#!/usr/bin/env bash
# SPDX-License-Identifier: GPL-2.0-only
#
# archbootcpio simplified and stripped down
# Arch Linux mkinitcpio - modular tool for building an initramfs images
# optimized for size and speed
# by Tobias Powalowski <tpowa@archlinux.org>

shopt -s extglob

### globals within mkinitcpio, but not intended to be used by hooks

# needed files/directories
_f_functions=/usr/lib/initcpio/functions
_f_functions_overwrite=/usr/lib/archboot/cpio.sh
_f_config=
_d_hooks=/lib/initcpio/hooks
_d_install=/lib/initcpio/install
_d_flag_hooks=
_d_flag_install=

# options and runtime data
_optmoduleroot='' _optgenimg=''
_optcompress='' _opttargetdir=''
_optosrelease=''
_optsavetree=0
_optquiet=1 _optcolor=1
_optaddhooks=() _hooks=()  _tmpfiles=()
declare -A _runhooks _addedmodules _modpaths _autodetect_cache

# Sanitize environment further
# GREP_OPTIONS="--color=always" will break everything
# CDPATH can affect cd and pushd
# LIBMOUNT_* options can affect findmnt and other tools
unset GREP_OPTIONS CDPATH "${!LIBMOUNT_@}"

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

  Options:
   -A, --addhooks <hooks>       Add specified hooks, comma separated, to image
   -c, --config <config>        Use config file
   -g, --generate <path>        Generate cpio image and write to specified path
   -h, --help                   Display this message and exit
   -k, --kernel <kernelver>     Use specified kernel version (default: $(uname -r))
   -r, --moduleroot <dir>       Root directory for modules (default: /)
   -s, --save                   Save build directory. (default: no)
   -d, --generatedir <dir>      Write generated image into <dir>
   -t, --builddir <dir>         Use DIR as the temporary build directory
   -D, --hookdir <dir>          Specify where to look for hooks
   -z, --compress <program>     Use an alternate compressor on the image (cat, xz, lz4, zstd)
EOF
}

# The function is called from the EXIT trap
# shellcheck disable=SC2317
cleanup() {
    local err="${1:-$?}"

    if (( ${#_tmpfiles[@]} )); then
        rm -f -- "${_tmpfiles[@]}"
    fi
    if [[ -n "$_d_workdir" ]]; then
        # when _optpreset is set, we're in the main loop, not a worker process
        if (( _optsavetree )) && [[ -z ${_optpreset[*]} ]]; then
            printf '%s\n' "${!_autodetect_cache[@]}" > "$_d_workdir/autodetect_modules"
            msg "build directory saved in '%s'" "$_d_workdir"
        else
            rm -rf -- "$_d_workdir"
        fi
    fi

    exit "$err"
}

resolve_kernver() {
    local kernel="$1" arch=''

    if [[ -z "$kernel" ]]; then
        uname -r
        return 0
    fi

    if [[ "${kernel:0:1}" != / ]]; then
        echo "$kernel"
        return 0
    fi

    if [[ ! -e "$kernel" ]]; then
        error "specified kernel image does not exist: '%s'" "$kernel"
        return 1
    fi

    kver "$kernel" && return

    error "invalid kernel specified: '%s'" "$1"

    arch="$(uname -m)"
    if [[ "$arch" != @(i?86|x86_64) ]]; then
        error "kernel version extraction from image not supported for '%s' architecture" "$arch"
        error "there's a chance the generic version extractor may work with a valid uncompressed kernel image"
    fi

    return 1
}

compute_hookset() {
    local h

    for h in "${HOOKS[@]}" "${_optaddhooks[@]}"; do
        _hooks+=("$h")
    done
}

build_image() {
    local out="$1" compressout="$1" compress="$2" errmsg pipestatus

    case "$compress" in
        cat)
            msg "Creating uncompressed initcpio image: '%s'" "$out"
            unset COMPRESSION_OPTIONS
            ;;
        *)
            msg "Creating %s-compressed initcpio image: '%s'" "$compress" "$out"
            ;;&
        xz)
            COMPRESSION_OPTIONS=('-T0' '--check=crc32' "${COMPRESSION_OPTIONS[@]}")
            ;;
        lz4)
            COMPRESSION_OPTIONS=('-l' "${COMPRESSION_OPTIONS[@]}")
            ;;
        zstd)
            COMPRESSION_OPTIONS=('-T0' "${COMPRESSION_OPTIONS[@]}")
            ;;
    esac

    if [[ -f "$out" ]]; then
        local curr_size space_left_on_device

        curr_size="$(stat --format="%s" "$out")"
        space_left_on_device="$(($(stat -f --format="%a*%S" "$out")))"

