flatcar-scripts/cros_generate_update_payload

#!/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 to generate a Chromium OS update for use by the update engine.
# If a source .bin is specified, the update is assumed to be a delta update.

# Load common constants.  This should be the first executable line.
# The path to common.sh should be relative to your script's location.
. "$(dirname "$0")/common.sh"

# Load functions and constants for chromeos-install
. "$(dirname "$0")/chromeos-common.sh"

SRC_MNT=""
DST_MNT=""
SRC_KERNEL=""
SRC_ROOT=""
DST_KERNEL=""
DST_ROOT=""
STATE_MNT=""
STATE_LOOP_DEV=""

# Pass an arg to not exit 1 at the end
cleanup() {
  set +e
  echo "Cleaning up"
  if [ -n "$SRC_MNT" ]; then
    sudo umount -d "$SRC_MNT"
    [ -d "$SRC_MNT" ] && rmdir "$SRC_MNT"
    SRC_MNT=""
  fi
  if [ -n "$DST_MNT" ]; then
    sudo umount -d "$DST_MNT"
    [ -d "$DST_MNT" ] && rmdir "$DST_MNT"
    DST_MNT=""
  fi
  if [ -n "$STATE_MNT" ]; then
    sudo umount "$STATE_MNT"
    [ -d "$STATE_MNT" ] && rmdir "$STATE_MNT"
    STATE_MNT=""
  fi
  if [ -n "$STATE_LOOP_DEV" ]; then
    sudo losetup -d "$STATE_LOOP_DEV"
    STATE_LOOP_DEV=""
  fi
  rm -f "$SRC_KERNEL"
  rm -f "$SRC_ROOT"
  rm -f "$DST_KERNEL"
  rm -f "$DST_ROOT"
  [ -n "$1" ] || exit 1
}

extract_partition_to_temp_file() {
  local filename="$1"
  local partition="$2"
  local temp_file=$(mktemp /tmp/generate_update_payload.XXXXXX)
  
  local offset=$(partoffset "${filename}" ${partition})  # 512-byte sectors
  local length=$(partsize "${filename}" ${partition})  # 512-byte sectors
  local bs=512
  local sectors_per_two_mib=$((2 * 1024 * 1024 / 512))
  if [ $(( $offset % $sectors_per_two_mib )) -eq 0 -a \
       $(( $length % $sectors_per_two_mib )) -eq 0 ]; then
    bs=$((2 * 1024 * 1024))
    offset=$(($offset / $sectors_per_two_mib))
    length=$(($length / $sectors_per_two_mib))
  else
    warn "partition offset or length not at 2MiB boundary"
  fi
  dd if="$filename" of="$temp_file" bs=$bs count="$length" skip="$offset"
  echo "$temp_file"
}

patch_kernel() {
  local IMAGE="$1"
  local KERN_FILE="$2"

  STATE_LOOP_DEV=$(sudo losetup -f)
  [ -n "$STATE_LOOP_DEV" ] || die "no free loop device"
  local offset=$(partoffset "${IMAGE}" 1)
  offset=$(($offset * 512))
  sudo losetup -o "$offset" "$STATE_LOOP_DEV" "$IMAGE"
  STATE_MNT=$(mktemp -d /tmp/state.XXXXXX)
  sudo mount "$STATE_LOOP_DEV" "$STATE_MNT"
  dd if="$STATE_MNT"/vmlinuz_hd.vblock of="$KERN_FILE" conv=notrunc
  sudo umount "$STATE_MNT"
  STATE_MNT=""
  sudo losetup -d "$STATE_LOOP_DEV"
  STATE_LOOP_DEV=""
}

# We should be in the chroot.
assert_inside_chroot

DEFINE_string image "" "The image that should be sent to clients."
DEFINE_string src_image "" "Optional: a source image. If specified, this makes\
 a delta update."
DEFINE_boolean old_style "$FLAGS_TRUE" "Generate an old-style .gz full update."
DEFINE_string output "" "Output file"

# Parse command line
FLAGS "$@" || exit 1
eval set -- "${FLAGS_ARGV}"

set -e

locate_gpt

DELTA=$FLAGS_TRUE
[ -n "$FLAGS_output" ] || die \
    "Error: you must specify an output filename with --output FILENAME"

if [ -z "$FLAGS_src_image" ]; then
  DELTA=$FLAGS_FALSE
  if [ "$FLAGS_old_style" = "$FLAGS_TRUE" ]; then
    echo "Generating an old-style full update"
  else
    die "Generating a new-style full update not yet supported"
  fi
fi

if [ "$DELTA" -eq "$FLAGS_TRUE" ]; then
  echo "Generating a delta update"
  
  # Sanity check that the real generator exists:
  GENERATOR="$(dirname "$0")/../platform/update_engine/delta_generator"
  [ -x "$GENERATOR" ] || die "$GENERATOR doesn't exist, or isn't executable"

  trap cleanup INT TERM EXIT
  SRC_KERNEL=$(extract_partition_to_temp_file "$FLAGS_src_image" 2)
  patch_kernel "$FLAGS_src_image" "$SRC_KERNEL"
  SRC_ROOT=$(extract_partition_to_temp_file "$FLAGS_src_image" 3)

  echo md5sum of src kernel:
  md5sum "$SRC_KERNEL"
  echo md5sum of src root:
  md5sum "$SRC_ROOT"
  
  DST_KERNEL=$(extract_partition_to_temp_file "$FLAGS_image" 2)
  patch_kernel "$FLAGS_image" "$DST_KERNEL"
  DST_ROOT=$(extract_partition_to_temp_file "$FLAGS_image" 3)
  
  SRC_MNT=$(mktemp -d /tmp/src_root.XXXXXX)
  sudo mount -o loop,ro "$SRC_ROOT" "$SRC_MNT"

  DST_MNT=$(mktemp -d /tmp/src_root.XXXXXX)
  sudo mount -o loop,ro "$DST_ROOT" "$DST_MNT"
  
  sudo "$GENERATOR" \
      -new_dir "$DST_MNT" -new_image "$DST_ROOT" -new_kernel "$DST_KERNEL" \
      -old_dir "$SRC_MNT" -old_image "$SRC_ROOT" -old_kernel "$SRC_KERNEL" \
      -out_file "$FLAGS_output"
  
  trap - INT TERM EXIT
  cleanup noexit
  echo "Done generating delta."
else
  echo "Generating full update"
  
  trap cleanup INT TERM EXIT
  DST_KERNEL=$(extract_partition_to_temp_file "$FLAGS_image" 2)
  patch_kernel "$FLAGS_image" "$DST_KERNEL"
  DST_ROOT=$(extract_partition_to_temp_file "$FLAGS_image" 3)
  
  GENERATOR="$(dirname "$0")/mk_memento_images.sh"

  "$GENERATOR" "$DST_KERNEL" "$DST_ROOT"
  mv "$(dirname "$DST_KERNEL")/update.gz" "$FLAGS_output"
  
  trap - INT TERM EXIT
  cleanup noexit
  echo "Done generating full update."
fi