#!/bin/bash
#
# Install to multiple ESPs

set -e

# Most of this is copy-paste from grub postinst, sigh.

. /usr/share/debconf/confmodule

# shamelessly stolen from ucf:
#
# Load our templates, just in case our template has
# not been loaded or the Debconf DB lost or corrupted
# since then.
db_x_loadtemplatefile "$(dpkg-query --control-path grub-common templates)" grub-common

###############################################################################
#                       COPY FROM POSTINST
###############################################################################
# This only works on a Linux system with udev running.  This is probably the
# vast majority of systems where we need any of this, though, and we fall
# back reasonably gracefully if we don't have it.
cached_available_ids=
available_ids()
{
  local id path

  if [ "$cached_available_ids" ]; then
    echo "$cached_available_ids"
    return
  fi

  [ -d /dev/disk/by-id ] || return
  cached_available_ids="$(
    for path in /dev/disk/by-id/*; do
      [ -e "$path" ] || continue
      printf '%s %s\n' "$path" "$(readlink -f "$path")"
    done | sort -k2 -s -u | cut -d' ' -f1
  )"
  echo "$cached_available_ids"
}

# Returns non-zero and no output if no mapping can be found.
device_to_id()
{
  local id
  for id in $(available_ids); do
    if [ "$(readlink -f "$id")" = "$(readlink -f "$1")" ]; then
      echo "$id"
      return 0
    fi
  done
  # Fall back to the plain device name if there's no by-id link for it.
  if [ -e "$1" ]; then
    echo "$1"
    return 0
  fi
  return 1
}

# for Linux
sysfs_size()
{
  local num_sectors sector_size size
  # Try to find out the size without relying on a partitioning tool being
  # installed. This isn't too hard on Linux 2.6 with sysfs, but we have to
  # try a couple of variants on detection of the sector size.
  if [ -e "$1/size" ]; then
    num_sectors="$(cat "$1/size")"
    sector_size=512
    if [ -e "$1/queue/logical_block_size" ]; then
      sector_size="$(cat "$1/queue/logical_block_size")"
    elif [ -e "$1/queue/hw_sector_size" ]; then
      sector_size="$(cat "$1/queue/hw_sector_size")"
    fi
    size="$(expr "$num_sectors" \* "$sector_size" / 1000 / 1000)"
  fi
  [ "$size" ] || size='???'
  echo "$size"
}

# for kFreeBSD
camcontrol_size()
{
  local num_sectors sector_size size=

  if num_sectors="$(camcontrol readcap "$1" -q -s -N)"; then
    sector_size="$(camcontrol readcap "$1" -q -b)"
    size="$(expr "$num_sectors" \* "$sector_size" / 1000 / 1000)"
  fi

  [ "$size" ] || size='???'
  echo "$size"
}

maybe_udevadm()
{
  if which udevadm >/dev/null 2>&1; then
    udevadm "$@" || true
  fi
}

# Parse /proc/mounts and find out the mount for the given device.
# The device must be a real device in /dev, not a symlink to one.
get_mounted_device()
{
  mountpoint="$1"
  cat /proc/mounts | while read -r line; do
    set -f
    set -- $line
    set +f
    if [ "$2" = "$mountpoint" ]; then
      echo "$1"
      break
    fi
  done
}

###############################################################################
#                            New or modified helpers
###############################################################################

# Fixed: Return nothing if the argument is empty
get_mountpoint()
{
  local relpath boot_mountpoint

  if [ -z "$1" ]; then
    return
  fi

  relpath="$(grub-mkrelpath "$1")"
  boot_mountpoint="${1#$relpath}"
  echo "${boot_mountpoint:-/}"
}


# Returns value in $RET, like a debconf command.
#
# Merged version of describe_disk and describe_partition, as disks can't be
# valid ESPs on their own, so we can't render them as an entry.
describe_efi_system_partition()
{
  local disk part id path sysfs_path diskbase partbase size
  local disk_basename disk_size model
  disk="$1"
  part="$2"
  id="$3"
  path="$4"

