Forum Debian Users Gang

#!/bin/bash

shopt -s extglob

out() { printf "$1 $2\n" "${@:3}"; }
error() { out "==> ERROR:" "$@"; } >&2
msg() { out "==>" "$@"; }
msg2() { out "  ->" "$@";}
die() { error "$@"; exit 1; }

in_array() {
  local i
  for i in "${@:2}"; do
    [[ $1 = "$i" ]] && return
  done
}

track_mount() {
  mount "$@" && CHROOT_ACTIVE_MOUNTS=("$2" "${CHROOT_ACTIVE_MOUNTS[@]}")
}

api_fs_mount() {
  CHROOT_ACTIVE_MOUNTS=()
  { mountpoint -q "$1" || track_mount "$1" "$1" --bind; } &&
  track_mount proc "$1/proc" -t proc -o nosuid,noexec,nodev &&
  track_mount sys "$1/sys" -t sysfs -o nosuid,noexec,nodev &&
  track_mount udev "$1/dev" -t devtmpfs -o mode=0755,nosuid &&
  track_mount devpts "$1/dev/pts" -t devpts -o mode=0620,gid=5,nosuid,noexec &&
  track_mount shm "$1/dev/shm" -t tmpfs -o mode=1777,nosuid,nodev &&
  track_mount run "$1/run" -t tmpfs -o nosuid,nodev,mode=0755 &&
  track_mount tmp "$1/tmp" -t tmpfs -o mode=1777,strictatime,nodev,nosuid
}

api_fs_umount() {
  umount "${CHROOT_ACTIVE_MOUNTS[@]}"
}

valid_number_of_base() {
  local base=$1 len=${#2} i=

  for (( i = 0; i < len; i++ )); do
    (( (${2:i:1} & ~(base - 1)) == 0 )) || return
  done
}

mangle() {
  local i= chr= out=

  unset {a..f} {A..F}

  for (( i = 0; i < ${#1}; i++ )); do
    chr=${1:i:1}
    case $chr in
      [[:space:]\\])
        printf -v chr '%03o' "'$chr"
        out+=\\
        ;;&
        # fallthrough
      *)
        out+=$chr
        ;;
    esac
  done

  printf '%s' "$out"
}

unmangle() {
  local i= chr= out= len=$(( ${#1} - 4 ))

  unset {a..f} {A..F}

  for (( i = 0; i < len; i++ )); do
    chr=${1:i:1}
    case $chr in
      \\)
        if valid_number_of_base 8 "${1:i+1:3}" ||
            valid_number_of_base 16 "${1:i+1:3}"; then
          printf -v chr '%b' "${1:i:4}"
          (( i += 3 ))
        fi
        ;;&
        # fallthrough
      *)
        out+=$chr
    esac
  done

  printf '%s' "$out${1:i}"
}

dm_name_for_devnode() {
  read dm_name <"/sys/class/block/${1#/dev/}/dm/name"
  if [[ $dm_name ]]; then
    printf '/dev/mapper/%s' "$dm_name"
  else
    # don't leave the caller hanging, just print the original name
    # along with the failure.
    print '%s' "$1"
    error 'Failed to resolve device mapper name for: %s' "$1"
  fi
}

fstype_is_pseudofs() {
  # list taken from util-linux source: libmount/src/utils.c
  local -A pseudofs_types=([anon_inodefs]=1
                           [autofs]=1
                           [bdev]=1
                           [binfmt_misc]=1
                           [cgroup]=1
                           [configfs]=1
                           [cpuset]=1
                           [debugfs]=1
                           [devfs]=1
                           [devpts]=1
                           [devtmpfs]=1
                           [dlmfs]=1
                           [fuse.gvfs-fuse-daemon]=1
                           [fusectl]=1
                           [hugetlbfs]=1
                           [mqueue]=1
                           [nfsd]=1
                           [none]=1
                           [pipefs]=1
                           [proc]=1
                           [pstore]=1
                           [ramfs]=1
                           [rootfs]=1
                           [rpc_pipefs]=1
                           [securityfs]=1
                           [sockfs]=1
                           [spufs]=1
                           [sysfs]=1
                           [tmpfs]=1)
  (( pseudofs_types["$1"] ))
}



write_source() {
  local src=$1 spec= label= uuid= comment=()

  label=$(blkid -s LABEL -o value "$1" 2>/dev/null)
  uuid=$(blkid -s UUID -o value "$1" 2>/dev/null)

