Don't use hardcoded offsets for parsing.

scripts/image_signing/unpack_firmwarefd.sh

 #!/bin/bash
 
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Script that unpacks a firmware image (in .fd format) into its component
 # pieces. Only outputs firmware A and B data, vblocks and the GBB.
 
 # The fmap_decode tool must be in the system path.
 
 # Abort on error
 set -e
 
 # Check arguments
 if [ $# -ne 1 ] ; then
   echo "Usage: $0 src_fd"
   echo "Outputs firmware.gbb, firmware[A|B].[data|vblock]"
   exit 1
 fi
 
 # Make sure the tools we need are available.
 type -P fmap_decode &>/dev/null || \
   { echo "fmap_decode tool not found."; exit 1; }
 
 src_fd=$1
 
-# Parse offsets and size of firmware data and vblocks
-let gbb_offset="$(fmap_decode $1 | grep GBB | cut -b 14-23)"
-let gbb_size="$(fmap_decode $1 | grep GBB | cut -b 37-46)"
-set -x
+# Grab GBB Area offset and size
+match_str="GBB Area"
+line=$(fmap_decode $1 | grep "$match_str")
+offset="$(echo $line | sed -e 's/.*area_offset=\"\([a-f0-9x]*\)\".*/\1/')"
+let gbb_offset="$offset"

[vb, 2010/07/27 18:18:50]

is 'let' needed here and in line 34?

[gauravsh, 2010/07/27 18:45:26]

Yes, to force hex->decimal conversion since dd doesn't like 0x.. style hex
number literals.

+size="$(echo $line | sed -e 's/.*area_size=\"\([a-f0-9x]*\)\".*/\1/')"
+let gbb_size="$size"
+
+# Grab Firmware A and B offset and size
 for i in "A" "B"
 do
   match_str="$i Key"
+  line=$(fmap_decode $1 | grep "$match_str")
+  offset="$(echo $line | sed -e 's/.*area_offset=\"\([a-f0-9x]*\)\".*/\1/')"
   eval let \
-    fw${i}_vblock_offset="$(fmap_decode $1 | grep "$match_str" | cut -b 14-23)"
+    fw${i}_vblock_offset="$offset"
+  size="$(echo $line | sed -e 's/.*area_size=\"\([a-f0-9x]*\)\".*/\1/')"
   eval let \
-    fw${i}_vblock_size="$(fmap_decode $1 | grep "$match_str" | cut -b 37-46)"
+    fw${i}_vblock_size="$size"
 
   match_str="$i Data"
-  eval let fw${i}_offset="$(fmap_decode $1 | grep "$match_str" | cut -b 14-23)"
-  eval let fw${i}_size="$(fmap_decode $1 | grep "$match_str" | cut -b 37-46)"
+  line=$(fmap_decode $1 | grep "$match_str")
+  offset="$(echo $line | sed -e 's/.*area_offset=\"\([a-f0-9x]*\)\".*/\1/')"
+  eval let \
+    fw${i}_offset="$offset"
+  size="$(echo $line | sed -e 's/.*area_size=\"\([a-f0-9x]*\)\".*/\1/')"
+  eval let \
+    fw${i}_size="$size"
 done
 
 echo "Extracting GBB"
 dd if="${src_fd}" of="firmware.gbb" skip="${gbb_offset}" bs=1 \
   count="${gbb_size}"
 echo "Extracting Firmware data and vblock(s)"
 dd if="${src_fd}" of="firmwareA.data" skip="${fwA_offset}" bs=1 \
   count="${fwA_size}"
 dd if="${src_fd}" of="firmwareA.vblock" skip="${fwA_vblock_offset}" bs=1 \
   count="${fwA_vblock_size}"
 dd if="${src_fd}" of="firmwareB.data" skip="${fwB_offset}" bs=1 \
   count="${fwB_size}"
 dd if="${src_fd}" of="firmwareB.vblock" skip="${fwB_vblock_offset}" bs=1 \
   count="${fwB_vblock_size}"