        # check if there is enough space on the device to write the image to a tempfile, fallback otherwise
        # this assumes that the new image is not more than 1¼ times the size of the old one
        (( $((curr_size + (curr_size/4))) < space_left_on_device )) && compressout="$out".tmp
    fi

    pushd "$BUILDROOT" >/dev/null || return

    # Reproducibility: set all timestamps to 0
    find . -mindepth 1 -execdir touch -hcd "@0" "{}" +

    # If this pipeline changes, |pipeprogs| below needs to be updated as well.
    find . -mindepth 1 -printf '%P\0' |
            sort -z |
            LANG=C bsdtar --null -cnf - -T - |
            LANG=C bsdtar --null -cf - --format=newc @- |
            $compress "${COMPRESSION_OPTIONS[@]}" > "$compressout"

    pipestatus=("${PIPESTATUS[@]}")
    pipeprogs=('find' 'sort' 'bsdtar (step 1)' 'bsdtar (step 2)' "$compress")

    popd >/dev/null || return

    for (( i = 0; i < ${#pipestatus[*]}; ++i )); do
        if (( pipestatus[i] )); then
            errmsg="${pipeprogs[i]} reported an error"
            break
        fi
    done

    if (( _builderrors )); then
        warning "errors were encountered during the build. The image may not be complete."
    fi

    if [[ -n "$errmsg" ]]; then
        error "Image generation FAILED: '%s'" "$errmsg"
        return 1
    elif (( _builderrors == 0 )); then
        msg "Image generation successful"
    fi

    # sync and rename as we only wrote to a tempfile so far to ensure consistency
    if [[ "$compressout" != "$out" ]]; then
        sync -d -- "$compressout"
        mv -f -- "$compressout" "$out"
    fi
}

process_preset() (
    . "$1" || die "Failed to load preset: \`%s'" "$1"
    exit 0
)

preload_builtin_modules() {
    local modname field value
    local -a path

    # Prime the _addedmodules list with the builtins for this kernel. We prefer
    # the modinfo file if it exists, but this requires a recent enough kernel
    # and kmod>=27.

    if [[ -r $_d_kmoduledir/modules.builtin.modinfo ]]; then
        while IFS=.= read -rd '' modname field value; do
            _addedmodules[${modname//-/_}]=2
            case "$field" in
                alias)
                    _addedmodules["${value//-/_}"]=2
                    ;;
            esac
        done <"$_d_kmoduledir/modules.builtin.modinfo"

    elif [[ -r "$_d_kmoduledir/modules.builtin" ]]; then
        while IFS=/ read -ra path; do
            modname="${path[-1]%.ko}"
            _addedmodules["${modname//-/_}"]=2
        done <"$_d_kmoduledir/modules.builtin"
    fi
}

# shellcheck source=functions
. "$_f_functions"
. "$_f_functions_overwrite"

trap 'cleanup' EXIT

_opt_short='A:c:D:g:H:hk:nLMPp:Rr:S:sd:t:U:Vvz:'
_opt_long=('add:' 'addhooks:' 'config:' 'generate:' 'hookdir': 'help'
          'kernel:' 'listhooks' 'moduleroot:' 'nocolor'
          'save' 'generatedir:' 'builddir:' 'compress:'
          'osrelease:')

parseopts "$_opt_short" "${_opt_long[@]}" -- "$@" || exit 1
set -- "${OPTRET[@]}"
unset _opt_short _opt_long OPTRET

if [[ -z "$1" ]]; then
    usage
    cleanup 0
fi

while :; do
    case "$1" in
        # --add remains for backwards compat
        -A|--add|--addhooks)
            shift
            IFS=, read -r -a add <<< "$1"
            _optaddhooks+=("${add[@]}")
            unset add
            ;;
        -c|--config)
            shift
            _f_config="$1"
            ;;
        -k|--kernel)
            shift
            KERNELVERSION="$1"
            ;;
        -s|--save)
            _optsavetree=1
            ;;
        -d|--generatedir)
            shift
            _opttargetdir="$1"
            ;;
        -g|--generate)
            shift
            [[ -d "$1" ]] && die 'Invalid image path -- must not be a directory'
            if ! _optgenimg="$(readlink -f "$1")" || [[ ! -e "${_optgenimg%/*}" ]]; then
                die "Unable to write to path: '%s'" "$1"
            fi
            ;;
        -h|--help)
            usage
            cleanup 0
            ;;
        -t|--builddir)
            shift
            export TMPDIR="$1"
            ;;
        -z|--compress)
            shift
            _optcompress="$1"
            ;;
        -r|--moduleroot)
            shift
            _optmoduleroot="$1"
            ;;
        -D|--hookdir)
            shift
            _d_flag_hooks+="$1/hooks:"
            _d_flag_install+="$1/install:"
            ;;
        --)
            shift
            break 2
            ;;
    esac
    shift
done

