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

resize_stateful_partition.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.
+
+# Utility methods used to resize a stateful partition and update the GPT table
+
+# Source constants and utility functions
+. "$(dirname "$0")/common.sh"
+. "$(dirname "$0")/chromeos-common.sh"
+
+locate_gpt
+
+umount_from_loop_dev() {
+  local mnt_pt=$1
+  mount | grep -q " on ${mnt_pt}" && sudo umount -d ${mnt_pt}
+  rmdir ${mnt_pt}
+}
+
+cleanup_loop_dev() {
+  sudo losetup -d ${1} || /bin/true
+}
+
+get_loop_dev() {
+  local loop_dev=$(sudo losetup -f)
+  if [ -z "${loop_dev}" ]; then
+    die "No free loop device. Free up a loop device or reboot. Exiting."
+  fi
+  echo ${loop_dev}
+}
+
+# Resize stateful partition of install shim to hold payload content
+# Due to this resize, we need to create a new partition table and a new image.
+# (see update_partition_table() for details)
+enlarge_partition_image() {
+  local source_part=$1  # source partition
+  local add_num_sectors=$2  # number of 512-byte sectors to be added
+
+  local source_sectors=$(roundup $(numsectors ${source_part}))
+  info "source partition has ${source_sectors} 512-byte sectors."
+  local resized_sectors=$(roundup $(expr $source_sectors + $add_num_sectors))
+  info "resized partition has ${resized_sectors} 512-byte sectors."
+
+  local loop_dev=$(get_loop_dev)
+  trap "cleanup_loop_dev ${loop_dev}" EXIT
+
+  # Extend the source file size to the new size.
+  dd if=/dev/zero of="${source_part}" bs=1 count=1 \
+      seek=$((512 * ${resized_sectors} - 1)) &>/dev/null
+
+  # Resize the partition.
+  sudo losetup "${loop_dev}" "${source_part}"
+  sudo e2fsck -fp "${loop_dev}" &> /dev/null
+  sudo resize2fs "${loop_dev}" &> /dev/null
+  # trap handler will clean up the loop device
+  echo "${resized_sectors}"
+}
+
+# Update partition table with resized stateful partition
+update_partition_table() {
+  local src_img=$1          # source image
+  local temp_state=$2       # stateful partition image
+  local resized_sectors=$3  # number of sectors in resized stateful partition
+  local temp_img=$4
+
+  local kernel_offset=$(partoffset ${src_img} 2)
+  local kernel_count=$(partsize ${src_img} 2)
+  local rootfs_offset=$(partoffset ${src_img} 3)
+  local rootfs_count=$(partsize ${src_img} 3)
+  local oem_offset=$(partoffset ${src_img} 8)
+  local oem_count=$(partsize ${src_img} 8)
+  local esp_offset=$(partoffset ${src_img} 12)
+  local esp_count=$(partsize ${src_img} 12)
+
+  local temp_pmbr=$(mktemp "/tmp/pmbr.XXXXXX")
+  dd if="${src_img}" of="${temp_pmbr}" bs=512 count=1 &>/dev/null
+
+  trap "rm -rf \"${temp_pmbr}\"" EXIT
+  # Set up a new partition table
+  install_gpt "${temp_img}" "${rootfs_count}" "${resized_sectors}" \
+    "${temp_pmbr}" "${esp_count}" false $(roundup ${rootfs_count})
+
+  # Copy into the partition parts of the file
+  dd if="${src_img}" of="${temp_img}" conv=notrunc bs=512 \
+    seek="${START_ROOTFS_A}" skip=${rootfs_offset} count=${rootfs_count}
+  dd if="${temp_state}" of="${temp_img}" conv=notrunc bs=512 \
+    seek="${START_STATEFUL}"
+  # Copy the full kernel (i.e. with vboot sections)
+  dd if="${src_img}" of="${temp_img}" conv=notrunc bs=512 \
+    seek="${START_KERN_A}" skip=${kernel_offset} count=${kernel_count}
+  dd if="${src_img}" of="${temp_img}" conv=notrunc bs=512 \
+    seek="${START_OEM}" skip=${oem_offset} count=${oem_count}
+  dd if="${src_img}" of="${temp_img}" conv=notrunc bs=512 \
+    seek="${START_ESP}" skip=${esp_offset} count=${esp_count}
+}