app-portage/prefix-toolkit: new packageprefix-toolkit-0

* For any Gentoo Prefix, provides the 'startprefix' script, and should
provide some 'runprefix' script later on, as inspired in
Bug: https://bugs.gentoo.org/673816

* For base Gentoo Prefix (as in "not stacked"), provides the
'prefix-stack-setup' script, superseding app-portage/prefix-chain-setup,
does force the prefix-stack implit USE flag in the stacked Prefix.
* For stacked Gentoo Prefix (set up using 'prefix-stack-setup'),
provides the toolchain wrapper, superseding sys-apps/prefix-chain-utils.
Bug: https://bugs.gentoo.org/658572

Closes: https://bugs.gentoo.org/509142
Package-Manager: Portage-2.3.51, Repoman-2.3.11
Signed-off-by: Michael Haubenwallner <haubi@gentoo.org>

(cherry picked from commit 84b9f582e8c8db69a3b3677de702c7cc00ac3dab)

7 files changed, 982 insertions, 0 deletions

diff --git a/prefix-stack-ccwrap b/prefix-stack-ccwrap
new file mode 100644
index 0000000..93f7a82
--- /dev/null
+++ b/prefix-stack-ccwrap
@@ -0,0 +1,94 @@
+#!@GENTOO_PORTAGE_BPREFIX@/bin/bash
+
+if [ -r /cygdrive/. ]; then
+	winpath2unix() { cygpath -u "$1"; }
+	unixpath2win() { cygpath -w "$1"; }
+fi
+
+myself=${0##*/} # basename $0
+link_dirs=()
+opts=()
+chost="@GENTOO_PORTAGE_CHOST@"
+prefix="@GENTOO_PORTAGE_EPREFIX@"
+absprefix=${prefix}
+if [[ ${chost} == *"-winnt"* ]]; then
+	# we may get called from windows binary, like pkgdata in dev-libs/icu
+	# in this case, PATH elements get the "/dev/fs/C/WINDOWS/SUA" prefix
+	absprefix=$(winpath2unix "$(unixpath2win "${absprefix}")")
+fi
+[[ ${myself} == *windres* ]] && mode=compile || mode=link
+orig_args=("$@")
+
+for opt in "$@"
+do
+	case "$opt" in
+	-L)
+		link_dirs=("${link_dirs[@]}" "-L$1")
+		shift
+		;;
+	-L*)
+		link_dirs=("${link_dirs[@]}" "${opt}")
+		;;
+	*)
+		case "${opt}" in
+		-v)
+			# -v done right: only use mode version if -v is the _only_
+			# argument on the command line.
+			[[ ${#orig_args[@]} -gt 1 ]] || mode=version
+			;;
+		--version)	mode=version ;;
+		-c|-E|-S)	mode=compile ;;
+		-print-search-dirs) mode=dirs ;;
+		esac
+		opts=("${opts[@]}" "${opt}")
+		;;
+	esac
+done
+
+# remove any path to current prefix, need base prefix only
+new_path=
+save_ifs=$IFS
+IFS=':'
+for p in $PATH
+do
+	IFS=$save_ifs
+	[[ ${p#${absprefix}} != "${p}" ]] && continue
+	if [[ -z "${new_path}" ]]; then
+		new_path="${p}"
+	else
+		new_path="${new_path}:${p}"
+	fi
+done
+IFS=$save_ifs
+
+PATH=${new_path}
+
+# binutils-config's ldwrapper understands '-R' for aix and hpux too.
+# parity (winnt) understands -rpath only ...
+case "${chost}" in
+*-winnt*) rpath_opt="-Wl,-rpath," ;;
+*) rpath_opt="-Wl,-R," ;;
+esac
+
+pfx_link=("-L${prefix}/usr/lib" "-L${prefix}/lib")
+pfx_link_r=("${rpath_opt}${prefix}/lib" "${rpath_opt}${prefix}/usr/lib")
+pfx_comp=("-I${prefix}/include" "-I${prefix}/usr/include")
+
+# ensure we run the right chost program in base prefix
+[[ ${myself} == *-*-*-* ]] || myself=${chost}-${myself#${chost}-}
+
+case "$mode" in
+link)    exec "${myself}" "${link_dirs[@]}" "${pfx_link[@]}" "${opts[@]}" "${pfx_comp[@]}" "${pfx_link_r[@]}" ;;
+compile) exec "${myself}" "${link_dirs[@]}" "${opts[@]}" "${pfx_comp[@]}" ;;
+version) exec "${myself}" "${orig_args[@]}" ;;
+dirs)
+	"${myself}" "${orig_args[@]}" | while read line; do
+		if [[ "${line}" == "libraries: ="* ]]; then
+			echo "libraries: =${prefix}/usr/lib:${prefix}/lib:${line#"libraries: ="}"
+		else
+			echo "${line}"
+		fi
+	done
+	;;
+*)			echo "cannot infer ${myself}'s mode from comamnd line arguments"; exit 1 ;;
+esac
diff --git a/prefix-stack-setup b/prefix-stack-setup
new file mode 100644
index 0000000..28e3efa
--- /dev/null
+++ b/prefix-stack-setup
@@ -0,0 +1,201 @@
+#!@GENTOO_PORTAGE_EPREFIX@/bin/bash
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+PARENT_EPREFIX="@GENTOO_PORTAGE_EPREFIX@"
+PARENT_CHOST="@GENTOO_PORTAGE_CHOST@"
+CHILD_EPREFIX=
+CHILD_PROFILE=
+
+#
+# get ourselfs the functions.sh script for ebegin/eend/etc.
