#!/bin/bash
#
# makerepropkg - rebuild a package to see if it is reproducible
#
# Copyright (c) 2019 by Eli Schwartz <eschwartz@archlinux.org>
#
# SPDX-License-Identifier: GPL-3.0-or-later

m4_include(lib/common.sh)
m4_include(lib/archroot.sh)

source /usr/share/makepkg/util/config.sh
source /usr/share/makepkg/util/message.sh

declare -A buildinfo
declare -a buildenv buildopts installed installpkgs

archiveurl='https://archive.archlinux.org/packages'
buildroot=/var/lib/archbuild/reproducible
diffoscope=0

chroot=$USER
[[ -n ${SUDO_USER:-} ]] && chroot=$SUDO_USER
[[ -z "$chroot" || $chroot = root ]] && chroot=copy

parse_buildinfo() {
    local line var val

    while read -r line; do
        var="${line%% = *}"
        val="${line#* = }"
        case ${var} in
            buildenv)
                buildenv+=("${val}")
                ;;
            options)
                buildopts+=("${val}")
                ;;
            installed)
                installed+=("${val}")
                ;;
            *)
                buildinfo["${var}"]="${val}"
                ;;
        esac
    done
}

get_pkgfile() {
    local cdir=${cache_dirs[0]}
    local pkgfilebase=${1}
    local mode=${2}
    local pkgname=${pkgfilebase%-*-*-*}
    local pkgfile ext

    # try without downloading
    if [[ ${mode} != localonly ]] && get_pkgfile "${pkgfilebase}" localonly; then
        return 0
    fi

    for ext in .zst .xz ''; do
        pkgfile=${pkgfilebase}.pkg.tar${ext}

        for c in "${cache_dirs[@]}"; do
            if [[ -f ${c}/${pkgfile} ]]; then
                cdir=${c}
                break
            fi
        done

        for f in "${pkgfile}" "${pkgfile}.sig"; do
            if [[ ! -f "${cdir}/${f}" ]]; then
                if [[ ${mode} = localonly ]]; then
                    continue 2
                fi
                msg2 "retrieving '%s'..." "${f}" >&2
                curl -Llf -# -o "${cdir}/${f}" "${archiveurl}/${pkgname:0:1}/${pkgname}/${f}" || continue 2
            fi
        done
        printf '%s\n' "file://${cdir}/${pkgfile}"
        return 0
    done

    return 1
}

get_makepkg_conf() {
    local fname=${1}
    local makepkg_conf="${2}"
    if ! buildtool_file=$(get_pkgfile "${fname}"); then
        error "failed to retrieve ${fname}"
        return 1
    fi
    msg2 "using makepkg.conf from ${fname}"
    bsdtar xOqf "${buildtool_file/file:\/\//}" usr/share/devtools/makepkg-x86_64.conf > "${makepkg_conf}"
    return 0
}

usage() {
    cat << __EOF__
usage: ${BASH_SOURCE[0]##*/} [options] <package_file>

Run this script in a PKGBUILD dir to build a package inside a
clean chroot while attempting to reproduce it. The package file
will be used to derive metadata needed for reproducing the
package, including the .PKGINFO as well as the buildinfo.

For more details see https://reproducible-builds.org/

OPTIONS
    -d            Run diffoscope if the package is unreproducible
    -c <dir>      Set pacman cache
    -M <file>     Location of a makepkg config file
    -l <chroot>   The directory name to use as the chroot namespace
                  Useful for maintaining multiple copies
                  Default: $chroot
    -h            Show this usage message
__EOF__
}

while getopts 'dM:c:l:h' arg; do
    case "$arg" in
        d) diffoscope=1 ;;
        M) archroot_args+=(-M "$OPTARG") ;;
        c) cache_dirs+=("$OPTARG") ;;
        l) chroot="$OPTARG" ;;
        h) usage; exit 0 ;;
        *|?) usage; exit 1 ;;
    esac
done
shift $((OPTIND - 1))

check_root

[[ -f PKGBUILD ]] || { error "No PKGBUILD in current directory."; exit 1; }

# without arguments, get list of packages from PKGBUILD
if [[ -z $1 ]]; then
    mapfile -t pkgnames < <(source PKGBUILD; pacman -Sddp --print-format '%r/%n' "${pkgname[@]}")
    wait $! || {
        error "No package file specified and failed to retrieve package names from './PKGBUILD'."
        plain "Try '${BASH_SOURCE[0]##*/} -h' for more information." >&2
        exit 1
    }
    msg "Reproducing all pkgnames listed in ./PKGBUILD"
    set -- "${pkgnames[@]}"
fi

# check each package to see if it's a file, and if not, try to download it
# using pacman -Sw, and get the filename from there
splitpkgs=()
for p in "$@"; do
    if [[ -f ${p} ]]; then
        splitpkgs+=("${p}")
    else
        pkgfile_remote=$(pacman -Sddp "${p}" 2>/dev/null) || { error "package name '%s' not in repos" "${p}"; exit 1; }
        pkgfile=${pkgfile_remote#file://}
        if [[ ! -f ${pkgfile} ]]; then
            msg "Downloading package '%s' into pacman's cache" "${pkgfile}"
            sudo pacman -Swdd --noconfirm --logfile /dev/null "${p}" || exit 1
            pkgfile_remote=$(pacman -Sddp "${p}" 2>/dev/null)
            pkgfile="${pkgfile_remote#file://}"
        fi
        splitpkgs+=("${pkgfile}")
    fi
done

for f in "${splitpkgs[@]}"; do
    if ! bsdtar -tqf "${f}" .BUILDINFO >/dev/null 2>&1; then
        error "file is not a valid pacman package: '%s'" "${f}"
        exit 1
    fi
done

if (( ${#cache_dirs[@]} == 0 )); then
	mapfile -t cache_dirs < <(pacman-conf CacheDir)
fi

