init

#!/bin/sh -x

# 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.
#
# /init script for use in factory install shim.  Requires busybox in
# /bin/busybox, and a symlink from /bin/sh -> busybox.

# USB card partition and mount point.
USB_DEVS="sdb3 sdc3 mmcblk1p3"
USB_SHIM_DEVS="sdb1 sdc1 mmcblk1p1"
USB_MNT=/usb
REAL_USB_DEV=
DM_NAME=

DST=

STATEFUL_MNT=/stateful
STATE_DEV=

LOG_DEV=
LOG_FILE="/log/recovery.log"

TPM_B_LOCKED=
TPM_PP_LOCKED=

# Developer script to run
SHIM_SCRIPT="$STATEFUL_MNT/userdir/runme"
SHIM_VBLOCK="$STATEFUL_MNT/userdir/runme.vblock"

KERN_B_VBLOCK="$STATEFUL_MNT/vmlinuz_hd.vblock"
REAL_KERN_B_HASH=

MOVE_MOUNTS="/sys /proc /dev"

# To be updated to keep logging after move_mounts.
TTY_PATH="/dev/tty"
TAIL_PID=

# Used to ensure the factory check only occurs with
# a properly matched root and kernel.
UNOFFICIAL_ROOT=0

# Size of the root ramdisk.
TMPFS_SIZE=300M

on_error() {
  # Exit, thus causing a kernel panic. We don't want to do anything else (like
  # start a shell) because it would be trivially easy to get here (just unplug
  # the USB drive after the kernel starts but before the USB drives are probed
  # by the kernel) and starting a shell here would be a BIG security hole.
  log
  log
  log "An unrecoverable error occurred during recovery!"
  log
  log "Please try again or try a newer recovery image."
  save_log_file
  sleep 1d
  exit 1
}

initial_mounts() {
  mkdir -p /var/lock
  mount -t proc -o nodev,noexec,nosuid none /proc
  mount -t sysfs -o nodev,noexec,nosuid none /sys
  if ! mount -t devtmpfs -o mode=0755 none /dev; then
    mount -t tmpfs -o mode=0755 none /dev
    mknod -m 0600 /dev/console c 5 1
    mknod -m 0601 /dev/tty1 c 4 1
    mknod -m 0601 /dev/tty2 c 4 2
    mknod -m 0601 /dev/tty3 c 4 3
    mknod -m 0600 /dev/tpm0 c 10 224
    mknod /dev/null c 1 3
  fi
  mkdir -p /dev/pts
  mount -t devpts -o noexec,nosuid none /dev/pts || true
}

# Look for a device with our GPT ID.
wait_for_gpt_root() {
  [ -z "$KERN_ARG_KERN_GUID" ] && return 1
  dlog -n "Looking for rootfs using kern_guid..."
  for try in $(seq 20); do
    plog " ."
    kern=$(cgpt find -1 -u $KERN_ARG_KERN_GUID)
    # We always try ROOT-A in recovery.
    newroot="${kern%[0-9]*}3"
    if [ -b "$newroot" ]; then
      USB_DEV="$newroot"
      dlog "Found $USB_DEV"
      return 0
    fi
    sleep 1
  done
  dlog "Failed waiting for kern_guid"
  return 1
}

# Look for any USB device.
wait_for_root() {
  dlog -n "Waiting for $USB_DEVS to appear"
  for try in $(seq 20); do
    plog " ."
    for dev in $USB_DEVS; do
      if [ -b "/dev/${dev}" ]; then
        USB_DEV="/dev/${dev}"
        dlog "Found $USB_DEV"
        return 0
      fi
    done
    sleep 1
  done
  dlog "Failed waiting for root!"
  return 1
}

# Wait for dm-0 to come up.
wait_for_dm_control() {
  MAPPER_CONTROL=/dev/mapper/control
  dlog -n "Waiting for $MAPPER_CONTROL to appear"
  for try in $(seq 20); do
    plog " ."
    if [ -c "$MAPPER_CONTROL" ]; then
      return 0
    fi
    sleep 1
  done
  dlog "Failed waiting for $MAPPER_CONTROL!"
  return 1
}

check_if_dm_root() {
  [ "$KERN_ARG_ROOT" = "/dev/dm-0" ]
}

# Attempt to find the root defined in the signed recovery
# kernel we're booted into to. Exports REAL_USB_DEV if there
# is a root partition that may be used - on succes or failure.
find_official_root() {
  plog "Checking for an official recovery image . . ."

