path: root/bin/emerge-webrsync

#!/usr/bin/env bash
# Copyright 1999-2023 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
# Author: Karl Trygve Kalleberg <karltk@gentoo.org>
# Rewritten from the old, Perl-based emerge-webrsync script
# Author: Alon Bar-Lev <alon.barlev@gmail.com>
# Major rewrite from Karl's scripts.

# TODO:
#  - all output should prob be converted to e* funcs
#  - add support for ROOT

# repos.conf configuration for use with emerge --sync and emaint sync
# using keyring from app-crypt/openpgp-keys-gentoo-release:
# [gentoo]
# sync-type = webrsync
# sync-webrsync-verify-signature = true
# sync-openpgp-key-path = /usr/share/openpgp-keys/gentoo-release.asc
#
# Alternative (legacy) PORTAGE_GPG_DIR configuration:
# gpg key import
# KEY_ID=0x96D8BF6D
# gpg --homedir /etc/portage/gnupg --keyserver subkeys.pgp.net --recv-keys ${KEY_ID}
# gpg --homedir /etc/portage/gnupg --edit-key ${KEY_ID} trust
#

# Opportunistically use gentoo-functions for nicer output
functions_script="${EPREFIX:-/}/lib/gentoo/functions.sh"
source "${functions_script}" || {
	echo "${argv0}: Could not source ${functions_script}!" 1>&2

	ebegin() {
		printf '%s*%s %s ... ' "${GOOD}" "${NORMAL}" "$*"
	}

	eend() {
		local r=${1:-0}
		shift
		if [[ $r -eq 0 ]] ; then
			printf '[ %sok%s ]\n' "${GOOD}" "${NORMAL}"
		else
			printf '%s [ %s!!%s ]\n' "$*" "${BAD}" "${NORMAL}"
		fi
		return "${r}"
	}

	einfo() {
		echo "${argv0##*/}: $*"
	}

	ewarn() {
		echo "${argv0##*/}: warning: $*" 1>&2
	}

	eerror() {
		echo "${argv0##*/}: error: $*" 1>&2
	}

}

# Only echo if in normal mode
vvecho() { [[ ${PORTAGE_QUIET} != 1 ]] && echo "$@" ; }
# Only echo if in quiet mode
nvecho() { [[ ${PORTAGE_QUIET} == 1 ]] && echo "$@" ; }

# Unfortunately, gentoo-functions doesn't yet have a die() (bug #878505)
die() {
	eerror "$@"
	exit 1
}

argv0=$0

# Use portageq from the same directory/prefix as the current script, so
# that we don't have to rely on PATH including the current EPREFIX.
scriptpath=${BASH_SOURCE[0]}
if [[ -x "${scriptpath%/*}/portageq" ]]; then
	portageq=${scriptpath%/*}/portageq
elif type -P portageq > /dev/null ; then
	portageq=portageq
else
	die "could not find 'portageq'; aborting"
fi

eval "$("${portageq}" envvar -v DISTDIR EPREFIX FEATURES \
	FETCHCOMMAND GENTOO_MIRRORS \
	PORTAGE_BIN_PATH PORTAGE_CONFIGROOT PORTAGE_GPG_DIR \
	PORTAGE_NICENESS PORTAGE_REPOSITORIES PORTAGE_RSYNC_EXTRA_OPTS \
	PORTAGE_RSYNC_OPTS PORTAGE_TEMP_GPG_DIR PORTAGE_TMPDIR \
	USERLAND http_proxy ftp_proxy)"
export http_proxy ftp_proxy

source "${PORTAGE_BIN_PATH}"/isolated-functions.sh || exit 1

repo_name=gentoo
repo_location=$(__repo_attr "${repo_name}" location)
if [[ -z ${repo_location} ]]; then
	die "Repository '${repo_name}' not found"
fi
repo_sync_type=$(__repo_attr "${repo_name}" sync-type)

