Refactor to be friendlier with OpenRC; expand README.

1 files changed, 99 insertions, 0 deletions

diff --git a/drain b/drain
new file mode 100755
index 0000000..c739b12
--- /dev/null
+++ b/drain
@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+# Copyright 2016 Luke Shumaker
+# This work is free. You can redistribute it and/or modify it under the
+# terms of the Do What The Fuck You Want To Public License, Version 2,
+# as published by Sam Hocevar. See the COPYING file for more details.
+
+# The user should not call this script directly.
+
+declare -r workdir=/var/lib/pristine-etc
+
+pacman-etc-name-ver() {
+	LC_ALL=C pacman -Qo /etc | sed 's|^/etc/ is owned by ||'
+}
+
+pacman-all-name-arch() {
+	LC_ALL=C pacman -Qni | tr $'\n' $'\r' | sed 's/\r\r/\n/g' | sed -r 's|(.*\r)?Name\s*:\s*(\S+)(\r.*)?\rArchitecture\s*:\s*(\S+)\r.*|\2 \4|'
+}
+
+commit() (
+	local msg="$1"
+
+	cd "$workdir"
+	if ! [[ -d etc.git ]]; then
+		mkdir -p etc
+		(cd etc && etckeeper init -d "$PWD")
+		mv etc/.git etc.git
+		ln -sr etc.git etc/.git
+	fi
+
+	rm -rf etc/
+
+	local err=false
+	local files=()
+	while IFS=' ' read -r pkgname pkgver arch; do
+		local file=("/var/cache/pacman/pkg/$pkgname-$pkgver-$arch".pkg.tar.*)
+		if ! test -f "$file"; then
+			printf "ERROR: no cached package for %s %s %s\n" "$pkgname" "$pkgver" "$arch"
+			err=true
+		fi
+		files+=("$file")
+	done < <(join <(pacman-etc-name-ver|sort) <(pacman-all-name-arch|sort))
+	if $err; then
+		return 1
+	fi
+	local file
+	for file in "${files[@]}"; do
+		printf " -> %s\n" "$file"
+		bsdtar xpvf "$file" etc
+	done
+
+	ln -sr etc.git etc/.git
+
+	cd etc/
+	etckeeper update-ignore -d "$PWD"
+	if etckeeper unclean -d "$PWD"; then
+		etckeeper commit -d "$PWD" "$msg"
+	fi
+)
+
+pull() (
+	cd /etc
+	git remote add pristine "${workdir}/etc" &>/dev/null || true
+	git fetch pristine
+)
+
+lock() {
+	local fd=$1
+	local file=$2
+	eval "exec $fd>"'"$file"'
+	flock "${@:3}" "$fd"
+}
+
+unlock() {
+	local fd=$1
+	exec {fd}>&-
+}
+
+main() {
+	set -e -o pipefail
+	umask 0022
+
+	if ! lock 7 "${workdir}/etc.lock" -n; then
+		return 0
+	fi
+	while true; do
+		lock 8 "${workdir}/spool.lock"
+		if ! [[ -f "${workdir}/spool" ]]; then
+			return 0
+		fi
+		msg="$(cat "${workdir}/spool")"
+		rm -f "${workdir}/spool"
+		unlock 8
+
+		commit "$msg"
+		pull
+	done
+}
+
+main "$@"