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diff --git a/eclass/go.eclass b/eclass/go.eclass
new file mode 100644
index 0000000..748f89f
--- /dev/null
+++ b/eclass/go.eclass
@@ -0,0 +1,730 @@
+# Copyright 2022 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: go.eclass
+# @MAINTAINER:
+# Ryan Qian <i@bitbili.net>
+# @AUTHOR:
+# Ryan Qian <i@bitbili.net>
+# @SUPPORTED_EAPIS: 7 8
+# @BLURB: basic eclass for building software written in golang
+# @DESCRIPTION:
+# This eclass provides basic settings and functions needed by software
+# written in the go programming language.
+#
+# This eclass has three methods for offline building and one methods for online building:
+#
+# THREE OFFLINE BUILDING METHODS:
+#
+# ** priority: 1. > 2. > 3. **
+#
+# 1. for packages with the go.sum file which line number is less than GO_SUM_LIST_MAX (default to 100),
+#    if the corresponding go.sum file exists in the 'files' directory with name 'go.sum.$PV', this ebuild
+#    will automatically set the local proxy url for all modules in the 'go.sum' file. You just need to
+#    add the GO_SUM_LIST_SRC_URI variable into the SRC_URI variable.
+#
+# @CODE
+#
+# inherit go
+#
+# SRC_URI="https://github.com/example-org/reponame/archive/refs/tags/v${PV}.tar.gz -> ${P}.tar.gz"
+# SRC_URI+=" ${GO_SUM_LIST_SRC_URI}"
+#
+# @CODE
+#
+# 2. use project embedded 'vendor' directory to build.
+#    just inherit this eclass, don't need to do other special works
+#
+# @CODE
+#
+# inherit go
+#
+# @CODE
+#
+# 3. use extra 'vendor' directory to offer offline building, the vendor tarball can
+#    be generated by the script https://github.com/bekcpear/vendor-for-go .
+#    The tarball should consist of the directory architecture:
+#    (name quoted by '[]' means optional)
+#
+#      [any-parent-directory/]
+#
+#          vendor/
+#
+#          [go-mod-sum.diff]   # should and expected to be empty if
+#                              # the upstream did `go mod tidy` before releasing
+#
+# @CODE
+#
+# inherit go
+#
+# SRC_URI="https://github.com/example-org/reponame/archive/refs/tags/v${PV}.tar.gz -> ${P}.tar.gz
+#  https://some.url/corresponding-vendor-path.tar.gz -> ${P}-vendor.tar.gz"
+#
+# @CODE
+#
+# THE ONLINE BUILDING METHOD:
+#
+# 1. If there is no corresponding 'go.sum.$PV' file in the 'files' directory and
+#    also no embedded 'vendor' directory under the $S path.
+#    This eclass will check whether the 'live' PROPERTY exists, if it is, this eclass
+#    will use `go mod vendor` to generate the 'vendor' directory through the network
+#    instead of checking the vendor tarball.
+#
+# @CODE
+#
+# inherit git-r3 go
+#
+# EGIT_REPO_URI="https://github.com/example-org/reponame.git"
+#
+# src_unpack() {
+#   git-r3_src_unpack
+#   go_set_go_cmd
+#   go_setup_vendor
+# }
+#
+# OR without using the git-r3 eclass and specifying the PROPERTIES manually:
+# #PROPERTIES="live"
+# #SRC_URI="https://github.com/example-org/reponame/archive/refs/tags/v${PV}.tar.gz -> ${P}.tar.gz"
+# #src_unpack() {
+# #  go_src_unpack # OR just omit this whole "src_unpack" function
+# #}
+#
+# @CODE
+#
+#
+# #############################################################
+# #############################################################
+#
+# Why use this eclass instead of the offical go-module.eclass, please refer to
+# https://github.com/bekcpear/ryans-repos/issues/4
+#
+# Since Go programs are statically linked, it is important that your ebuild's
+# LICENSE= setting includes the licenses of all modules.
+# This script will be helpful to get the job done:
+# https://github.com/bekcpear/go-licenses-for-gentoo
+#
+if [[ -z ${_ECLASS_GO} ]]; then
+_ECLASS_GO=1
+
+case ${EAPI} in
+	7|8) ;;
+	*) die "${ECLASS}: EAPI ${EAPI:-0} not supported" ;;
+esac
+
+inherit edo version
+
+BDEPEND=">=dev-lang/go-1.16"
+
+EXPORT_FUNCTIONS src_unpack src_compile src_install
+
+IUSE="pie"
+
+# @ECLASS_VARIABLE: GOFLAGS
+# @DESCRIPTION:
+# the default GOFLAGS.
