#! /bin/sh

for d in "$@"; do
   if [ "$d" = .. ]; then
      echo 'Cannot operate on ".."!' >&2
      exit 1
   fi
   find "$d" -type d -print0 | xargs -r0 chmod u=rwX,go=rX
   find "$d" -type f -print0 | xargs -r0 chmod u=rw,go=r
done