io/xfs_property

#!/bin/bash -f
# SPDX-License-Identifier: GPL-2.0
#
# Copyright (c) 2024 Oracle.  All Rights Reserved.
# Author: Darrick J. Wong <djwong@kernel.org>
#

OPTS=""
USAGE="Usage: xfs_property [-V] [mountpoint|device|file] [list [-v]|get name...|set name=value...|remove name...]"

# Try to find a loop device associated with a file.  We only want to return
# one loopdev (multiple loop devices can attach to a single file) so we grab
# the last line and return it if it's actually a block device.
try_find_loop_dev_for_file() {
	local x="$(losetup -O NAME -j "$1" 2> /dev/null | tail -n 1)"
	test -b "${x}" && echo "${x}"
}

while getopts "V" c
do
	case $c in
	V)	xfs_io -p xfs_info -V
		status=$?
		exit ${status}
		;;
	*)	echo "${USAGE}" 1>&2
		exit 2
		;;
	esac
done
set -- extra "$@"
shift $OPTIND

if [ $# -lt 2 ]; then
	echo "${USAGE}" 1>&2
	exit 2
fi

target="$1"
shift
subcommand="$1"
shift

db_args=()
io_args=()

case "$subcommand" in
"list")
	vparam=
	if [ $# -eq 1 ] && [ "$1" = "-v" ]; then
		vparam=" -v"
	fi
	db_args+=('-c' "attr_list -Z${vparam}")
	io_args+=('-c' "listfsprops${vparam}")
	;;
"get"|"remove"|"set")
	for arg in "$@"; do
		db_args+=('-c' "attr_${subcommand} -Z ${arg/=/ }")
		io_args+=('-c' "${subcommand}fsprops ${arg}")
	done
	;;
*)
	echo "${USAGE}" 1>&2
	exit 2
esac

# See if we can map the arg to a loop device
loopdev="$(try_find_loop_dev_for_file "${target}")"
test -n "${loopdev}" && target="${loopdev}"

# If we find a mountpoint for the device, do a live query; otherwise try
# reading the fs with xfs_db.
if mountpt="$(findmnt -t xfs -f -n -o TARGET "${target}" 2> /dev/null)"; then
	exec xfs_io -p xfs_property "${io_args[@]}" "${mountpt}"
else
	exec xfs_db -p xfs_property -x -c 'path /' "${db_args[@]}" "${target}"
fi