sys-apps/nix: new package, The Purely Functional Package Manager

Nix is a source-based package manager with strong support for
binary packages. It uses multiple tricks to make package
source dependencies robust:

- nix installs every package into it's own --prefix=.
  Example: /nix/store/xsqz79bzclgrgnnlffp3qa0g4wnbcrp1-firefox-50.1.0
- nix builds packages with PATH (and similar) only including explicitly
  listed depends. This eliminates automagic dependency.
- nix tracks full environment where package was built.
  Once environment changes new package needs to be built.

That's how you install firefox just for your current user:

    $ nix-env -iA nixpkgs.firefox

Package-Manager: Portage-2.3.3, Repoman-2.3.1

sys-apps/nix/Manifest

@@ -0,0 +1 @@
+DIST nix-1.11.6.tar.xz 621796 SHA256 e729d55a9276756108a56bc1cbe2e182ee2e4be2b59b1c77d5f0e3edd879b2a3 SHA512 a2d9eed52d6791e0649e3e456c8751ab3055573def110ffbf9645d2106313adf6c3868c0ecd69e5ba95c7a742c6fb92f69722adf7381584f7c2c4efe4b400d65 WHIRLPOOL 262ce049d9cf616aaa4d5bd612accee827f04b684d1ee36b3b63bfc2004fb9d1f19e1455196183fc259b81913d318acb519fa79271b4915369780efb8f02200b

sys-apps/nix/files/60nix-remote-daemon

@@ -0,0 +1 @@
+NIX_REMOTE="daemon"

sys-apps/nix/files/nix-1.11.6-per-user.patch

@@ -0,0 +1,11 @@
+By default created symlink poins to a directory not accessible by user.
+Make a symlink the same way NixOS does symlinking.
+diff --git a/scripts/nix-profile.sh.in b/scripts/nix-profile.sh.in
+index 672d1f0..e3b0978 100644
+--- a/scripts/nix-profile.sh.in
++++ b/scripts/nix-profile.sh.in
+@@ -6,3 +6,3 @@ if [ -n "$HOME" ]; then
+         echo "creating $NIX_LINK" >&2
+-        _NIX_DEF_LINK=@localstatedir@/nix/profiles/default
++        _NIX_DEF_LINK=@localstatedir@/nix/profiles/per-user/$USER/profile
+         @coreutils@/ln -s "$_NIX_DEF_LINK" "$NIX_LINK"

sys-apps/nix/files/nix-1.11.6-systemd.patch

@@ -0,0 +1,10 @@
+Make 'nix-daemon' a goof unit for 'systemctl enable nix-daemon.service'.
+diff --git a/misc/systemd/nix-daemon.service.in b/misc/systemd/nix-daemon.service.in
+index 5fc04a3..2565520 100644
+--- a/misc/systemd/nix-daemon.service.in
++++ b/misc/systemd/nix-daemon.service.in
+@@ -9 +9,4 @@ ExecStart=@@bindir@/nix-daemon nix-daemon --daemon
+ KillMode=process
++
++[Install]
++WantedBy=multi-user.target

sys-apps/nix/files/nix-daemon.initd

@@ -0,0 +1,16 @@
+#!/sbin/openrc-run
+# Copyright 1999-2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+# $Id$
+
+start() {
+	ebegin "Starting ${SVCNAME}"
+	start-stop-daemon --start --quiet --background --exec /usr/bin/nix-daemon
+	eend ${?}
+}
+
+stop() {
+	ebegin "Stopping ${SVCNAME}"
+	start-stop-daemon --stop --quiet --exec /usr/bin/nix-daemon
+	eend ${?}
+}

sys-apps/nix/metadata.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+	<maintainer type="person">
+		<email>slyfox@gentoo.org</email>
+		<name>Sergei Trofimovich</name>
+	</maintainer>
+	<maintainer type="project">
+		<email>haskell@gentoo.org</email>
+		<name>Gentoo Haskell</name>
+	</maintainer>
+	<use>
+		<flag name="etc_profile">Install /etc/profile.d/ entry to inject nix support for all users.</flag>
+		<flag name="gc">Enable garbage collection in the Nix expression evaluator (use <pkg>dev-libs/boehm-gc</pkg>).</flag>
+		<flag name="sodium">Use <pkg>dev-libs/libsodium</pkg> for cryptography</flag>
+	</use>
+</pkgmetadata>

