go unguarded (#111)
+# The pty checks above prove the two 'bin/box' gates. This proves the CLASS,
+# repo-wide, and it exists because the class is exactly what the first pass at
+# #111 missed: 'host/revoke-user.sh' and 'host/teardown-host.sh' carried the
+# identical defect and survived, because nothing here was looking for the shape.
+#
+# The shape: a 'read' at the start of a statement, fed from the script's own
+# stdin (so a human, or an EOF), inside a file that turns on errexit. On EOF
+# 'read' returns non-zero and 'set -e' ends the run BEFORE the 'case' that was
+# going to name the abort — the tool goes mute at the moment it asked.
+#
+# What is deliberately NOT flagged, because it is not the shape:
+#   · 'while IFS= read -r' loops — fed by a redirect at 'done', and a non-zero
+#     read is how the loop is supposed to end;
+#   · '<<<' herestring reads — fed from a string, never from a human;
+#   · files without errexit ('drill/wipe.sh', 'drill/drill.sh',
+#     'drill/multiuser.sh' run under 'set -u' only, wipe.sh documents why), where
+#     EOF simply falls through to the '*)' arm and aborts out loud on its own.
+# A guard is any '||' on the read's own line: '|| die', '|| reply=""',
+# '|| { echo …; exit 1; }' — the spelling is each script's to choose, the
+# guard is not.
+eof_guard_sweep() {
+  local f n line bad=0 files
+  files="$(cd "$ROOT" && shopt -s globstar && printf '%s\n' bin/* ./**/*.sh | sed 's|^\./||' | sort -u)"
+  while IFS= read -r f; do
+    [ -f "$ROOT/$f" ] || continue
+    grep -qE '^[[:space:]]*set[[:space:]]+-[a-zA-Z]*e' "$ROOT/$f" || continue
+    while IFS=: read -r n line; do
+      case "$line" in
+        *'<<<'*) continue ;;   # herestring, not a prompt
+        *'||'*)  continue ;;   # guarded — the whole point
+      esac
+      echo "$f:$n: prompt-shaped 'read' under 'set -e' with no '||' guard:$line"
+      bad=1
+    done < <(grep -nE '^[[:space:]]*(IFS=[^[:space:]]+[[:space:]]+)?read([[:space:]]|$)' "$ROOT/$f")
+  done <<<"$files"
+  return "$bad"
+}
+check "no prompt-shaped 'read' under 'set -e' goes unguarded, repo-wide (#111)" \
+  0 "" eof_guard_sweep
+
 rm -rf "$CSHIM" "$CWORK"
 
 # ---------------------------------------------------------------------------