+#
+for f in \
+	/lib/gentoo/functions.sh \
+	/etc/init.d/functions.sh \
+	/sbin/functions.sh \
+; do
+	if [[ -r ${PARENT_EPREFIX}${f} ]] ; then
+		. "${PARENT_EPREFIX}${f}"
+		f=found
+		break
+	fi
+done
+
+if [[ ${f} != found ]] ; then
+	echo "Cannot find Gentoo functions, aborting." >&2
+	exit 1
+fi
+
+for arg in "$@"; do
+	case "${arg}" in
+	--eprefix=*)	CHILD_EPREFIX="${arg#--eprefix=}"	;;
+	--profile=*)	CHILD_PROFILE="${arg#--profile=}"	;;
+
+	--help)
+		einfo "$0 usage:"
+		einfo "  --eprefix=[PATH]       Path to new EPREFIX to create stacked to the prefix"
+		einfo "                         where this script is installed (${PARENT_EPREFIX})"
+		einfo "  --profile=[PATH]       The absolute path to the profile to use. This path"
+		einfo "                         must point to a directory within ${PARENT_EPREFIX}"
+		exit 0
+		;;
+	esac
+done
+
+#
+# sanity check of given values
+#
+
+test -n "${CHILD_EPREFIX}" || { eerror "no eprefix argument given"; exit 1; }
+test -d "${CHILD_EPREFIX}" && { eerror "${CHILD_EPREFIX} already exists"; exit 1; }
+test -n "${CHILD_PROFILE}" || { eerror "no profile argument given"; exit 1; }
+test -d "${CHILD_PROFILE}" || { eerror "${CHILD_PROFILE} does not exist"; exit 1; }
+
+einfo "creating stacked prefix ${CHILD_EPREFIX}"
+
+#
+# functions needed below.
+#
+eend_exit() {
+	eend $1
+	[[ $1 != 0 ]] && exit 1
+}
+
+#
+# create the directories required to bootstrap the least.
+#
+ebegin "creating directory structure"
+(
+	set -e
+	mkdir -p "${CHILD_EPREFIX}"/etc/portage/profile/use.mask
+	mkdir -p "${CHILD_EPREFIX}"/etc/portage/profile/use.force
+	mkdir -p "${CHILD_EPREFIX}"/etc/portage/env
+	mkdir -p "${CHILD_EPREFIX}"/etc/portage/package.env
+	ln -s "${PARENT_EPREFIX}"/etc/portage/repos.conf "${CHILD_EPREFIX}"/etc/portage/repos.conf
+)
+eend_exit $?
+
+#
+# create a make.conf and set PORTDIR and PORTAGE_TMPDIR
+#
+ebegin "creating make.conf"
+(
+	set -e
+	echo "#"
+	echo "# The following values where taken from the parent prefix's"
+	echo "# environment. Feel free to adopt them as you like."
+	echo "#"
+	echo "CFLAGS=\"$(portageq envvar CFLAGS)\""
+	echo "CXXFLAGS=\"$(portageq envvar CXXFLAGS)\""
+	echo "MAKEOPTS=\"$(portageq envvar MAKEOPTS)\""
+	niceness=$(portageq envvar PORTAGE_NICENESS || true)
+	[[ -n ${niceness} ]] &&
+		echo "PORTAGE_NICENESS=\"${niceness}\""
+	echo
+	echo "# Mirrors from parent prefix."
+	echo "GENTOO_MIRRORS=\"$(portageq envvar GENTOO_MIRRORS || true)\""
+	echo
+	echo "# Below comes the prefix-stack setup. Only change things"
+	echo "# if you know exactly what you are doing!"
+	echo "EPREFIX=\"${CHILD_EPREFIX}\""
+	echo "PORTAGE_OVERRIDE_EPREFIX=\"${PARENT_EPREFIX}\""
+	echo "BROOT=\"${PARENT_EPREFIX}\""
+) > "${CHILD_EPREFIX}"/etc/portage/make.conf
+eend_exit $?
+
+ebegin "creating use.mask/prefix-stack"
+printf -- '-%s\n' prefix{,-guest,-stack} > "${CHILD_EPREFIX}"/etc/portage/profile/use.mask/prefix-stack
+eend_exit $?
+
+ebegin "creating use.force/prefix-stack"
+printf -- '%s\n' prefix{,-guest,-stack} > "${CHILD_EPREFIX}"/etc/portage/profile/use.force/prefix-stack
+eend_exit $?
+
+ebegin "creating env/host-cc.conf"
+cat > "${CHILD_EPREFIX}"/etc/portage/env/host-cc.conf <<-EOM
+	CC=${PARENT_CHOST}-gcc
+	CXX=${PARENT_CHOST}-g++
+	EOM
+eend_exit $?
+
+ebegin "creating package.env/prefix-stack"
+cat > "${CHILD_EPREFIX}"/etc/portage/package.env/prefix-stack <<-'EOM'
+	# merge with the parent's chost. this forces the use of the parent
+	# compiler, which generally would be illegal - this is an exception.
+	# This is required for example on winnt, because the wrapper has to
+	# be able to use/resolve symlinks, etc. native winnt binaries miss
+	# that ability, but cygwin binaries don't.