sys-apps/nix/nix-1.11.6-r1.ebuild

@@ -0,0 +1,114 @@
+# Copyright 1999-2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+# $Id$
+
+EAPI=6
+
+inherit readme.gentoo-r1 user
+
+DESCRIPTION="A purely functional package manager"
+HOMEPAGE="https://nixos.org/nix"
+
+SRC_URI="http://nixos.org/releases/${PN}/${P}/${P}.tar.xz"
+LICENSE="LGPL-2.1"
+SLOT="0"
+KEYWORDS="~amd64 ~x86"
+IUSE="+etc_profile +gc doc sodium"
+
+RDEPEND="
+	app-arch/bzip2
+	app-arch/xz-utils
+	dev-db/sqlite
+	dev-libs/openssl:0=
+	net-misc/curl
+	sys-libs/zlib
+	gc? ( dev-libs/boehm-gc )
+	doc? ( dev-libs/libxml2
+		dev-libs/libxslt
+		app-text/docbook-xsl-stylesheets
+	)
+	sodium? ( dev-libs/libsodium )
+	dev-lang/perl:=
+	dev-perl/DBD-SQLite
+	dev-perl/WWW-Curl
+	dev-perl/DBI
+"
+DEPEND="${RDEPEND}
+	>=sys-devel/bison-2.6
+	>=sys-devel/flex-2.5.35
+	virtual/perl-ExtUtils-ParseXS
+"
+
+PATCHES=(
+	"${FILESDIR}"/${P}-systemd.patch
+	"${FILESDIR}"/${P}-per-user.patch
+)
+
+DISABLE_AUTOFORMATTING=yes
+DOC_CONTENTS=" Quick start user guide on Gentoo:
+
+[as root] enable nix-daemon service:
+	[systemd] # systemctl enable nix-daemon
+	[openrc]  # rc-update add nix-daemon
+[as an user] relogin to get environment and profile update
+[as an user] fetch nixpkgs update:
+	\$ nix-channel --update
+[as an user] install nix packages:
+	\$ nix-env -i mc
+[as an user] configure environment:
+	Somewhere in .bash_profile you might want to set
+	LOCALE_ARCHIVE=\$HOME/.nix-profile/lib/locale/locale-archive
+	but please read https://github.com/NixOS/nixpkgs/issues/21820
+
+Next steps:
+	nix package manager user manual: http://nixos.org/nix/manual/
+"
+
+pkg_setup() {
+	enewgroup nixbld 30000
+	for i in {1..10}; do
+		# we list 'nixbld' twice to
+		# both assign a primary group for user
+		# and add an user to /etc/group
+		enewuser nixbld${i} $((30000 +$i)) -1 /var/empty nixbld,nixbld
+	done
+}
+
+src_configure() {
+	econf \
+		--localstatedir="${EPREFIX}"/nix/var \
+		$(use_enable gc)
+}
+
+src_install() {
+	# TODO: emacs highlighter
+	default
+
+	readme.gentoo_create_doc
+
+	# here we an eager variant of something that
+	# is lazily done by  nix-daemo and root nix-env
+
+	# TODO: will need a tweak for prefix
+	keepdir             /nix/store
+	fowners root:nixbld /nix/store
+	fperms 1775         /nix/store
+
+	keepdir             /nix/var/nix/profiles/per-user
+	fperms 1777         /nix/var/nix/profiles/per-user
+
+	doenvd "${FILESDIR}"/60nix-remote-daemon
+	newinitd "${FILESDIR}"/nix-daemon.initd nix-daemon
+
+	if ! use etc_profile; then
+		rm "${ED}"/etc/profile.d/nix.sh || die
+	fi
+}
+
+pkg_postinst() {
+	if ! use etc_profile; then
+		ewarn "${EROOT}etc/profile.d/nix.sh was removed (due to USE=-etc_profile)."
+	fi
+
+	readme.gentoo_print_elog
+}