#!/bin/bash
# License: GNU GPLv2
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

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

shopt -s nullglob

usage() {
	print "Usage: %s [options] -r <chrootdir> [--] [makepkg args]" "${0##*/}"
	echo ''
	prose 'Builds a package inside a clean chroot, assuming that a PKGBUILD
	       exists in the present working directory. Arguments passed to this
	       script after the end-of-options marker (--) will be passed to makepkg.'
	echo ''
	prose 'The chroot dir consists of the following directories:
	       <chrootdir>/{root, copy}; but only "root" is required
	       by default. The working copy will be created as needed.'
	echo ''
	prose 'The chroot "root" directory must be created via the following
	       command:'
	echo  '  mkarchroot <chrootdir>/root base-devel'
	echo ''
	prose 'Note that this script is not normally initiated by the user,
	       but is used internally by `libremakepkg`. `libremakepkg` is the
	       preferred tool for building "release-ready" Parabola packages.
	       When using `libremakepkg`, create the chroot with `librechroot`.'
	echo ''
	prose 'This script reads {SRC,SRCPKG,PKG,LOG}DEST, MAKEFLAGS and PACKAGER
	       from makepkg.conf(5), if those variables are not part of the
	       environment.'
	echo ''
	prose 'Note that, when run on a PKGBUILD which includes a mksource() function,
	       and if a new libre source-ball was created as a result,
	       or if the libre sources do not match the checksums in the PKGBUILD,
	       this script will inject the correct checksums into the PKGBUILD,
	       fork a new instance of the calling process to handle it
	       (usually libremakepkg), and exit immediately'
	echo ''
	print "Default makepkg args: %s" "${default_makepkg_args[*]}"
	print "Default working copy name: %s" "${copy}"
	echo ''
	flag 'Options:'                                                               \
	     '-h'             'This help'                                             \
	     '-c'             'Clean the chroot before building'                      \
	     "-d <$(_ DIR)>"  'Bind a directory into build chroot as read-write
	                       This option may be given multiple times'               \
	     "-D <$(_ DIR)>"  'Bind a directory into build chroot as read-only
	                       This option may be given multiple times'               \
	     '-u'             'Update the working copy of the chroot before building
	                       This is useful for rebuilds without dirtying the
	                       pristine chroot'                                       \
	     "-r <$(_ DIR)>"  'The base dir of the chroot-set to use'                 \
	     "-I <$(_ PKG)>"  'Install a package into the working copy of the chroot
	                       This option may be given multiple times'               \
	     "-l <$(_ COPY)>" 'The directory to use as the working copy of the chroot
	                       Useful for maintaining multiple copies.'               \
	     '-n'             'Run namcap on the package'                             \
	     '-T'             'Build in a temporary directory'                        \
	     '-U'             'Run makepkg as a specified user'

	exit 1
}

# {{{ functions
# Usage: load_vars $makepkg_conf
# Globals:
#  - SRCDEST
#  - SRCPKGDEST
#  - PKGDEST
#  - LOGDEST
#  - MAKEFLAGS
#  - PACKAGER
load_vars() {
	local makepkg_conf="$1" var

	[[ -f $makepkg_conf ]] || return 1

	for var in {SRC,SRCPKG,PKG,LOG}DEST MAKEFLAGS PACKAGER; do
		[[ -z ${!var:-} ]] && eval "$(grep -a "^${var}=" "$makepkg_conf")"
	done

	return 0
}

# Usage: sync_chroot $rootdir $copydir [$copy]
sync_chroot() {
	local rootdir=$1
	local copydir=$2
	local copy=${3:-$2}

	if [[ "$rootdir" -ef "$copydir" ]]; then
		error 'Cannot sync copy with itself: %s' "$copydir"
		return 1
	fi

	# Get a read lock on the root chroot to make
	# sure we don't clone a half-updated chroot
	slock 8 "$rootdir.lock" \
		"Locking clean chroot [%s]" "$rootdir"

	stat_busy "Synchronizing chroot copy [%s] -> [%s]" "$rootdir" "$copy"
	if is_subvolume "$rootdir" && is_same_fs "$rootdir" "$(dirname -- "$copydir")" && ! mountpoint -q "$copydir"; then
		if is_subvolume "$copydir"; then
			subvolume_delete_recursive "$copydir" ||
				die "Unable to delete subvolume %s" "$copydir"
		else
			# avoid change of filesystem in case of an umount failure
			rm --recursive --force --one-file-system "$copydir" ||
				die "Unable to delete %s" "$copydir"
		fi
		btrfs subvolume snapshot "$rootdir" "$copydir" >/dev/null ||
			die "Unable to create subvolume %s" "$copydir"
	else
		mkdir -p "$copydir"
		rsync -a --delete -q -W -x "$rootdir/" "$copydir"
	fi
	stat_done

