#!/bin/sh

[ -z "$1" ] || [ -z "$2" ] && {
# usage
  echo "usage: $0 <directory> <diff-extension>" 1>&2
  exit 1
}

: ${DIFF:=diff}
: ${GENDIFF_DIFF_ARGS:=-up}
: ${GENDIFF_DIFF_CHANGELOG_ARGS:=-U0}

find $1 \( -name "*$2" -o -name ".*$2" \) -print | sort |
while read f; do
    U="${GENDIFF_DIFF_ARGS}"
    [ "`basename $f`" = "ChangeLog$2" ] && U="${GENDIFF_DIFF_CHANGELOG_ARGS}"
    F=/dev/null
    [ -r "${f}" ] && F="${f}"
    echo "${DIFF} ${U} ${F} ${f%$2}"
    ${DIFF} ${U} "${F}" "${f%$2}"
done