pacstrap

#!/bin/bash

#
# Assumptions:
#  1) User has partitioned, formatted, and mounted partitions on /mnt
#  2) Network is functional
#  3) Arguments passed to the script are valid pacman targets
#  4) A valid mirror appears in /etc/pacman.d/mirrorlist
#

shopt -s extglob

# generated from util-linux source: libmount/src/utils.c
declare -A pseudofs_types=([anon_inodefs]=1
                           [autofs]=1
                           [bdev]=1
                           [bpf]=1
                           [binfmt_misc]=1
                           [cgroup]=1
                           [cgroup2]=1
                           [configfs]=1
                           [cpuset]=1
                           [debugfs]=1
                           [devfs]=1
                           [devpts]=1
                           [devtmpfs]=1
                           [dlmfs]=1
                           [efivarfs]=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)

# generated from: pkgfile -vbr '/fsck\..+' | awk -F. '{ print $NF }' | sort
declare -A fsck_types=([cramfs]=1
                       [exfat]=1
                       [ext2]=1
                       [ext3]=1
                       [ext4]=1
                       [ext4dev]=1
                       [jfs]=1
                       [minix]=1
                       [msdos]=1
                       [reiserfs]=1
                       [vfat]=1
                       [xfs]=1)

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

ignore_error() {
  "$@" 2>/dev/null
  return 0
}

in_array() {
  local i
  for i in "${@:2}"; do
    [[ $1 = "$i" ]] && return 0
  done
  return 1
}

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

chroot_maybe_add_mount() {
  local cond=$1; shift
  if eval "$cond"; then
    chroot_add_mount "$@"
  fi
}

chroot_setup() {
  CHROOT_ACTIVE_MOUNTS=()
  [[ $(trap -p EXIT) ]] && die '(BUG): attempting to overwrite existing EXIT trap'
  trap 'chroot_teardown' EXIT

  chroot_add_mount proc "$1/proc" -t proc -o nosuid,noexec,nodev &&
  chroot_add_mount sys "$1/sys" -t sysfs -o nosuid,noexec,nodev,ro &&
  ignore_error chroot_maybe_add_mount "[[ -d '$1/sys/firmware/efi/efivars' ]]" \
      efivarfs "$1/sys/firmware/efi/efivars" -t efivarfs -o nosuid,noexec,nodev &&
  chroot_add_mount udev "$1/dev" -t devtmpfs -o mode=0755,nosuid &&
  chroot_add_mount devpts "$1/dev/pts" -t devpts -o mode=0620,gid=5,nosuid,noexec &&
  chroot_add_mount shm "$1/dev/shm" -t tmpfs -o mode=1777,nosuid,nodev &&
  chroot_add_mount /run "$1/run" --bind &&
  chroot_add_mount tmp "$1/tmp" -t tmpfs -o mode=1777,strictatime,nodev,nosuid
}

chroot_teardown() {
  if (( ${#CHROOT_ACTIVE_MOUNTS[@]} )); then
    umount "${CHROOT_ACTIVE_MOUNTS[@]}"
  fi
  unset CHROOT_ACTIVE_MOUNTS
}

try_cast() (
  _=$(( $1#$2 ))
) 2>/dev/null

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

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

  return 0
}

mangle() {
  local i= chr= out=
  local {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+=\\
        ;;
    esac
    out+=$chr
  done

  printf '%s' "$out"
}

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

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

optstring_match_option() {
  local candidate pat patterns

  IFS=, read -ra patterns <<<"$1"
  for pat in "${patterns[@]}"; do
    if [[ $pat = *=* ]]; then
      # "key=val" will only ever match "key=val"
      candidate=$2
    else
      # "key" will match "key", but also "key=anyval"
      candidate=${2%%=*}
    fi