	# Drop the read lock again
	lock_close 8

	# Update mtime
	touch "$copydir"
}

# Usage: delete_chroot $copydir [$copy]
delete_chroot() {
	local copydir=$1
	local copy=${1:-$2}

	stat_busy "Removing chroot copy [%s]" "$copy"
	if is_subvolume "$copydir" && ! mountpoint -q "$copydir"; then
		subvolume_delete_recursive "$copydir" ||
			die "Unable to delete subvolume %s" "$copydir"
	else
		# avoid change of filesystem in case of an umount failure
		rm --recursive --force --one-file-system "$copydir" ||
			die "Unable to delete %s" "$copydir"
	fi

	# remove lock file
	rm -f "$copydir.lock"
	stat_done
}

# Usage: install_packages $copydir $pkgs...
install_packages() {
	local copydir=$1
	local install_pkgs=("${@:2}")

	local -a pkgnames
	local ret

	pkgnames=("${install_pkgs[@]##*/}")

	cp -- "${install_pkgs[@]}" "$copydir/root/"
	chroot-run "$copydir" "${bindmounts_ro[@]}" "${bindmounts_rw[@]}" \
		pacman -U --noconfirm -- "${pkgnames[@]/#//root/}"
	ret=$?
	rm -- "${pkgnames[@]/#/$copydir/root/}"

	return $ret
}

# Usage: prepare_chroot $copydir $HOME $keepbuilddir $run_namcap
# Globals:
#  - MAKEFLAGS
#  - PACKAGER
prepare_chroot() {
	local copydir=$1
	local USER_HOME=$2
	local keepbuilddir=$3
	local run_namcap=$4

	[[ $keepbuilddir = true ]] || rm -rf "$copydir/build"

	local builduser_uid builduser_gid
	builduser_uid="${SUDO_UID:-$UID}"
	builduser_gid="$(id -g "$builduser_uid")"
	local install="install -o $builduser_uid -g $builduser_gid"
	local x

	# We can't use useradd without chrooting, otherwise it invokes PAM modules
	# which we might not be able to load (i.e. when building i686 packages on
	# an x86_64 host).
	sed -e '/^builduser:/d' -i "$copydir"/etc/{passwd,shadow,group}
	printf >>"$copydir/etc/group"  'builduser:x:%d:\n' "$builduser_gid"
	printf >>"$copydir/etc/passwd" 'builduser:x:%d:%d:builduser:/build:/bin/bash\n' "$builduser_uid" "$builduser_gid"
	printf >>"$copydir/etc/shadow" 'builduser:!!:%d::::::\n' "$(( $(date -u +%s) / 86400 ))"

	$install -d "$copydir"/{build,startdir,{pkg,srcpkg,src,log}dest}

	sed -e '/^MAKEFLAGS=/d' -e '/^PACKAGER=/d' -i "$copydir/etc/makepkg.conf"
	for x in BUILDDIR=/build PKGDEST=/pkgdest SRCPKGDEST=/srcpkgdest SRCDEST=/srcdest LOGDEST=/logdest \
		"MAKEFLAGS='${MAKEFLAGS:-}'" "PACKAGER='${PACKAGER:-}'"
	do
		grep -q "^$x" "$copydir/etc/makepkg.conf" && continue
		echo "$x" >>"$copydir/etc/makepkg.conf"
	done

	cat > "$copydir/etc/sudoers.d/builduser-pacman" <<EOF
builduser ALL = NOPASSWD: /usr/bin/pacman
EOF
	chmod 440 "$copydir/etc/sudoers.d/builduser-pacman"

	if ! grep -q '^\[repo\]' "$copydir/etc/pacman.conf"; then
		local line
		line=$(grep -n '^\[' "$copydir/etc/pacman.conf" |grep -Fv ':[options]'|sed 's/:.*//;1q')
		local ins='[repo]
SigLevel = Optional TrustAll
Server = file:///repo
'
		sed -i "${line}i${ins//$'\n'/\\n}" "$copydir/etc/pacman.conf"
	fi
	# Avoid having to use `pacman -Sy` to update [repo], as
	# networking might be disabled inside of the chroot.
	cp "$copydir/repo/repo.db" "$copydir/var/lib/pacman/sync/repo.db"

