Add a script to generate builds signed using the official keys.

scripts/image_signing/customize_image.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.
 
 # Customize a Chrome OS release image. The cgpt utility must be on the
 # sudo path.
 #
 # The following changes are applied:
 # - Set the root password.
 
-# Usage: ./customize_image <image.bin> <root_password>
+# Usage: ./customize_image.sh <image.bin> <root_password>
+
+# Load common constants and variables.
+. "$(dirname "$0")/common.sh"
 
 readonly ROOTFS_DIR=$(mktemp -d)
 readonly GPT=cgpt
 
 cleanup() {
   set +e
   echo Cleaning up...
   sudo umount -d "$ROOTFS_DIR"
   rm -rf "$ROOTFS_DIR"
 }
 
 failure() {
   cleanup
   exit 1
 }
 
-# Read GPT table to find the starting location of a specific partition.
-# Args: DEVICE PARTNUM
-# Returns: offset (in sectors) of partition PARTNUM
-partoffset() {
-  sudo $GPT show -b -i $2 $1
-}
-
-mount_image() {
-  local image=$1
-  echo "Mounting image '$image'..."
-  local offset=$(partoffset "$image" 3)
-  sudo mount -o loop,offset=$((offset * 512)) "$image" "$ROOTFS_DIR"
-}
-
 change_root_password() {
   local password=$1
   echo "Changing root password to '$password'..."
   local crypted_password="$(echo $password | openssl passwd -1 -stdin)"
   local temp_shadow="$ROOTFS_DIR/etc/tempshadow"
   echo "root:$crypted_password:14500:0:::::" \
     | sudo tee "$temp_shadow" > /dev/null
   grep -Ev ^root: "$ROOTFS_DIR/etc/shadow" \
     | sudo tee -a "$temp_shadow" > /dev/null
   sudo mv -f "$temp_shadow" "$ROOTFS_DIR/etc/shadow"
 }
 
 main() {
   local image=$1
   local root_password=$2
   if [ $# -ne 2 ]; then
     echo "Usage: $0 <image.bin> <root_password>"
     exit 1
   fi
 
   set -e
   trap failure EXIT
-  mount_image "$image"
+  mount_image_partition "$image" 3 $ROOTFS_DIR
   change_root_password "$root_password"
   cleanup
   echo "Done."
   trap - EXIT
 }
 
 main $@