#!/usr/local/bin/bash

# Determine file's CRC hex digest and return it in little-endian format
function crc32hex() {
  file=$1
  crc=$(~/bin/crc32 $file)

  n=()
  i=0 
  hex=""

  while read -r -N4 -n2 n[i]; do
    b=${n[$i]}
    hex="\x${n[$i]}${hex}"
    ((++i))
  done < <(echo $crc)

  echo $hex
}

CRAMFS=/srv/home/matt/cramfs

# Rebuild cramfs image (as root)
su - root -c "rm -v $CRAMFS.image; mkcramfs $CRAMFS $CRAMFS.image"
cp $CRAMFS.image ./03_cramfs_MODIFIED

# Update cramfs crc32 in header
echo -ne $(crc32hex 03_cramfs_MODIFIED) | dd of=01_header bs=1 seek=52 count=4 conv=notrunc

# Update header's own crc32
dd if=01_header bs=1 skip=4 of=header_for_crc32
echo -ne $(crc32hex header_for_crc32) | dd of=01_header bs=1 seek=0 count=4 conv=notrunc

# Construct firmware image
cat 01_header 02_before_cramfs 03_cramfs_MODIFIED 04_after_cramfs > firmimg_MODIFIED.d6

# Copy to TFTP location
ssh root@deepthought "cp -v ~matt/tmp/firmimg_MODIFIED.d6 /var/tftpd/firmimg.d6"

# Initiate firmware upgrade
ssh root@deepthought-idrac "racadm fwupdate -g -u -a 192.168.1.3"