  # bind mounts do not have a UUID!

  case $bytag in
    '')
      [[ $uuid ]] && comment=("UUID=$uuid")
      [[ $label ]] && comment+=("LABEL=$label")
      ;;
    LABEL)
      spec=$label
      [[ $uuid ]] && comment=("$src" "UUID=$uuid")
      ;;
    UUID)
      spec=$uuid
      comment=("$src")
      [[ $label ]] && comment+=("LABEL=$label")
      ;;
    *)
      [[ $uuid ]] && comment=("$1" "UUID=$uuid")
      [[ $label ]] && comment+=("LABEL=$label")
      [[ $bytag ]] && spec=$(blkid -s "$bytag" -o value "$1")
      ;;
  esac

  [[ $comment ]] && printf '# %s\n' "${comment[*]}"

  if [[ $spec ]]; then
    printf '%-20s' "$bytag=$spec"
  else
    printf '%-20s' "$(mangle "$src")"
  fi
}

usage() {
  cat <<EOF
usage: ${0##*/} [options] root

  Options:
    -L             Use labels for source identifiers (shortcut for -t LABEL)
    -p             Avoid printing pseudofs mounts
    -t TAG         Use TAG for source identifiers
    -U             Use UUIDs for source identifiers (shortcut for -t UUID)

    -h             Print this help message

genfstab generates output suitable for addition to an fstab file based on the
devices mounted under the mountpoint specified by the given root.

EOF
}

if [[ -z $1 || $1 = @(-h|--help) ]]; then
  usage
  exit $(( $# ? 0 : 1 ))
fi

while getopts ':Lpt:U' flag; do
  case $flag in
    L)
      bytag=LABEL
      ;;
    U)
      bytag=UUID
      ;;
    p)
      nopseudofs=1
      ;;
    t)
      bytag=${OPTARG^^}
      ;;
    :)
      die '%s: option requires an argument -- '\''%s'\' "${0##*/}" "$OPTARG"
      ;;
    ?)
      die '%s: invalid option -- '\''%s'\' "${0##*/}" "$OPTARG"
      ;;
  esac
done
shift $(( OPTIND - 1 ))

(( $# )) || die "No root directory specified"
root=$1; shift

if ! mountpoint -q "$root"; then
  die "$root is not a mountpoint"
fi

if (( bylabel && byuuid )); then
  die "cannot specify both -U and -L"
fi

# handle block devices
findmnt -Recvruno SOURCE,TARGET,FSTYPE,OPTIONS,FSROOT "$root" |
    while read -r src target fstype opts fsroot; do
  # default 5th and 6th columns
  dump=0 pass=2

  src=$(unmangle "$src")
  target=$(unmangle "$target")
  target=${target#$root}

  if (( !foundroot )) && findmnt "$src" "$root" >/dev/null; then
    # this is root. we can't possibly have more than one...
    pass=1 foundroot=1
  fi

  # we don't fsck pseudofs
  if fstype_is_pseudofs "$fstype"; then
    (( nopseudofs )) && continue
    pass=0
  fi

  if [[ $fsroot != / ]]; then
    if [[ $fstype = btrfs ]]; then
      opts+=,subvol=${fsroot#/}
    else
      # it's a bind mount
      src=$(findmnt -funcevo TARGET "$src")$fsroot
      if [[ $src -ef $target ]]; then
        # hrmm, this is weird. we're probably looking at a file or directory
        # that was bound into a chroot from the host machine. Ignore it,
        # because this won't actually be a valid mount. Worst case, the user
        # just re-adds it.
        continue
      fi
      fstype=none
      opts+=,bind
      pass=0
    fi
  fi

