scripts/make-ras.sh

   1 #!/usr/bin/env bash
   2 #
   3 # --- ZyXEL header format ---
   4 # Original Version by Benjamin Berg <benjamin@sipsolutions.net>
   5 #
   6 # The firmware image prefixed with a header (which is written into the MTD device).
   7 # The header is one erase block (~64KiB) in size, but the checksum only convers the
   8 # first 2KiB. Padding is 0xff. All integers are in big-endian.
   9 #
  10 # The checksum is always a 16-Bit System V checksum (sum -s) stored in a 32-Bit integer.
  11 #
  12 #   4 bytes:  checksum of the rootfs image
  13 #   4 bytes:  length of the contained rootfs image file (big endian)
  14 #  32 bytes:  Firmware Version string (NUL terminated, 0xff padded)
  15 #   4 bytes:  checksum over the header partition (big endian - see below)
  16 #  32 bytes:  Model (e.g. "NBG6617", NUL termiated, 0xff padded)
  17 #   4 bytes:  checksum of the kernel partition
  18 #   4 bytes:  length of the contained kernel image file (big endian)
  19 #      rest: 0xff padding
  20 #
  21 # The checksums are calculated by adding up all bytes and if a 16bit
  22 # overflow occurs, one is added and the sum is masked to 16 bit:
  23 #   csum = csum + databyte; if (csum > 0xffff) { csum += 1; csum &= 0xffff };
  24 # Should the file have an odd number of bytes then the byte len-0x800 is
  25 # used additionally.
  26 #
  27 # The checksum for the header is calculated over the first 2048 bytes with
  28 # the rootfs image checksum as the placeholder during calculation.
  29 #
  30 # The header is padded with 0xff to the erase block size of the device.
  31 #
  32 board=""
  33 version=""
  34 kernel=""
  35 rootfs=""
  36 outfile=""
  37 err=""
  38
  39 while [ "$1" ]; do
  40         case "$1" in
  41         "--board")
  42                 board="$2"
  43                 shift
  44                 shift
  45                 continue
  46                 ;;
  47         "--version")
  48                 version="$2"
  49                 shift
  50                 shift
  51                 continue
  52                 ;;
  53         "--kernel")
  54                 kernel="$2"
  55                 shift
  56                 shift
  57                 continue
  58                 ;;
  59         "--rootfs")
  60                 rootfs="$2"
  61                 shift
  62                 shift
  63                 continue
  64                 ;;
  65         "--rootfssize")
  66                 rootfssize="$2"
  67                 shift
  68                 shift
  69                 continue
  70                 ;;
  71         *)
  72                 if [ ! "$outfile" ]; then
  73                         outfile=$1
  74                         shift
  75                         continue
  76                 fi
  77                 ;;
  78         esac
  79 done
  80
  81 if [ ! -n "$board" -o ! -n "$version" -o ! -r "$kernel" -o ! -r "$rootfs" -o ! "$rootfssize" -o ! "$outfile" ]; then
  82         echo "syntax: $0 [--board ras-boardname] [--version ras-version] [--kernel kernelimage] [--rootfs rootfs] out"
  83         exit 1
  84 fi
  85
  86 rootfs_len=$(wc -c < "$rootfs")
  87
  88 if [ "$rootfs_len" -lt "$rootfssize" ]; then
  89         dd if=$rootfs of=$rootfs.new bs=$rootfssize conv=sync
  90         mv $rootfs.new $rootfs
  91 fi
  92
  93 if [ ${#version} -ge 28 ]; then
  94         echo "version: '$version' is too long"
  95         exit 1
  96 fi
  97
  98 tmpdir="$( mktemp -d 2> /dev/null )"
  99 if [ -z "$tmpdir" ]; then
 100         # try OSX signature
 101         tmpdir="$( mktemp -t 'ubitmp' -d )"
 102 fi
 103
 104 if [ -z "$tmpdir" ]; then
 105         exit 1
 106 fi
 107
 108 to_be() {
 109         local val="$1"
 110         local size="$2"
 111
 112         case "$size" in
 113         4)
 114                 echo $(( "$val" >> 24 | ("$val" & 0xff0000) >> 8 | ("$val" & 0xff00) << 8 | ("$val" & 0xff) << 24 ))
 115                 ;;
 116         2)
 117                 echo $(( "$val" >> 8 | ("$val" & 0xff) << 8))
 118                 ;;
 119         esac
 120 }
 121
 122 checksum_file() {
 123         local file=$1
 124
 125         # ZyXEL seems to use System V sum mode... Now this is classy, who would have thought?!
