#!/bin/sh
  # extracts .config info from a [b]zImage file
  # uses: binoffset (new), dd, zcat, strings, grep
  # $arg1 is [b]zImage filename
  
  binoffset="./scripts/binoffset"

  test -e $binoffset || cc -o $binoffset ./scripts/binoffset.c || exit 1

  
  IKCFG_ST="0x49 0x4b 0x43 0x46 0x47 0x5f 0x53 0x54"
  IKCFG_ED="0x49 0x4b 0x43 0x46 0x47 0x5f 0x45 0x44"

  dump_config() {
      file="$1"

  
      start=`$binoffset $file $IKCFG_ST 2>/dev/null`
      [ "$?" != "0" ] && start="-1"
      if [ "$start" -eq "-1" ]; then
  	return
      fi
      end=`$binoffset $file $IKCFG_ED 2>/dev/null`

      start=`expr $start + 8`
      size=`expr $end - $start`

      dd if="$file" ibs=1 skip="$start" count="$size" 2>/dev/null | zcat

  
      clean_up
      exit 0
  }
  
  
  usage()
  {
  	echo "  usage: extract-ikconfig [b]zImage_filename"
  }
  
  clean_up()
  {
  	if [ "$TMPFILE" != "" ]; then
  		rm -f $TMPFILE
  	fi
  }
  
  if [ $# -lt 1 ]
  then
  	usage
  	exit 1
  fi

  TMPFILE=`mktemp -t ikconfig-XXXXXX` || exit 1

  image="$1"
  
  # vmlinux: Attempt to dump the configuration from the file directly
  dump_config "$image"
  
  GZHDR1="0x1f 0x8b 0x08 0x00"
  GZHDR2="0x1f 0x8b 0x08 0x08"
  
  # vmlinux.gz: Check for a compressed images
  off=`$binoffset "$image" $GZHDR1 2>/dev/null`
  [ "$?" != "0" ] && off="-1"
  if [ "$off" -eq "-1" ]; then
  	off=`$binoffset "$image" $GZHDR2 2>/dev/null`
  	[ "$?" != "0" ] && off="-1"
  fi
  if [ "$off" -eq "0" ]; then
  	zcat <"$image" >"$TMPFILE"
  	dump_config "$TMPFILE"
  elif [ "$off" -ne "-1" ]; then
  	(dd ibs="$off" skip=1 count=0 && dd bs=512k) <"$image" 2>/dev/null | \
  		zcat >"$TMPFILE"
  	dump_config "$TMPFILE"
  fi
  
  echo "ERROR: Unable to extract kernel configuration information."
  echo "       This kernel image may not have the config info."
  
  clean_up
  exit 1