	# This is a little gross, but this way the script is recreated every time in the
	# working copy
	{
		printf '#!/bin/bash\n'
		declare -f _chrootbuild
		declare -p SOURCE_DATE_EPOCH 2>/dev/null || true
		printf '_chrootbuild "$@" || exit\n'

		if [[ $run_namcap = true ]]; then
			declare -f _chrootnamcap
			printf '_chrootnamcap || exit\n'
		fi
	} >"$copydir/chrootbuild"
	chmod +x "$copydir/chrootbuild"
}

# These functions aren't run in makechrootpkg,
# so no global variables
_chrootbuild() {
	# No coredumps
	ulimit -c 0

	# shellcheck source=/dev/null
	. /etc/profile

	# Beware, there are some stupid arbitrary rules on how you can
	# use "$" in arguments to commands with "sudo -i".  ${foo} or
	# ${1} is OK, but $foo or $1 isn't.
	# https://bugzilla.sudo.ws/show_bug.cgi?id=765
	sudo --preserve-env=SOURCE_DATE_EPOCH -iu builduser bash -c 'cd /startdir; makepkg "$@"' -bash "$@"
	ret=$?
	case $ret in
		0|14)
			return 0;;
		*)
			return $ret;;
	esac
}

_chrootnamcap() {
	pacman -S --needed --noconfirm namcap
	for pkgfile in /startdir/PKGBUILD /pkgdest/*; do
		echo "Checking ${pkgfile##*/}"
		sudo -u builduser namcap "$pkgfile" 2>&1 | tee "/logdest/${pkgfile##*/}-namcap.log"
	done
}


# Usage: VerifyLibreSources
# Description: verify the number of libre source-balls which should be,
#              and were downloaded/created via the mksource() mechanism
# Globals:
#  - SRCDEST
# Output:
#  - "N N" (n_srcs_required n_srcs_exist)
VerifyLibreSources()
(
  local is_sig_required=$( [[ -n "$1" ]] ; echo $(( ! $? )) )
  local src_n src_file_url src_file repo
  local is_libre_src src_exists is_sig
  local n_srcs_required=0
  local n_srcs_exist=0

  load_conf librefetch.conf MIRRORS || exit
  source PKGBUILD ; cd ${SRCDEST} ;

  for (( src_n=0 ; src_n < ${#source[@]} ; ++src_n ))
  do  src_file_url=${source[src_n]}
      src_file=${src_file_url##*/}

      for repo in "${MIRRORS[@]}"
      do  is_libre_src=$( [[ "$src_file_url" == "$repo"*   ]] ; echo $(( ! $? )) )
          src_exists=$(   [[ -f "${src_file}"              ]] ; echo $(( ! $? )) )
          is_sig=$(       [[ "${src_file/*.}" =~ (asc|sig) ]] ; echo $(( ! $? )) )
          if (( is_libre_src )); then
            n_srcs_required=$(( n_srcs_required + ( ! is_sig || is_sig_required ) ))
            n_srcs_exist=$((    n_srcs_exist    + ( src_exists                  ) ))
          fi
      done
  done
)

# Usage: download_sources $copydir $makepkg_user
# Globals:
#  - SRCDEST
#  - SRCPKGDEST
#  - PKGDEST
download_sources() {
	local copydir=$1
	local makepkg_user=$2
	local n_libre_sources_in=$(VerifyLibreSources)
	local n_libre_sources_out n_libre_sources_required n_libre_sources_exist
	local sums_msg done_msg restart_msg rerun_msg fail_msg die_msg
	local this_cmd=() h_rule

	local builddir
	builddir="$(mktemp -d)"
	chown "$makepkg_user:" "$builddir"