+# -trimpath remove all file system paths from the resulting executable
+# -v prints the names of packages as they are compiled
+# -work prints the temporary work dir's name and don't delete it when exiting
+# -x prints the commands
+export GOFLAGS="-trimpath -v -work -x"
+
+# Respect the job number explictly set in the MAKEOPTS variable if exists.
+# No number means the max number of available cpus which should be the same
+# as the default GOMAXPROCS (defaults to nproc), so should be ignored.
+# Should use GOMAXPROCS env var instead of the '-p' flag here due to:
+# 	1. '-p' only limits the number of parallel building goroutines
+# 	2. '-p' leaves the parallel number of GC, compiling and so on unchanged
+# 	3. when '-p' is set to 1, the default '-c' for the compile tool will be set to
+# 	   the GOMAXPROCS instead of min(4, GOMAXPROCS)
+# 	4. GOMAXPROCS env variable can affect through the whole process,
+# 	   N means N building goroutines and each building goroutine will call the compile
+# 	   tool with '-c=I' which I=min(4, N). This is the behavior that best matches -j.
+# 	   (The max number of -c may change in the future)
+# 	   Also see https://go-review.googlesource.com/c/go/+/41192 for the performance of
+# 	   concurrency of compiling process.
+[[ $MAKEOPTS =~ (-[a-z]*j|--jobs[=[:space:]])[[:space:]]*([0-9]+) ]] || true
+_MAXPROCS=${BASH_REMATCH[2]}
+if [[ -n $_MAXPROCS ]]; then
+	export GOMAXPROCS=$_MAXPROCS
+fi
+unset _MAXPROCS
+
+# @ECLASS_VARIABLE: EXTRA_GOFLAGS
+# @DESCRIPTION:
+# the extra GOFLAGS environment variable, default is empty,
+# this value will be appended to the GOFLAGS if provided.
+# Only valid when using the default src_compile of this eclass
+# or 'go_build' function of this eclass.
+
+# @ECLASS_VARIABLE: QA_FLAGS_IGNORED
+# @INTERNAL
+# @DESCRIPTION:
+# ignore FLAGS due to go projects do not use them,
+# this is a regex used by sed (without leading ^ and ending $).
+QA_FLAGS_IGNORED='.*'
+
+# Go packages should not be stripped with strip(1).
+RESTRICT+=" strip"
+
+# @ECLASS_VARIABLE: GO_LDFLAGS
+# @DESCRIPTION:
+# Flags pass to -ldflags, '-s' and '-w' flags will always be
+# applied except calling go command directly.
+
+# @ECLASS_VARIABLE: GO_SBIN
+# @DESCRIPTION:
+# names of binaries which should be installed as sbin
+
+# @ECLASS_VARIABLE: GO_TAGS
+# @DESCRIPTION:
+# a comma-separated list of additional build tags to consider satisfied
+# during the build
+#
+# @ECLASS_VARIABLE: GO_TARGET_PKGS
+# @DESCRIPTION:
+# A space-separated list of patterns which describe paths and target names
+# of packages which should be built instead of the default '.' or './cmd/...' .
+# The pattern has the following form:
+# 	<PACKAGE-PATH>[ -> <TARGET-NAME>]
+# <PACKAGE-PATH> is relative to the current temporary build dir (normally $S)
+# <TARGET-NAME> is the binary name instead of the package path name
+# e.g.:
+# 	./main -> foo
+# 	./cmd/bar
+
+# @ECLASS_VARIABLE: GO_LDFLAGS_EXMAP
+# @DESCRIPTION:
+# Extra "variable name <-> output command" maps, the output command will be called
+# and assign the standard output to the corresponding variable in src_compile phase.
+# These variables will replace the corresponding formatted strings in GO_LDFLAGS.
+# The formatted string should be like '@@VARIABLE-NAME@@'
+# e.g.:
+# 	GO_LDFLAGS_EXMAP[BUILD_DATE]="date '+%F %T%z'"
+# 	GO_LDFLAGS="-X 'main.buildDate=@@BUILD_DATE@@'"
+declare -A -g GO_LDFLAGS_EXMAP
+
+# @ECLASS_VARIABLE: _GO_LDFLAGS_EXMAP_CACHE
+# @INTERNAL
+# @DESCRIPTION:
+# cache for GO_LDFLAGS_EXMAP
+declare -A -g _GO_LDFLAGS_EXMAP_CACHE
+
+# @ECLASS_VARIABLE: GO_CMD
+# @DESCRIPTION:
+# The version matched Go command used to build packages.
+# Default is 'go'.
+# When dev-lang/go is installed from the 'ryans' repo, the slot is enabled,
+# and the default is the latest version, may be restricted to the penultimate
+# latest version due to the requirement of BDEPEND.
