Issue 6759: reduce size of stateful partition for non-developer recovery image

mod_image_for_recovery.sh

Index: mod_image_for_recovery.sh
diff --git a/mod_image_for_recovery.sh b/mod_image_for_recovery.sh
index 6acf46daa80b338d1cce948101e2f56219e280e7..7d59095753a2e78dd2e14084fb5e274e292a3c9c 100755
--- a/mod_image_for_recovery.sh
+++ b/mod_image_for_recovery.sh
@@ -6,16 +6,15 @@
 
 # Script to modify a pristine/dev Chrome OS image to be used for recovery
 
-. "$(dirname "$0")/common.sh"
-
-# Load functions and constants for chromeos-install
-. "$(dirname "$0")/chromeos-common.sh"
+. "$(dirname "$0")/resize_stateful_partition.sh"
 
 # Script must be run inside the chroot.
 restart_in_chroot_if_needed $*
 
 get_default_board
 
+# Constants
+TEMP_IMG=$(mktemp "/tmp/temp_img.XXXXXX")
 RECOVERY_IMAGE="recovery_image.bin"
 
 DEFINE_string board "$DEFAULT_BOARD" "Board for which the image was built"
@@ -33,7 +32,7 @@ if [ -z $FLAGS_image ] && [ -z $FLAGS_board ] ; then
   die "mod_image_for_recovery failed.  No board set and no image set"
 fi
 
-# We have a board name but no image set.  Use image at default location
+# We have a board name but no image set. Use image at default location
 if [ -z $FLAGS_image ] ; then
   IMAGES_DIR="${DEFAULT_BUILD_ROOT}/images/${FLAGS_board}"
   FILENAME="chromiumos_image.bin"
@@ -49,75 +48,73 @@ if [ ! -f $FLAGS_image ] ; then
   exit 1
 fi
 
+set -u
 set -e
 
 # Constants
 IMAGE_DIR="$(dirname "$FLAGS_image")"
-IMAGE_NAME="$(basename "$FLAGS_image")"
-
-# loop device utility methods mostly duplicated from
-#   src/platform/installer/chromeos-install
-# TODO(tgao): minimize duplication by refactoring these methods into a separate
-# library script which both scripts can reference
-
-# Set up loop device for an image file at specified offset
-loop_offset_setup() {
-  local filename=$1
-  local offset=$2  # 512-byte sectors
-
-  LOOP_DEV=$(sudo losetup -f)
-  if [ -z "$LOOP_DEV" ]
-  then
-    echo "No free loop device. Free up a loop device or reboot. Exiting."
-    exit 1
-  fi
-
-  sudo losetup -o $(($offset * 512)) ${LOOP_DEV} ${filename}
-}
-
-loop_offset_cleanup() {
-  sudo losetup -d ${LOOP_DEV} || /bin/true
-}
-
-mount_on_loop_dev() {
-  TMPMNT=$(mktemp -d)
-  sudo mount ${LOOP_DEV} ${TMPMNT}
-}
 
-# Unmount loop-mounted device.
-umount_from_loop_dev() {
-  mount | grep -q " on ${TMPMNT} " && sudo umount ${TMPMNT}
-}
-
-# Undo both mount and loop.
-my_cleanup() {
-  umount_from_loop_dev
-  loop_offset_cleanup
-}
-
-# Modifies an existing image for recovery use
-update_recovery_packages() {
-  local image_name=$1
-
-  echo "Modifying image ${image_name} for recovery use"
-
-  locate_gpt  # set $GPT env var
-  loop_offset_setup ${image_name} $(partoffset "${image_name}" 1)
-  trap loop_offset_cleanup EXIT
-  mount_on_loop_dev "readwrite"
-  trap my_cleanup EXIT
-  sudo touch ${TMPMNT}/.recovery
-  umount_from_loop_dev
-  trap loop_offset_cleanup EXIT
-  loop_offset_cleanup
+# Creates a dev recovery image using an existing dev install shim
+# If successful, content of --payload_dir is copied to a directory named
+# "dev_payload" under the root of stateful partition.
+create_recovery_image() {
+  local src_img=$1  # base image
+  local src_state=$(mktemp "/tmp/src_state.XXXXXX")
+  local stateful_offset=$(partoffset ${src_img} 1)
+  local stateful_count=$(partsize ${src_img} 1)
+
+  dd if="${src_img}" of="${src_state}" conv=notrunc bs=512 \
+    skip=${stateful_offset} count=${stateful_count}
+
+  # Mount original stateful partition to figure out its actual size
+  local src_loop_dev=$(get_loop_dev)
+  trap "cleanup_loop_dev ${src_loop_dev}" EXIT
+
+  # Setup loop dev
+  sudo losetup $src_loop_dev $src_state
+  local block_size=$(sudo /sbin/dumpe2fs $src_loop_dev | grep "Block size:" \
+                     | tr -d ' ' | cut -f2 -d:)
+  echo "block_size = $block_size"
+  local min_size=$(sudo /sbin/resize2fs -P $src_loop_dev | tr -d ' ' \
+                   | cut -f2 -d:)
+  echo "min_size = $min_size $block_size blocks"
+
+  # Add 20%, convert to 512-byte sectors and round up to 2Mb boundary
+  local min_sectors=$(roundup $(((min_size * block_size * 120) / (512 * 100))))
+  echo "min_sectors = ${min_sectors} 512-byte blocks"
+  sudo e2fsck -fp "${src_loop_dev}"
+  # Resize using 512-byte sectors
+  sudo /sbin/resize2fs $src_loop_dev ${min_sectors}s
+
+  # Delete the loop
   trap - EXIT
+  cleanup_loop_dev ${src_loop_dev}
+
+  # Truncate the image at the new size
+  dd if=/dev/zero of=$src_state bs=512 seek=$min_sectors count=0
+
+  # Mount and touch .recovery  # Soon not to be needed :/
+  local new_mnt=$(mktemp -d "/tmp/src_mnt.XXXXXX")
+  mkdir -p "${new_mnt}"
+  local new_loop_dev=$(get_loop_dev)
+  trap "cleanup_loop_dev ${new_loop_dev} && rmdir ${new_mnt} && \
+        rm -f ${src_state}" EXIT
+  sudo mount -o loop=${new_loop_dev} "${src_state}" "${new_mnt}"
+  trap "umount_from_loop_dev ${new_mnt} && rm -f ${src_state}" EXIT
+  sudo touch "${new_mnt}/.recovery"
+
+  (update_partition_table $src_img $src_state $min_sectors $TEMP_IMG)
+  # trap handler will handle unmount and clean up of loop device and temp files
 }
 
 # Main
-
 DST_PATH="${IMAGE_DIR}/${FLAGS_output}"
 echo "Making a copy of original image ${FLAGS_image}"
-cp $FLAGS_image $DST_PATH
-update_recovery_packages $DST_PATH
+(create_recovery_image $FLAGS_image)
 
-echo "Recovery image created at ${DST_PATH}"
+if [ -n ${TEMP_IMG} ] && [ -f ${TEMP_IMG} ]; then
+  mv -f $TEMP_IMG $DST_PATH
+  echo "Recovery image created at ${DST_PATH}"
+else
+  echo "Failed to create recovery image"
+fi