Add binfmt service to sysinit runlevel

This makes binfmt processing behave like tmpfiles processing which
follows the same specification as systemd.

This fixes #48.

X-Gentoo-Bug: 545162
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=545162

sh/.gitignore

@@ -8,3 +8,4 @@ init-early.sh
 rc-cgroup.sh
 tmpfiles.sh
 migrate-to-run.sh
+binfmt.sh

sh/Makefile

@@ -12,9 +12,9 @@ include ${MK}/os.mk
 SRCS-FreeBSD=
 BIN-FreeBSD=
 
-SRCS-Linux=	cgroup-release-agent.sh.in init-early.sh.in migrate-to-run.sh.in \
-	rc-cgroup.sh.in
-BIN-Linux=	cgroup-release-agent.sh init-early.sh migrate-to-run.sh \
+SRCS-Linux=	binfmt.sh.in cgroup-release-agent.sh.in init-early.sh.in \
+	migrate-to-run.sh.in rc-cgroup.sh.in
+BIN-Linux=	binfmt.sh cgroup-release-agent.sh init-early.sh migrate-to-run.sh \
 	rc-cgroup.sh
 
 SRCS-NetBSD=

sh/binfmt.sh.in

@@ -0,0 +1,85 @@
+#!@SHELL@
+# This is a reimplementation of the systemd binfmt.d code to register
+# misc binary formats with the kernel.
+#
+# Copyright (c) 2015 William Hubbs <w.d.hubbs@gmail.com>
+# Released under the 2-clause BSD license.
+#
+# See the binfmt.d manpage as well:
+# http://0pointer.de/public/systemd-man/binfmt.d.html
+# This script should match the manpage as of 2015/03/31
+#
+
+apply_file() {
+	[ $# -lt 1 ] && return 0
+	FILE="$1"
+	LINENUM=0
+
+	### FILE FORMAT ###
+	# See https://www.kernel.org/doc/Documentation/binfmt_misc.txt
+	while read line; do
+		LINENUM=$(( LINENUM+1 ))
+		case $line in
+			\#*) continue ;;
+			\;*) continue ;;
+		esac
+
+		echo "${line}" > /proc/sys/fs/binfmt_misc/register
+		rc=$?
+		if [ $rc -ne 0 ]; then
+			printf "binfmt: invalid entry on line %d of \`%s'\n" \
+				"$LINENUM" "$FILE" >&2
+			error=1
+		fi
+	done <$FILE
+	return $rc
+}
+
+[ -e /proc/sys/fs/binfmt_misc/register ] || exit 0
+error=0
+if [ $# -gt 0 ]; then
+	while [ $# -gt 0 ]; do
+		apply_file "$1"
+		shift
+	done
+else
+	# The hardcoding of these paths is intentional; we are following the
+	# systemd spec.
+	binfmt_dirs='/usr/lib/binfmt.d/ /run/binfmt.d/ /etc/binfmt.d/'
+	binfmt_basenames=''
+	binfmt_d=''
+
+	# Build a list of sorted unique basenames
+	# directories declared later in the binfmt_d list will override earlier
+	# directories, on a per file basename basis.
+	# `/run/binfmt.d/foo.conf' supersedes `/usr/lib/binfmt.d/foo.conf'.
+	# `/run/binfmt.d/foo.conf' will always be read after `/etc/binfmt.d/bar.conf'
+	for d in ${binfmt_dirs} ; do
+		[ -d $d ] && for f in ${d}/*.conf ; do
+			case "${f##*/}" in
+				systemd.conf|systemd-*.conf) continue;;
+			esac
+			[ -e $f ] && binfmt_basenames="${binfmt_basenames}\n${f##*/}"
+		done # for f in ${d}
+	done # for d in ${binfmt_dirs}
+	binfmt_basenames="$(printf "${binfmt_basenames}\n" | sort -u )"
+
+	for b in $binfmt_basenames ; do
+		real_f=''
+		for d in $binfmt_dirs ; do
+			f=${d}/${b}
+			[ -e "${f}" ] && real_f=$f
+		done
+		[ -e "${real_f}" ] && binfmt_d="${binfmt_d} ${real_f}"
+	done
+
+	# loop through the gathered fragments, sorted globally by filename.
+	# `/run/binfmt.d/foo.conf' will always be read after `/etc/binfmt.d/bar.conf'
+	for FILE in $binfmt_d ; do
+		apply_file "$FILE"
+	done
+fi
+
+exit $error
+
+# vim: set ts=2 sw=2 sts=2 noet ft=sh: