[gentoo-dev] [PATCH 1/1] go-module.eclass: introduce new eclass to handle go modules

[William Hubbs <williamh@gentoo.org>]

Signed-off-by: William Hubbs <williamh@gentoo.org>
---
 eclass/go-module.eclass | 161 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 161 insertions(+)
 create mode 100644 eclass/go-module.eclass

diff --git a/eclass/go-module.eclass b/eclass/go-module.eclass
new file mode 100644
index 00000000000..6f609e94542
--- /dev/null
+++ b/eclass/go-module.eclass
@@ -0,0 +1,161 @@
+# Copyright 2019 gentoo authors
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: go-module.eclass
+# @MAINTAINER:
+# William Hubbs <williamh@gentoo.org>
+# @SUPPORTED_EAPIS: 7
+# @BLURB: basic eclass for building software written in the go
+# programming language that uses go modules.
+# @DESCRIPTION:
+# This eclass provides some basic things needed by all software
+# written in the go programming language that uses go modules.
+#
+# You will know the software you are packaging uses modules because
+# it will have files named go.sum and go.mod in its top-level source
+# directory. If it does not have these files, use the golang-* eclasses.
+#
+# This eclass provides a src_unpack function which unpacks the 
+# first tarball mentioned in SRC_URI to the usual location and unpacks
+# any modules mentioned in EGO_VENDOR to ${S}/vendor if upstream doesn't
+# vendor its own dependencies.
+#
+# If upstream vendors its dependencies, setting EGO_VENDOR is an error.
+#
+# Please note that this eclass currently handles only tarballs
+# (.tar.gz), but support for more formats may be added in the future.
+#
+# Since Go programs are statically linked, it is important that your ebuild's
+# LICENSE= setting includes the licenses of all statically linked
+# dependencies. So please make sure it is accurate.
+#
+# @EXAMPLE:
+#
+# @CODE
+# EGO_VENDOR=(
+#	"github.com/xenolf/lego 6cac0ea7d8b28c889f709ec7fa92e92b82f490dd"
+# "golang.org/x/crypto 453249f01cfeb54c3d549ddb75ff152ca243f9d8 github.com/golang/crypto"
+# )
+#
+# inherit go-module
+#
+# SRC_URI="https://github.com/example/${PN}/archive/v${PV}.tar.gz -> ${P}.tar.gz
+# ${EGO_VENDOR_URI}"
+# @CODE
+#
+# The above example will extract the tarball to ${S} and
+# extract the contents of EGO_VENDOR to ${S}/vendor.
+
+case ${EAPI:-0} in
+	7) ;;
+	*) die "${ECLASS} API in EAPI ${EAPI} not yet established."
+esac
+
+if [[ -z ${_GO_MODULE} ]]; then
+
+_GO_MODULE=1
+
+BDEPEND=">=dev-lang/go-1.12"
+
+# Force go to build in module mode.
+# In this mode the GOPATH environment variable is ignored.
+# this will become the default in the future.
+export GO111MODULE=on
+
+# The following go flags should be used for all builds.
+# -mod=vendor stopps downloading of dependencies from the internet.
+# -v prints the names of packages as they are compiled
+# -x prints commands as they are executed
+export GOFLAGS="-mod=vendor -v -x"
+
+# Do not complain about CFLAGS etc since go projects do not use them.
+QA_FLAGS_IGNORED='.*'
+
+# Go packages should not be stripped with strip(1).
+RESTRICT="strip"
+
+EXPORT_FUNCTIONS src_unpack pkg_postinst
+
+# @ECLASS-VARIABLE: EGO_VENDOR
+# @DESCRIPTION:
+# This variable contains a list of vendored packages.
+# The items of this array are strings that contain the
+# import path and the git commit hash for a vendored package.
+# If the import path does not start with github.com, the third argument
+# can be used to point to a github repository.
+
+declare -arg EGO_VENDOR
+
+_go-module_set_vendor_uri() {
+	EGO_VENDOR_URI=
+	local lib
+	for lib in "${EGO_VENDOR[@]}"; do
+		lib=(${lib})
+		if [[ -n ${lib[2]} ]]; then
+			EGO_VENDOR_URI+=" https://${lib[2]}/archive/${lib[1]}.tar.gz -> ${lib[2]//\//-}-${lib[1]}.tar.gz"
+		else
+			EGO_VENDOR_URI+=" https://${lib[0]}/archive/${lib[1]}.tar.gz -> ${lib[0]//\//-}-${lib[1]}.tar.gz"
+		fi
+	done
+	readonly EGO_VENDOR_URI
+}
+
+_go-module_set_vendor_uri
+unset -f _go-module_set_vendor_uri
+
+_go-module_dovendor() {
+	local VENDOR_PATH=$1 VENDORPN=$2 TARBALL=$3
+	rm -fr "${VENDOR_PATH}/${VENDORPN}" || die
+	mkdir -p "${VENDOR_PATH}/${VENDORPN}" || die
+	tar -C "${VENDOR_PATH}/${VENDORPN}" -x --strip-components 1\
+		-f "${DISTDIR}/${TARBALL}" || die
+}
+
+# @FUNCTION: go-module_src_unpack
+# @DESCRIPTION:
+# Extract the first archive from ${A} to ${S}, then extract
+# any sources mentioned in ${EGO_VENDOR} to ${S}/vendor.
+go-module_src_unpack() {
+	local lib vendor_path x
+	set -- ${A}
+	x="$1"
+	mkdir -p "${S}" || die
+	tar -C "${S}/" -x --strip-components 1 \
+		-f "${DISTDIR}/${x}" || die
+
+	if [[ -n "${EGO_VENDOR}" ]]; then
+		vendor_path="${S}/vendor"
+		if [[ -d "${vendor_path}" ]]; then
+			eerror "Upstream for ${P}.ebuild vendors dependencies."
+			die "Remove EGO_VENDOR from the ebuild."
+		fi
+		mkdir -p "${vendor_path}" || die
+		for lib in "${EGO_VENDOR[@]}"; do
+			lib=(${lib})
+			if [[ -n ${lib[2]} ]]; then
+				einfo "Vendoring ${lib[0]} ${lib[2]//\//-}-${lib[1]}.tar.gz"
+				_go-module_dovendor "${vendor_path}" ${lib[0]} \
+					${lib[2]//\//-}-${lib[1]}.tar.gz
+			else
+				einfo "Vendoring ${lib[0]} ${lib[0]//\//-}-${lib[1]}.tar.gz"
+				_go-module_dovendor "${vendor_path}" ${lib[0]} \
+				${lib[0]//\//-}-${lib[1]}.tar.gz
+			fi
+		done
+	fi
+}
+
+# @FUNCTION: go-module_pkg_postinst
+# @DESCRIPTION:
+# Display a warning about security updates for Go programs.
+go-module_pkg_postinst() {
+	ewarn "${PN} is written in the Go programming language."
+	ewarn "Since this language is statically linked, security"
+	ewarn "updates will be handled in individual packages and will be"
+	ewarn "difficult for us to track as a distribution."
+	ewarn "For this reason, please update any go packages asap when new"
+	ewarn "versions enter the tree or go stable if you are running the"
+	ewarn "stable tree."
+}
+
+fi
-- 
2.21.0