#! /bin/sh
#
# This script is used to configure the linux kernel.
#
# It was inspired by the challenge in the original Configure script
# to ``do something better'', combined with the actual need to ``do
# something better'' because the old configure script wasn't flexible
# enough.
#
# Please send comments / questions / bug fixes to raymondc@microsoft.com.
#
# Each line in the config file is a command.
#
# 050793 - use IFS='@' to get around a bug in a pre-version of bash-1.13
# with an empty IFS.

#
# Make sure we're really running bash.
#
# I would really have preferred to write this script in a language with
# better string handling, but alas, bash is the only scripting language
# that I can be reasonable sure everybody has on their linux machine.
#
[ -z "$BASH" ] && { echo "Configure requires bash" 1>&2; exit 1; }

# Disable filename globbing once and for all.
# Enable function cacheing.
set -f -h

#
# readln reads a line into $ans.
#
#	readln prompt default
#
function readln () {
	if [ "$DEFAULT" = "-d" ]; then
		echo "$1"
		ans=$2
	else
		echo -n "$1"
		IFS='@' read ans </dev/tty || exit 1
		[ -z "$ans" ] && ans=$2
	fi
}

#
# change updates the "config.new" file according to the answer
#
#	change define old new
#
function change () {
	if [ "$2" != "$3" ]; then
		sed "s/$1 $2$/$1 $3/" < $CONFIG_NEW > .tmpc
		mv .tmpc $CONFIG_NEW
	fi
}

#
# comment does some pretty-printing
#
#	comment 'xxx'
# 
function comment () {
	echo "*"; echo "* $1" ; echo "*"
	(echo "" ; echo "#"; echo "# $1" ; echo "#") >>$CONFIG
	(echo "" ; echo "/*"; echo " * $1" ; echo " */") >>$CONFIG_H
}

#
# bool processes a boolean argument
#
#	bool question define default
#
function bool () {
	ans=""
	while [ "$ans" != "y" -a "$ans" != "n" ]; do
		readln "$1 ($2) [$3] " "$3"
	done
	if [ "$ans" = "y" ]; then
		echo "  $2 = $2" >>$CONFIG
		echo "#define $2 1" >>$CONFIG_H
	else
		echo "# $2 is not set" >>$CONFIG
		echo "#undef  $2" >>$CONFIG_H
	fi
	change $2 $3 $ans
	eval "$2=$ans"
}

#
# int processes an integer argument
#
#	int question define default
#
function int () {
	# Slimier hack to get bash to rescan a line.
	ans="x"
	while [ $[$ans+0] != "$ans" ]; do
		readln "$1 ($2) [$3] " "$3"
	done
	echo "  $2 = $ans" >>$CONFIG
	echo "#define $2 ($ans)" >>$CONFIG_H
	eval "$2=$ans"
}

CONFIG=.tmpconfig
CONFIG_H=.tmpconfig.h
CONFIG_NEW=config.new
trap "rm -f $CONFIG $CONFIG_H $CONFIG_NEW ; exit 1" 1 2

#
# Make sure we start out with a clean slate.
#
cp config.in $CONFIG_NEW
echo "#" > $CONFIG
echo "# Automatically generated make config: don't edit" >> $CONFIG
echo "#" >> $CONFIG

echo "/*" > $CONFIG_H
echo " * Automatically generated C config: don't edit" >> $CONFIG_H
echo " */" >> $CONFIG_H

DEFAULT=$1

. ./config.in

if [ "$CONFIG_SOUND" = "y" ] ; then
	$MAKE -C drivers/sound config || exit 1
fi

mv .tmpconfig .config
mv .tmpconfig.h include/linux/autoconf.h
mv config.in config.old
mv config.new config.in

echo
echo "The linux kernel is now hopefully configured for your setup."
echo "Check the top-level Makefile for additional configuration,"
echo "and do a 'make dep ; make clean' if you want to be sure all"
echo "the files are correctly re-made"
echo

exit 0