Revert "feat: removed pre unlock hosts script"

This reverts commit ec8d91fe69.

hosts/guard/install_pacman_hooks.sh

@@ -9,8 +9,21 @@ HOOKS_DIR="/etc/pacman.d/hooks"
 
 install -d -m 755 "$HOOKS_DIR"
 
-# Ensure any legacy pre-transaction hook is removed so pre-unlock only occurs via the wrapper
-rm -f "$HOOKS_DIR/10-unlock-etc-hosts.hook" 2>/dev/null || true
+# Pre-transaction hook
+cat >"$HOOKS_DIR/10-unlock-etc-hosts.hook" <<'HOOK'
+[Trigger]
+Operation = Upgrade
+Operation = Install
+Operation = Remove
+Type = Package
+Target = *
+
+[Action]
+Description = Temporarily unlocking /etc/hosts for transaction
+When = PreTransaction
+Exec = /bin/bash /usr/local/share/hosts-guard/pacman-pre-unlock-hosts.sh
+NeedsTargets
+HOOK
 
 # Post-transaction hook
 cat >"$HOOKS_DIR/90-relock-etc-hosts.hook" <<'HOOK'
@@ -30,9 +43,7 @@ HOOK
 
 # Place helper scripts into a shared location
 install -d -m 755 /usr/local/share/hosts-guard
+install -m 755 "$SCRIPT_DIR/pacman-hooks/pacman-pre-unlock-hosts.sh" /usr/local/share/hosts-guard/
 install -m 755 "$SCRIPT_DIR/pacman-hooks/pacman-post-relock-hosts.sh" /usr/local/share/hosts-guard/
 
-# Remove legacy pre-unlock helper if present to reduce accidental execution surface
-rm -f /usr/local/share/hosts-guard/pacman-pre-unlock-hosts.sh 2>/dev/null || true
-
 echo "Pacman hooks installed into $HOOKS_DIR."

hosts/guard/pacman-hooks/pacman-post-relock-hosts.sh

@@ -8,7 +8,7 @@ LOGTAG=hosts-guard-hook
 mount_layers_count() { awk '$5=="/etc/hosts"{c++} END{print c+0}' /proc/self/mountinfo 2>/dev/null || echo 0; }
 collapse_mounts() {
   local i=0
-  if command -v mountpoint >/dev/null 2>&1; then
+  if command -v mountpoint >/devnull 2>&1; then
     while mountpoint -q "$TARGET"; do
       umount -l "$TARGET" >/dev/null 2>&1 || break
       i=$((i+1))

hosts/guard/pacman-hooks/pacman-pre-unlock-hosts.sh

@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+# Non-interactive pre-transaction hook to temporarily unlock /etc/hosts
+
+TARGET=/etc/hosts
+LOGTAG=hosts-guard-hook
+
+stop_units_if_present() {
+  local units=(hosts-bind-mount.service hosts-guard.path)
+  for u in "${units[@]}"; do
+    if command -v systemctl >/dev/null 2>&1; then
+      if systemctl list-unit-files 2>/dev/null | grep -q "^$u"; then
+        systemctl stop "$u" >/dev/null 2>&1 || true
+      fi
+    fi
+  done
+}
+
+is_ro_mount() { findmnt -no OPTIONS -T "$TARGET" 2>/dev/null | grep -qw ro; }
+is_bind_mount() { findmnt -no OPTIONS -T "$TARGET" 2>/dev/null | grep -qw bind; }
+
+mount_layers_count() { awk '$5=="/etc/hosts"{c++} END{print c+0}' /proc/self/mountinfo 2>/dev/null || echo 0; }
+cleanup_mount_stacks() {
+  local i=0
+  # Unmount bind layers until /etc/hosts is no longer a mountpoint
+  if command -v mountpoint >/dev/null 2>&1; then
+    while mountpoint -q "$TARGET"; do
+      umount -l "$TARGET" >/dev/null 2>&1 || break
+      i=$((i+1))
+      (( i > 20 )) && break
+    done
+  else
+    # Fallback to best-effort using mountinfo count
+    local cnt
+    cnt=$(mount_layers_count)
+    while (( cnt > 1 )); do
+      umount -l "$TARGET" >/dev/null 2>&1 || break
+      i=$((i+1))
+      (( i > 20 )) && break
+      cnt=$(mount_layers_count)
+    done
+  fi
+}
+
+# Drop protective attributes if present
+if command -v lsattr >/dev/null 2>&1; then
+  attrs=$(lsattr -d "$TARGET" 2>/dev/null || true)
+  echo "$attrs" | grep -q " i " && chattr -i "$TARGET" >/dev/null 2>&1 || true
+  echo "$attrs" | grep -q " a " && chattr -a "$TARGET" >/dev/null 2>&1 || true
+fi
+
+stop_units_if_present
+
+logger -t "$LOGTAG" "pre: unlocking /etc/hosts (starting)"
+echo "$(date -Is) pre-unlock" >> /run/hosts-guard-hook.log 2>/dev/null || true
+
+# Always collapse any existing layers; we'll operate on the plain file
+cleanup_mount_stacks
+
+# If someone managed a ro single-layer mount, ensure rw by remounting or collapsing again
+if is_ro_mount; then
+  mount -o remount,rw "$TARGET" >/dev/null 2>&1 || cleanup_mount_stacks
+fi
+
+logger -t "$LOGTAG" "pre: unlocking /etc/hosts (done)"
+
+exit 0