* Fix the regular expression to find the sshd parent process.

[code/molly-guard.git] / shutdown

diff --git a/shutdown b/shutdown
index 0a6efd6011e590fea9ef6e80dc6ae0c2ce48fe37..0135f1aa435ba2fb38e77529b767983e44b0ad21 100755 (executable)
--- a/shutdown
+++ b/shutdown
@@ -9,31 +9,73 @@
 #
 set -eu
 
+ME=molly-guard
+
 CMD="${0##*/}"
 EXEC="/sbin/$CMD"
+
 case "$CMD" in
-  halt|reboot|shutdown)
+  halt|reboot|shutdown|poweroff)
+    if [ ! -f $EXEC ]; then
+      echo "E: $ME: not a regular file: $EXEC" >&2
+      exit 4
+    fi
     if [ ! -x $EXEC ]; then
-      echo "E: not an executable: $EXEC" >&2
+      echo "E: $ME: not an executable: $EXEC" >&2
       exit 3
     fi
     ;;
   *)
-    echo "E: unsupported command: $CMD" >&2
+    echo "E: $ME: unsupported command: $CMD" >&2
     exit 1
     ;;
 esac
+ARGS="$@"
+
+do_real_cmd()
+{
+  case "$ARGS" in
+    (*--molly-guard-do-nothing*)
+      ARGS0="${ARGS%%--molly-guard-do-nothing*}"
+      ARGS1="${ARGS##*--molly-guard-do-nothing}"
+      echo "$ME: would run: $EXEC ${ARGS0# } ${ARGS1# }"
+      exit 0;;
+    *) eval exec $EXEC "$ARGS";;
+  esac
+}
+
+# require an interactive terminal connected to stdin
+test -t 0                    || do_real_cmd
+
+# only run if we are being called over SSH, that is if the current terminal
+# was created by sshd.
+PTS=$(readlink /proc/$$/fd/0)
+pgrep -f "^sshd.+${PTS#/dev/}[[:space:]]*$" >/dev/null || do_real_cmd
+
+# pass through help commands
+case "$CMD $ARGS" in
+  (shutdown\ *-c*) do_real_cmd;;
+  (shutdown\ *-h*) do_real_cmd;;
+  (*--help*) do_real_cmd;;
+  *) :;;
+esac
+
+HOSTNAME="$(hostname)"
+
+sigh()
+{
+  echo "Good thing I asked; I won't $CMD $HOSTNAME ..."
+  exit 2
+}
+
+trap 'echo;sigh' 1 2 3 9 10 12 15
 
-if [ -n "${SSH_CONNECTION:-}" ] && test -t 0 && [ "${1:-}" != '--help' ]; then
-  echo -n "SSH session detected, type in hostname of the machine to $CMD: "
-  read HOSTNAME_USER
+echo "$ME: SSH session detected!"
+echo -n "Please type in hostname of the machine to $CMD: "
+read HOSTNAME_USER || :
 
-  HOSTNAME="$(hostname)"
+[ "$HOSTNAME_USER" = "$HOSTNAME" ] || sigh
 
-  if [ "$HOSTNAME_USER" != "$HOSTNAME" ]; then
-    echo "Good thing I asked; I won't $CMD $HOSTNAME ..."
-    exit 2
-  fi
-fi
+trap - 1 2 3 9 10 12 15
 
-exec $EXEC "$@"
+do_real_cmd