  # Check for a kernel selected root device or one in a well known location.
  wait_for_gpt_root || wait_for_root || return 1

  # Now see if it has a Chrome OS rootfs partition.
  cgpt find -t rootfs "$(strip_partition "$USB_DEV")" || return 1
  REAL_USB_DEV="$USB_DEV"

  LOG_DEV="$(strip_partition "$USB_DEV")"1  # Default to stateful.

  # Now see if the root should be integrity checked.
  if check_if_dm_root; then
    setup_dm_root || return 1
  fi

  mount_usb || return 1
  return 0
}

find_developer_root() {
  is_developer_mode || return 1
  # Lock the TPM prior to using an untrusted root.
  lock_tpm || return 1
  plog "\nSearching for developer root . . ."
  # If an official root could not be mounted, free up the underlying device
  # if it is claimed by verity.
  dmsetup remove "$DM_NAME"

  # If we found a valid rootfs earlier, then we're done.
  USB_DEV="$REAL_USB_DEV"
  [ -z "$USB_DEV" ] && return 1
  set_unofficial_root || return 1
  mount_usb || return 1
  return 0
}

# If this kernel image has been placed on a drive with only a
# stateful partition, root detection will rightly fail.  However,
# we can still run a developer supplied script so we will pretend
# stateful is the root (USB_DEV).
find_shim_root() {
  # Lock the TPM prior to using an untrusted root.
  lock_tpm || return 1
  plog "\nSearching for an alternate recovery image . . ."
  dlog -n "Waiting for $USB_SHIM_DEVS to appear"
  for try in $(seq 20); do
    plog " ."
    for dev in $USB_SHIM_DEVS; do
      if [ -b "/dev/${dev}" ]; then
        USB_DEV="/dev/${dev}"
        REAL_USB_DEV="$USB_DEV"
        dlog "Found $USB_DEV"
        set_unofficial_root || on_error
        mount_usb || return 1
        return 0
      fi
    done
    sleep 1
  done
  return 1
}

# If we have a verified recovery root, ensure all blocks are valid before
# handing it off to the installer.
validate_recovery_root() {
  # Allow test recovery roots that are unverified.
  [ "$USB_DEV" = "/dev/dm-0" ] || return 0
  is_unofficial_root && return 0

  plog "Validating official recovery image . . . "
  # Ensure the verified rootfs is fully intact or fail with no USB_DEV.
  # REAL_USB_DEV is left intact.
  # Correctness wins over speed for this.
  if ! dd if="$USB_DEV" of=/dev/null bs=$((16 * 1024 * 1024)); then
    dlog "Included root filesystem could not be verified."
    log " failed!"
    dmsetup remove "$DM_NAME"  # Free up the real root for use.
    USB_DEV=
    return 1
  fi
  log " completed."
  return 0
}

setup_dm_root() {
  dlog -n "Extracting the device mapper configuration..."
  # export_args can't handle dm="..." at present.
  DMARG=$(cat /proc/cmdline | sed -e 's/.*dm="\([^"\]*\)".*/\1/g')
  DM_NAME=$(echo "$DMARG" | cut -f1 -d' ')
  # We override the reboot-to-recovery error behavior so that we can fail
  # gracefully on invalid rootfs.
  DM_TABLE="$(echo "$DMARG" | cut -f2 -d,) eio"

  # Don't attempt to call dmsetup if the root device isn't one that was
  # discovered as the creation process will hang.
  # TODO(wad) once we pass the UUID this will be easier to robustly check.
  if [ -n "${USB_DEV}" ]; then
    [ "${DM_TABLE%$USB_DEV*}" = "${DM_TABLE}" ] && return 1
  fi

  if ! dmsetup create -r "$DM_NAME" --major 254 --minor 0 --table "$DM_TABLE"
  then
    dlog "Failed to configure device mapper root"
    return 1
  fi
  USB_DEV="/dev/dm-0"
  if [ ! -b "$USB_DEV" ]; then
    mknod -m 0600 "$USB_DEV" b 254 0
  fi
  dlog "Created device mapper root $DM_NAME."
  return 0
}

