#!/bin/sh
#
# shutdown -- wrapper script to guard against accidental shutdowns
#
# Copyright © martin f. krafft <madduck@madduck.net>
# Released under the terms of the Artistic Licence 2.0
#
set -eu

ME=molly-guard
VERSION=0.4
SCRIPTSDIR=/etc/molly-guard/run.d
SCRIPTSDIR="${0%/*}/run.d"

CMD="${0##*/}"
EXEC="/sbin/$CMD"

case "$CMD" in
  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: $ME: not an executable: $EXEC" >&2
      exit 3
    fi
    ;;
  *)
    echo "E: $ME: unsupported command: $CMD" >&2
    exit 1
    ;;
esac

usage()
{
  cat <<-_eousage
	Usage: $ME [options] [-- script options]
	       (shielding $EXEC)
	
	molly-guard's primary goal is to guard against accidental
	shutdowns/reboots. $ME will run all scripts in $SCRIPTSDIR and only
	invokes $EXEC if all scripts exited successfully.

	Specifying --molly-guard-do-nothing as argument to the command will
	make $ME echo the command it would execute rather than actually
	executing it.

	Options following the double hyphen will be passed unchanged to the
	scripts.

	Please see molly-guard(8) for more information.

	The actual command's help output follows:

	_eousage
}

CMDARGS=
SCRIPTARGS=
END_OF_ARGS=0
DO_NOTHING=0
for arg in "$@"; do
  case "$arg" in
    (*-molly-guard-do-nothing) DO_NOTHING=1;;
    (*-help)
      usage 2>&1
      eval $EXEC --help 2>&1
      exit 0
      ;;
    --) END_OF_ARGS=1;;
    *) 
      if [ $END_OF_ARGS -eq 0 ]; then
        CMDARGS="${args:+$args }$arg"
      else
        SCRIPTARGS="${args:+$args }--arg $arg"
      fi
      ;;
  esac
done

do_real_cmd()
{
  if [ $DO_NOTHING -eq 1 ]; then
    echo "$ME: would run: $EXEC $CMDARGS"
    exit 0
  else
    eval exec $EXEC "$CMDARGS"
  fi
}

if [ $DO_NOTHING -eq 1 ]; then
  echo "I: demo mode; $ME will not do anything due to --molly-guard-do-nothing." >&2
fi

# pass through certain commands
case "$CMD $CMDARGS" in
  (*shutdown\ *-c*)
    # allow canceling shutdowns
    echo "I: executing $CMD $CMDARGS regardless of check results." >&2
    do_real_cmd
    ;;
esac

MOLLYGUARD_CMD=$CMD; export MOLLYGUARD_CMD
MOLLYGUARD_DO_NOTHING=$DO_NOTHING; export MOLLYGUARD_DO_NOTHING
MOLLYGUARD_SETTINGS="/etc/default/$ME"; export MOLLYGUARD_SETTINGS

for script in $(run-parts --test $SCRIPTSDIR); do
  ret=0
  eval $script $SCRIPTARGS || ret=$?
  if [ $ret -ne 0 ]; then
    echo "W: aborting $CMD due to ${script##*/} exiting with code $ret." >&2
    exit $ret
  fi
done

do_real_cmd