#!/bin/sh
# Convert an ls-style permission string, like drwxr----x and -rw-r-x-wx
# to the equivalent chmod --mode (-m) argument, (=,u=rwx,g=r,o=x and
# =,u=rw,g=rx,o=wx).  Ignore ACLs.

case $# in
  1) rwx=$1;;
  *) echo "$0: wrong number of arguments" 1>&2
    echo "Usage: $0 ls-style-mode-string" 1>&2
    exit 1;;
esac

case $rwx in
  [ld-][rwx-][rwx-][rwxsS-][rwx-][rwx-][rwxsS-][rwx-][rwx-][rwxtT-]) ;;
  [ld-][rwx-][rwx-][rwxsS-][rwx-][rwx-][rwxsS-][rwx-][rwx-][rwxtT-]+) ;;
  *) echo "$0: invalid mode string: $rwx" 1>&2; exit 1;;
esac

# Perform these conversions:
# S  s
# s  xs
# T  t
# t  xt
# The `T' and `t' ones are only valid for `other'.
s='s/S/@/;s/s/x@/;s/@/s/'
t='s/T/@/;s/t/x@/;s/@/t/'

u=`echo $rwx|sed 's/^.\(...\).*/,u=\1/;s/-//g;s/^,u=$//;'$s`
g=`echo $rwx|sed 's/^....\(...\).*/,g=\1/;s/-//g;s/^,g=$//;'$s`
o=`echo $rwx|sed 's/^.......\(...\).*/,o=\1/;s/-//g;s/^,o=$//;'$s';'$t`
echo "=$u$g$o"
exit 0