mount_usb() {
  dlog -n "Mounting usb"
  for try in $(seq 20); do
    plog " ."
    if mount -n -o ro "$USB_DEV" "$USB_MNT"; then
      dlog "ok"
      return 0
    fi
    sleep 1
  done
  dlog "Failed to mount usb!"
  return 1
}

check_if_factory_install() {
  if is_unofficial_root; then
    dlog "Skipping factory install check."
    return 1
  fi

  if [ -e "${USB_MNT}/root/.factory_installer" ]; then
    log "Detected factory install."
    return 0
  fi
  return 1
}

get_stateful_dev() {
  STATE_DEV=${REAL_USB_DEV%[0-9]*}1
  if [ ! -b "$STATE_DEV" ]; then
    dlog "Failed to determine stateful device"
    return 1
  fi
  return 0
}

mount_tmpfs() {
  dlog "Mounting tmpfs..."
  mount -n -t tmpfs tmpfs "$NEWROOT_MNT" -o "size=$TMPFS_SIZE"
  return $?
}

copy_contents() {
  log "Copying usb->tmpfs..."
  (cd "${USB_MNT}" ; tar cf - . | (cd "${NEWROOT_MNT}" && tar xf  -))
  RES=$?
  log "Copy returned with result $RES"
  return $RES
}

copy_lsb() {
  STATEFUL_LSB="dev_image/etc/lsb-factory"
  mkdir -p "${NEWROOT_MNT}/mnt/stateful_partition/dev_image/etc"
  # Mounting ext3 as ext2 since the journal is unneeded in ro.
  mount -n -o ro -t ext2 "$STATE_DEV" "$STATEFUL_MNT"
  if [ -f "${STATEFUL_MNT}/${STATEFUL_LSB}" ]; then
    log "Found ${STATEFUL_MNT}/${STATEFUL_LSB}"
    cp -a "${STATEFUL_MNT}/${STATEFUL_LSB}" \
        "${NEWROOT_MNT}/mnt/stateful_partition/${STATEFUL_LSB}"
  fi
  umount "$STATEFUL_MNT"
  rmdir "$STATEFUL_MNT"
}

move_mounts() {
  dlog "Moving sys. proc, dev to $NEWROOT_MNT"
  for mnt in $MOVE_MOUNTS; do
    mkdir -p "$NEWROOT_MNT$mnt"
    mount -n -o move "$mnt" "$NEWROOT_MNT$mnt"
  done
  TTY_PATH="$NEWROOT_MNT/dev/tty"
  dlog "Done."
  return 0
}

unmove_mounts() {
  dlog "Moving sys. proc, dev to $NEWROOT_MNT"
  for mnt in $MOVE_MOUNTS; do
    mount -n -o move "$NEWROOT_MNT$mnt" "$mnt"
  done
  TTY_PATH="/dev/tty"
  dlog "Done."
  return 0
}

unmount_usb() {
  dlog "Unmounting $USB_MNT"
  umount "$USB_MNT"
  # Make sure we clean up a device-mapper root.
  if [ "$USB_DEV" = "/dev/dm-0" ]; then
    dlog "Removing dm-verity target"
    dmsetup remove "$DM_NAME"
  fi
  dlog
  dlog "$REAL_USB_DEV can now be safely removed"
  dlog
  return 0
}

strip_partition() {
  local dev="${1%[0-9]*}"
  # handle mmcblk0p case as well
  echo "${dev%p*}"
}

# Accomodate sd* or mmcblk* devices
get_dst() {
  DST=$(echo ${REAL_USB_DEV%[0-9]*} | \
        tr -s '[0-9]' '0' | \
        sed -e 's/sd[b-z]/sda/g')
}

dev_wait_or_error() {
  is_developer_mode || on_error  # terminal if we get here in regular mode.
  log ""
  log "A developer key change is required to proceed."
  plog "Please wait 300 seconds . . ."
  # TODO(wad) Divvy the total up into a few different prompts.
  make_user_wait 300
  log ""
}

recovery_wait() {
  log ""
  log "Preparing to recover your system image."
  plog "If you do not wish to proceed, please reboot in the next 10 seconds ."
  make_user_wait 10
  log ""
  log "System recovery is beginning."
  log "Please do not disconnect from a power source or power down."
  log ""
}

make_user_wait() {
  local delay_in_sec="${1-300}"
  while [ $delay_in_sec -gt 0 ]; do
    plog " ."
    sleep 1
    delay_in_sec=$((delay_in_sec - 1))
  done
  log ""
}

check_key_or_wait() {
  plog "Searching the system disk for a matching kernel key . . ."
  if ! cgpt find -t kernel -M "$1" "$DST"; then
    log " failed."
    dev_wait_or_error
    return 0
  fi
  log " found."

