#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or https://opensource.org/licenses/CDDL-1.0.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#

#
# Copyright (c) 2025, Klara, Inc.
#

#
# This file provides the following helpers to read kstats from tests.
#
#   kstat [-g] <stat>
#   kstat_pool [-g] <pool> <stat>
#   kstat_dataset [-N] <dataset | pool/objsetid> <stat>
#
# `kstat` and `kstat_pool` return the value of of the given <stat>, either
# a global or pool-specific state.
#
#   $ kstat dbgmsg
#   timestamp    message
#   1736848201   spa_history.c:304:spa_history_log_sync(): txg 14734896 ...
#   1736848201   spa_history.c:330:spa_history_log_sync(): ioctl ...
#   ...
#
#   $ kstat_pool garden state
#   ONLINE
#
# To get a single stat within a group or collection, separate the name with
# '.' characters.
#
#   $ kstat dbufstats.cache_target_bytes
#   3215780693
#
#   $ kstat_pool crayon iostats.arc_read_bytes
#   253671670784
#
# -g is "group" mode. If the kstat is a group or collection, all stats in that
# group are returned, one stat per line, key and value separated by a space.
#
#   $ kstat -g dbufstats
#   cache_count 1792
#   cache_size_bytes 87720376
#   cache_size_bytes_max 305187768
#   cache_target_bytes 97668555
#   ...
#
#   $ kstat_pool -g crayon iostats
#   trim_extents_written 0
#   trim_bytes_written 0
#   trim_extents_skipped 0
#   trim_bytes_skipped 0
#   ...
#
# `kstat_dataset` accesses the per-dataset group kstat. The dataset can be
# specified by name:
#
#   $ kstat_dataset crayon/home/robn nunlinks
#   2628514
#
# or, with the -N switch, as <pool>/<objsetID>:
#
#   $ kstat_dataset -N crayon/7 writes
#   125135
#

####################
# Public interface

#
# kstat [-g] <stat>
#
function kstat
{
	typeset -i want_group=0

	OPTIND=1
	while getopts "g" opt ; do
		case $opt in
			'g') want_group=1 ;;
			*) log_fail "kstat: invalid option '$opt'" ;;
		esac
	done
	shift $(expr $OPTIND - 1)

	typeset stat=$1

	$_kstat_os 'global' '' "$stat" $want_group
}

#
# kstat_pool [-g] <pool> <stat>
#
function kstat_pool
{
	typeset -i want_group=0

	OPTIND=1
	while getopts "g" opt ; do
		case $opt in
			'g') want_group=1 ;;
			*) log_fail "kstat_pool: invalid option '$opt'" ;;
		esac
	done
	shift $(expr $OPTIND - 1)

	typeset pool=$1
	typeset stat=$2

	$_kstat_os 'pool' "$pool" "$stat" $want_group
}

#
# kstat_dataset [-N] <dataset | pool/objsetid> <stat>
#
function kstat_dataset
{
	typeset -i opt_objsetid=0

	OPTIND=1
	while getopts "N" opt ; do
		case $opt in
			'N') opt_objsetid=1 ;;
			*) log_fail "kstat_dataset: invalid option '$opt'" ;;
		esac
	done
	shift $(expr $OPTIND - 1)

	typeset dsarg=$1
	typeset stat=$2

	if [[ $opt_objsetid == 0 ]] ; then
		typeset pool="${dsarg%%/*}"	# clear first / -> end
		typeset objsetid=$($_resolve_dsname_os "$pool" "$dsarg")
		if [[ -z "$objsetid" ]] ; then
			log_fail "kstat_dataset: dataset not found: $dsarg"
		fi
		dsarg="$pool/$objsetid"
	fi