+GO_CMD=go
+
+# @ECLASS_VARIABLE: GO_SUM_LIST_MAX
+# @DESCRIPTION:
+# The max line number of go.sum which can be used to set a local proxy,
+# default to 100. This variable should be set before the eclass inherited.
+: "${GO_SUM_LIST_MAX:=100}"
+
+# @ECLASS_VARIABLE: GO_SUM_LIST_SRC_URI
+# @DESCRIPTION:
+# SRC_URI for go.sum entiries
+GO_SUM_LIST_SRC_URI=
+
+# @ECLASS_VARIABLE: GO_SUM_LIST_SRC_URI_R
+# @INTERNAL
+# @DESCRIPTION:
+# (internal variable) reversed map for GO_SUM_LIST_SRC_URI
+declare -A -g GO_SUM_LIST_SRC_URI_R
+
+# @FUNCTION: _go_escape_go_sum_path
+# @INTERNAL
+# @DESCRIPTION:
+# convert all capital letters in path to '!<lowercase>' format
+_go_escape_go_sum_path() {
+	local path="${1}" l
+	while [[ "${path}" =~ (.*)([[:upper:]])(.*) ]]; do
+		l=${BASH_REMATCH[2]@L}
+		path="${BASH_REMATCH[1]}!${l}${BASH_REMATCH[3]}"
+	done
+	echo -n "${path}"
+}
+
+# @FUNCTION: _go_set_go_sum_list_src_uri
+# @INTERNAL
+# @DESCRIPTION:
+# set GO_SUM_LIST_SRC_URI
+_go_set_go_sum_list_src_uri() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	if [[ -n ${GO_SUM_LIST_SRC_URI} ]]; then
+		return 0
+	fi
+
+	local _go_sum_list_file="${EBUILD%/*}/files/go.sum.$PV"
+	if [[ ! -f "${_go_sum_list_file}" ]]; then
+		return 0
+	fi
+	local -a _go_sum_list
+	while read -r line; do
+		_go_sum_list+=("${line}")
+	done <"${_go_sum_list_file}"
+	if [[ ${#_go_sum_list[@]} -gt ${GO_SUM_LIST_MAX} ]]; then
+		return 0
+	fi
+
+	local _distfile_name _src_uri _ver _ext
+	for line in "${_go_sum_list[@]}"; do
+		<<<$(_go_escape_go_sum_path "${line}") read -r path ver _
+		_ext=".zip"
+		_ver=${ver%/go.mod}
+		if [[ ${_ver} != ${ver} ]]; then
+			_ext=".mod"
+		fi
+		path="${path}/@v/${_ver}${_ext}"
+		_distfile_name="${path//\//%2F}"
+		eval "GO_SUM_LIST_SRC_URI_R['${_distfile_name}']='${path}'"
+		GO_SUM_LIST_SRC_URI+=" mirror://goproxy/${path} -> ${_distfile_name}"
+	done
+
+	export GOPROXY="file://${T}/go-proxy"
+}
+_go_set_go_sum_list_src_uri
+
+# @FUNCTION: go_version
+# @USAGE: [-f]
+# @DESCRIPTION:
+# Get version with format major.minor of the current executing go binary,
+# optionally specify -f to show the full version with the patch number.
+go_version() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	local output=$($GO_CMD version | cut -d' ' -f3) \
+		major= minor= patch=
+
+	IFS='.' read major minor patch <<<"$output"
+	major=${major#go}
+
+	if [[ $1 == '-f' ]] && [[ -n $patch ]]; then
+		output="${major}.${minor}.${patch}"
+	else
+		output="${major}.${minor}"
+	fi
+
+	echo -n $output
+}
+
+# @FUNCTION: go_set_go_cmd
+# @DESCRIPTION:
+# Try to get the version matched Go command, this is useful when the
+# go module to compile is restricted to the penultimate latest go version,
+# only functional when used with multi-version support of Go from
+# the ryans repository or other similar.
+# This function is called within the src_unpack phase by default.
