packages+frontends: dtail packaging follow-ups (vs0 review items)

- dtail-freebsd.json.tpl: move HostKeyFile from volatile
  /var/run/dserver/cache to persistent /var/db/dserver/ssh_host_key —
  FreeBSD's cleanvar purges /var/run at boot, so the host key was
  regenerated on every reboot (mirrors the NetBSD/OpenBSD templates)
- dserver-freebsd.tpl rc.d: start_precmd now creates /var/db/dserver
  (0700, dserver-owned) and re-runs dserver-update-key-cache.sh on
  every start, so the volatile key cache repopulates right after a
  reboot or restart instead of waiting for the daily periodic job
- packages/Makefile: .SHELLFLAGS gains -o pipefail — the
  "git archive | ssh ... tar" pipeline could mask a git archive
  failure as long as tar succeeded on the truncated stream (the only
  recipe-level pipeline; $(shell ...) calls are unaffected)
- packages/Makefile: OS-suffixed /tmp staging names for the OpenBSD
  and NetBSD dtail tgz (dtail-openbsd-*/dtail-netbsd-*) — a dash-less
  version would have made both targets stage to the same
  /tmp/dtail-<version>.tgz locally and on f0; the final repo copy
  keeps the canonical dtail-<version>.tgz name
- dserver-update-key-cache.sh.tpl (OpenBSD): port the NetBSD
  hardening — quote all variable expansions, derive the user via
  basename suffix stripping instead of cut -d. -f1 (dotted usernames
  broke), fix the obsolete-cachefile echo that used single quotes and
  never interpolated $cachefile, add a header comment documenting the
  rc_pre and /etc/daily.local call sites
- dserver.tpl (OpenBSD rc.d): replace 'rc_cmd $1 &' with rc_bg=YES and
  a plain rc_cmd "$1" — the daemon needs backgrounding because it does
  not daemonize, but backgrounding the whole rc framework made rc_pre
  failures and the start result invisible to rcctl; rc_bg is rc.subr's
  supported way to background only the daemon
- dserver-update-key-cache-freebsd.sh.tpl: header now documents the
  new rc.d start_precmd call site

Deployed: FreeBSD pkg republished, f0/f1/f2 upgraded with host key
migrated to /var/db/dserver first (sha256 verified identical); f3
unreachable, still on the old package. OpenBSD pkg republished,
fishfinger reinstalled + restarted, host key unchanged, dcat verified.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

2 files changed, 19 insertions, 16 deletions

diff --git a/frontends/scripts/dserver-update-key-cache-freebsd.sh.tpl b/frontends/scripts/dserver-update-key-cache-freebsd.sh.tpl
index 22173d7..5b11acf 100644
--- a/frontends/scripts/dserver-update-key-cache-freebsd.sh.tpl
+++ b/frontends/scripts/dserver-update-key-cache-freebsd.sh.tpl
@@ -1,6 +1,8 @@
 #!/bin/sh
 # Refresh the dserver SSH key cache from user authorized_keys files.
-# Called by /usr/local/etc/periodic/daily/200.dserver-update-key-cache.
+# FreeBSD variant: called from the dserver rc.d start_precmd (because
+# /var/run is volatile across reboots — cleanvar purges it) and by
+# /usr/local/etc/periodic/daily/200.dserver-update-key-cache.
 
 CACHEDIR=/var/run/dserver/cache
 DSERVER_USER=dserver
diff --git a/frontends/scripts/dserver-update-key-cache.sh.tpl b/frontends/scripts/dserver-update-key-cache.sh.tpl
index 86b5ecf..fc6bf9e 100644
--- a/frontends/scripts/dserver-update-key-cache.sh.tpl
+++ b/frontends/scripts/dserver-update-key-cache.sh.tpl
@@ -1,4 +1,8 @@
 #!/bin/ksh
+# Refresh the dserver SSH key cache from user authorized_keys files.
+# OpenBSD variant: called from the dserver rc.d rc_pre (because /var/run is
+# wiped by /etc/rc at boot) and from a daily /etc/daily.local entry added by
+# the Rex 'dtail' task — see the pkgrepo skill's dtail-package.md.
 
 CACHEDIR=/var/run/dserver/cache
 DSERVER_USER=_dserver
@@ -7,27 +11,24 @@ DSERVER_GROUP=_dserver
 echo 'Updating SSH key cache'
 
 ls /home/ | while read remoteuser; do
-    keysfile=/home/$remoteuser/.ssh/authorized_keys
+    keysfile="/home/$remoteuser/.ssh/authorized_keys"
 
-    if [ -f $keysfile ]; then
-        cachefile=$CACHEDIR/$remoteuser.authorized_keys
+    if [ -f "$keysfile" ]; then
+        cachefile="$CACHEDIR/$remoteuser.authorized_keys"
         echo "Caching $keysfile -> $cachefile"
 
-        cp $keysfile $cachefile
-        chown $DSERVER_USER:$DSERVER_GROUP $cachefile
-        chmod 600 $cachefile
+        cp "$keysfile" "$cachefile"
+        chown "$DSERVER_USER:$DSERVER_GROUP" "$cachefile"
+        chmod 600 "$cachefile"
     fi
 done
 
-# Cleanup obsolete public SSH keys
-find $CACHEDIR -name \*.authorized_keys -type f |
-while read cachefile; do
-    remoteuser=$(basename $cachefile | cut -d. -f1)
-    keysfile=/home/$remoteuser/.ssh/authorized_keys
-
-    if [ ! -f $keysfile ]; then
-        echo 'Deleting obsolete cache file $cachefile'
-        rm $cachefile
+# Remove stale cache entries for users whose authorized_keys no longer exist
+find "$CACHEDIR" -name '*.authorized_keys' -type f | while read cachefile; do
+    remoteuser=$(basename "$cachefile" .authorized_keys)
+    if [ ! -f "/home/$remoteuser/.ssh/authorized_keys" ]; then
+        echo "Deleting obsolete cache file $cachefile"
+        rm "$cachefile"
     fi
 done