# If PORTAGE_NICENESS is overriden via the env then it will
# still pass through the portageq call and override properly.
if [[ -n "${PORTAGE_NICENESS}" ]]; then
	renice "${PORTAGE_NICENESS}" $$ > /dev/null
fi

do_debug=0
keep=false

handle_pgp_setup() {
	# WEBRSYNC_VERIFY_SIGNATURE=0: disable PGP verification
	# WEBRSYNC_VERIFY_SIGNATURE=1: use gemato for verification, fallback to regular gpg
	# WEBRSYNC_VERIFY_SIGNATURE=2: use legacy FEATURES="webrsync-gpg"
	WEBRSYNC_VERIFY_SIGNATURE=1

	has webrsync-gpg ${FEATURES} && webrsync_gpg=1 || webrsync_gpg=0

	repo_has_webrsync_verify=$(
		has $(__repo_attr "${repo_name}" sync-webrsync-verify-signature	| LC_ALL=C tr '[:upper:]' '[:lower:]') true yes
	)

	if [[ -n ${PORTAGE_TEMP_GPG_DIR} ]] || [[ ${repo_has_webrsync_verify} -eq 1 ]]; then
		# If FEATURES=webrsync-gpg is enabled then allow direct emerge-webrsync
		# calls for backward compatibility (this triggers a deprecation warning
		# above). Since direct emerge-webrsync calls do not use gemato for secure
		# key refresh, this behavior will not be supported in a future release.
		if [[ ! ( -d ${PORTAGE_GPG_DIR} && ${webrsync_gpg} -eq 1 ) && -z ${PORTAGE_TEMP_GPG_DIR} ]]; then
			die "Do not call ${argv0##*/} directly, instead call emerge --sync or emaint sync."
		fi

		# Use gemato for the standard Portage-calling-us case w/ sync-type='webrsync'.
		WEBRSYNC_VERIFY_SIGNATURE=1
	elif [[ ${webrsync_gpg} -eq 1 ]]; then
		# We only warn if FEATURES="webrsync-gpg" is in make.conf, not if
		# Portage is calling us for 'sync-type=webrsync' with verification, because
		# that path uses gemato now (plus the user can't help it, obviously).
		ewarn "FEATURES=webrsync-gpg is deprecated, see the make.conf(5) man page."
		WEBRSYNC_VERIFY_SIGNATURE=2
	elif [[ -n ${no_pgp_verify} ]]; then
		WEBRSYNC_VERIFY_SIGNATURE=0
	else
		# The default at the beginning of handle_pgp_setup is WEBRSYNC_VERIFY_SIGNATURE=1
		# i.e. gemato.
		:;
	fi

	case "${WEBRSYNC_VERIFY_SIGNATURE}" in
		0)
			[[ ${PORTAGE_QUIET} -eq 1 ]] || ewarn "PGP verification method: disabled"
			;;
		1)
			[[ ${PORTAGE_QUIET} -eq 1 ]] || einfo "PGP verification method: gemato"
			;;
		2)
			ewarn "PGP verification method: legacy gpg path"
			;;
		*)
			die "Unknown WEBRSYNC_VERIFY_SIGNATURE state: \${WEBRSYNC_VERIFY_SIGNATURE}=${WEBRSYNC_VERIFY_SIGNATURE}"
			;;
	esac

	if [[ -n ${PORTAGE_TEMP_GPG_DIR} ]]; then
		PORTAGE_GPG_DIR=${PORTAGE_TEMP_GPG_DIR}
	fi

	if [[ ${WEBRSYNC_VERIFY_SIGNATURE} == 2 && -z "${PORTAGE_GPG_DIR}" ]]; then
		die "Please set PORTAGE_GPG_DIR in make.conf!"
	fi
}