ORIG_HOME=${HOME}
IFS=: read -r _ _ _ _ _ HOME _ < <(getent passwd "${SUDO_USER:-$USER}")
load_makepkg_config
HOME=${ORIG_HOME}
[[ -d ${SRCDEST} ]] || SRCDEST=${PWD}

parse_buildinfo < <(bsdtar -xOqf "${splitpkgs[0]}" .BUILDINFO)
export SOURCE_DATE_EPOCH="${buildinfo[builddate]}"
PACKAGER="${buildinfo[packager]}"
BUILDDIR="${buildinfo[builddir]}"
BUILDTOOL="${buildinfo[buildtool]}"
BUILDTOOLVER="${buildinfo[buildtoolver]}"
PKGEXT=${splitpkgs[0]#${splitpkgs[0]%.pkg.tar*}}

# nuke and restore reproducible testenv
namespace="$buildroot/$chroot"
lock 9 "${namespace}.lock" "Locking chroot namespace '%s'" "${namespace}"
for copy in "${namespace}"/*/; do
    [[ -d ${copy} ]] || continue
    subvolume_delete_recursive "${copy}"
done
rm -rf --one-file-system "${namespace}"
(umask 0022; mkdir -p "${namespace}")

for fname in "${installed[@]}"; do
    if ! allpkgfiles+=("$(get_pkgfile "${fname}")"); then
        error "failed to retrieve ${fname}"
        exit 1
    fi
done

trap 'rm -rf $TEMPDIR' EXIT INT TERM QUIT
TEMPDIR=$(mktemp -d --tmpdir makerepropkg.XXXXXXXXXX)

makepkg_conf="${TEMPDIR}/makepkg.conf"
# anything before buildtool support is pinned to the last none buildtool aware release
if [[ -z "${BUILDTOOL}" ]]; then
    get_makepkg_conf "devtools-20210202-3-any" "${makepkg_conf}" || exit 1
# prefere to assume devtools up until matching makepkg version so repository packages remain reproducible
elif [[ "${BUILDTOOL}" = makepkg ]] && (( $(vercmp "${BUILDTOOLVER}" 6.0.1) <= 0 )); then
    get_makepkg_conf "devtools-20210202-3-any" "${makepkg_conf}" || exit 1
# all devtools builds
elif [[ "${BUILDTOOL}" = devtools ]] && get_makepkg_conf "${BUILDTOOL}-${BUILDTOOLVER}" "${makepkg_conf}"; then
    true
# fallback to current makepkg.conf
else
    warning "Unknown buildtool (${BUILDTOOL}-${BUILDTOOLVER}), using fallback"
    makepkg_conf=@pkgdatadir@/makepkg-x86_64.conf
fi
printf '%s\n' "${allpkgfiles[@]}" | mkarchroot -M "${makepkg_conf}" -U "${archroot_args[@]}" "${namespace}/root" - || exit 1

# use makechrootpkg to prep the build directory
makechrootpkg -r "${namespace}" -l build -- --packagelist || exit 1

# set detected makepkg.conf options
{
    for var in PACKAGER BUILDDIR BUILDTOOL BUILDTOOLVER PKGEXT; do
        printf '%s=%s\n' "${var}" "${!var@Q}"
    done
    printf 'OPTIONS=(%s)\n' "${buildopts[*]@Q}"
    printf 'BUILDENV=(%s)\n' "${buildenv[*]@Q}"
} >> "${namespace}/build"/etc/makepkg.conf
install -d -o "${SUDO_UID:-$UID}" -g "$(id -g "${SUDO_UID:-$UID}")" "${namespace}/build/${BUILDDIR}"

# kick off the build
arch-nspawn "${namespace}/build" \
    --bind="${PWD}:/startdir" \
    --bind="${SRCDEST}:/srcdest" \
    /chrootbuild -C --noconfirm --log --holdver --skipinteg
ret=$?

if (( ${ret} == 0 )); then
    msg2 "built succeeded! built packages can be found in ${namespace}/build/pkgdest"
    msg "comparing artifacts..."

    for pkgfile in "${splitpkgs[@]}"; do
        comparefiles=("${pkgfile}" "${namespace}/build/pkgdest/${pkgfile##*/}")
        if cmp -s "${comparefiles[@]}"; then
            msg2 "Package '%s' successfully reproduced!" "${pkgfile}"
        else
            ret=1
            warning "Package '%s' is not reproducible. :(" "${pkgfile}"
            sha256sum "${comparefiles[@]}"
            if (( diffoscope )); then
                diffoscope "${comparefiles[@]}"
            fi
        fi
    done
fi

# return failure from chrootbuild, or the reproducibility status
exit ${ret}