+go_set_go_cmd() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	local goCmdPath=
+	local -a versions=() goCmds=()
+	for goCmdPath in $(ls -1v "${EROOT}"/usr/bin/go[[:digit:]].[[:digit:]]* 2>/dev/null); do
+		[[ -x "$goCmdPath" ]] || continue
+		goCmds+=( ${goCmdPath} )
+		versions+=( ${goCmdPath##*go} )
+	done
+
+	if [[ ${#versions[@]} -eq 0 ]]; then
+		# just return it if has no multi-version go binaries
+		return 0
+	fi
+
+	local _bdeps bdeps i d _ver_range _opt _ver _slot use usemark
+	local -a contained
+	local -i depth=0
+	local ver_range slot
+	_bdeps=( $(echo "$BDEPEND" | sed -E 's@(^|[[:space:]])[>=<~]{0,2}[[:alnum:]_\.-]+/[^g][^o][^[:space:]]*@ @g') )
+	contained[0]=1
+	for d in ${_bdeps[@]}; do
+		if [[ $d =~ ^(!?)([[:alpha:]][[:alnum:]]+)\?$ ]]; then
+			usemark=${BASH_REMATCH[1]}
+			use=${BASH_REMATCH[2]}
+			(( depth+=1 ))
+			if eval "$usemark use $use"; then
+				eval "contained[$depth]=1"
+			else
+				eval "contained[$depth]=0"
+			fi
+		elif [[ $d == "(" ]]; then
+			:
+		elif [[ $d == ")" ]]; then
+			(( depth-=1 ))
+		elif [[ $d == "||" ]]; then
+			# ignore it due to dev-lang/go dependency should not inside this
+			(( depth+=1 ))
+			eval "contained[$depth]=0"
+		else
+			if [[ ${contained[$depth]} == 1 ]]; then
+				bdeps+=( "$d" )
+			fi
+		fi
+	done
+	for d in ${bdeps[@]}; do
+		if [[ $d =~ ([>=<~]*)dev-lang/go(-([^[:space:]:]+))?(:([^[:space:]=]*))? ]]; then
+			_opt=${BASH_REMATCH[1]}
+			_ver=${BASH_REMATCH[3]}
+			_slot="${BASH_REMATCH[5]}"
+
+			if [[ $_opt =~ ^[=~] && -n $_ver ]]; then
+				ver_range="= $_ver"
+				# break loop when caught an exact version
+				break
+			elif [[ $_opt =~ [\>\<] && -n $_ver ]]; then
+				_ver_range="$_opt $_ver"
+			elif [[ -z $_slot ]]; then
+				_ver_range=
+			elif [[ -n $_slot ]]; then
+				slot=$_slot
+			fi
+
+			if [[ -n $_ver_range ]]; then
+				ver_range=$(version_make_range "$ver_range" "$_ver_range")
+			fi
+		fi
+	done
+
+	local ver oS oE vS vE
+	# match non-zero slot first then ver_range
+	for (( i = 0; i < ${#versions[@]}; i++ )); do
+		ver=${versions[$i]}
+		if [[ -n $slot && $slot != 0 ]]; then
+			if ! version_compare e $ver $slot; then
+				continue
+			fi
+		elif [[ -n $ver_range ]]; then
+			read -r oS vS oE vE <<<"$ver_range"
+			if [[ $oS == "=" ]]; then
+				VERSION_COMPARED_PARTS="minor"
+				if  ! version_compare e $ver $vS; then
+					continue
+				fi
+			else
+				if [[ ${oS:1:1} == "=" ]]; then
+					if version_compare l $ver $vS; then
+						continue
+					fi
+				else
+					if version_compare le $ver $vS; then
+						continue
+					fi
+				fi
+				if [[ -n $oE ]]; then
+					if [[ ${oE:1:1} == "=" ]]; then
+						if version_compare g $ver $vE; then
+							continue
+						fi
+					else
+						if version_compare ge $ver $vE; then
+							continue
+						fi
+					fi
+				fi
+			fi
+		fi
+		GO_CMD="${goCmds[$i]}"
+	done
+}
+
+# @FUNCTION: go_set_pie
+# @DESCRIPTION:
+# Setup the buildmode to pie when pie USE enabled and supported.
+go_set_pie() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	if ! use pie; then
+		return 0
+	fi
+
+	local pie_supported=0 supported_platform="" target_platform=""
+	target_platform="$($GO_CMD env GOOS)/$($GO_CMD env GOARCH)"
+	local supported_platforms=(
+		"linux/386" "linux/amd64" "linux/arm" "linux/arm64" "linux/ppc64le" "linux/riscv64" "linux/s390x"
+		"android/amd64" "android/arm" "android/arm64" "android/386"
+		"freebsd/amd64"
+		"darwin/amd64" "darwin/arm64"
+		"ios/amd64" "ios/arm64"
+		"aix/ppc64"
+		"windows/386" "windows/amd64" "windows/arm" "windows/arm64"
+	)
+	for supported_platform in "${supported_platforms[@]}"; do
+		if [[ $supported_platform == "$target_platform" ]]; then
+			pie_supported=1
+			break
+		fi
+	done
+	if [[ $pie_supported == 1 ]]; then
+		GOFLAGS="-buildmode=pie ${GOFLAGS}"
+	else
+		eerror "PIE: unsupported platform '${target_platform}', ignore the 'pie' USE flag!"