do_tar() {
	local file=$1
	shift
	local decompressor

	case ${file} in
		*.xz)   decompressor="xzcat" ;;
		*.bz2)  decompressor="bzcat" ;;
		*.gz)   decompressor="zcat"  ;;
		*)      decompressor="cat"   ;;
	esac
	${decompressor} "${file}" | tar "$@"
	_pipestatus=${PIPESTATUS[*]}
	[[ ${_pipestatus// /} -eq 0 ]]
}

get_utc_date_in_seconds() {
	date -u +"%s"
}

get_date_part() {
	local utc_time_in_secs="$1"
	local part="$2"

	if [[ ${USERLAND} == BSD ]] ; then
		date -r "${utc_time_in_secs}" -u +"${part}"
	else
		date -d "@${utc_time_in_secs}" -u +"${part}"
	fi
}

get_utc_second_from_string() {
	local s="$1"

	if [[ ${USERLAND} == BSD ]] ; then
		# Specify zeros for the least significant digits, or else those
		# digits are inherited from the current system clock time.
		date -juf "%Y%m%d%H%M.%S" "${s}0000.00" +"%s"
	else
		date -d "${s:0:4}-${s:4:2}-${s:6:2}" -u +"%s"
	fi
}

get_repository_timestamp() {
	local portage_current_timestamp=0

	if [[ -f "${repo_location}/metadata/timestamp.x" ]]; then
		portage_current_timestamp=$(cut -f 1 -d " " "${repo_location}/metadata/timestamp.x" )
	fi

	echo "${portage_current_timestamp}"
}

fetch_file() {
	local URI="$1"
	local FILE="$2"
	local opts

	if [[ "${FETCHCOMMAND/wget/}" != "${FETCHCOMMAND}" ]]; then
		opts="--continue $(nvecho -q)"
	elif [[ "${FETCHCOMMAND/curl/}" != "${FETCHCOMMAND}" ]]; then
		opts="--continue-at - $(nvecho -s -f)"
	else
		rm -f "${DISTDIR}/${FILE}"
	fi

	[[ ${PORTAGE_QUIET} -eq 1 ]] || einfo "Fetching file ${FILE} ..."
	# Already set DISTDIR=
	eval "${FETCHCOMMAND} ${opts}"

	if [[ $? -eq 0 && -s ${DISTDIR}/${FILE} ]] ; then
		return 0
	else
		rm -f "${DISTDIR}/${FILE}"
		return 1
	fi
}

check_file_digest() {
	local digest="$1"
	local file="$2"
	local r=1

	[[ ${PORTAGE_QUIET} -eq 1 ]] || einfo "Checking digest ..."

	if type -P md5sum > /dev/null; then
		local md5sum_output=$(md5sum "${file}")
		local digest_content=$(< "${digest}")
		[[ "${md5sum_output%%[[:space:]]*}" = "${digest_content%%[[:space:]]*}" ]] && r=0
	elif type -P md5 > /dev/null; then
		[[ "$(md5 -q "${file}")" == "$(cut -d ' ' -f 1 "${digest}")" ]] && r=0
	else
		die "cannot check digest: no suitable md5/md5sum binaries found"
	fi

	return "${r}"
}

check_file_signature_gemato() {
	local signature="$1"
	local file="$2"
	local r=1

	if type -P gemato > /dev/null; then
		if [[ -n ${PORTAGE_GPG_KEY} ]] ; then
			local key="${PORTAGE_GPG_KEY}"
		else
			local key="${EPREFIX:-/}"/usr/share/openpgp-keys/gentoo-release.asc
		fi

		local keyserver
		if [[ -n ${PORTAGE_GPG_KEY_SERVER} ]] ; then
			keyserver="--keyserver ${PORTAGE_GPG_KEY_SERVER}"
		fi

		local gemato_args=(
			openpgp-verify-detached
			-K "${key}"
		)

		[[ -n ${PORTAGE_GPG_KEY_SERVER} ]] && gemato_args+=( --keyserver "${PORTAGE_GPG_KEY_SERVER}" )
		[[ ${PORTAGE_QUIET} == 1 ]] && gemato_args+=( --quiet )
		[[ ${do_debug} == 1 ]] && gemato_args+=( --debug )

		gemato "${gemato_args[@]}" -- "${signature}" "${file}"
		r=$?