+	sys-devel/gcc-config host-cc.conf
+	sys-apps/gentoo-functions host-cc.conf
+	EOM
+eend_exit $?
+
+#
+# create the make.profile symlinks.
+#
+ebegin "creating make.profile"
+(
+	ln -s "${CHILD_PROFILE}" "${CHILD_EPREFIX}/etc/portage/make.profile"
+)
+eend_exit $?
+
+#
+# adjust permissions of generated files.
+#
+ebegin "adjusting permissions"
+(
+	set -e
+	chmod 644 "${CHILD_EPREFIX}"/etc/portage/make.conf
+	chmod 644 "${CHILD_EPREFIX}"/etc/portage/env/host-cc.conf
+	chmod 644 "${CHILD_EPREFIX}"/etc/portage/package.env/prefix-stack
+)
+eend_exit $?
+
+#
+# now merge some basics.
+#
+ebegin "installing required basic packages"
+(
+	set -e
+	export PORTAGE_CONFIGROOT@=@"${CHILD_EPREFIX}"
+	export EPREFIX@=@"${CHILD_EPREFIX}"
+	export PORTAGE_OVERRIDE_EPREFIX@=@"${PARENT_EPREFIX}"
+
+#	# this -pv is there to avoid the global update output, which is
+#	# there on the first emerge run. (thus, just cosmetics).
+#	emerge --pretend --oneshot --nodeps baselayout-prefix
+
+	# let baselayout create the directories
+	USE@=@"${USE} build" \
+	emerge --verbose --nodeps --oneshot \
+		'>=baselayout-prefix-2.6'
+
+	# Record the prefix-toolkit into @world file, as it provides the
+	# env.d telling the PM to manage this stacked Prefix, but may not
+	# (unlike baselayout) be part of @system set per the profile.
+	emerge --verbose --nodeps \
+		prefix-toolkit
+
+	emerge --verbose --nodeps --oneshot \
+		gentoo-functions \
+		elt-patches \
+		gnuconfig \
+		gcc-config
+
+	# select the stack wrapper profile from gcc-config
+	env -i PORTAGE_CONFIGROOT="${CHILD_EPREFIX}" "$(type -P bash)" "${CHILD_EPREFIX}"/usr/bin/gcc-config 1
+
+	# do this _after_ selecting the correct compiler!
+	emerge --verbose --nodeps --oneshot \
+		libtool
+)
+eend_exit $?
+
+#
+# wow, all ok :)
+#
+ewarn
+ewarn "all done. don't forget to tune ${CHILD_EPREFIX}/etc/portage/make.conf."
+ewarn "to enter the new prefix, run \"${CHILD_EPREFIX}/startprefix\"."
+ewarn
diff --git a/prefix-stack.bash_login b/prefix-stack.bash_login
new file mode 100644
index 0000000..25b12ce
--- /dev/null
+++ b/prefix-stack.bash_login
@@ -0,0 +1,19 @@
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+#
+# In stacked Prefix there is no bash installed, so there is
+# no bash able to load this Prefix' profile as login shell.
+# Instead, you can specify this one as bash rcfile to mimic
+# a bash login shell using this stacked Prefix profile.
+#
+
+if [[ -s '@GENTOO_PORTAGE_EPREFIX@/etc/profile' ]] ; then
+	. '@GENTOO_PORTAGE_EPREFIX@/etc/profile'
+fi
+if [[ -s ~/.bash_profile ]] ; then
+	. ~/.bash_profile
+elif [[ -s ~/.bash_login ]] ; then
+	. ~/.bash_login
+elif [[ -s ~/.profile ]] ; then
+	. ~/.profile
+fi
diff --git a/prefix-stack.bashrc b/prefix-stack.bashrc
new file mode 100644
index 0000000..7e9b951
--- /dev/null
+++ b/prefix-stack.bashrc
@@ -0,0 +1,24 @@
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+#
+# In stacked Prefix there is no bash installed, yet
+# etc/bash/bashrc from base Prefix still is useful.
+#
+
+if [[ $- != *i* ]] ; then
+	# Shell is non-interactive, bashrc does not apply
+	return
+fi
+
+if [[ -r @GENTOO_PORTAGE_BPREFIX@/etc/bash/bashrc ]] ; then
+	source '@GENTOO_PORTAGE_BPREFIX@/etc/bash/bashrc'
+	# only if base Prefix does have an etc/bash/bashrc, we also
+	# run bashrc snippets provided by packages in stacked Prefix
+	for sh in '@GENTOO_PORTAGE_EPREFIX@'/etc/bash/bashrc.d/* ; do
+		[[ -r ${sh} ]] && source "${sh}"
+	done
+	unset sh
+else
+	# etc/profile does expect etc/bash/bashrc to set PS1
+	PS1='\u@\h \w \$ '
+fi
diff --git a/prefix-stack.envd.99stack b/prefix-stack.envd.99stack
new file mode 100644
index 0000000..accb12f
--- /dev/null
+++ b/prefix-stack.envd.99stack
@@ -0,0 +1,3 @@
+PKG_CONFIG_PATH@=@"@GENTOO_PORTAGE_EPREFIX@/usr/lib/pkgconfig:@GENTOO_PORTAGE_EPREFIX@/usr/share/pkgconfig"
+PORTAGE_CONFIGROOT@=@"@GENTOO_PORTAGE_EPREFIX@"
+EPREFIX@=@"@GENTOO_PORTAGE_EPREFIX@"
diff --git a/prefix-toolkit-0.ebuild b/prefix-toolkit-0.ebuild
new file mode 100644
index 0000000..23f4845
--- /dev/null
+++ b/prefix-toolkit-0.ebuild
@@ -0,0 +1,565 @@
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=7
+
+DESCRIPTION="Utilities for users of Gentoo Prefix"
+HOMEPAGE="https://prefix.gentoo.org/"
+SRC_URI=""
+
+LICENSE="GPL-3"
+SLOT="0"
+
+[[ ${PV} == 9999 ]] ||
+KEYWORDS="~x64-cygwin ~amd64-linux ~x86-linux ~x86-winnt"
+
+DEPEND=""
+RDEPEND="
+	>sys-apps/portage-2.3.62
+	!app-portage/prefix-chain-setup
+	!sys-apps/prefix-chain-utils
+	prefix-stack? (
+		>=sys-apps/baselayout-prefix-2.6
+	)
+"
+
+S="${WORKDIR}"
+
+my_unpack() {
+	local infile=$1
+	local outfile=${2:-${infile}}
+	ebegin "extracting ${outfile}"
+	sed -ne "/^: ${infile} /,/EOIN/{/EOIN/d;p}" "${EBUILD}" \
+		> "${outfile}" || die "Failed to unpack ${outfile}"
+	eend $?