 126         echo $(sum -s ${file} | cut -f1 -d" ")
 127 }
 128
 129 append_bin() {
 130         local val=$1
 131         local size=$2
 132         local file=$3
 133
 134         while [ "$size" -ne 0 ]; do
 135                 printf \\$(printf %o $(("$val" & 0xff)))  >> "$file"
 136                 val=$(($val >> 8))
 137                 let size-=1
 138         done
 139         return
 140 }
 141
 142 tf=${tmpdir}/out
 143 pad=$(printf '%0.1s' $(printf "\xff"){1..64})
 144
 145 rootfs_header_file="$tmpdir/rootfs_header"
 146 rootfs_chksum=$(to_be $(checksum_file ${rootfs}) 4)
 147 rootfs_len=$(to_be $(wc -c < "$rootfs") 4)
 148
 149 versionpadlen=$(( 32 - ( ${#version} + 1) ))
 150
 151 # 4 bytes:  checksum of the rootfs image
 152 append_bin "$rootfs_chksum" 4 "$rootfs_header_file"
 153 # 4 bytes:  length of the contained rootfs image file (big endian)
 154 append_bin "$rootfs_len" 4 "$rootfs_header_file"
 155 # 32 bytes:  Firmware Version string (NUL terminated, 0xff padded)
 156 printf "%s\x00%.*s" "$version" "$versionpadlen" "$pad" >> "$rootfs_header_file"
 157
 158 kernel_header_file="$tmpdir/kernel_header"
 159 kernel_chksum=$(to_be $(checksum_file ${kernel}) 4)
 160 kernel_len=$(to_be $(wc -c < "$kernel") 4)
 161
 162 # 4 bytes:  checksum of the kernel image
 163 append_bin "$kernel_chksum" 4 "$kernel_header_file"
 164 # 4 bytes:  length of the contained kernel image file (big endian)
 165 append_bin "$kernel_len" 4 "$kernel_header_file"
 166
 167 board_header_file="$tmpdir/board_header"
 168 board_file="$tmpdir/board"
 169 boardpadlen=$(( 64 - ( ${#board} + 1) ))
 170 # 32 bytes:  Model (e.g. "NBG6617", NUL termiated, 0xff padded)
 171 printf "%s\x00%.*s" "$board" "$boardpadlen" "$pad" > "$board_file"
 172 cat "$kernel_header_file" >> "$board_file"
 173 printf "%.12s" "$pad" >> "$board_file"
 174 #      rest: 0xff padding
 175 for i in {1..511}; do
 176         printf "%s%s" "$pad" "$pad" >> "$board_file"
 177 done
 178
 179 tmp_board_file="$tmpdir/tmp_board_file"
 180 cat "$rootfs_header_file" > "$tmp_board_file"
 181
 182 # The checksum for the header is calculated over the first 2048 bytes with
 183 # the rootfs image checksum as the placeholder during calculation.
 184 append_bin "$rootfs_chksum" 4 "$tmp_board_file"
 185 cat "$board_file" >> "$tmp_board_file"
 186
 187 truncate -s 2048 $tmp_board_file
 188 board_chksum=$(to_be $(checksum_file ${tmp_board_file}) 4)
 189
 190 # 4 bytes:  checksum over the header partition (big endian)
 191 append_bin "$board_chksum" 4 "$board_header_file"
 192 cat "$board_file" >> "$board_header_file"
 193
 194 cat "$rootfs_header_file" "$board_header_file" "$rootfs" "$kernel" > "$outfile"
 195
 196 rm -rf "$tmpdir"