		if [[ ${r} -ne 0 ]]; then
			# Exit early since it's typically inappropriate to
			# try other mirrors in this case (it may indicate
			# a keyring problem).
			die "signature verification failed"
		fi
	else
		return 127
	fi

	return "${r}"
}

check_file_signature_gpg_unwrapped() {
	local signature="$1"
	local file="$2"

	if type -P gpg > /dev/null; then
		if [[ -n ${PORTAGE_GPG_KEY} ]] ; then
			local key="${PORTAGE_GPG_KEY}"
		else
			local key="${EPREFIX:-/}"/usr/share/openpgp-keys/gentoo-release.asc
		fi

		local gpgdir="${PORTAGE_GPG_DIR}"
		if [[ -z ${gpgdir} ]] ; then
			gpgdir=$(mktemp -d "${PORTAGE_TMPDIR}/portage/webrsync-XXXXXX")
			if [[ ! -w ${gpgdir} ]] ; then
				die "gpgdir is not writable: ${gpgdir}"
			fi

			# If we're created our own temporary directory, it's okay for us
			# to import the keyring by ourselves. But we'll avoid doing it
			# if the user has set PORTAGE_GPG_DIR by themselves.
			gpg --no-default-keyring --homedir "${gpgdir}" --batch --import "${key}"
		fi

		if gnupg_status=$(gpg --no-default-keyring --homedir "${gpgdir}" --batch \
			--status-fd 1 --verify "${signature}" "${file}"); then
			while read -r line; do
				if [[ ${line} == "[GNUPG:] GOODSIG"* ]]; then
					r=0
					break
				fi
			done <<< "${gnupg_status}"
		fi

		if [[ ${r} -ne 0 ]]; then
			# Exit early since it's typically inappropriate to
			# try other mirrors in this case (it may indicate
			# a keyring problem).
			die "signature verification failed"
		fi
	else
		die "cannot check signature: gpg binary not found"
	fi
}

check_file_signature() {
	local signature="$1"
	local file="$2"
	local r=1
	local gnupg_status line

	if [[ ${WEBRSYNC_VERIFY_SIGNATURE} != 0 ]]; then
		[[ ${PORTAGE_QUIET} -eq 1 ]] || einfo "Checking signature ..."

		case ${WEBRSYNC_VERIFY_SIGNATURE} in
			1)
				check_file_signature_gemato "${signature}" "${file}"
				r=$?

				if [[ ${r} -eq 127 ]] ; then
					ewarn "Falling back to gpg as gemato is not installed"
					check_file_signature_gpg_unwrapped "${signature}" "${file}"
					r=$?
				fi

				;;
			2)
				check_file_signature_gpg_unwrapped "${signature}" "${file}"
				r=$?
				;;
		esac

		if [[ ${r} != 0 ]] ; then
			eerror "Error occurred in check_file_signature: ${r}. Aborting."
			die "Verification error occured."
		fi
	else
		r=0
	fi

	return "${r}"
}

get_snapshot_timestamp() {
	local file="$1"

	do_tar "${file}" --to-stdout -f - --wildcards -x '*/metadata/timestamp.x' | cut -f 1 -d " "
}

sync_local() {
	local file="$1"

	[[ ${PORTAGE_QUIET} -eq 1 ]] || einfo "Syncing local repository ..."