+}
+
+src_unpack() {
+	if use prefix-stack ; then
+		my_unpack prefix-stack.bash_login
+		my_unpack prefix-stack.bashrc
+		my_unpack prefix-stack.envd.99stack
+		my_unpack prefix-stack-ccwrap
+		local editor pager
+		for editor in "${EDITOR}" {"${EPREFIX}","${BROOT}"}/bin/nano
+		do
+			[[ -x ${editor} ]] || continue
+		done
+		for pager in "${PAGER}" {"${EPREFIX}","${BROOT}"}/usr/bin/less
+		do
+			[[ -x ${pager} ]] || continue
+		done
+		printf '%s\n' "EDITOR=\"${editor}\"" "PAGER=\"${pager}\"" > 000fallback
+	else
+		my_unpack prefix-stack-setup
+	fi
+	my_unpack startprefix
+}
+
+my_prefixify() {
+	local ebash eenv
+	if use prefix-stack ; then
+		ebash="${BROOT}/bin/bash"
+		eenv="${BROOT}/usr/bin/env"
+	else
+		ebash="${EPREFIX}/bin/bash"
+		eenv="${EPREFIX}/usr/bin/env"
+	fi
+
+	# the @=@ prevents repoman from believing we set readonly vars
+	sed -e "s,@GENTOO_PORTAGE_BPREFIX@,${BROOT},g" \
+		-e "s,@GENTOO_PORTAGE_EPREFIX@,${EPREFIX},g" \
+		-e "s,@GENTOO_PORTAGE_CHOST@,${CHOST},g" \
+		-e "s,@GENTOO_PORTAGE_EBASH@,${ebash},g" \
+		-e "s,@GENTOO_PORTAGE_EENV@,${eenv},g" \
+		-e "s,@=@,=,g" \
+		-i "$@" || die
+}
+
+src_configure() {
+	# do not eprefixify during unpack, to allow userpatches to apply
+	my_prefixify *
+}
+
+src_install-prefix-stack-ccwrap() {
+	# install toolchain wrapper.
+	local wrapperdir=/usr/${CHOST}/gcc-bin/${CHOST}-${PN}/${PV}
+	local wrappercfg=${CHOST}-${P}
+
+	exeinto $wrapperdir
+	doexe prefix-stack-ccwrap
+
+	local cc
+	for cc in \
+		gcc \
+		g++ \
+		cpp \
+		c++ \
+		windres \
+	; do
+		dosym prefix-stack-ccwrap $wrapperdir/${CHOST}-${cc}
+		dosym ${CHOST}-${cc} $wrapperdir/${cc}
+	done
+
+	# LDPATH is required to keep gcc-config happy :(
+	cat > ./${wrappercfg} <<-EOF
+		GCC_PATH="${EPREFIX}$wrapperdir"
+		LDPATH="${EPREFIX}$wrapperdir"
+		EOF
+
+	insinto /etc/env.d/gcc
+	doins ./${wrappercfg}
+}
+
+src_install() {
+	if use prefix-stack; then
+		src_install-prefix-stack-ccwrap
+		insinto /etc
+		doins prefix-stack.bash_login
+		insinto /etc/bash
+		newins prefix-stack.bashrc bashrc
+		newenvd prefix-stack.envd.99stack 99stack
+		doenvd 000fallback
+	else
+		dobin prefix-stack-setup
+	fi
+	exeinto /
+	doexe startprefix
+}
+
+return 0
+
+: startprefix <<'EOIN'
+#!@GENTOO_PORTAGE_EBASH@
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# Fabian Groffen <grobian@gentoo.org> -- 2007-03-10
+# Enters the prefix environment by starting a login shell from the
+# prefix.  The SHELL environment variable is elevated in order to make
+# applications that start login shells to work, such as `screen`.