  # write one line
  write_source "$src"
  printf '\t%-10s' "/$(mangle "${target#/}")" "$fstype" "$opts"
  printf '\t%s %s' "$dump" "$pass"
  printf '\n\n'
done

# handle swaps devices
{
  # ignore header
  read

  while read -r device type _ _ prio; do
    options=defaults
    if [[ $prio != -1 ]]; then
      options+=,pri=$prio
    fi

    # skip files marked deleted by the kernel
    [[ $device = *'\\040(deleted)' ]] && continue

    if [[ $type = file ]]; then
      printf '%-20s' "$device"
    elif [[ $device = /dev/dm-+([0-9]) ]]; then
      # device mapper doesn't allow characters we need to worry
      # about being mangled, and it does the escaping of dashes
      # for us in sysfs.
      write_source "$(dm_name_for_devnode "$device")"
    else
      write_source "$(unmangle "$device")"
    fi

    printf '\t%-10s\t%-10s\t%-10s\t0 0\n\n' 'none' 'swap' "$options"
  done
} </proc/swaps

# vim: et ts=2 sw=2 ft=sh:

root@ubuntu:/home# ./genfstab -p -U /mnt 
findmnt: unknown column: FSROOT
# /dev/mapper/deb_crypt-swap
UUID=e0b1508e-ab42-4a88-8eda-1cc11a52097e    none          swap          defaults      0 0

root@ubuntu:/home# lsblk -o name,fstype,mountpoint,label,uuid,ro,rm,size,type
NAME                        FSTYPE      MOUNTPOINT         LABEL             UUID                                   RO RM   SIZE TYPE
sda                                                                                                                  0  0  74.5G disk
├─sda1                      ntfs                           WinXP             5668FA8468FA6263                        0  0    28G part
├─sda2                      ext4        /mnt/boot          boot              27e5bccf-256b-4239-a3a4-c0ed81892869    0  0   957M part
├─sda3                                                                                                               0  0     1K part
├─sda5                      crypto_LUKS                                      a8bf24ad-c8da-4a4b-bb1b-647144a873c8    0  0  18.6G part
├─sda6                      crypto_LUKS                                      194f4523-475d-45e7-9bfe-e1fe500c250a    0  0  18.6G part
│ └─sda6_crypt (dm-0)       LVM2_member                                      k54xxU-RxHg-agNb-M2cY-AQh4-sKzx-PxRSBD  0  0  18.6G crypt
│   ├─deb_crypt-root (dm-1) ext4        /mnt               root              27cf5e5f-ffaa-4db0-8337-ecff43656386    0  0    12G lvm
│   ├─deb_crypt-home (dm-2) ext4        /mnt/home          home              1cbeec68-59c9-4d46-9db8-dfff06f13018    0  0     3G lvm
│   ├─deb_crypt-tmp (dm-3)  ext4        /mnt/tmp           tmp               b55c540a-573a-42a5-a648-bc037e2eb23f    0  0     2G lvm
│   └─deb_crypt-swap (dm-4) swap        [SWAP]                               e0b1508e-ab42-4a88-8eda-1cc11a52097e    0  0   1.6G lvm
└─sda7                      ext4        /mnt/media/backup  backup            c751ab48-fe9b-4c83-920e-d3205c6ba7ff    0  0   8.4G part
sdb                                                                                                                  0  1  14.5G disk
├─sdb1                      ext4        /media/ubuntu/arch arch              77ef557b-c739-4d96-8072-1aa8ac2ab20f    0  1   6.6G part
├─sdb2                                                                                                               0  1   4.9G part
└─sdb3                      vfat        /media/ubuntu/fat  fat               9798-CEE7                               0  1   3.1G part
sr0                         iso9660     /cdrom             Ubuntu 13.04 i386                                         0  1   4.4G rom
loop0                       squashfs    /rofs                                                                        1  0 757.3M loop