rpm-build/gendiff

#!/bin/sh -efu

Usage()
{
	[ $1 = 0 ] || exec >&2
	echo "Usage: ${0##*/} [diff-options] <directory> <diff-suffix> [patch-name]"
	exit $1
}

diff_options=-up

argv=`getopt -n "${0##*/}" -l help \
	-o +i,E,b,w,B,a \
	-l ignore-case,ignore-tab-expansion,ignore-space-change \
	-l ignore-all-space,ignore-blank-lines,text -- "$@"` || Usage 2
eval set -- "$argv"

while :; do
	case "$1" in
		--help) Usage 0 ;;
		--) shift; break ;;
		-*) diff_options="$diff_options $1" ;;
		*) echo "${0##*/}: unrecognized option $1" >&2; exit 2 ;;
	esac
	shift
done

if [ $# -lt 2 ]; then
	echo "${0##*/}: not enough arguments" >&2
	Usage 2
fi
if [ $# -gt 3 ]; then
	echo "${0##*/}: too many arguments" >&2
	Usage 2
fi

ls "$1"/ >/dev/null || Usage 2

patch=
if [ $# = 3 ]; then
	patch="${1%/}"
	if [ "$patch" = . ]; then
		patch="${PWD##*/}"
	fi
	if [ -n "$3" ]; then
		patch="$patch-$3"
	fi
	: ${SOURCEDIR:=`rpm --eval %_sourcedir`}
	patch="$SOURCEDIR/$patch.patch"
	: >"$patch"
fi

find "$1" -mindepth 1 \( -name "*$2" -o -name ".*$2" \) -print |
	LC_COLLATE=C sort -u |
	while read -r fin; do
		fin="${fin#./}"
		fou="${fin%$2}"
		[ -r "$fin" ] || fin="/dev/null"
		[ -r "$fou" ] || fou="/dev/null"
		if [ -n "$patch" ]; then
			diff $diff_options -- "$fin" "$fou" |tee -a "$patch"
		else
			diff $diff_options -- "$fin" "$fou" || [ $? = 1 ]
		fi
	done

if [ -n "$patch" ]; then
	echo
	ls -l "$patch"
fi