#!/bin/ksh
# (c)INRIA 1999 Christophe.Lavarenne@inria.fr
# $Id: rshcd,v 1.1 2000/04/17 13:02:52 lavarenn Exp $
# SynDEx v5 remote-shell-call for use by U.m4m (Unix workstation target)
# use: rshcd <hostname> <command> [-- extra inputs -o extra outputs]
# WARNING: requires /bin/ksh for its '${variable#pattern}' construct

hostname=$1 ; shift ; command="$1" ; shift

# rshcd executes <command> on <hostname>, like rsh, but unlike rsh:
# - <command> is executed in the same user's subdirectory (relative to $HOME),
# - <command> argument files are local, not remote.
# - provision is given to transfer files not passed to <command>

# If <hostname> is the local hostname,
# rshcd simply executes <command> locally:

if [ "$hostname" = `uname -n` ] ; then
  while [ -n "$1" ] ; do
    case $1 in
      --) break ;; # skip extra
       *) command="$command $1" ;;
    esac
    shift
  done
  echo "$command"
  exec sh -c "$command"
fi

# Otherwise, rshcd uses rsh and cd, but `pwd` must be a subdirectory of $HOME:

case `pwd` in
  $HOME*)  PWD=`pwd` ; relpwd=.${PWD#$HOME} ;;
  *)  echo "rshcd $hostname: must be run from a subdirectory of HOME" >&2 ;
      echo "PWD=`pwd` is not a subdirectory of HOME=$HOME" >&2 ;
      exit 1 ;;
esac

# If the local and remote $HOME directory are physically identical,
# i.e. share (are mounted on) the same partition,
# rshcd simply uses rsh and cd:

if [ ! -x $hostname.mnt ]
then  rsh $hostname  ln -s /bin/true  $relpwd/$hostname.mnt
  test -x $hostname.mnt  ||  ln -s /bin/false $hostname.mnt
fi
if ./$hostname.mnt ; then
  command="rsh $hostname cd $relpwd \&\& $command"
  while [ -n "$1" ] ; do
    case $1 in
      --) break ;; # skip extra
       *) command="$command $1" ;;
    esac
    shift
  done
  echo "$command"
  exec sh -c "$command"
fi

# Otherwise rshcd also uses tar to transfer <command> argument files (arguments
# not prefixed with a "-"), before executing <command> for input files (those
# before any "-o" argument), and after for output files (those after "-o").
# Moreover, files passed after "--" are extra inputs until any "-o" argument,
# and extra outputs after "-o"; extra inputs and outputs are not passed to
# <command>, but are transfered.

# concatenate command inputs:
while [ -n "$1" ] ; do
  case $1 in
   -o*) command="$command $1" ;
	output=${1#-o} ; # in case "-ofile" without space
	shift ; break ;; # skip to outputs
    --) break ;; # skip to extras
    -*) command="$command $1";;
     *) command="$command $1" ; inputs="$inputs $relpwd/$1" ;;
  esac
  shift
done
# concatenate command outputs:
while [ -n "$1" ] ; do
  case $1 in
    --) break ;; # skip to extras
    -*) command="$command $1" ;;
     *) command="$command $1" ; output="$output $1" ;;
  esac
  shift
done
# concatenate extra inputs:
while [ -n "$1" ] ; do
  case $1 in
   -o*) output="$output ${1#-o}" ; # case "-ofile" w/o space
	shift ; break ;;
    -*) ;; # ignore options
     *) inputs="$inputs $relpwd/$1" ;;
  esac
  shift
done
# concatenate extra outputs:
while [ -n "$1" ] ; do
  case $1 in
    -*) ;; # ignore options
     *) output="$output $1" ;;
  esac
  shift
done

test -n "$inputs" && rcommand="(cd ; tar cf - $inputs) | " || rcommand=""
                     rcommand="$rcommand""rsh $hostname"
test -n "$inputs" && rcommand="$rcommand tar xf - \&\&"
                     rcommand="$rcommand cd $relpwd \&\& $command"
test -n "$output" && rcommand="$rcommand \&\& tar cf - $output | tar xf -"

echo "$rcommand" && exec sh -c "$rcommand"

# For example, "rshcd myhost cc -S my.c b.o -lm -o my -- my.h -o my.s" will:
# - if myhost is the local host:
#
#   cc -g my.c b.o -lm -o my
#
# - otherwise, if $HOME is shared with myhost, with X=relpwd:
#
#   rsh myhost cd $X '&&' cc -g my.c b.o -lm -o my
#
# - otherwise:
#
#   (cd; tar cf - $X/my.c $X/b.o $X/my.h) | (rsh myhost tar xf - '&&'\
#    cd $X '&&' cc -g my.c b.o -lm -o my '&&' tar cf - my my.s) | tar xf -