	$_kstat_os 'dataset' "$dsarg" "$stat" 0
}

####################
# Platform-specific interface

#
# Implementation notes
#
# There's not a lot of uniformity between platforms, so I've written to a rough
# imagined model that seems to fit the majority of OpenZFS kstats.
#
# The main platform entry points look like this:
#
#    _kstat_freebsd <scope> <object> <stat> <want_group>
#    _kstat_linux <scope> <object> <stat> <want_group>
#
# - scope: one of 'global', 'pool', 'dataset'. The "kind" of object the kstat
#          is attached to.
# - object: name of the scoped object
#           global:  empty string
#           pool:    pool name
#           dataset: <pool>/<objsetId> pair
# - stat: kstat name to get
# - want_group: 0 to get the single value for the kstat, 1 to treat the kstat
#               as a group and get all the stat names+values under it. group
#               kstats cannot have values, and stat kstats cannot have
#               children (by definition)
#
# Stat values can have multiple lines, so be prepared for those.
#
# These functions either succeed and produce the requested output, or call
# log_fail. They should never output empty, or 0, or anything else.
#
# Output:
#
# - want_group=0: the single stat value, followed by newline
# - want_group=1: One stat per line, <name><SP><value><newline>
#

#
# To support kstat_dataset(), platforms also need to provide a dataset
# name->object id resolver function.
#
#   _resolve_dsname_freebsd <pool> <dsname>
#   _resolve_dsname_linux <pool> <dsname>
#
# - pool: pool name. always the first part of the dataset name
# - dsname: dataset name, in the standard <pool>/<some>/<dataset> format.
#
# Output is <objsetID>. objsetID is a decimal integer, > 0
#

####################
# FreeBSD

#
# All kstats are accessed through sysctl. We model "groups" as interior nodes
# in the stat tree, which are normally opaque. Because sysctl has no filtering
# options, and requesting any node produces all nodes below it, we have to
# always get the name and value, and then consider the output to understand
# if we got a group or a single stat, and post-process accordingly.
#
# Scopes are mostly mapped directly to known locations in the tree, but there
# are a handful of stats that are out of position, so we need to adjust.
#

#
# _kstat_freebsd <scope> <object> <stat> <want_group>
#
function _kstat_freebsd
{
	typeset scope=$1
	typeset obj=$2
	typeset stat=$3
	typeset -i want_group=$4

	typeset oid=""
	case "$scope" in
	global)
		oid="kstat.zfs.misc.$stat"
		;;
	pool)
		# For reasons unknown, the "multihost", "txgs" and "reads"
		# pool-specific kstats are directly under kstat.zfs.<pool>,
		# rather than kstat.zfs.<pool>.misc like the other pool kstats.
		# Adjust for that here.
		case "$stat" in
		multihost|txgs|reads)
		    oid="kstat.zfs.$obj.$stat"
		    ;;
		*)
		    oid="kstat.zfs.$obj.misc.$stat"
		    ;;
		esac
		;;
	dataset)
		typeset pool=""
		typeset -i objsetid=0
		_split_pool_objsetid $obj pool objsetid
		oid=$(printf 'kstat.zfs.%s.dataset.objset-0x%x.%s' \
		    $pool $objsetid $stat)
		;;
	esac

	# Calling sysctl on a "group" node will return everything under that
	# node, so we have to inspect the first line to make sure we are
	# getting back what we expect. For a single value, the key will have
	# the name we requested, while for a group, the key will not have the
	# name (group nodes are "opaque", not returned by sysctl by default.