+	fi
+}
+
+# @FUNCTION: go_setup_proxy
+# @DESCRIPTION:
+# Setup the local proxy for downloading go modules.
+go_setup_proxy() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	local -a _default_A
+	local _f _go_proxy_dir="${GOPROXY#file:\/\/}"
+
+	mkdir -p ${_go_proxy_dir} || die
+
+	for f in ${A}; do
+		_f="${GO_SUM_LIST_SRC_URI_R[${f}]}"
+		if [[ -n ${_f} ]]; then
+			_f="${_go_proxy_dir}/${_f}"
+			mkdir -p "$(dirname ${_f})" || die
+			ln -sf ${DISTDIR}/${f} ${_f} || die
+		else
+			_default_A+=("${f}")
+		fi
+	done
+
+	if [[ "$1" == "i" ]]; then
+		declare -p _default_A
+	fi
+}
+
+# @FUNCTION: go_setup_vendor
+# @DESCRIPTION:
+# setup vendor directory
+go_setup_vendor() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	if [[ ! -d "${S}/vendor" ]]; then
+		if [[ ${PROPERTIES} =~ (^|[[:space:]])live([[:space:]]|$) ]]; then
+			# Golang does not support the 'socks5h://' schema for http[s]_proxy env variable:
+			#   https://github.com/golang/go/blob/9123221ccf3c80c741ead5b6f2e960573b1676b9/src/vendor/golang.org/x/net/http/httpproxy/proxy.go#L152-L159
+			# while libcurl supports it:
+			#   https://github.com/curl/curl/blob/ae98b85020094fb04eee7e7b4ec4eb1a38a98b98/docs/libcurl/opts/CURLOPT_PROXY.3#L48-L59
+			# So, if a 'https_proxy=socks5h://127.0.0.1:1080' env has been set in the
+			# make.conf to make curl (assuming curl is the current download command) to
+			# download all packages through the proxy, go-module_live_vendor will
+			# fail.
+			# The only difference between these two schemas is, 'socks5h' will solve
+			# the hostname via the proxy while 'socks5' will not. I think it's ok to
+			# fallback 'socks5h' to 'socks5' for `go vendor` command and warn user,
+			# until golang supports it.
+			# related to issue: https://github.com/golang/go/issues/24135
+			local hp
+			local -a hps
+			if [[ -n $HTTP_PROXY ]]; then
+				hps+=( HTTP_PROXY )
+			elif [[ -n $http_proxy ]]; then
+				hps+=( http_proxy )
+			fi
+			if [[ -n $HTTPS_PROXY ]]; then
+				hps+=( HTTPS_PROXY )
+			elif [[ -n $https_proxy ]]; then
+				hps+=( https_proxy )
+			fi
+			for hp in "${hps[@]}"; do
+				if [[ -n ${!hp} ]] && [[ ${!hp} =~ ^socks5h:// ]]; then
+					set -- export ${hp}="socks5${!hp#socks5h}"
+					ewarn "golang does not support the 'socks5h://' schema for '${hp}', fallback to the 'socks5://' schema"
+					einfo "${@}"
+					"${@}"
+				fi
+			done
+			pushd "${S}" >/dev/null || die
+			# We don't care the compatibility with other go versions due to it's a temporary dir and the
+			# only purpose here is to build this package under current version of the go binary,
+			# so specify a compatible go version with current version number here to avoid incompatibility,
+			# such as go1.16 and go1.17 has different build list calculation methods (https://go.dev/ref/mod#graph-pruning).
+			edo $GO_CMD mod tidy -compat $(go_version)
+			edo $GO_CMD mod vendor
+			popd >/dev/null || die
+		else
+			local -a vendors
+			local vendor go_mod_sum_diff
+			vendors=($(find "${WORKDIR}" -maxdepth 2 -name 'vendor' 2>/dev/null || true))
+			if [[ ${#vendors[@]} -gt 0 ]]; then
+				vendor="${vendors[0]}"
+				mv "${vendor}" "${S}" || die
+				go_mod_sum_diff="$(dirname ${vendor})/go-mod-sum.diff"
+				if [[ -s "${go_mod_sum_diff}" ]]; then
+					pushd "${S}" >/dev/null || die
+					eapply "${go_mod_sum_diff}"
+					popd >/dev/null || die
+				fi
+			fi
+		fi
+	fi
+}
+
+# @FUNCTION: go_src_unpack
+# @DESCRIPTION:
+# src_unpack
+go_src_unpack() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	go_set_go_cmd
+	go_set_pie
+
+	if [[ -n ${GO_SUM_LIST_SRC_URI} ]]; then
+		# prepare local proxy
+		eval "$(go_setup_proxy i)" || die
+		for f in "${_default_A[@]}"; do
+			unpack "${f}"
+		done
+	else
+		# prepare vendor directory
+		default
+		go_setup_vendor
+	fi
+}
+
+# @FUNCTION: _go_print_cmd
+# @INTERNAL
+# @USAGE: <message>...