+
+# if you come from a substantially polluted environment (another
+# Prefix), a cleanup as follows resolves most oddities I've ever seen:
+# env -i HOME=$HOME TERM=$TERM USER=$USER $SHELL -l
+# hence this script starts the Prefix shell like this
+
+if [[ ${SHELL#@GENTOO_PORTAGE_EPREFIX@} != ${SHELL} ]]
+then
+	echo "You appear to be in prefix already (SHELL=${SHELL})" > /dev/stderr
+	exit -1
+elif [[ ${SHELL#@GENTOO_PORTAGE_BPREFIX@} != ${SHELL} ]] &&
+	 [[ ${EPREFIX-unset} == '@GENTOO_PORTAGE_EPREFIX@' ]]
+then
+	echo "You appear to be in stacked prefix already (EPREFIX=${EPREFIX})" > /dev/stderr
+	exit -1
+fi
+
+# What is our prefix?
+EPREFIX@=@'@GENTOO_PORTAGE_EPREFIX@'
+BPREFIX@=@'@GENTOO_PORTAGE_BPREFIX@'
+
+# not all systems have the same location for shells, however what it
+# boils down to, is that we need to know what the shell is, and then we
+# can find it in the bin dir of our prefix
+for SHELL in \
+	"${EPREFIX}/bin/${SHELL##*/}" \
+	"${BPREFIX}/bin/${SHELL##*/}" \
+	${SHELL##*/}
+do
+	[[ ${SHELL} == */* && -x ${SHELL} ]] && break
+done
+
+# check if the shell exists
+if [[ ${SHELL} != */* ]]
+then
+	echo "Failed to find the Prefix shell, this is probably" > /dev/stderr
+	echo "because you didn't emerge the shell ${SHELL}" > /dev/stderr
+	exit 1
+fi
+
+# set the prefix shell in the environment
+export SHELL
+
+# give a small notice
+echo "Entering Gentoo Prefix ${EPREFIX}"
+# start the login shell, clean the entire environment but what's needed
+RETAIN="HOME=$HOME TERM=$TERM USER=$USER SHELL=$SHELL"
+# PROFILEREAD is necessary on SUSE not to wipe the env on shell start
+[[ -n ${PROFILEREAD} ]] && RETAIN+=" PROFILEREAD=$PROFILEREAD"
+# ssh-agent is handy to keep, of if set, inherit it
+[[ -n ${SSH_AUTH_SOCK} ]] && RETAIN+=" SSH_AUTH_SOCK=$SSH_AUTH_SOCK"
+# if we're on some X terminal, makes sense to inherit that too
+[[ -n ${DISPLAY} ]] && RETAIN+=" DISPLAY=$DISPLAY"
+# do it!
+if [[ ${SHELL#${EPREFIX}} != ${SHELL} ]] ; then
+	'@GENTOO_PORTAGE_EENV@' -i $RETAIN $SHELL -l
+elif [[ ' bash ' == *" ${SHELL##*/} "* ]] ; then
+	# shell coming from different prefix would load it's own
+	# etc/profile upon -l, so we have to override
+	'@GENTOO_PORTAGE_EENV@' -i ${RETAIN} "${SHELL}" --rcfile "${EPREFIX}"/etc/prefix-stack.bash_login -i
+else
+	echo "Only bash is supported with stacked Prefix (you have ${SHELL##*/}), sorry!" > /dev/stderr
+	exit 1
+fi
+# and leave a message when we exit... the shell might return non-zero
+# without having real problems, so don't send alarming messages about
+# that
+echo "Leaving Gentoo Prefix with exit status $?"
+EOIN
+
+: prefix-stack.bashrc <<'EOIN'
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+#
+# In stacked Prefix there is no bash installed, yet
+# etc/bash/bashrc from base Prefix still is useful.
+#
+
+if [[ $- != *i* ]] ; then
+	# Shell is non-interactive, bashrc does not apply
+	return
+fi
+
+if [[ -r @GENTOO_PORTAGE_BPREFIX@/etc/bash/bashrc ]] ; then
+	source '@GENTOO_PORTAGE_BPREFIX@/etc/bash/bashrc'
+	# only if base Prefix does have an etc/bash/bashrc, we also
+	# run bashrc snippets provided by packages in stacked Prefix
+	for sh in '@GENTOO_PORTAGE_EPREFIX@'/etc/bash/bashrc.d/* ; do
+		[[ -r ${sh} ]] && source "${sh}"
+	done
+	unset sh
+else
+	# etc/profile does expect etc/bash/bashrc to set PS1
+	PS1='\u@\h \w \$ '
+fi
+EOIN
+
+: prefix-stack.bash_login <<'EOIN'
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+#
+# In stacked Prefix there is no bash installed, so there is
+# no bash able to load this Prefix' profile as login shell.
+# Instead, you can specify this one as bash rcfile to mimic
+# a bash login shell using this stacked Prefix profile.
+#
+
+if [[ -s '@GENTOO_PORTAGE_EPREFIX@/etc/profile' ]] ; then
+	. '@GENTOO_PORTAGE_EPREFIX@/etc/profile'
+fi
+if [[ -s ~/.bash_profile ]] ; then
+	. ~/.bash_profile
+elif [[ -s ~/.bash_login ]] ; then
+	. ~/.bash_login
+elif [[ -s ~/.profile ]] ; then
+	. ~/.profile
+fi
+EOIN
+
+: prefix-stack.envd.99stack <<'EOIN'
+PKG_CONFIG_PATH@=@"@GENTOO_PORTAGE_EPREFIX@/usr/lib/pkgconfig:@GENTOO_PORTAGE_EPREFIX@/usr/share/pkgconfig"
+PORTAGE_CONFIGROOT@=@"@GENTOO_PORTAGE_EPREFIX@"
+EPREFIX@=@"@GENTOO_PORTAGE_EPREFIX@"
+EOIN
+
+: prefix-stack-setup <<'EOIN'
+#!@GENTOO_PORTAGE_EPREFIX@/bin/bash
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+PARENT_EPREFIX="@GENTOO_PORTAGE_EPREFIX@"
+PARENT_CHOST="@GENTOO_PORTAGE_CHOST@"
+CHILD_EPREFIX=
+CHILD_PROFILE=
+
+#
+# get ourselfs the functions.sh script for ebegin/eend/etc.