	# Ensure sources are downloaded
	sudo -u "$makepkg_user" --preserve-env=GNUPGHOME \
		env SRCDEST="$SRCDEST" SRCPKGDEST="$SRCPKGDEST" PKGDEST="$PKGDEST" BUILDDIR="$builddir" \
		makepkg --config="$copydir/etc/makepkg.conf" --allsource ||
		: # die "Could not download sources."
	if   (( $? ))
	then # Ensure that all libre sources have been downloaded,
	     #   or created via the mksource() mechanism.
	     # There are multiple reasons for why the preceding `makepkg` invokation may have failed
	     #   (invalid checksums/sigs, download failure, borked PKGBUILD, etc);
	     #   so we must deduce the cause of failure here.
	     # The expected failure here, is a missing signature or an invalid checksum
	     #   for the newly created libre source-ball.
	     # In that case, we inject the new checksum into the PKGBUILD,
	     #   then fork a new instance of libremakepkg, and exit this process.
	     # The newly spawned instance of libremakepkg will not validate the GPG signature;
	     #   because it was intentionally not created (librerelease will create it later).
	     is_new_srcball=$( [[ -f "$LIBRE_SRCBALL_CREATION_MARKER" ]] ; echo $(( ! $? )) ; )
	     n_libre_sources_out=$(VerifyLibreSources $(( ! is_new_srcball)))
	     n_libre_sources_required=${n_libre_sources_out% *}
	     n_libre_sources_exist=${n_libre_sources_out#* }
	     sums_msg="$(_ "Running \`updpkgsums\` to account for the newly created libre source-ball(s)")"
	     done_msg="$(_ "MkSource completed successfully")"
	     restart_msg="$(_ "Restarting libremakepkg to complete the build")"
	     rerun_msg="$(_ "Run libremakepkg again to complete the build")"
	     fail_msg="$(_ "Could not download upstream sources")"
	     this_cmd=( $(ps --pid=$$ --format=args --no-headers) )
	     h_rule="--$(dd if=/dev/zero bs=${#restart_msg} count=1 2> /dev/null | tr '\0' '-')--"

	     if   [[ "$n_libre_sources_out" != "$n_libre_sources_in"    ]] &&
	          (( n_libre_sources_exist   + n_libre_sources_required )) &&
	          (( n_libre_sources_exist  == n_libre_sources_required ))
	     then msg "${sums_msg}"
	          sudo -u "$makepkg_user" updpkgsums
	          msg "${done_msg}"

	          if   [[ "${this_cmd[@]}" =~ ([^\ ]*libremakepkg)(\ .*)? ]]
	          then this_cmd=(${BASH_REMATCH[@]:1})

	               printf "\n${h_rule}\n| ${restart_msg} |\n${h_rule}\n"
	               sleep 5 && ${this_cmd[@]} &

	               die_msg='<EMPTY>'
	          else die_msg="${rerun_msg}"
	          fi
	     else die_msg="${fail_msg}"
	     fi
	fi

	# Clean up garbage from verifysource
	rm -rf "$builddir"

	[[ -z "${die_msg}" ]] || die "${die_msg/<EMPTY>/}"
}

# Usage: move_products $copydir $owner
# Globals:
#  - PKGDEST
#  - LOGDEST
#  - SRCPKGDEST
move_products() {
	local copydir=$1
	local src_owner=$2

	local pkgfile
	for pkgfile in "$copydir"/pkgdest/*; do
		chown "$src_owner" "$pkgfile"
		mv "$pkgfile" "$PKGDEST"

		# Fix broken symlink because of temporary chroot PKGDEST /pkgdest
		if [[ "$PWD" != "$PKGDEST" && -L "$PWD/${pkgfile##*/}" ]]; then
			ln -sf "$PKGDEST/${pkgfile##*/}"
		fi
	done

	local l
	for l in "$copydir"/logdest/*; do
		[[ $l == */logpipe.* ]] && continue
		chown "$src_owner" "$l"
		mv "$l" "$LOGDEST"
	done

	for s in "$copydir"/srcpkgdest/*; do
		chown "$src_owner" "$s"
		mv "$s" "$SRCPKGDEST"

		# Fix broken symlink because of temporary chroot SRCPKGDEST /srcpkgdest
		if [[ "$PWD" != "$SRCPKGDEST" && -L "$PWD/${s##*/}" ]]; then
			ln -sf "$SRCPKGDEST/${s##*/}"
		fi
	done
}
# }}}

main() {
	default_makepkg_args=(--syncdeps --noconfirm --log --holdver --skipinteg)
	local makepkg_args=("${default_makepkg_args[@]}")
	local keepbuilddir=false
	local update_first=false
	local clean_first=false
	local run_namcap=false
	local temp_chroot=false
	local chrootdir=
	local passeddir=
	local makepkg_user=
	declare -a install_pkgs
	declare -i ret=0

	bindmounts_ro=()
	bindmounts_rw=()