  plog "Validating matching signature(s) . . ."
  # If we found a keyblock, at the right offset, make sure it actually signed
  # the subsequent payload.
  local kdev=
  for kdev in $(cgpt find -t kernel -M "$1" "$DST"); do
    plog " ."
    verify_kernel_signature "$kdev" "/tmp/kern.keyblock" || continue
    log " done."
    return 0
  done

  log " failed."
  dev_wait_or_error
  return 0
}

# Never returns on success.
attempt_shim_script() {
  # TODO(wad) Add static root of trust validation then remove the next line.
  #           http://crosbug/8390
  is_developer_mode || return 1

  # Now we will either install a colocated Chromium OS image by
  # checking the keys on KERN-B against any on disk (KERN-[ABC])
  # or by checking a signed script on stateful.
  dlog "Checking for a shim script . . ."
  [ -x "$SHIM_SCRIPT" ] || return 1
  [ -f "$SHIM_VBLOCK" ] || return 1
  log "Shim script and signing file found!"

  plog "Verifying the signature on the script . . ."
  # Extract pubkey and check signature
  if ! dev_sign_file --verify "$SHIM_SCRIPT" \
                     --vblock "$SHIM_VBLOCK" \
                     --keyblock /tmp/shim.keyblock; then
    log " failed."
  fi
  log " done."

  # If we're not in developer mode, this will be terminal on failure.
  check_key_or_wait /tmp/shim.keyblock

  # Run the user supplied script. It is done in the current environment
  # to avoid needing anything other than the script/program on the partition.
  log "Executing shim script . . ."

  dlog "calling $SHIM_SCRIPT with exec"
  # Fix up the input/output
  stop_log_file
  set +x
  exec &> "$TTY_PATH"1
  exec < "$TTY_PATH"1
  # Call the script!
  exec "$SHIM_SCRIPT"

  # Never reached.
  save_log_file
  return 0
}

get_kern_b_device() {
  # TODO(wad) By changing boot priority, could we end up
  # checking the recovery image or the recovery image could not
  # be in slot A. In that case, it should fail in normal mode.
  KERN_B_DEV=${REAL_USB_DEV%[0-9]*}4
  if [ ! -b "${KERN_B_DEV}" ]; then
    return 1
  fi
  return 0
}

get_real_kern_b_hash() {
  REAL_KERN_B_HASH=$(dd if="${KERN_B_DEV}" | \
                     sha1sum | \
                     cut -f1 -d' ')
  [ -n "$REAL_KERN_B_HASH" ]
}

verify_kernel_signature() {
  local kern_dev="$1"
  local keyblock="$2"

  if ! dd if="$kern_dev" of="/tmp/kern.bin"; then
    return 1
  fi

  # Validates the signature and outputs a keyblock.
  if ! vbutil_kernel --verify "/tmp/kern.bin" \
                     --keyblock "$keyblock"; then
    return 1
  fi
  return 0
}

verify_install_kernel() {
  get_kern_b_device || return 1
  get_real_kern_b_hash || return 1

  # TODO(wad) check signatures from stateful on kern b using the
  #           root of trust instead of using a baked in cmdline.
  if [ "$REAL_KERN_B_HASH" != "$KERN_ARG_KERN_B_HASH" ]; then
    if ! is_developer_mode; then
      log "The recovery image cannot be verified."
      return 1
    fi

    # Extract the kernel so that vbutil_kernel will happily consume it.
    log "Checking the install kernel for a valid developer signature . . ."
    verify_kernel_signature "$KERN_B_DEV" "/tmp/kern_b.keyblock" || return 1
    check_key_or_wait /tmp/kern_b.keyblock
  fi
  return 0
}

touch_developer_mode_file() {
  is_developer_mode || return 1
  mount -n -o rw -t ext3 "$DST"1 "$STATEFUL_MNT" || return 1
  touch "$STATEFUL_MNT/.developer_mode" || return 1
  umount "$STATEFUL_MNT" || return 1
  return 0
}

call_image_recovery_script() {
  mount -t tmpfs -o mode=1777 none "$USB_MNT/tmp" || return 1
  move_mounts || return 1