if [[ -t 1 ]] && (( _optcolor )); then
    try_enable_color
fi

if [[ -n "$_d_flag_hooks" && -n "$_d_flag_install" ]]; then
    _d_hooks="${_d_flag_hooks%:}"
    _d_install="${_d_flag_install%:}"
fi

# insist that /proc and /dev be mounted (important for chroots)
# NOTE: avoid using mountpoint for this -- look for the paths that we actually
# use in mkinitcpio. Avoids issues like FS#26344.
[[ -e /proc/self/mountinfo ]] || die "/proc must be mounted!"
[[ -e /dev/fd ]] || die "/dev must be mounted!"

# use preset $_optpreset (exits after processing)
if (( ${#_optpreset[*]} )); then
    map process_preset "${_optpreset[@]}"
    exit
fi

if [[ "$KERNELVERSION" != 'none' ]]; then
    KERNELVERSION="$(resolve_kernver "$KERNELVERSION")" || exit 1
    _d_kmoduledir="$_optmoduleroot/lib/modules/$KERNELVERSION"
    [[ -d "$_d_kmoduledir" ]] || die "'$_d_kmoduledir' is not a valid kernel module directory"
fi

_d_workdir="$(initialize_buildroot "$KERNELVERSION" "$_opttargetdir")" || exit 1
BUILDROOT="${_opttargetdir:-$_d_workdir/root}"

# shellcheck source=mkinitcpio.conf
! . "$_f_config" 2>/dev/null && die "Failed to read configuration '%s'" "$_f_config"

arrayize_config

# after returning, hooks are populated into the array '_hooks'
# HOOKS should not be referenced from here on
compute_hookset

if (( ${#_hooks[*]} == 0 )); then
    die "Invalid config: No hooks found"
fi

if [[ -n "$_optgenimg" ]]; then
    # check for permissions. if the image doesn't already exist,
    # then check the directory
    if [[ ( -e $_optgenimg && ! -w $_optgenimg ) ||
            ( ! -d ${_optgenimg%/*} || ! -w ${_optgenimg%/*} ) ]]; then
        die "Unable to write to '%s'" "$_optgenimg"
    fi

    _optcompress="${_optcompress:-"${COMPRESSION:-zstd}"}"
    if ! type -P "$_optcompress" >/dev/null; then
        warning "Unable to locate compression method: '%s'" "$_optcompress"
        _optcompress='cat'
    fi

    msg "Starting build: '%s'" "$KERNELVERSION"
elif [[ -n "$_opttargetdir" ]]; then
    msg "Starting build: '%s'" "$KERNELVERSION"
else
    msg "Starting dry run: '%s'" "$KERNELVERSION"
fi

# set functrace and trap to catch errors in add_* functions
declare -i _builderrors=0
set -o functrace
trap '(( $? )) && [[ "$FUNCNAME" == add_* ]] && (( ++_builderrors ))' RETURN

preload_builtin_modules

map run_build_hook "${_hooks[@]}" || (( ++_builderrors ))

# process config file
parse_config "$_f_config"

# switch out the error handler to catch all errors
trap -- RETURN
trap '(( ++_builderrors ))' ERR
set -o errtrace

install_modules "${!_modpaths[@]}"

# unset errtrace and trap
set +o functrace
set +o errtrace
trap -- ERR

# this is simply a nice-to-have -- it doesn't matter if it fails.
ldconfig -r "$BUILDROOT" &>/dev/null
# remove /var/cache/ldconfig/aux-cache for reproducability
rm -f -- "$BUILDROOT/var/cache/ldconfig/aux-cache"

# Set umask to create initramfs images and unified kernel images as 600
umask 077

if [[ -n "$_optgenimg" ]]; then
    build_image "$_optgenimg" "$_optcompress" || exit 1
elif [[ -n "$_opttargetdir" ]]; then
    msg "Build complete."
else
    msg "Dry run complete, use -g IMAGE to generate a real image"
fi

exit $(( !!_builderrors ))

# vim: set ft=sh ts=4 sw=4 et: