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

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

api_fs_mount() {
  if ! mountpoint -q "$1"; then
    mount -B "$1" "$1" && ROOT_IS_BIND=1
  fi &&
  mount -t proc proc "$1/proc" -o nosuid,noexec,nodev &&
  mount -t sysfs sys "$1/sys" -o nosuid,noexec,nodev &&
  mount -t devtmpfs udev "$1/dev" -o mode=0755,nosuid &&
  mount -t devpts devpts "$1/dev/pts" -o mode=0620,gid=5,nosuid,noexec &&
  mount -t tmpfs shm "$1/dev/shm" -o mode=1777,nosuid,nodev &&
  mount -t tmpfs run "$1/run" -o nosuid,nodev,mode=0755 &&
  mount -t tmpfs tmp "$1/tmp" -o mode=1777,strictatime,nodev,nosuid,size=50M
}

api_fs_umount() {
  umount \
    "$1/tmp" \
    "$1/run" \
    "$1/dev/shm" \
    "$1/dev/pts" \
    "$1/dev" \
    "$1/sys" \
    "$1/proc"

  (( ROOT_IS_BIND )) && umount "$1"
}

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}"
}

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