  # Start the copy.
  log ""
  log "Beginning system image copy. This will take some time . . ."
  log ""
  # Until images are built with the installer keyblock in KERN-B by
  # default, we keep copying over the installer vblock from the
  # stateful partition.
  # TODO(wad) http://crosbug/8378
  export IS_RECOVERY_INSTALL=1
  chroot "$USB_MNT" \
    /usr/sbin/chromeos-install --run_as_root --yes \
                               --payload_image="$1" \
                               --use_payload_kern_b
  if [  $? -eq 0 ]; then
    log "System copy completed."
  else
    log "Error performing system recovery!"
  fi

  # Clean up doesn't need to be successful.
  umount "$USB_MNT/tmp"
  unmove_mounts

  # If we're in developer mode, touch the .developer_mode file on stateful
  # to avoid a bonus wait period on reboot.
  # Failure here is non-terminal and it may not succeed just because the
  # partition table of the destination has not been synchronized.
  dlog "Prepping destination stateful to avoid a secondary delay."
  touch_developer_mode_file && log "Prepped image for developer use."

  return 0
}

clear_tpm() {
  plog "Resetting security device . . ."
  # TODO(wad) should we fail on this?
  tpmc ppon || dlog "tpmc ppon error: $?"
  tpmc clear || dlog "tpmc clear error: $?"
  tpmc enable || dlog "tpmc enable error: $?"
  tpmc activate || dlog "tpmc activate error: $?"
  tpmc pplock || dlog "tpmc pplock error: $?"
  log " done."
  return 0
}

save_log_file() {
  local log_dev="${1:-$LOG_DEV}"
  [ -z "$log_dev" ] && return 0
  # The recovery stateful is usually too small for ext3.
  # TODO(wad) We could also just write the data raw if needed.
  #           Should this also try to save
  dlog "Attempting to save log file: $LOG_FILE -> $log_dev"
  mount -n -o sync,rw -t ext2 "$log_dev" /tmp
  cp "$LOG_FILE" /tmp
  umount -n /tmp
}

stop_log_file() {
  # Drop logging
  exec &> "$TTY_PATH"3
  [ -n "$TAIL_PID" ] && kill $TAIL_PID
}

is_unofficial_root() {
  [ $UNOFFICIAL_ROOT -eq 1 ]
}

set_unofficial_root() {
  UNOFFICIAL_ROOT=1
  return 0
}

recover_system() {
  local source=$(strip_partition "$REAL_USB_DEV")
  dlog "Beginning system recovery from $source"

  recovery_wait

  if is_unofficial_root; then
    dlog "Attempting to use shim  . . ."
    # Mounting read only so a journal is not needed.
    # If it fails, we can still proceed on a normal recovery path.
    mount -n -o ro -t ext2 "$STATE_DEV" "$STATEFUL_MNT"
    attempt_shim_script  # never returns on success.
    umount "$STATEFUL_MNT"
  fi

  # If we're not running a developer script then we're either
  # installing a developer image or an official one. If we're
  # in normal recovery mode, then we require that the KERN-B
  # on the recovery image matches the hash on the command line.
  # In developer mode, we will just check the keys.
  verify_install_kernel || return 1

  # Only clear on full installs. Shim scripts can call tpmc if they
  # like.  Only bGlobalLock will be in place in advance.
  clear_tpm || return 1

  call_image_recovery_script "$source" || return 1

  return 0
}

use_new_root() {
  move_mounts || on_error

  # Chroot into newroot, erase the contents of the old /, and exec real init.
  log "About to switch root"
  stop_log_file
  exec switch_root -c /dev/console "$NEWROOT_MNT" /sbin/init

  # This should not really happen.
  log "Failed to switch root."
  save_log_file
  return 1
}

is_developer_mode() {
  # See Firmware High-Level Spec for details on CHSW values
  CHSW=$(cat /sys/devices/platform/chromeos_acpi/CHSW)
  # If the switch is unsupported, treat as developer mode.
  [ -z "$CHSW" ] && return 0
  if [ $CHSW -gt 0 -a $((CHSW & 32)) -eq 32 ]; then
    return 0
  fi
  return 1
}

lock_tpm() {
  if [ -z "$TPM_B_LOCKED" ]; then
    # Depending on the system, the tpm may need to be started.
    # Don't fail if it doesn't work though.
    tpmc startup
    tpmc ctest
    if ! tpmc block; then
      log "An unrecoverable error occurred with your security device"
      log "Please power down and try again."
      dlog "Failed to lock bGlobalLock."
      on_error
      return 1  # Never reached.
    fi
    TPM_B_LOCKED=y
  fi
  if [ -z "$TPM_PP_LOCKED" ]; then
    # TODO: tpmc pplock if appropriate
    TPM_PP_LOCKED=y
  fi
  return 0
}

