mudo

#! /bin/sh
# shellcheck shell=sh
#
# try to keep it bourne shell so it stays snappy
#
# shellcheck disable=SC2236
# shellcheck disable=SC2166
# shellcheck disable=SC2006

[ "${TRACE}" = 'YES' -o "${MUDO_TRACE}" = 'YES' ] && set -x && : "$0" "$@"


if [ $# -eq 0 ]
then
   cat <<EOF >&2
usage:
   mudo [-e|-f] <command> ...

   mudo lets you execute commands with an unrestricted PATH from within a
   mulle-env environment. It does not let you break out of a sandbox though.
   With the -e option you can replace the current environment with the
   unrestricted user environment.
   With the -f option you can run mudo even if there is no current environment
   making mudo basicaly a no-op. This can be useful in scripts.

   See the difference by comparing \`env\` with \`mudo env\` and \`mudo -e env\`.

EOF
   exit 1
fi

if [ -z "${MULLE_VIRTUAL_ROOT}" -o -z "${MULLE_HOSTNAME}" ]
then
   if [ "$1" = "-f" ]
   then
      shift
      exec "$@"
   fi
   echo "error: mudo must be run from within the mulle virtual environment" >&2
   exit 1
fi

# we are in a virtual env, so if -f is given remove it
if [ "$1" = "-f" ]
then
   shift
fi

if [ "$1" != "-e" ]
then
   #
   # does not work with builtins like `command -v ps`
   #
   if [ -z "${MULLE_OLDPATH}" ]
   then
      exec "$@"
   else
      PATH="${MULLE_OLDPATH}" exec "$@"
   fi
   exit $?
fi

# remove -e
shift

# we are in a virtual env, so if -f is given, remove it (do it one more time)
if [ "$1" = "-f" ]
then
   shift
fi


# get mulle-env paths into this shell script environment like f.i.:
#
#    MULLE_ENV_VAR_DIR='/Volumes/Source/srcM/mulle-cpp/.mulle/var/walitza/env'
#    MULLE_ENV_ETC_DIR='/Volumes/Source/srcM/mulle-cpp/.mulle/etc/env'
#    MULLE_ENV_SHARE_DIR='/Volumes/Source/srcM/mulle-cpp/.mulle/share/env'
#
# If this doesn't work we are in a "none" environment, presumably
if ! MULLE_ENV="${MULLE_ENV:-"`command -v mulle-env`"}"
then
   echo "error: mulle-env not in PATH ($PATH)
Tip: mudo can not be used from a \"none\" environment." >&2
   exit 1
fi

eval "`"${MULLE_ENV}" --search-as-is mulle-tool-env env`"

if [ -z "${MULLE_ENV_VAR_DIR}" ]
then
   echo "error: mulle-env failed to provide MULLE_ENV_VAR_DIR" >&2
   exit 1
fi

# TODO: should probably be in MULLE_ENV_TMP_DIR if that existed
filename="${MULLE_ENV_VAR_DIR}/old-environment.${MULLE_ENV_PID}"
environment="`cat "${filename}" 2> /dev/null`"
if [ -z "${environment}" ]
then
   echo "error: mudo did not find a previous environment (${filename})" >&2
   exit 1
fi

#
# does not work with builtins like `command -v ps`
#
OLDIFS="${IFS}"
IFS="
"
for line in ${environment}
do
   set -- "${line}" "$@"
done
IFS="${OLDIFS}"

if [ -z "${MULLE_OLDPATH}" ]
then
   exec env -i - "$@"
else
   PATH="${MULLE_OLDPATH}" exec env -i - "$@"
fi