	local ownership="portage:portage"
	if has usersync ${FEATURES} ; then
		case "${USERLAND}" in
			BSD)
				ownership=$(stat -f '%Su:%Sg' "${repo_location}")
				;;
			*)
				ownership=$(stat -c '%U:%G' "${repo_location}")
				;;
		esac
	fi

	if type -P tarsync > /dev/null ; then
		local chown_opts="-o ${ownership%:*} -g ${ownership#*:}"
		chown ${ownership} "${repo_location}" > /dev/null 2>&1 || chown_opts=""

		if ! tarsync $(vvecho -v) -s 1 ${chown_opts} \
			-e /distfiles -e /packages -e /local "${file}" "${repo_location}"; then

			eerror "tarsync failed; tarball is corrupt? (${file})"
			return 1
		fi
	else
		if ! do_tar "${file}" -x --strip-components=1 -f -; then
			eerror "tar failed to extract the image. tarball is corrupt? (${file})"
			return 1
		fi

		# Free disk space
		${keep} || rm -f "${file}"

		local rsync_opts="${PORTAGE_RSYNC_OPTS} ${PORTAGE_RSYNC_EXTRA_OPTS} $(nvecho -q)"
		if chown ${ownership} . > /dev/null 2>&1; then
			chown -R ${ownership} .
			rsync_opts+=" --owner --group"
		fi

		chmod 755 .
		rsync ${rsync_opts} . "${repo_location%%/}" || {
			eerror "rsync failed: $?"
			die "Aborting because of rsync failure"
		}

		[[ ${PORTAGE_QUIET} == 1 ]] || einfo "Cleaning up ..."
	fi

	if has metadata-transfer ${FEATURES} ; then
		einfo "Updating cache ..."
		emerge --metadata
	fi

	local post_sync=${PORTAGE_CONFIGROOT%/}/etc/portage/bin/post_sync
	[[ -x "${post_sync}" ]] && "${post_sync}"

	# --quiet suppresses output if there are no relevant news items
	has news ${FEATURES} && emerge --check-news --quiet
	return 0
}

do_snapshot() {
	local ignore_timestamp="$1"
	local date="$2"

	local r=1

	local compression

	local have_files=0
	local mirror

	local compressions=""

	type -P xzcat > /dev/null && compressions="${compressions} ${repo_name}:xz portage:xz"
	type -P bzcat > /dev/null && compressions="${compressions} ${repo_name}:bz2 portage:bz2"
	type -P zcat > /dev/null && compressions="${compressions} ${repo_name}:gz portage:gz"
	if [[ -z ${compressions} ]] ; then
		die "unable to locate any decompressors (xzcat or bzcat or zcat)"
	fi

	for mirror in ${GENTOO_MIRRORS} ; do
		mirror=${mirror%/}
		[[ ${PORTAGE_QUIET} -eq 1 ]] || einfo "Trying to retrieve ${date} snapshot from ${mirror} ..."

		for compression in ${compressions} ; do
			local name=${compression%%:*}

			compression=${compression#*:}

			local file="${name}-${date}.tar.${compression}"
			local digest="${file}.md5sum"
			local signature="${file}.gpgsig"

			if [[ -s "${DISTDIR}/${file}" && -s "${DISTDIR}/${digest}" && -s "${DISTDIR}/${signature}" ]] ; then
				check_file_digest "${DISTDIR}/${digest}" "${DISTDIR}/${file}" && \
				check_file_signature "${DISTDIR}/${signature}" "${DISTDIR}/${file}" && \
				have_files=1
			fi

			if [[ ${have_files} -eq 0 ]] ; then
				fetch_file "${mirror}/snapshots/${digest}" "${digest}" && \
					fetch_file "${mirror}/snapshots/${signature}" "${signature}" && \
					fetch_file "${mirror}/snapshots/${file}" "${file}" && \
					check_file_digest "${DISTDIR}/${digest}" "${DISTDIR}/${file}" && \
					check_file_signature "${DISTDIR}/${signature}" "${DISTDIR}/${file}" && \

				have_files=1
			fi

			#
			# If timestamp is invalid
			# we want to try and retrieve
			# from a different mirror
			#
			if [[ ${have_files} -eq 1 ]]; then
				[[ ${PORTAGE_QUIET} -eq 1 ]] || einfo "Getting snapshot timestamp ..."

