#!/bin/bash

#  Copyright (C) 2018 Oracle.  All Rights Reserved.
#
#  Author: Darrick J. Wong <darrick.wong@oracle.com>
#
#  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; either version 2
#  of the License, or (at your option) any later version.
#
#  This program is distributed in the hope that it would 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.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write the Free Software Foundation,
#  Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

if (( $EUID != 0 )); then
    echo "e2scrub_all must be run as root"
    exit 1
fi

periodic_e2scrub=0
scrub_all=0
snap_size_mb=256
reap=0
conffile="/etc/e2scrub.conf"

test -f "${conffile}" && . "${conffile}"

scrub_args=""

print_help() {
	echo "Usage: $0 [OPTIONS]"
	echo " -n: Show what commands e2scrub_all would execute."
	echo " -r: Remove e2scrub snapshots."
	echo " -A: Scrub all ext[234] filesystems even if not mounted."
	echo " -V: Print version information and exit."
}

print_version() {
	echo "e2scrub_all 1.45.6 (20-Mar-2020)"
}

exitcode() {
	ret="$1"

	# If we're being run as a service, the return code must fit the LSB
	# init script action error guidelines, which is to say that we
	# compress all errors to 1 ("generic or unspecified error", LSB 5.0
	# section 22.2) and hope the admin will scan the log for what
	# actually happened.

	if [ -n "${SERVICE_MODE}" -a "${ret}" -ne 0 ]; then
		test "${ret}" -ne 0 && ret=1
	fi

	exit "${ret}"
}

while getopts "nrAV" opt; do
	case "${opt}" in
	"n") DBG="echo Would execute: " ;;
	"r") scrub_args="${scrub_args} -r"; reap=1;;
	"A") scrub_all=1;;
	"V") print_version; exitcode 0;;
	*) print_help; exitcode 2;;
	esac
done
shift "$((OPTIND - 1))"

# If we're in service mode and the service is not enabled via config file...
if [ -n "${SERVICE_MODE}" -a "${periodic_e2scrub}" -ne 1 ]; then
	# ...don't start e2scrub processes.
	if [ "${reap}" -eq 0 ]; then
		exitcode 0
	fi

	# ...and if we don't see any leftover e2scrub snapshots, don't
	# run the reaping process either, because lvs can be slow.
	if ! readlink -q -s -e /dev/mapper/*.e2scrub* > /dev/null; then
		exitcode 0
	fi
fi

# close file descriptor 3 (from cron) since it causes lvm to kvetch
exec 3<&-

# If some prerequisite packages are not installed, exit with a code
# indicating success to avoid spamming the sysadmin with fail messages
# when e2scrub_all is run out of cron or a systemd timer.

if ! type mapfile >& /dev/null ; then
    test -n "${SERVICE_MODE}" && exitcode 0
    echo "e2scrub_all: can't find mapfile --- is bash 4.xx installed?"
    exitcode 1
fi

if ! type lsblk >& /dev/null ; then
    test -n "${SERVICE_MODE}" && exitcode 0
    echo "e2scrub_all: can't find lsblk --- is util-linux installed?"
    exitcode 1
fi

if ! type lvcreate >& /dev/null ; then
    test -n "${SERVICE_MODE}" && exitcode 0
    echo "e2scrub_all: can't find lvcreate --- is lvm2 installed?"
    exitcode 1
fi

# Find scrub targets, make sure we only do this once.
ls_scan_targets() {
    local devices=$(lvs -o lv_path --noheadings -S "lv_active=active,lv_role=public,lv_role!=snapshot,vg_free>=${snap_size_mb}")

    if [ -z "$devices" ]; then
	return 0;
    fi
    lsblk -o NAME,MOUNTPOINT,FSTYPE,TYPE -P -n -p $devices | \
	grep FSTYPE=\"ext\[234\]\" | grep TYPE=\"lvm\" | \
	while read vars ; do
		eval "${vars}"

		if [ "${scrub_all}" -eq 1 ] || [ -n "${MOUNTPOINT}" ]; then
		    echo ${MOUNTPOINT:-${NAME}}
		fi
	done
}

# Find leftover scrub snapshots
ls_reap_targets() {
    lvs -o lv_path -S lv_role=snapshot -S lv_name=~\(e2scrub$\) \
	--noheadings | sed -e 's/.e2scrub$//'
}

# Figure out what we're targeting
ls_targets() {
	if [ "${reap}" -eq 1 ]; then
		ls_reap_targets
	else
		ls_scan_targets
	fi
}

# systemd doesn't know to do path escaping on the instance variable we pass
# to the e2scrub service, which breaks things if there is a dash in the path
# name.  Therefore, do the path escaping ourselves if needed.
#
# systemd path escaping also drops the initial slash so we add that back in so
# that log messages from the service units preserve the full path and users can
# look up log messages using full paths.  However, for "/" the escaping rules
# do /not/ drop the initial slash, so we have to special-case that here.
escape_path_for_systemd() {
	local path="$1"

	if [ "${path}" != "/" ]; then
		echo "-$(systemd-escape --path "${path}")"
	else
		echo "-"
	fi
}

# Scrub any mounted fs on lvm by creating a snapshot and fscking that.
mapfile -t targets < <(ls_targets)
for tgt in "${targets[@]}"; do
	# If we're not reaping and systemd is present, try invoking the
	# systemd service.
	if [ "${reap}" -ne 1 ] && type systemctl > /dev/null 2>&1; then
		tgt_esc="$(escape_path_for_systemd "${tgt}")"
		${DBG} systemctl start "e2scrub@${tgt_esc}" 2> /dev/null
		res=$?
		if [ "${res}" -eq 0 ] || [ "${res}" -eq 1 ]; then
			continue;
		fi
	fi

	# Otherwise use direct invocation
	${DBG} "/sbin/e2scrub" ${scrub_args} "${tgt}"
done

exitcode 0
