#!/bin/bash
# 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/common.sh)

shopt -s nullglob

makepkg_args=(-s --noconfirm -L --holdver)
repack=false
update_first=false
clean_first=false
install_pkg=
run_namcap=false
temp_chroot=false
chrootdir=
passeddir=
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}

usage() {
	echo "Usage: ${0##*/} [options] -r <chrootdir> [--] [makepkg args]"
	echo ' Run this script in a PKGBUILD dir to build a package inside a'
	echo ' clean chroot. Arguments passed to this script after the'
	echo ' end-of-options marker (--) will be passed to makepkg.'
	echo ''
	echo ' The chroot dir consists of the following directories:'
	echo ' <chrootdir>/{root, copy} but only "root" is required'
	echo ' by default. The working copy will be created as needed'
	echo ''
	echo 'The chroot "root" directory must be created via the following'
	echo 'command:'
	echo '    mkarchroot <chrootdir>/root base-devel'
	echo ''
	echo "Default makepkg args: ${makepkg_args[*]}"
	echo ''
	echo 'Flags:'
	echo '-h         This help'
	echo '-c         Clean the chroot before building'
	echo '-d <dir>   Bind directory into build chroot as read-write'
	echo '-D <dir>   Bind directory into build chroot as read-only'
	echo '-u         Update the working copy of the chroot before building'
	echo '           This is useful for rebuilds without dirtying the pristine'
	echo '           chroot'
	echo '-r <dir>   The chroot dir to use'
	echo '-I <pkg>   Install a package into the working copy of the chroot'
	echo '-l <copy>  The directory to use as the working copy of the chroot'
	echo '           Useful for maintaining multiple copies'
	echo "           Default: $copy"
	echo '-n         Run namcap on the package'
	echo '-T         Build in a temporary directory'
	exit 1
}

# {{{ functions
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 $(grep "^${var}=" "$makepkg_conf")
	done

	return 0
}

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

	if [[ ! -d $copydir ]] || $clean_first; then
		# Get a read lock on the root chroot to make
		# sure we don't clone a half-updated chroot
		slock 8 "$chrootdir/root.lock" "Locking clean chroot"

		stat_busy "Creating clean working copy [$copy]"
		if [[ "$chroottype" == btrfs ]] && ! mountpoint -q "$copydir"; then
			if [[ -d $copydir ]]; then
				btrfs subvolume delete "$copydir" >/dev/null ||
					die "Unable to delete subvolume %s" "$copydir"
			fi
			btrfs subvolume snapshot "$chrootdir/root" "$copydir" >/dev/null ||
				die "Unable to create subvolume %s" "$copydir"
		else
			mkdir -p "$copydir"
			rsync -a --delete -q -W -x "$chrootdir/root/" "$copydir"
		fi
		stat_done

		# Drop the read lock again
		exec 8>&-
	fi

	# Update mtime
	touch "$copydir"
}

clean_temporary() {
	stat_busy "Removing temporary copy [$copy]"
	if [[ "$chroottype" == btrfs ]] && ! mountpoint -q "$copydir"; then
		btrfs subvolume delete "$copydir" >/dev/null ||
			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
}

install_packages() {
	local -a pkgnames
	local ret

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

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

	# If there is no PKGBUILD we are done
	[[ -f PKGBUILD ]] || exit $ret
}

prepare_chroot() {
	$repack || rm -rf "$copydir/build"

	local builduser_uid="${SUDO_UID:-$UID}"
	local 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 "$copydir"/etc/{passwd,group}
	printf >>"$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

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

	for x in .gnupg/pubring.{kbx,gpg}; do
		[[ -r $USER_HOME/$x ]] || continue
		$install -m 644 "$USER_HOME/$x" "$copydir/build/$x"
	done

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

	# 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
		printf '_chrootbuild'
		printf ' %q' "${makepkg_args[@]}"
		printf ' || exit\n'

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

# These functions aren't run in makechrootpkg,
# so no global variables
_chrootbuild() {
	. /etc/profile
	export HOME=/build
	cd /startdir
	sudo -u builduser makepkg "$@"
}

_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
}

download_sources() {
	local builddir="$(mktemp -d)"
	chmod 1777 "$builddir"

	# Ensure sources are downloaded
	if [[ -n $SUDO_USER ]]; then
		sudo -u $SUDO_USER env SRCDEST="$SRCDEST" BUILDDIR="$builddir" \
			makepkg --config="$copydir/etc/makepkg.conf" --verifysource -o
	else
		( export SRCDEST BUILDDIR="$builddir"
			makepkg --asroot --config="$copydir/etc/makepkg.conf" --verifysource -o
		)
	fi
	(( $? != 0 )) && die "Could not download sources."

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

move_products() {
	for pkgfile in "$copydir"/pkgdest/*; do
		chown "$src_owner" "$pkgfile"
		mv "$pkgfile" "$PKGDEST"
	done

	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"
	done
}
# }}}

orig_argv=("$@")

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

[[ ! -f PKGBUILD && -z "${install_pkgs[*]}" ]] && die 'This must be run in a directory containing a PKGBUILD.'

check_root "$0" "${orig_argv[@]}"

# 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"

# Detect chrootdir filesystem type
chroottype=$(stat -f -c %T "$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 was passed to makepkg
for arg in "${@:OPTIND}"; do
	case ${arg%%=*} in
		-*R*|--repackage)
			repack=true
			break 2
			;;
	esac
done

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

umask 0022

XDG_PACMAN_DIR="${XDG_CONFIG_HOME:-$USER_HOME/.config}/pacman"
if [[ -r "$XDG_PACMAN_DIR/makepkg.conf" ]]; then
	load_vars "$XDG_PACMAN_DIR/makepkg.conf"
elif [[ -r "$USER_HOME/.makepkg.conf" ]]; then
	load_vars "$USER_HOME/.makepkg.conf"
fi
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

create_chroot

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

[[ -n ${install_pkgs[*]} ]] && install_packages

download_sources

prepare_chroot

if arch-nspawn "$copydir" \
	--bind="$PWD:/startdir" \
	--bind="$SRCDEST:/srcdest" \
	"${bindmounts_ro[@]}" "${bindmounts_rw[@]}" \
	/chrootbuild
then
	move_products
else
	(( ret += 1 ))
fi

$temp_chroot && clean_temporary

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