#!/bin/sh
#
# (c) 2007 Marc Andre Tanner <mat[at]brain-dump.org>
#     feel free to use, copy modify, and/or distribute
#     this software for any purpose you wish.

ARCH="i386"
CONFIG="defconfig"
KERNEL_SRC="."
OUTPUT="/dev/stdout"
TMP="/tmp/config.tmp.$$"

error(){
	echo "$1" > /dev/stderr
	exit 1
}

debug(){
	echo "$1" > /dev/null
}

usage(){
	echo "Usage: `basename $0:` [-a arch] [-i] [-k kernel-source] [config]"
}

help(){
	usage
	cat > /dev/stdout <<- EOF
	 -a	kernel architecture (name of directory under arch/)
	 -i	edit config file in place, don't print to stdout
	 -k	directory containing the unpacked kernel source
	 config	kernel configuration file if ommited .config is used
	EOF
}

parse_args(){
	[ -z "$1" ] && usage && exit 1
	until [ -z "$1" ]; do
		case "$1" in
			-a)
				shift
				([ -z "$1" ] || [ ! -d "$KERNEL_SRC/arch/$1" ]) && \
					error "$1 doesn't seem to be a valid architecture."
				ARCH="$1"
			;;
			-i)
				OUTPUT="$TMP"
			;;
			-k)
				shift
				([ -z "$1" ] || [ ! -d "$1" ] || [ ! -e "$1/init/main.c" ]) && \
					error "$1 is not a valid kernel source directory."
				KERNEL_SRC="$1"
			;;
			-h|--help)
				help
				exit 0
			;;
			*)
			CONFIG="$1"
		esac
		shift
	done
}

# $1 => config file, $2 => kernel source dir
explain(){
	# get all Kconfig files from the kernel source based on the selected architecture
	local files=`find "$2" -name 'Kconfig*' -a \( \( -wholename './arch/*' -a !  -wholename "./arch/$ARCH/*" \) -prune -o -print \)`

	cat "$1" | while read line; do
		debug "Line  : $line"
		echo $line
		#([ -z "$line" ] || `echo "$line" | grep -q '#'`) && continue
		# skip empty line and comments
		if [ ! -z "$line" ] && ! `echo "$line" | grep -q '#'`; then
			# remove CONFIG_ prefix
			local symbol=`echo $line | sed 's/CONFIG_\(.*\)=.*/\1/'`
			debug "Symbol: $symbol"
			# search the file which defines the config option
			local file=`grep -l "config $symbol$" $files`
			debug "File  : $file"
			if [ ! -z "$file" ]; then
				# extract the config option definition
				local info=`sed -n "/config $symbol$/,/^[a-z]/p" $file`
				# check if there is a help text for this config option
				if [ ! -z "$info" ] && `echo "$info" | grep -q 'help'`; then
					# remove first and last line, prefix with #
					echo "$info" | sed -n '2,$p' | sed -n '$!p' | sed 's/^/#/'
				fi
			fi
		fi
	done
}

parse_args $*
explain $CONFIG $KERNEL_SRC > $OUTPUT
[ "$OUTPUT" != "/dev/stdout" ] && mv "$OUTPUT" "$CONFIG"
exit 0