+# @DESCRIPTION:
+# print the command and arguments with a pretty format
+_go_print_cmd() {
+	local msg is_cmd
+	echo -ne "\x1b[32;01m===\x1b[0m"
+	for msg; do
+		if [[ ${msg} =~ [[:space:]] ]] && [[ -n ${is_cmd} ]]; then
+			msg="\"${msg//\"/\\\"}\""
+		elif [[ ${msg} == $GO_CMD ]]; then
+			is_cmd=1
+		fi
+		echo -ne " ${msg}"
+	done
+	echo
+}
+
+# @FUNCTION: go_build
+# @USAGE: [-o <output>] <package>...
+# @DESCRIPTION:
+# parse necessary arguments for go build and build packages,
+# the binaries will be installed into the ${T}/go-bin/ directory by default.
+go_build() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	local go_ldflags="${GO_LDFLAGS}"
+
+	[[ "${go_ldflags}" =~ (^|[[:space:]])-w([[:space:]]|$) ]] || go_ldflags="-w ${go_ldflags}"
+	[[ "${go_ldflags}" =~ (^|[[:space:]])-s([[:space:]]|$) ]] || go_ldflags="-s ${go_ldflags}"
+
+	local key value
+	for key in "${!GO_LDFLAGS_EXMAP[@]}"; do
+		if [[ -n "${_GO_LDFLAGS_EXMAP_CACHE[$key]}" ]]; then
+			value="${_GO_LDFLAGS_EXMAP_CACHE[$key]}"
+		else
+			value=$(eval "${GO_LDFLAGS_EXMAP[$key]}" || true)
+			if [[ -z ${value} ]]; then
+				die "the stdout of command '$GO_LDFLAGS_EXMAP[$key]' (GO_LDFLAGS_EXMAP[$key]) is empty"
+			fi
+			_GO_LDFLAGS_EXMAP_CACHE[$key]=${value}
+		fi
+		go_ldflags=$(<<<"${go_ldflags}" sed "s/@@${key}@@/${value}/g")
+	done
+
+	local output="${T}/go-bin/"
+	local -a args
+	while :; do
+		case "${1}" in
+			-o)
+				shift
+				output="${1}"
+				shift
+				;;
+			"")
+				break
+				;;
+			*)
+				args+=( "${1}" )
+				shift
+				;;
+		esac
+	done
+	set -- "${args[@]}"
+
+	GOFLAGS="${GOFLAGS}${EXTRA_GOFLAGS:+ }${EXTRA_GOFLAGS}"
+	set -- $GO_CMD build -o "${output}" ${GO_TAGS:+-tags} ${GO_TAGS} -ldflags "${go_ldflags}" "${@}"
+	$GO_CMD env
+	_go_print_cmd "      GOFLAGS:" "${GOFLAGS}"
+	_go_print_cmd "Build command:" "${@}"
+	"${@}" || die
+}
+
+# @FUNCTION: go_src_compile
+# @DESCRIPTION:
+# src_compile
+go_src_compile() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	if [[ -d "cmd" ]] && [[ -z ${GO_TARGET_PKGS} ]] && \
+		[[ $(find cmd/ -maxdepth 2 -type f -name '*.go' -exec \
+			grep -E '^package[[:space:]]+main([[:space:]]|$)' '{}' \; 2>/dev/null || true) != "" ]]; then
+		go_build ./cmd/...
+	elif [[ -z ${GO_TARGET_PKGS} ]]; then
+		go_build .