  # BEGIN: Stolen from describe_disk
  model=
  case $(uname -s) in
    Linux)
      sysfs_path="$(maybe_udevadm info -n "$disk" -q path)"
      if [ -z "$sysfs_path" ]; then
        sysfs_path="/block/$(printf %s "${disk#/dev/}" | sed 's,/,!,g')"
      fi
      disk_size="$(sysfs_size "/sys$sysfs_path")"

      model="$(maybe_udevadm info -n "$disk" -q property | sed -n 's/^ID_MODEL=//p')"
      if [ -z "$model" ]; then
        model="$(maybe_udevadm info -n "$disk" -q property | sed -n 's/^DM_NAME=//p')"
        if [ -z "$model" ]; then
          model="$(maybe_udevadm info -n "$disk" -q property | sed -n 's/^MD_NAME=//p')"
          if [ -z "$model" ] && which dmsetup >/dev/null 2>&1; then
            model="$(dmsetup info -c --noheadings -o name "$disk" 2>/dev/null || true)"
          fi
        fi
      fi
    ;;
    GNU/kFreeBSD)
      disk_basename=$(basename "$disk")
      disk_size="$(camcontrol_size "$disk_basename")"
      model="$(camcontrol inquiry "$disk_basename" | sed -ne "s/^pass0: <\([^>]*\)>.*/\1/p")"
    ;;
  esac

  [ "$model" ] || model='???'

  # END: Stolen from describe_disk

  sysfs_path="$(maybe_udevadm info -n "$part" -q path)"
  if [ -z "$sysfs_path" ]; then
    diskbase="${disk#/dev/}"
    diskbase="$(printf %s "$diskbase" | sed 's,/,!,g')"
    partbase="${part#/dev/}"
    partbase="$(printf %s "$partbase" | sed 's,/,!,g')"
    sysfs_path="/block/$diskbase/$partbase"
  fi
  size="$(sysfs_size "/sys$sysfs_path")"

  db_subst grub-efi/partition_description DEVICE "$part"
  db_subst grub-efi/partition_description SIZE "$size"
  db_subst grub-efi/partition_description PATH "$path"
  db_subst grub-efi/partition_description DISK_MODEL "$model"
  db_subst grub-efi/partition_description DISK_SIZE "$disk_size"
  db_metaget grub-efi/partition_description description
}


# Parse /proc/mounts and find out the mount for the given device.
# The device must be a real device in /dev, not a symlink to one.
find_mount_point()
{
  real_device="$1"
  cat /proc/mounts | while read -r line; do
    set -f
    set -- $line
    set +f
    if [ "$1" = "$real_device" -a "$3" = "vfat" ]; then
      echo "$2"
      break
    fi
  done
}

# Return all devices that are a valid ESP
usable_efi_system_partitions()
{
  local last_partition path partition partition_id
  local ID_PART_ENTRY_TYPE ID_PART_ENTRY_SCHEME

  last_partition=
  (
  for partition in /dev/disk/by-id/*; do
    eval "$(udevadm info -q property -n "$partition" | grep -E '^ID_PART_ENTRY_(TYPE|SCHEME)=')"
    if [ -z "$ID_PART_ENTRY_TYPE" -o -z "$ID_PART_ENTRY_SCHEME" -o \
    \( "$ID_PART_ENTRY_SCHEME" != gpt -a "$ID_PART_ENTRY_SCHEME" != dos \) -o \
    \( "$ID_PART_ENTRY_SCHEME" = gpt -a "$ID_PART_ENTRY_TYPE" != c12a7328-f81f-11d2-ba4b-00a0c93ec93b \) -o \
    \( "$ID_PART_ENTRY_SCHEME" = dos -a "$ID_PART_ENTRY_TYPE" != 0xef \) ]; then
      continue
    fi
    # unify the partition id
    partition_id="$(device_to_id "$partition" || true)"
    real_device="$(readlink -f "$partition")"
    path="$(find_mount_point $real_device)"
    echo "$path:$partition_id"
  done
  ) | sort -t: -k2 -u
}

###############################################################################
#                            MAGIC SCRIPT
###############################################################################
FALLBACK_MOUNTPOINT=/var/lib/grub/esp

# Initial install/upgrade from /boot/efi?
db_fget grub-efi/install_devices seen
seen="$RET"

# Get configured value
question=grub-efi/install_devices
priority=high
db_get grub-efi/install_devices
valid=1

# We either migrate /boot/efi over, or we check if we have invalid devices
if [ -z "$RET" ] && [ "$seen" != "true" ]; then
  echo "Trying to migrate /boot/efi into esp config"
  esp="$(get_mounted_device /boot/efi)"
  if [ "$esp" ]; then
    esp="$(device_to_id "$esp")"
  fi
  if [ "$esp" ]; then
    db_set grub-efi/install_devices "$esp"
    db_fset grub-efi/install_devices seen true
    RET="$esp"
  fi
else
  for device in $RET; do
    if [ ! -e "${device%,}" ]; then
      valid=0
      break
    fi
  done
fi