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

	while getopts 'hcur:I:l:nTD:d:U:' arg; do
		case "$arg" in
			c) clean_first=true ;;
			D) bindmounts_ro+=(-b "-Br:$OPTARG:$OPTARG") ;;
			d) bindmounts_rw+=(-b "-B:$OPTARG:$OPTARG") ;;
			u) update_first=true ;;
			r) passeddir="$OPTARG" ;;
			I) install_pkgs+=("$OPTARG") ;;
			l) copy="$OPTARG" ;;
			n) run_namcap=true; makepkg_args+=(--install) ;;
			T) temp_chroot=true; copy+="-$$" ;;
			U) makepkg_user="$OPTARG" ;;
			h|*) usage ;;
		esac
	done

	[[ ! -f PKGBUILD && -z "${install_pkgs[*]}" ]] && die 'This must be run in a directory containing a PKGBUILD.'
	[[ -n $makepkg_user && -z $(id -u "$makepkg_user") ]] && die 'Invalid makepkg user.'
	makepkg_user=${makepkg_user:-${SUDO_USER:-$USER}}

	check_root SOURCE_DATE_EPOCH,GNUPGHOME

	# Canonicalize chrootdir, getting rid of trailing /
	chrootdir=$(readlink -e "$passeddir")
	[[ ! -d $chrootdir ]] && die "No chroot dir defined, or invalid path '%s'" "$passeddir"
	[[ ! -d $chrootdir/root ]] && die "Missing chroot dir root directory. Try using: mkarchroot %s/root base-devel" "$chrootdir"

	if [[ ${copy:0:1} = / ]]; then
		copydir=$copy
	else
		copydir="$chrootdir/$copy"
	fi

	# Pass all arguments after -- right to makepkg
	makepkg_args+=("${@:$OPTIND}")

	# See if -R or -e was passed to makepkg
	for arg in "${makepkg_args[@]}"; do
		case ${arg%%=*} in
			--repackage|--noextract) keepbuilddir=true; break ;;
			--repackage|--noextract) keepbuilddir=true; break ;;
			--*) ;;
			-*R*|-*e*) keepbuilddir=true; break ;;
		esac
	done

	if [[ -n $SUDO_USER ]]; then
		eval "USER_HOME=~$SUDO_USER"
	else
		USER_HOME=$HOME
	fi

	umask 0022

	load_vars "${XDG_CONFIG_HOME:-$USER_HOME/.config}/pacman/makepkg.conf" || load_vars "$USER_HOME/.makepkg.conf"
	load_vars /etc/makepkg.conf

	# Use PKGBUILD directory if these don't exist
	[[ -d $PKGDEST ]]    || PKGDEST=$PWD
	[[ -d $SRCDEST ]]    || SRCDEST=$PWD
	[[ -d $SRCPKGDEST ]] || SRCPKGDEST=$PWD
	[[ -d $LOGDEST ]]    || LOGDEST=$PWD

	# Lock the chroot we want to use. We'll keep this lock until we exit.
	lock 9 "$copydir.lock" "Locking chroot copy [%s]" "$copy"

	if [[ ! -d $copydir ]] || $clean_first; then
		sync_chroot "$chrootdir/root" "$copydir" "$copy"
	fi

	$update_first && chroot-run "$copydir" \
			"${bindmounts_ro[@]}" "${bindmounts_rw[@]}" \
			pacman -Syu --noconfirm

	if [[ -n ${install_pkgs[*]:-} ]]; then
		install_packages "$copydir" "${install_pkgs[@]}"
		ret=$?
		# If there is no PKGBUILD we have done
		[[ -f PKGBUILD ]] || return $ret
	fi

	if [[ "$(id -u "$makepkg_user")" == 0 ]]; then
		error "Running makepkg as root is not allowed."
		exit 1
	fi

	download_sources "$copydir" "$makepkg_user"

	prepare_chroot "$copydir" "$USER_HOME" "$keepbuilddir" "$run_namcap"
	if chroot-run "$copydir" \
		-b "-B:$PWD:/startdir" \
		-b "-B:$SRCDEST:/srcdest" \
		"${bindmounts_ro[@]}" "${bindmounts_rw[@]}" \
		/chrootbuild "${makepkg_args[@]}"
	then
		move_products "$copydir" "$src_owner"
	else
		(( ret += 1 ))
	fi

	$temp_chroot && delete_chroot "$copydir" "$copy"

	if (( ret != 0 )); then
		if $temp_chroot; then
			die "Build failed"
		else
			die "Build failed, check %s/build" "$copydir"
		fi
	else
		true
	fi
}

main "$@"