# Extract and export kernel arguments
export_args() {
  # We trust out kernel command line explicitly.
  local arg=
  local key=
  local val=
  local acceptable_set='[A-Za-z0-9]_'
  for arg in "$@"; do
    key=$(echo "${arg%=*}" | tr 'a-z' 'A-Z' | \
                   tr -dc "$acceptable_set" '_')
    val="${arg#*=}"
    export "KERN_ARG_$key"="$val"
    dlog "Exporting kernel argument $key as KERN_ARG_$key"
  done
}

dlog() {
  echo "$@" | tee -a "$TTY_PATH"2 "$TTY_PATH"3
}

# User visible
log() {
  echo "$@" | tee -a "$TTY_PATH"1 "$TTY_PATH"2
}

plog() {
  # plog doesn't go to /dev/tty3 or log file.
  printf "$@" | tee "$TTY_PATH"1 "$TTY_PATH"2
}

main() {
  exec &> "$LOG_FILE"

  # Set up basic mounts, console.
  initial_mounts

  # Send all verbose output to tty3
  (tail -f "$LOG_FILE" > "$TTY_PATH"3) &
  TAIL_PID=$!

  log "Recovery image booting . . ."
  log ""
  log "Press Ctrl + Alt + F1 - F3 for more detailed information."
  log ""

  # Export the kernel command line as a parsed blob prepending KERN_ARG_ to each
  # argument.
  export_args $(cat /proc/cmdline | sed -e 's/"[^"]*"/DROPPED/g')

  if is_developer_mode; then
    log "! Your computer's developer mode switch is in the ENABLED position."
    log "!"
    log "! If this is unintentional, you should power off and toggle it back "
    log "! after recovery is completed."
    log ""
  fi

  if find_official_root || find_developer_root || find_shim_root; then
    log " found."
  else
    log " not found."
    on_error
  fi

  # Extract the real boot source which may be masked by dm-verity.
  get_stateful_dev || on_error

  # Check if we want to run from RAM, in the factory.
  if check_if_factory_install; then
    is_developer_mode || on_error  # factory install requires it.
    # Copy rootfs contents to tmpfs, then unmount USB device.
    NEWROOT_MNT=/newroot
    mount_tmpfs || on_error
    copy_contents || on_error
    copy_lsb || on_error
    # USB device is unmounted, we can remove it now.
    unmount_usb || on_error
    # Switch to the new root
    use_new_root || on_error
    on_error # !! Never reached. !!
  fi

  # If not, we must be a recovery kernel.
  NEWROOT_MNT="$USB_MNT"

  # Always lock the TPM.  If a NVRAM reset is ever needed, we can change it.
  lock_tpm || on_error

  # Perform a full device mapper root validation to avoid any unexpected
  # failures during postinst.  It also allows us to detect if the root is
  # intentionally mismatched - such as during Chromium OS recovery with a
  # Chrome OS recovery kernel.
  if ! validate_recovery_root; then
    is_developer_mode || on_error
    find_developer_root || find_shim_root || on_error
    log " found."
    # This logic is duplicated to avoid double validating factory media.  It
    # will only be hit if a verified root can be mounted but is actually not
    # intact.
    get_stateful_dev || on_error
  fi

  get_dst || on_error

  recover_system || on_error

  log "System recovery is complete!"
  log "Please remove the recovery device and reboot."

  stop_log_file
  # Save the recovery log to the target on success and the USB.
  save_log_file "$DST"1
  save_log_file

  unmount_usb

  log ""
  log ""
  plog "The system will automatically reboot in 2 minutes"
  make_user_wait 120
  reboot -f
  exit 0
}

# Make this source-able for testing.
if [ "$0" = "/init" ]; then
  main "$@"
  # Should never reach here.
  exit 1
fi