# If /boot/efi points to a device that's not in the list, trigger the
# install_devices_disks_changed prompt below, but add the device behind
# /boot/efi to the defaults.
boot_efi_device=$(get_mounted_device /boot/efi || true)
if [ "$boot_efi_device" ]; then
  for device in $RET; do
    device="${device%,}"
    real_device="$(readlink -f "$device" || true)"
    if [ "$real_device" = "$boot_efi_device" ]; then
      boot_efi_device=""
      break
    fi
  done

  if [ "$boot_efi_device" ]; then
    boot_efi_device="$(device_to_id "$boot_efi_device" || true)"
    if [ "$RET" ]; then
      RET="$RET, $boot_efi_device"
    else
      RET="$boot_efi_device"
    fi
    valid=0
  fi
fi


if [ "$valid" = 0 ]; then
  question=grub-efi/install_devices_disks_changed
  priority=critical
  db_set "$question" "$RET"
  db_fset "$question" seen false
  db_fset grub-efi/install_devices_empty seen false
fi

while :; do
  ids=
  descriptions=
  partitions="$(usable_efi_system_partitions)"

  for partition_pair in $partitions; do
    partition_id="${partition_pair#*:}"
    device="${partition_id%%-part*}"
    ids="${ids:+$ids, }$partition_id"
    describe_efi_system_partition "$(readlink -f "$device")" "$(readlink -f "$partition_id")" "$partition_id" "$(get_mountpoint "${partition_pair%%:*}")"
    RET="$(printf %s "$RET" | sed 's/,/\\,/g')"
    descriptions="${descriptions:+$descriptions, }$RET"
  done

  db_subst "$question" RAW_CHOICES "$ids"
  db_subst "$question" CHOICES "$descriptions"
  db_input "$priority" "$question" || true
  db_go
  db_get "$question"


  # Run the installer
  failed_devices=
  for i in `echo $RET | sed -e 's/, / /g'` ; do
    real_device="$(readlink -f "$i")"
    mntpoint=$(find_mount_point $real_device)
    if [ -z "$mntpoint" ]; then
      mntpoint=$FALLBACK_MOUNTPOINT
      mount $real_device $mntpoint
    fi
    echo "Installing grub to $mntpoint." >&2
    if _UBUNTU_ALTERNATIVE_ESPS="$RET" grub-install --efi-directory=$mntpoint "$@" ; then
      # We just installed GRUB 2; then also generate grub.cfg.
      touch /boot/grub/grub.cfg
    else
      failed_devices="$failed_devices $real_device"
    fi

    if [ "$mntpoint" = "$FALLBACK_MOUNTPOINT" ]; then
      umount $mntpoint
    fi
  done

  if [ "$question" != grub-efi/install_devices ] && [ "$RET" ]; then
    # XXX cjwatson 2019-02-26: The description of
    # grub-efi/install_devices_disks_changed ought to explain that
    # selecting no devices will leave the configuration unchanged
    # so that you'll be prompted again next time, but it's a bit
    # close to the Debian 10 release to be introducing new
    # translatable text.  For now, it should be sufficient to
    # avoid losing configuration data.
    db_set grub-efi/install_devices "$RET"
    db_fset grub-efi/install_devices seen true
  fi

  if [ "$failed_devices" ]; then
    db_subst grub-efi/install_devices_failed FAILED_DEVICES "$failed_devices"
    db_fset grub-efi/install_devices_failed seen false
    if db_input critical grub-efi/install_devices_failed; then
      db_go
      db_get grub-efi/install_devices_failed
      if [ "$RET" = true ]; then
        break
      else
        db_fset "$question" seen false
        db_fset grub-efi/install_devices_failed seen false
        continue
      fi
    else
      exit 1 # noninteractive
    fi
  fi

  db_get "$question"
  if [ -z "$RET" ]; then
    # Reset the seen flag if the current answer is false, since
    # otherwise we'll loop with no indication of why.
    db_get grub-efi/install_devices_empty
    if [ "$RET" = false ]; then
      db_fset grub-efi/install_devices_empty seen false
    fi
    if db_input critical grub-efi/install_devices_empty; then
      db_go
      db_get grub-efi/install_devices_empty
      if [ "$RET" = true ]; then
        break
      else
        db_fset "$question" seen false
        db_fset grub-efi/install_devices_empty seen false
      fi
    else
      # if question was seen we are done
      # Otherwise, abort
      db_fget grub-efi/install_devices_empty seen
      if [ "$RET" = true ]; then
        break
      else
        exit 1
      fi
    fi
  else
    break
  fi
done