	if [[ $want_group == 0 ]] ; then
		sysctl -e "$oid" | awk -v oid="$oid" -v oidre="^$oid=" '
			NR == 1 && $0 !~ oidre { exit 1 }
			NR == 1 { print substr($0, length(oid)+2) ; next }
			{ print }
		'
	else
		sysctl -e "$oid" | awk -v oid="$oid" -v oidre="^$oid=" '
			NR == 1 && $0 ~ oidre { exit 2 }
			{
			    sub("^" oid "\.", "")
			    sub("=", " ")
			    print
			}
		'
	fi

	typeset -i err=$?
	case $err in
		0) return ;;
		1) log_fail "kstat: can't get value for group kstat: $oid" ;;
		2) log_fail "kstat: not a group kstat: $oid" ;;
	esac

	log_fail "kstat: unknown error: $oid"
}

#
#   _resolve_dsname_freebsd <pool> <dsname>
#
function _resolve_dsname_freebsd
{
	# we're searching for:
	#
	# kstat.zfs.shed.dataset.objset-0x8087.dataset_name: shed/poudriere
	#
	# We split on '.', then get the hex objsetid from field 5.
	#
	# We convert hex to decimal in the shell because there isn't a _simple_
	# portable way to do it in awk and this code is already too intense to
	# do it a complicated way.
	typeset pool=$1
	typeset dsname=$2
	sysctl -e kstat.zfs.$pool | \
	    awk -F '.' -v dsnamere="=$dsname$" '
		/\.objset-0x[0-9a-f]+\.dataset_name=/ && $6 ~ dsnamere {
		    print substr($5, 8)
		    exit
		}
	    ' | xargs printf %d
}

####################
# Linux

#
# kstats all live under /proc/spl/kstat/zfs. They have a flat structure: global
# at top-level, pool in a directory, and dataset in a objset- file inside the
# pool dir.
#
# Groups are challenge. A single stat can be the entire text of a file, or
# a single line that must be extracted from a "group" file. The only way to
# recognise a group from the outside is to look for its header. This naturally
# breaks if a raw file had a matching header, or if a group file chooses to
# hid its header. Fortunately OpenZFS does none of these things at the moment.
#

#
# _kstat_linux <scope> <object> <stat> <want_group>
#
function _kstat_linux
{
	typeset scope=$1
	typeset obj=$2
	typeset stat=$3
	typeset -i want_group=$4

	typeset singlestat=""

	if [[ $scope == 'dataset' ]] ; then
		typeset pool=""
		typeset -i objsetid=0
		_split_pool_objsetid $obj pool objsetid
		stat=$(printf 'objset-0x%x.%s' $objsetid $stat)
		obj=$pool
		scope='pool'
	fi

	typeset path=""
	if [[ $scope == 'global' ]] ; then
		path="/proc/spl/kstat/zfs/$stat"
	else
		path="/proc/spl/kstat/zfs/$obj/$stat"
	fi

	if [[ ! -e "$path" && $want_group -eq 0 ]] ; then
		# This single stat doesn't have its own file, but the wanted
		# stat could be in a group kstat file, which we now need to
		# find. To do this, we split a single stat name into two parts:
		# the file that would contain the stat, and the key within that
		# file to match on. This works by converting all bar the last
		# '.' separator to '/', then splitting on the remaining '.'
		# separator. If there are no '.' separators, the second arg
		# returned will be empty.
		#
		#   foo              -> (foo)
		#   foo.bar          -> (foo, bar)
		#   foo.bar.baz      -> (foo/bar, baz)
		#   foo.bar.baz.quux -> (foo/bar/baz, quux)
		#
		# This is how we will target single stats within a larger NAMED
		# kstat file, eg dbufstats.cache_target_bytes.
		typeset -a split=($(echo "$stat" | \
		    sed -E 's/^(.+)\.([^\.]+)$/\1 \2/ ; s/\./\//g'))
		typeset statfile=${split[0]}
		singlestat=${split[1]:-""}

		if [[ $scope == 'global' ]] ; then
			path="/proc/spl/kstat/zfs/$statfile"
		else
			path="/proc/spl/kstat/zfs/$obj/$statfile"
		fi
	fi
	if [[ ! -r "$path" ]] ; then
		log_fail "kstat: can't read $path"
	fi