    [[ $pat = "$candidate" ]] && return 0
  done

  return 1
}

optstring_remove_option() {
  local o options_ remove=$2 IFS=,

  read -ra options_ <<<"${!1}"

  for o in "${!options_[@]}"; do
    optstring_match_option "$remove" "${options_[o]}" && unset 'options_[o]'
  done

  declare -g "$1=${options_[*]}"
}

optstring_normalize() {
  local o options_ norm IFS=,

  read -ra options_ <<<"${!1}"

  # remove empty fields
  for o in "${options_[@]}"; do
    [[ $o ]] && norm+=("$o")
  done

  # avoid empty strings, reset to "defaults"
  declare -g "$1=${norm[*]:-defaults}"
}

optstring_append_option() {
  if ! optstring_has_option "$1" "$2"; then
    declare -g "$1=${!1},$2"
  fi

  optstring_normalize "$1"
}

optstring_prepend_option() {
  local options_=$1

  if ! optstring_has_option "$1" "$2"; then
    declare -g "$1=$2,${!1}"
  fi

  optstring_normalize "$1"
}

optstring_get_option() {
  local opts o

  IFS=, read -ra opts <<<"${!1}"
  for o in "${opts[@]}"; do
    if optstring_match_option "$2" "$o"; then
      declare -g "$o"
      return 0
    fi
  done

  return 1
}

optstring_has_option() {
  local "${2%%=*}"

  optstring_get_option "$1" "$2"
}

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() {
  (( pseudofs_types["$1"] ))
}

fstype_has_fsck() {
  (( fsck_types["$1"] ))
}


hostcache=0
copykeyring=1
copymirrorlist=1

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

  Options:
    -C config      Use an alternate config file for pacman
    -c             Use the package cache on the host, rather than the target
    -G             Avoid copying the host's pacman keyring to the target
    -i             Prompt for package confirmation when needed (run interactively)
    -M             Avoid copying the host's mirrorlist to the target

    -h             Print this help message

pacstrap installs packages to the specified new root directory. If no packages
are given, pacstrap defaults to the "base" group.

EOF
}

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

(( EUID == 0 )) || die 'This script must be run with root privileges'

while getopts ':C:cdGiM' flag; do
  case $flag in
    C)
      pacman_config=$OPTARG
      ;;
    d)
      # retired flag. does nothing.
      ;;
    c)
      hostcache=1
      ;;
    i)
      interactive=1
      ;;
    G)
      copykeyring=0
      ;;
    M)
      copymirrorlist=0
      ;;
    :)
      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"
newroot=$1; shift
pacman_args=("${@:-base}")

if (( ! hostcache )); then
  pacman_args+=(--cachedir="$newroot/var/cache/pacman/pkg")
fi

if (( ! interactive )); then
  pacman_args+=(--noconfirm)
fi

if [[ $pacman_config ]]; then
  pacman_args+=(--config="$pacman_config")
fi

[[ -d $newroot ]] || die "%s is not a directory" "$newroot"

# create obligatory directories
msg 'Creating install root at %s' "$newroot"
mkdir -m 0755 -p "$newroot"/var/{cache/pacman/pkg,lib/pacman,log} "$newroot"/{dev,run,etc}
mkdir -m 1777 -p "$newroot"/tmp
mkdir -m 0555 -p "$newroot"/{sys,proc}

# mount API filesystems
chroot_setup "$newroot" || die "failed to setup chroot %s" "$newroot"

msg 'Installing packages to %s' "$newroot"
if ! pacman -r "$newroot" -Sy "${pacman_args[@]}"; then
  die 'Failed to install packages to new root'
fi

if (( copykeyring )); then
  # if there's a keyring on the host, copy it into the new root, unless it exists already
  if [[ -d /etc/pacman.d/gnupg && ! -d $newroot/etc/pacman.d/gnupg ]]; then
    cp -a /etc/pacman.d/gnupg "$newroot/etc/pacman.d/"
  fi
fi

if (( copymirrorlist )); then
  # install the host's mirrorlist onto the new root
  cp -a /etc/pacman.d/mirrorlist "$newroot/etc/pacman.d/"
fi

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