Add a script to put in a rootfs from one image into another.

Also add an option to prevent sign_official_build from attempting to re-sign the firmware.

This is needed because we want both the SSD and RECOVERY images to have the same rootfs for delta updates to work correctly.

BUG=chromium-os:7242
TEST=manually verified that rootfs gets replaced correctly (by verifying the rootfs hash).

Change-Id: I2ca4f2bef938ca14301fed6a0b16c1a7dc2ba6d9

Review URL: http://codereview.chromium.org/3529007

scripts/image_signing/sign_official_build.sh

@@ -186,6 +186,11 @@ get_firmwarebin_from_shellball() {
 resign_firmware_payload() {
   local image=$1
 
+  if [ -n "${NO_FWUPDATE}" ]; then
+    echo "Skipping firmware update."
+    return
+  fi
+
   # Grab firmware image from the autoupdate shellball.
   local rootfs_dir=$(make_temp_dir)
   mount_image_partition ${image} 3 ${rootfs_dir}

scripts/image_signing/swap_rootfs.sh

@@ -0,0 +1,29 @@
+#!/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.
+
+# Load common constants and variables.
+. "$(dirname "$0")/common.sh"
+
+# Print usage string
+usage() {
+    cat <<EOF
+Usage: $PROG dst_image src_image
+This will put the root file system from src_image into dst_image.
+EOF
+}
+
+if [ $# -ne 2 ]; then
+  usage
+  exit 1
+fi
+
+DST_IMAGE=$1
+SRC_IMAGE=$2
+
+temp_rootfs=$(make_temp_file)
+extract_image_partition ${SRC_IMAGE} 3 ${temp_rootfs}
+replace_image_partition ${DST_IMAGE} 3 ${temp_rootfs}
+echo "RootFS from ${SRC_IMAGE} was copied into ${DST_IMAGE}"