AU Payload Generator: allow extracting kernel/rootfs for debugging

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.
@@ skipping 38 matching lines @@
   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 temp_file="$3"
+  if [ -z "$temp_file" ]; then
+    temp_file=$(mktemp /tmp/cros_generate_update_payload.XXXXXX)
+    echo "$temp_file"
+  fi
+  
   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=""
 }
 
+extract_kern_root() {
+  local bin_file="$1"
+  local kern_out="$2"
+  local root_out="$3"
+  
+  if [ -z "$kern_out" ]; then
+    die "missing kernel output filename"
+  fi
+  if [ -z "$root_out" ]; then
+    die "missing root output filename"
+  fi
+  
+  extract_partition_to_temp_file "$bin_file" 2 "$kern_out"
+  if [ "$FLAGS_patch_kernel" -eq "$FLAGS_TRUE" ]; then
+    patch_kernel "$bin_file" "$kern_out"
+  fi
+  extract_partition_to_temp_file "$bin_file" 3 "$root_out"
+}
+
 DEFINE_string image "" "The image that should be sent to clients."
 DEFINE_string src_image "" "Optional: a source image. If specified, this makes\
  a delta update."
 DEFINE_boolean old_style "$FLAGS_TRUE" "Generate an old-style .gz full update."
 DEFINE_string output "" "Output file"
 DEFINE_boolean patch_kernel "$FLAGS_FALSE" "Whether or not to patch the kernel \
 with the patch from the stateful partition (default: false)"
 DEFINE_string private_key "" "Path to private key in .pem format."
+DEFINE_boolean extract "$FLAGS_FALSE" "If set, extract old/new kernel/rootfs \
+to [old|new]_[kern|root].dat. Useful for debugging (default: false)"
 
 # Parse command line
 FLAGS "$@" || exit 1
 eval set -- "${FLAGS_ARGV}"
 
 set -e
 
 if [ -n "$FLAGS_src_image" ]; then
   # We need to be in the chroot for generating delta images
   assert_inside_chroot
 fi
 
 locate_gpt
 
+if [ "$FLAGS_extract" -eq "$FLAGS_TRUE" ]; then
+  if [ -n "$FLAGS_src_image" ]; then
+    extract_kern_root "$FLAGS_src_image" old_kern.dat old_root.dat
+  fi
+  if [ -n "$FLAGS_image" ]; then
+    extract_kern_root "$FLAGS_image" new_kern.dat new_root.dat
+  fi
+  echo Done extracting kernel/root
+  exit 0
+fi
+
 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"
@@ skipping 51 matching lines @@
 
   GENERATOR="$(dirname "$0")/mk_memento_images.sh"
 
   CROS_GENERATE_UPDATE_PAYLOAD_CALLED=1 "$GENERATOR" "$DST_KERNEL" "$DST_ROOT"
   mv "$(dirname "$DST_KERNEL")/update.gz" "$FLAGS_output"
 
   trap - INT TERM EXIT
   cleanup noexit
   echo "Done generating full update."
 fi