+#
+for f in \
+	/lib/gentoo/functions.sh \
+	/etc/init.d/functions.sh \
+	/sbin/functions.sh \
+; do
+	if [[ -r ${PARENT_EPREFIX}${f} ]] ; then
+		. "${PARENT_EPREFIX}${f}"
+		f=found
+		break
+	fi
+done
+
+if [[ ${f} != found ]] ; then
+	echo "Cannot find Gentoo functions, aborting." >&2
+	exit 1
+fi
+
+for arg in "$@"; do
+	case "${arg}" in
+	--eprefix=*)	CHILD_EPREFIX="${arg#--eprefix=}"	;;
+	--profile=*)	CHILD_PROFILE="${arg#--profile=}"	;;
+
+	--help)
+		einfo "$0 usage:"
+		einfo "  --eprefix=[PATH]       Path to new EPREFIX to create stacked to the prefix"
+		einfo "                         where this script is installed (${PARENT_EPREFIX})"
+		einfo "  --profile=[PATH]       The absolute path to the profile to use. This path"
+		einfo "                         must point to a directory within ${PARENT_EPREFIX}"
+		exit 0
+		;;
+	esac
+done
+
+#
+# sanity check of given values
+#
+
+test -n "${CHILD_EPREFIX}" || { eerror "no eprefix argument given"; exit 1; }
+test -d "${CHILD_EPREFIX}" && { eerror "${CHILD_EPREFIX} already exists"; exit 1; }
+test -n "${CHILD_PROFILE}" || { eerror "no profile argument given"; exit 1; }
+test -d "${CHILD_PROFILE}" || { eerror "${CHILD_PROFILE} does not exist"; exit 1; }
+
+einfo "creating stacked prefix ${CHILD_EPREFIX}"
+
+#
+# functions needed below.
+#
+eend_exit() {
+	eend $1
+	[[ $1 != 0 ]] && exit 1
+}
+
+#
+# create the directories required to bootstrap the least.
+#
+ebegin "creating directory structure"
+(
+	set -e
+	mkdir -p "${CHILD_EPREFIX}"/etc/portage/profile/use.mask
+	mkdir -p "${CHILD_EPREFIX}"/etc/portage/profile/use.force
+	mkdir -p "${CHILD_EPREFIX}"/etc/portage/env
+	mkdir -p "${CHILD_EPREFIX}"/etc/portage/package.env
+	ln -s "${PARENT_EPREFIX}"/etc/portage/repos.conf "${CHILD_EPREFIX}"/etc/portage/repos.conf
+)
+eend_exit $?
+
+#
+# create a make.conf and set PORTDIR and PORTAGE_TMPDIR
+#
+ebegin "creating make.conf"
+(
+	set -e
+	echo "#"
+	echo "# The following values where taken from the parent prefix's"
+	echo "# environment. Feel free to adopt them as you like."
+	echo "#"
+	echo "CFLAGS=\"$(portageq envvar CFLAGS)\""
+	echo "CXXFLAGS=\"$(portageq envvar CXXFLAGS)\""
+	echo "MAKEOPTS=\"$(portageq envvar MAKEOPTS)\""
+	niceness=$(portageq envvar PORTAGE_NICENESS || true)
+	[[ -n ${niceness} ]] &&
+		echo "PORTAGE_NICENESS=\"${niceness}\""
+	echo
+	echo "# Mirrors from parent prefix."
+	echo "GENTOO_MIRRORS=\"$(portageq envvar GENTOO_MIRRORS || true)\""
+	echo
+	echo "# Below comes the prefix-stack setup. Only change things"
+	echo "# if you know exactly what you are doing!"
+	echo "EPREFIX=\"${CHILD_EPREFIX}\""
+	echo "PORTAGE_OVERRIDE_EPREFIX=\"${PARENT_EPREFIX}\""
+	echo "BROOT=\"${PARENT_EPREFIX}\""
+) > "${CHILD_EPREFIX}"/etc/portage/make.conf
+eend_exit $?
+
+ebegin "creating use.mask/prefix-stack"
+printf -- '-%s\n' prefix{,-guest,-stack} > "${CHILD_EPREFIX}"/etc/portage/profile/use.mask/prefix-stack
+eend_exit $?
+
+ebegin "creating use.force/prefix-stack"
+printf -- '%s\n' prefix{,-guest,-stack} > "${CHILD_EPREFIX}"/etc/portage/profile/use.force/prefix-stack
+eend_exit $?
+
+ebegin "creating env/host-cc.conf"
+cat > "${CHILD_EPREFIX}"/etc/portage/env/host-cc.conf <<-EOM
+	CC=${PARENT_CHOST}-gcc
+	CXX=${PARENT_CHOST}-g++
+	EOM
+eend_exit $?
+
+ebegin "creating package.env/prefix-stack"
+cat > "${CHILD_EPREFIX}"/etc/portage/package.env/prefix-stack <<-'EOM'
+	# merge with the parent's chost. this forces the use of the parent
+	# compiler, which generally would be illegal - this is an exception.