+	else
+		local pkg_path
+		local -a pkg_paths
+		set -- ${GO_TARGET_PKGS}
+		while :; do
+			case "${1}" in
+				'')
+					break
+					;;
+				'->')
+					shift
+					go_build -o "${T}/go-bin/${1}" ${pkg_path}
+					pkg_path=
+					shift
+					;;
+				*)
+					if [[ ${pkg_path} != "" ]]; then
+						pkg_paths+=( "${pkg_path}" )
+						pkg_path=
+					fi
+					pkg_path="${1}"
+					shift
+					;;
+			esac
+		done
+		if [[ ${pkg_path} != "" ]]; then
+			pkg_paths+=( "${pkg_path}" )
+		fi
+		if [[ ${#pkg_paths[@]} -gt 0 ]]; then
+			go_build "${pkg_paths[@]}"
+		fi
+	fi
+}
+
+# @FUNCTION: go_src_install
+# @DESCRIPTION:
+# src_install
+go_src_install() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	pushd "${T}"/go-bin >/dev/null || die
+
+	local _sb _sbin
+	if [[ $(declare -p GO_SBIN 2>/dev/null) =~ declare[[:space:]]+-a ]]; then
+		_sbin="${GO_SBIN[*]}"
+	else
+		_sbin="${GO_SBIN}"
+	fi
+	for _sb in ${_sbin}; do
+		if ls ${_sb} &>/dev/null; then
+			dosbin ${_sb}
+			rm -f ${_sb} || die
+		fi
+	done
+
+	dobin *
+
+	popd >/dev/null || die
+}
+
+fi
diff --git a/eclass/version.eclass b/eclass/version.eclass
new file mode 100644
index 0000000..b0f3264
--- /dev/null
+++ b/eclass/version.eclass
@@ -0,0 +1,257 @@
+# Copyright 2023
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: version.eclass
+# @MAINTAINER:
+# Ryan Qian <i@bitbili.net>
+# @AUTHOR:
+# Ryan Qian <i@bitbili.net>
+# @SUPPORTED_EAPIS: 7 8
+# @BLURB: functions to handle the version number
+# @DESCRIPTION:
+# This eclass provides functions to handle the version number.
+
+if [[ -z ${_ECLASS_VERSION} ]]; then
+_ECLASS_VERSION=1
+
+# @ECLASS_VARIABLE: VERSION_COMPARED_PARTS
+# @DESCRIPTION:
+# the version parts to compare, default is the full parts,
+# avaliable values are:
+#   major  # major parts
+#   minor  # major and minor parts
+#   patch  # major, minor and patch parts
+#   full   # major, minor, patch and pre-release parts
+VERSION_COMPARED_PARTS="full"
+
+# @FUNCTION: _version_compare_ver
+# @INTERNAL
+# @DESCRIPTION:
+# _version_compare_ver sub function
+_version_compare_ver() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	local v0=${1} v1=${2} is_num=1 res=
+	if [[ ! ${v0} =~ ^[0-9]+$ ]] || [[ ! ${v1} =~ ^[0-9]+$ ]]; then
+		is_num=0
+		: "${v0/-1/\\/}"
+		: "${v1/-1/\\/}"
+	fi
+	if [[ ${is_num} == 1 ]]; then
+		if (( ${v0} > ${v1} )); then
+			res="g"
+		elif (( ${v0} == ${v1} )); then
+			res="e"
+		elif (( ${v0} < ${v1} )); then
+			res="l"
+		fi
+	else
+		if [[ ${v0} > ${v1} ]]; then
+			res="g"
+		elif [[ ${v0} == ${v1} ]]; then
+			res="e"
+		elif [[ ${v0} < ${v1} ]]; then
+			res="l"
+		fi
+	fi
+	echo -n "${res}"
+}
+
+# @FUNCTION: _version_compare
+# @INTERNAL
+# @DESCRIPTION:
+# _version_compare sub function
+_version_compare() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	local v0 v1 vv0 vv1 len _len res
+	OIFS=$IFS; IFS="."
+	v0=(${1}) v1=(${2})
+	IFS=$OIFS
+	if [[ ${#v0[@]} -ge ${#v1[@]} ]]; then
+		len=${#v0[@]}
+	else
+		len=${#v1[@]}
+	fi
+	case $VERSION_COMPARED_PARTS in
+		major)
+			_len=1
+			;;
+		minor)
+			_len=2
+			;;
+		patch)
+			_len=3
+			;;
+	esac
+	if [[ -n $_len && $_len -lt $len ]]; then
+		len=$_len
+	fi
+	for (( i=0; i<${len}; i++ )); do
+		vv0=${v0[$i]:--1}
+		vv1=${v1[$i]:--1}
+		res=$(_version_compare_ver ${vv0} ${vv1})
+		if [[ ${res} != "e" ]]; then
+			break
+		fi
+	done
+	echo -n "${res}"
+}
+
+# @FUNCTION: version_compare
+# @USAGE: g|ge|l|le|e STRING0 STRING1
+# @DESCRIPTION:
+# Compare the version numbers contained in the two strings to determine their precedence
+# according to the specifications defined in https://semver.org/spec/v2.0.0.html
+# The build metadata will be ignored.
+#
+# The prefixed package name will be removed automatically if exists.