				local snapshot_timestamp
				snapshot_timestamp=$(get_snapshot_timestamp "${DISTDIR}/${file}")

				if [[ ${ignore_timestamp} == 0 ]]; then
					if [[ ${snapshot_timestamp} -lt $(get_repository_timestamp) ]]; then
						ewarn "Repository (age) is newer than fetched snapshot"
						have_files=0
					fi
				else
					local utc_seconds
					utc_seconds=$(get_utc_second_from_string "${date}")

					# Check that this snapshot is what the age it claims to be
					if [[ ${snapshot_timestamp} -lt ${utc_seconds} || \
						${snapshot_timestamp} -gt $((${utc_seconds}+ 2*86400)) ]]; then

						ewarn "Snapshot timestamp is not within acceptable period!"
						have_files=0
					fi
				fi
			fi

			if [[ ${have_files} -eq 1 ]]; then
				break
			else
				# Remove files and use a different mirror
				rm -f "${DISTDIR}/${file}" "${DISTDIR}/${digest}" "${DISTDIR}/${signature}"
			fi
		done

		[[ ${have_files} -eq 1 ]] && break
	done

	if [[ ${have_files} -eq 1 ]]; then
		sync_local "${DISTDIR}/${file}" && r=0
	else
		ewarn "${date} snapshot was not found"
	fi

	${keep} || rm -f "${DISTDIR}/${file}" "${DISTDIR}/${digest}" "${DISTDIR}/${signature}"
	return "${r}"
}

do_latest_snapshot() {
	local attempts=0
	local r=1

	[[ ${PORTAGE_QUIET} -eq 1 ]] || einfo "Fetching most recent snapshot ..."

	# The snapshot for a given day is generated at 00:45 UTC on the following
	# day, so the current day's snapshot (going by UTC time) hasn't been
	# generated yet.  Therefore, always start by looking for the previous day's
	# snapshot (for attempts=1, subtract 1 day from the current UTC time).

	# Timestamps that differ by less than 2 hours
	# are considered to be approximately equal.
	local min_time_diff=$(( 2 * 60 * 60 ))

	local existing_timestamp
	local timestamp_difference
	local timestamp_problem
	local approx_snapshot_time
	local start_time
	local start_hour
	local snapshot_date
	local snapshot_date_seconds

	existing_timestamp=$(get_repository_timestamp)
	start_time=$(get_utc_date_in_seconds)
	start_hour=$(get_date_part "${start_time}" "%H")

	# Daily snapshots are created at 00:45 and are not
	# available until after 01:00. Don't waste time trying
	# to fetch a snapshot before it's been created.
	if [[ ${start_hour#0} -lt 1 ]] ; then
		(( start_time -= 86400 ))
	fi

	snapshot_date=$(get_date_part "${start_time}" "%Y%m%d")
	snapshot_date_seconds=$(get_utc_second_from_string "${snapshot_date}")

	while (( ${attempts} < 40 )) ; do
		(( attempts++ ))
		(( snapshot_date_seconds -= 86400 ))
		# snapshots are created at 00:45
		(( approx_snapshot_time = snapshot_date_seconds + 86400 + 2700 ))
		(( timestamp_difference = existing_timestamp - approx_snapshot_time ))

		[[ ${timestamp_difference} -lt 0 ]] && (( timestamp_difference = -1 * timestamp_difference ))
		snapshot_date=$(get_date_part "${snapshot_date_seconds}" "%Y%m%d")

		timestamp_problem=""
		if [[ ${timestamp_difference} -eq 0 ]]; then
			timestamp_problem="is identical to"
		elif [[ ${timestamp_difference} -lt ${min_time_diff} ]]; then
			timestamp_problem="is possibly identical to"
		elif [[ ${approx_snapshot_time} -lt ${existing_timestamp} ]] ; then
			timestamp_problem="is newer than"
		fi