+	# This is required for example on winnt, because the wrapper has to
+	# be able to use/resolve symlinks, etc. native winnt binaries miss
+	# that ability, but cygwin binaries don't.
+	sys-devel/gcc-config host-cc.conf
+	sys-apps/gentoo-functions host-cc.conf
+	EOM
+eend_exit $?
+
+#
+# create the make.profile symlinks.
+#
+ebegin "creating make.profile"
+(
+	ln -s "${CHILD_PROFILE}" "${CHILD_EPREFIX}/etc/portage/make.profile"
+)
+eend_exit $?
+
+#
+# adjust permissions of generated files.
+#
+ebegin "adjusting permissions"
+(
+	set -e
+	chmod 644 "${CHILD_EPREFIX}"/etc/portage/make.conf
+	chmod 644 "${CHILD_EPREFIX}"/etc/portage/env/host-cc.conf
+	chmod 644 "${CHILD_EPREFIX}"/etc/portage/package.env/prefix-stack
+)
+eend_exit $?
+
+#
+# now merge some basics.
+#
+ebegin "installing required basic packages"
+(
+	set -e
+	export PORTAGE_CONFIGROOT@=@"${CHILD_EPREFIX}"
+	export EPREFIX@=@"${CHILD_EPREFIX}"
+	export PORTAGE_OVERRIDE_EPREFIX@=@"${PARENT_EPREFIX}"
+
+#	# this -pv is there to avoid the global update output, which is
+#	# there on the first emerge run. (thus, just cosmetics).
+#	emerge --pretend --oneshot --nodeps baselayout-prefix
+
+	# let baselayout create the directories
+	USE@=@"${USE} build" \
+	emerge --verbose --nodeps --oneshot \
+		'>=baselayout-prefix-2.6'
+
+	# Record the prefix-toolkit into @world file, as it provides the
+	# env.d telling the PM to manage this stacked Prefix, but may not
+	# (unlike baselayout) be part of @system set per the profile.
+	emerge --verbose --nodeps \
+		prefix-toolkit
+
+	emerge --verbose --nodeps --oneshot \
+		gentoo-functions \
+		elt-patches \
+		gnuconfig \
+		gcc-config
+
+	# select the stack wrapper profile from gcc-config
+	env -i PORTAGE_CONFIGROOT="${CHILD_EPREFIX}" "$(type -P bash)" "${CHILD_EPREFIX}"/usr/bin/gcc-config 1
+
+	# do this _after_ selecting the correct compiler!
+	emerge --verbose --nodeps --oneshot \
+		libtool
+)
+eend_exit $?
+
+#
+# wow, all ok :)
+#
+ewarn
+ewarn "all done. don't forget to tune ${CHILD_EPREFIX}/etc/portage/make.conf."
+ewarn "to enter the new prefix, run \"${CHILD_EPREFIX}/startprefix\"."
+ewarn
+EOIN
+
+: prefix-stack-ccwrap <<'EOIN'
+#!@GENTOO_PORTAGE_BPREFIX@/bin/bash
+
+if [ -r /cygdrive/. ]; then
+	winpath2unix() { cygpath -u "$1"; }
+	unixpath2win() { cygpath -w "$1"; }
+fi
+
+myself=${0##*/} # basename $0
+link_dirs=()
+opts=()
+chost="@GENTOO_PORTAGE_CHOST@"
+prefix="@GENTOO_PORTAGE_EPREFIX@"
+absprefix=${prefix}
+if [[ ${chost} == *"-winnt"* ]]; then
+	# we may get called from windows binary, like pkgdata in dev-libs/icu
+	# in this case, PATH elements get the "/dev/fs/C/WINDOWS/SUA" prefix
+	absprefix=$(winpath2unix "$(unixpath2win "${absprefix}")")
+fi
+[[ ${myself} == *windres* ]] && mode=compile || mode=link
+orig_args=("$@")
+
+for opt in "$@"
+do
+	case "$opt" in
+	-L)
+		link_dirs=("${link_dirs[@]}" "-L$1")
+		shift
+		;;
+	-L*)
+		link_dirs=("${link_dirs[@]}" "${opt}")
+		;;
+	*)
+		case "${opt}" in
+		-v)
+			# -v done right: only use mode version if -v is the _only_
+			# argument on the command line.
+			[[ ${#orig_args[@]} -gt 1 ]] || mode=version
+			;;
+		--version)	mode=version ;;
+		-c|-E|-S)	mode=compile ;;
+		-print-search-dirs) mode=dirs ;;
+		esac
+		opts=("${opts[@]}" "${opt}")
+		;;
+	esac
+done
+
+# remove any path to current prefix, need base prefix only
+new_path=
+save_ifs=$IFS
+IFS=':'
+for p in $PATH
+do
+	IFS=$save_ifs
+	[[ ${p#${absprefix}} != "${p}" ]] && continue
+	if [[ -z "${new_path}" ]]; then
+		new_path="${p}"
+	else
+		new_path="${new_path}:${p}"
+	fi
+done
+IFS=$save_ifs
+
+PATH=${new_path}
+
+# binutils-config's ldwrapper understands '-R' for aix and hpux too.
+# parity (winnt) understands -rpath only ...