+#
+# options:
+#
+#   g:      compare if the version contained in STRING0 is greater than the version in STRING1
+#   ge:     compare if the version contained in STRING0 is greater than or equal to the version in STRING1
+#   l:      compare if the version contained in STRING0 is less than the version in STRING1
+#   le      compare if the version contained in STRING0 is less than or equal to the version in STRING1
+#   e:      compare if the version contained in STRING0 is equal to the version in STRING1
+#
+# The return code is
+#
+#   0:      when the above comparison holds
+#   1:      when the above comparison does not hold
+#
+version_compare() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	local LC_ALL=C
+	local action result
+	case ${1} in
+		g|ge|l|le|e)
+			action="${1}"
+			;;
+		*)
+			die "unexpected argument '${1}'"
+			;;
+	esac
+	shift
+
+	local -a str0 str1
+	local str0_pkgname str0_ver str0_pre
+	local str1_pkgname str1_ver str1_pre
+
+	OIFS=$IFS; IFS="-"
+	str0=( ${1} ) str1=( ${2} )
+	IFS=$OIFS
+
+	for _str in "str0" "str1"; do
+		local _strA="${_str}[@]" _strV="${_str}_ver" _strP="${_str}_pre" _strN="${_str}_pkgname"
+		for _s in "${!_strA}"; do
+			if [[ -n ${!_strV} ]]; then
+				eval "${_str}_pre=\"${_s}\""
+			elif [[ ${_s} =~ ^[vV]?[0-9]+\.? ]]; then
+				_s="${_s#v}"
+				eval "${_str}_ver=\"${_s#V}\""
+			else
+				if [[ -n ${!_strN} ]]; then
+					eval "${_str}_pkgname+=\"-\""
+				fi
+				eval "${_str}_pkgname+=\"${_s}\""
+			fi
+		done
+	done
+
+	if [[ ${str0_pkgname} != ${str1_pkgname} ]]; then
+		die "compare with different package names '${str0_pkgname}', '${str1_pkgname}'"
+	fi
+
+	result=$(_version_compare ${str0_ver} ${str1_ver})
+	if [[ ${result} == "e" ]]; then
+		result=$(_version_compare ${str0_pre:-zzzz} ${str1_pre:-zzzz})
+	fi
+
+	if [[ ${result} =~ [${action}] ]]; then
+		return 0
+	else
+		return 1
+	fi
+}
+
+# @FUNCTION: version_make_range
+# @USAGE: CURRENT_RANGE NEW_CONDITION
+# @DESCRIPTION:
+# create a version range through the NEW_CONDITION
+# input format:
+#   CURRENT_RANGE: ">[=] version-str <[=] version-str"
+#   NEW_CONDITION: "(>|<)[=] version-str"
+# output:
+#   NEW_RANGE: ">[=] version-str <[=] version-str"
+version_make_range() {
+	debug-print-function "${FUNCNAME}" "${@}"
+
+	if [[ -z $2 ]]; then
+		die "no new condition provided"
+	fi
+
+	local oS vS oE vE o v equal replace
+	read -r oS vS oE vE <<<"$1"
+	read -r o v <<<"$2"
+	if [[ ! $o =~ ^[\>\<]=?$ ]] || ! version_is_valid $v; then
+		die "wrong format of the new condition"
+	fi
+	if [[ ${o:1:1} == "=" ]]; then
+		equal=1
+	fi
+	case ${o:0:1} in
+		">")
+			if [[ -z $oS ]]; then
+				replace=1
+			elif [[ ${oS:1:1} == "=" ]] && \
+				version_compare ge $v $vS; then
+				replace=1
+			else
+				if [[ -n $equal ]] && \
+					version_compare g $v $vS; then
+					replace=1
+				elif version_compare ge $v $vS; then
+					replace=1
+				fi
+			fi
+			if [[ -n $replace ]]; then
+				oS=$o
+				vS=$v
+			fi
+			;;
+		"<")
+			if [[ -z $oE ]]; then
+				replace=1
+			elif [[ ${oE:1:1} == "=" ]] && \
+				version_compare le $v $vE; then
+				replace=1
+			else
+				if [[ -n $equal ]] && \
+					version_compare le $v $vE; then
+					replace=1
+				elif version_compare l $v $vE; then
+					replace=1
+				fi
+			fi
+			if [[ -n $replace ]]; then
+				oE=$o
+				vE=$v
+			fi
+			;;
+	esac
+
+	echo -n "${oS:->=} ${vS:-0} ${oE:-<=} ${vE:-9999}"
+}
+
+# @FUNCTION: version_is_valid
+# @USAGE: version-str
+# @DESCRIPTION:
+# check the version-str is a valid semantic version
+version_is_valid() {
+	# TODO
+	:
+}
+
+fi