	if [[ $want_group == 1 ]] ; then
		# "group" (NAMED) kstats on Linux start:
		#
		#   $ cat /proc/spl/kstat/zfs/crayon/iostats
		#   70 1 0x01 26 7072 8577844978 661416318663496
		#   name                            type data
		#   trim_extents_written            4    0
		#   trim_bytes_written              4    0
		#
		# The second value on the first row is the ks_type. Group
		# mode only works for type 1, KSTAT_TYPE_NAMED. So we check
		# for that, and eject if it's the wrong type. Otherwise, we
		# skip the header row and process the values.
		awk '
			NR == 1 && ! /^[0-9]+ 1 / { exit 2 }
			NR < 3 { next }
			{ print $1 " " $NF }
		' "$path"
	elif [[ -n $singlestat ]] ; then
		# single stat. must be a single line within a group stat, so
		# we look for the header again as above.
		awk -v singlestat="$singlestat" \
		    -v singlestatre="^$singlestat " '
			NR == 1 && /^[0-9]+ [^1] / { exit 2 }
			NR < 3 { next }
			$0 ~ singlestatre { print $NF ; exit 0 }
			ENDFILE { exit 3 }
		' "$path"
	else
		# raw stat. dump contents, exclude group stats
		awk '
			NR == 1 && /^[0-9]+ 1 / { exit 1 }
			{ print }
		' "$path"
	fi

	typeset -i err=$?
	case $err in
		0) return ;;
		1) log_fail "kstat: can't get value for group kstat: $path" ;;
		2) log_fail "kstat: not a group kstat: $path" ;;
		3) log_fail "kstat: stat not found in group: $path $singlestat" ;;
	esac

	log_fail "kstat: unknown error: $path"
}

#
#   _resolve_dsname_linux <pool> <dsname>
#
function _resolve_dsname_linux
{
	# We look inside all:
	#
	#   /proc/spl/kstat/zfs/crayon/objset-0x113
	#
	# and check the dataset_name field inside. If we get a match, we split
	# the filename on /, then extract the hex objsetid.
	#
	# We convert hex to decimal in the shell because there isn't a _simple_
	# portable way to do it in awk and this code is already too intense to
	# do it a complicated way.
	typeset pool=$1
	typeset dsname=$2
	awk -v dsname="$dsname" '
	    $1 == "dataset_name" && $3 == dsname {
		split(FILENAME, a, "/")
		print substr(a[7], 8)
		exit
	    }
	    ' /proc/spl/kstat/zfs/$pool/objset-0x* | xargs printf %d
}

####################

#
# _split_pool_objsetid <obj> <*pool> <*objsetid>
#
# Splits pool/objsetId string in <obj> and fills <pool> and <objsetid>.
#
function _split_pool_objsetid
{
	typeset obj=$1
	typeset -n pool=$2
	typeset -n objsetid=$3

	pool="${obj%%/*}"		# clear first / -> end
	typeset osidarg="${obj#*/}"	# clear start -> first /

	# ensure objsetid arg does not contain a /. we're about to convert it,
	# but ksh will treat it as an expression, and a / will give a
	# divide-by-zero
	if [[ "${osidarg%%/*}" != "$osidarg" ]] ; then
		log_fail "kstat: invalid objsetid: $osidarg"
	fi

	typeset -i id=$osidarg
	if [[ $id -le 0 ]] ; then
		log_fail "kstat: invalid objsetid: $osidarg"
	fi
	objsetid=$id
}

####################

#
# Per-platform function selection.
#
# To avoid needing platform check throughout, we store the names of the
# platform functions and call through them.
#
if is_freebsd ; then
	_kstat_os='_kstat_freebsd'
	_resolve_dsname_os='_resolve_dsname_freebsd'
elif is_linux ; then
	_kstat_os='_kstat_linux'
	_resolve_dsname_os='_resolve_dsname_linux'
else
	_kstat_os='_kstat_unknown_platform_implement_me'
	_resolve_dsname_os='_resolve_dsname_unknown_platform_implement_me'
fi