#! /bin/ksh

POLICYDIR=/opt/ECSpooler/systrace-policy
INTERPRETER=/opt/swiprolog/bin/pl
OPTIONS="-q -f none -t halt"

# Check that the policy file is readable for the current user
POLICYFILE=${INTERPRETER//[\/.-]/_}
POLICYFILE=${POLICYFILE/_}

if [[ ! -r "$POLICYDIR/$POLICYFILE" ]]; then
   print "Internal error: Policy file not readable.  Please contact the administrator."
   exit 1
fi

trap 'kill $! && trap - TERM && kill $$' TERM

# The problem with the SWI Prolog interpreter is that it doesn't exit
# with an error if a syntax error is encountered.  So we execute the
# script we were handed, collect all STDOUT and STDERR output in $OP
# and exit with an error ourselves if the output from the interpreter
# contains a line that starts with "ERROR".

# Explanation of the command line options in use:
#
# -q
#     Be quiet.
#
# -f none
#     Don't load any startup scripts.
#
# -t halt
#     Halt the interpreter after the script has been executed
#     instead of switching to the top-level.
#
# -s script
#    Execute this script.

tmpfile=$(mktemp -t pl+systrace)
systrace -a -d $POLICYDIR $INTERPRETER $OPTIONS -s "$@" > $tmpfile 2>&1 &
wait %%
ERR=$?

cat $tmpfile

if [[ $ERR != 0 ]]
then
  # The interpreter's exit code is != 0.  Fine, exit with this one.
  exit $ERR
else
  # Exit with an error if the interpreter's output contains a line
  # that starts with "ERROR" or if it contains a line that says "Goal
  # (directive) failed".
  if grep -q '^ERROR\|Goal (directive) failed:' $tmpfile
  then
     rm $tmpfile
     exit 1
  else
     rm $tmpfile
     exit 0
  fi
fi