+case "${chost}" in
+*-winnt*) rpath_opt="-Wl,-rpath," ;;
+*) rpath_opt="-Wl,-R," ;;
+esac
+
+pfx_link=("-L${prefix}/usr/lib" "-L${prefix}/lib")
+pfx_link_r=("${rpath_opt}${prefix}/lib" "${rpath_opt}${prefix}/usr/lib")
+pfx_comp=("-I${prefix}/include" "-I${prefix}/usr/include")
+
+# ensure we run the right chost program in base prefix
+[[ ${myself} == *-*-*-* ]] || myself=${chost}-${myself#${chost}-}
+
+case "$mode" in
+link)    exec "${myself}" "${link_dirs[@]}" "${pfx_link[@]}" "${opts[@]}" "${pfx_comp[@]}" "${pfx_link_r[@]}" ;;
+compile) exec "${myself}" "${link_dirs[@]}" "${opts[@]}" "${pfx_comp[@]}" ;;
+version) exec "${myself}" "${orig_args[@]}" ;;
+dirs)
+	"${myself}" "${orig_args[@]}" | while read line; do
+		if [[ "${line}" == "libraries: ="* ]]; then
+			echo "libraries: =${prefix}/usr/lib:${prefix}/lib:${line#"libraries: ="}"
+		else
+			echo "${line}"
+		fi
+	done
+	;;
+*)			echo "cannot infer ${myself}'s mode from comamnd line arguments"; exit 1 ;;
+esac
+EOIN
diff --git a/startprefix b/startprefix
new file mode 100644
index 0000000..89ce10f
--- /dev/null
+++ b/startprefix
@@ -0,0 +1,76 @@
+#!@GENTOO_PORTAGE_EBASH@
+# Copyright 1999-2019 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# Fabian Groffen <grobian@gentoo.org> -- 2007-03-10
+# Enters the prefix environment by starting a login shell from the
+# prefix.  The SHELL environment variable is elevated in order to make
+# applications that start login shells to work, such as `screen`.
+
+# if you come from a substantially polluted environment (another
+# Prefix), a cleanup as follows resolves most oddities I've ever seen:
+# env -i HOME=$HOME TERM=$TERM USER=$USER $SHELL -l
+# hence this script starts the Prefix shell like this
+
+if [[ ${SHELL#@GENTOO_PORTAGE_EPREFIX@} != ${SHELL} ]]
+then
+	echo "You appear to be in prefix already (SHELL=${SHELL})" > /dev/stderr
+	exit -1
+elif [[ ${SHELL#@GENTOO_PORTAGE_BPREFIX@} != ${SHELL} ]] &&
+	 [[ ${EPREFIX-unset} == '@GENTOO_PORTAGE_EPREFIX@' ]]
+then
+	echo "You appear to be in stacked prefix already (EPREFIX=${EPREFIX})" > /dev/stderr
+	exit -1
+fi
+
+# What is our prefix?
+EPREFIX@=@'@GENTOO_PORTAGE_EPREFIX@'
+BPREFIX@=@'@GENTOO_PORTAGE_BPREFIX@'
+
+# not all systems have the same location for shells, however what it
+# boils down to, is that we need to know what the shell is, and then we
+# can find it in the bin dir of our prefix
+for SHELL in \
+	"${EPREFIX}/bin/${SHELL##*/}" \
+	"${BPREFIX}/bin/${SHELL##*/}" \
+	${SHELL##*/}
+do
+	[[ ${SHELL} == */* && -x ${SHELL} ]] && break
+done
+
+# check if the shell exists
+if [[ ${SHELL} != */* ]]
+then
+	echo "Failed to find the Prefix shell, this is probably" > /dev/stderr
+	echo "because you didn't emerge the shell ${SHELL}" > /dev/stderr
+	exit 1
+fi
+
+# set the prefix shell in the environment
+export SHELL
+
+# give a small notice
+echo "Entering Gentoo Prefix ${EPREFIX}"
+# start the login shell, clean the entire environment but what's needed
+RETAIN="HOME=$HOME TERM=$TERM USER=$USER SHELL=$SHELL"
+# PROFILEREAD is necessary on SUSE not to wipe the env on shell start
+[[ -n ${PROFILEREAD} ]] && RETAIN+=" PROFILEREAD=$PROFILEREAD"
+# ssh-agent is handy to keep, of if set, inherit it
+[[ -n ${SSH_AUTH_SOCK} ]] && RETAIN+=" SSH_AUTH_SOCK=$SSH_AUTH_SOCK"
+# if we're on some X terminal, makes sense to inherit that too
+[[ -n ${DISPLAY} ]] && RETAIN+=" DISPLAY=$DISPLAY"
+# do it!
+if [[ ${SHELL#${EPREFIX}} != ${SHELL} ]] ; then
+	'@GENTOO_PORTAGE_EENV@' -i $RETAIN $SHELL -l
+elif [[ ' bash ' == *" ${SHELL##*/} "* ]] ; then
+	# shell coming from different prefix would load it's own
+	# etc/profile upon -l, so we have to override
+	'@GENTOO_PORTAGE_EENV@' -i ${RETAIN} "${SHELL}" --rcfile "${EPREFIX}"/etc/prefix-stack.bash_login -i
+else
+	echo "Only bash is supported with stacked Prefix (you have ${SHELL##*/}), sorry!" > /dev/stderr
+	exit 1
+fi
+# and leave a message when we exit... the shell might return non-zero
+# without having real problems, so don't send alarming messages about
+# that
+echo "Leaving Gentoo Prefix with exit status $?"