qemu-binfmt.initd

#!/sbin/openrc-run
# vim: set ft=sh: ts=4:
# source: https://github.com/jirutka/qemu-openrc

VERSION='0.11.1'

#   <magic>                                  <offset>                                 <arch>
FMTS="7f454c460201010000000000000000000200b7 ffffffffffffff00fffffffffffffffffeffff aarch64
	7f454c4602010100000000000000000002002690 ffffffffffffff00fffffffffffffffffeffffff alpha
	7f454c4601010100000000000000000002002800 ffffffffffffff00fffffffffffffffffeffffff arm
	7f454c4601020100000000000000000000020028 ffffffffffffff00fffffffffffffffffffeffff armeb
	7f454c4601010100000000000000000002004c00 ffffffffffffff00fffffffffffffffffeffffff cris
	7f454c4601010100000000000000000002000300 fffffffffffefefffffffffffffffffffeffffff i386
	7f454c4601010100000000000000000002000600 fffffffffffefefffffffffffffffffffeffffff i486
	7f454c4601020100000000000000000000020004 ffffffffffffff00fffffffffffffffffffeffff m68k
	7f454c460102010000000000000000000002baab ffffffffffffff00fffffffffffffffffffeffff microblaze
	7f454c4601020100000000000000000000020008 ffffffffffffff00fefffffffffffffffffeffff mips
	7f454c4602020100000000000000000000020008 ffffffffffffff00fefffffffffffffffffeffff mips64
	7f454c4602010100000000000000000002000800 ffffffffffffff00fefffffffffffffffeffffff mips64el
	7f454c4601010100000000000000000002000800 ffffffffffffff00fefffffffffffffffeffffff mipsel
	7f454c460102010000000000000000000002005c ffffffffffffff00fffffffffffffffffffeffff or1k
	7f454c4601020100000000000000000000020014 fffffffffffffffffffffffffffffffffffeffff ppc
	7f454c4602020100000000000000000000020015 fffffffffffffffffffffffffffffffffffeffff ppc64
	7f454c4601020100000000000000000000020015 fffffffffffffffffffffffffffffffffffeffff ppc64abi32
	7f454c4602010100000000000000000002001500 fffffffffffffffffffffffffffffffffeffff00 ppc64le
	7f454c460101010000000000000000000200f300 ffffffffffffff00fffffffffffffffffeffffff riscv32
	7f454c460201010000000000000000000200f300 ffffffffffffff00fffffffffffffffffeffffff riscv64
	7f454c4602020100000000000000000000020016 fffffffffffffffffffffffffffffffffffeffff s390x
	7f454c4601010100000000000000000002002a00 ffffffffffffff00fffffffffffffffffeffffff sh4
	7f454c460102010000000000000000000002002a ffffffffffffff00fffffffffffffffffffeffff sh4eb
	7f454c4601020100000000000000000000020002 fffffffffffffffffffffffffffffffffffeffff sparc
	7f454c4601020100000000000000000000020012 fffffffffffffffffffffffffffffffffffeffff sparc32plus
	7f454c460202010000000000000000000002002b fffffffffffffffcfffffffffffffffffffeffff sparc64
	7f454c4602010100000000000000000002003e00 fffffffffffefe00fffffffffffffffffeffffff x86_64"

: ${binfmt_flags:=OCF}
: ${qemu_suffix:=}

describe='Configure binfmt misc emulation via QEMU'

extra_commands='version'
describe_version='Show version of this script'


depend() {
	after procfs
}

start() {
	ebegin 'Registering QEMU binaries in binfmt misc'

	if [ ! -d /proc/sys/fs/binfmt_misc ]; then
		modprobe binfmt_misc || eend $? || return 1
	fi

	if [ ! -f /proc/sys/fs/binfmt_misc/register ]; then
		mount -t binfmt_misc binfmt_misc /proc/sys/fs/binfmt_misc >/dev/null \
			|| eend $? || return 1
	fi

	local retval=0
	local host_arch="$(normalize_arch "$(uname -m)")"

	local magic mask arch
	echo "$FMTS" | while read magic mask arch; do
		local qemu_arch="$(normalize_arch $arch)"
		local interpreter="/usr/bin/qemu-${qemu_arch}$qemu_suffix"

		if qemu_needed "$host_arch" "$qemu_arch" && [ -x "$interpreter" ]; then
			register ":qemu-$arch:M:0:$(hex $magic):$(hex $mask):$interpreter:$binfmt_flags" || {
				eerror "Failed to register binfmt qemu-$arch"
				retval=1
			}
		fi
	done

	eend $retval
}

stop() {
	ebegin 'Unregistering QEMU binaries in binfmt misc'

	find /proc/sys/fs/binfmt_misc -name 'qemu-*' | while read path; do
		echo -1 > "$path"
	done

	eend $?
}

version() {
	echo "qemu-openrc $VERSION"
}


hex() {
	printf '%s\n' "$1" | sed -E 's/(..)/\\x\1/g'
}

normalize_arch() {
	case "$1" in
		i[3456]86) echo 'i386';;
		armv[4-9]*) echo 'arm';;
		*) echo "$1";;
	esac
}

qemu_needed() {
	local host_arch="$1"
	local target_arch="$2"

	[ "$host_arch" = "$target_arch" ] && return 1

	# See https://github.com/jirutka/qemu-openrc/pull/24#issuecomment-1563070333
	[ "$host_arch" = 'x86_64' ] && [ "$target_arch" = 'i386' ] && return 1

	return 0
}

register() {
	if yesno "$EINFO_VERBOSE"; then
		einfo "Registering $(echo "$1" | cut -d: -f2)"
	fi
	echo "$1" > /proc/sys/fs/binfmt_misc/register
}