		if [[ -n "${timestamp_problem}" ]]; then
			ewarn "Latest snapshot date: ${snapshot_date}"
			ewarn
			ewarn "Approximate snapshot timestamp: ${approx_snapshot_time}"
			ewarn "       Current local timestamp: ${existing_timestamp}"
			ewarn
			echo -e "The current local timestamp" \
				"${timestamp_problem} the" \
				"timestamp of the latest" \
				"snapshot. In order to force sync," \
				"use the --revert option or remove" \
				"the timestamp file located at" \
				"'${repo_location}/metadata/timestamp.x'." | fmt -w 70 | \
				while read -r line ; do
					ewarn "${line}"
				done
			r=0
			break
		fi

		if do_snapshot 0 "${snapshot_date}"; then
			r=0
			break;
		fi
	done

	return "${r}"
}

usage() {
	cat <<-EOF
	Usage: $0 [options]

	Options:
	  --revert=yyyymmdd   Revert to snapshot
	  --no-pgp-verify     Disable PGP verification of snapshot
	  -k, --keep          Keep snapshots in DISTDIR (don't delete)
	  -q, --quiet         Only output errors
	  -v, --verbose       Enable verbose output (no-op)
	  -x, --debug         Enable debug output
	  -h, --help          This help screen (duh!)
	EOF
	if [[ -n $* ]] ; then
		printf "\nError: %s\n" "$*" 1>&2
		exit 1
	else
		exit 0
	fi
}

main() {
	local arg
	local revert_date

	for arg in "$@" ; do
		local v=${arg#*=}
		case ${arg} in
			-h|--help)    usage ;;
			-k|--keep)    keep=true ;;
			-q|--quiet)   PORTAGE_QUIET=1 ;;
			-v|--verbose) unset PORTAGE_QUIET ;;
			-x|--debug)   do_debug=1 ;;
			--revert=*)   revert_date=${v} ;;
			--no-pgp-verify) no_pgp_verify=1 ;;
			*)            usage "Invalid option '${arg}'" ;;
		esac
	done

	handle_pgp_setup

	[[ -d ${repo_location} ]] || mkdir -p "${repo_location}"
	if [[ ! -w ${repo_location} ]] ; then
		die "Repository '${repo_name}' is not writable: ${repo_location}"
	fi

	[[ -d ${PORTAGE_TMPDIR}/portage ]] || mkdir -p "${PORTAGE_TMPDIR}/portage"
	TMPDIR=$(mktemp -d "${PORTAGE_TMPDIR}/portage/webrsync-XXXXXX")
	if [[ ! -w ${TMPDIR} ]] ; then
		die "TMPDIR is not writable: ${TMPDIR}"
	fi
	trap 'set -u ; cd / ; rm -rf "${TMPDIR}"' EXIT
	cd "${TMPDIR}" || exit 1

	${keep} || DISTDIR=${TMPDIR}
	[[ ! -d "${DISTDIR}" ]] && mkdir -p "${DISTDIR}"

	if ${keep} && [[ ! -w ${DISTDIR} ]] ; then
		die "DISTDIR is not writable: ${DISTDIR}"
	fi

	# This is a sanity check to help prevent people like funtoo users
	# from accidentally wiping out their git tree.
	if [[ -n ${repo_sync_type} && ${repo_sync_type} != rsync && ${repo_sync_type} != webrsync ]] ; then
		eerror "The current sync-type attribute of repository 'gentoo' is not set to 'rsync' or 'webrsync':"
		eerror
		eerror "  sync-type=${repo_sync_type}"
		eerror
		eerror "If you intend to use emerge-webrsync then please"
		eerror "adjust sync-type and sync-uri attributes to refer to rsync."
		eerror "emerge-webrsync exiting due to abnormal sync-type setting."
		die
	fi

	[[ ${do_debug} -eq 1 ]] && set -x

	if [[ -n ${revert_date} ]] ; then
		do_snapshot 1 "${revert_date}"
	else
		do_latest_snapshot
	fi
}

main "$@"