tinyramfs/init

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#!/sbin/busybox sh
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#
# tiny init script
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panic() {
printf "panic >> %s\n" "$1" && sh
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}
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# parse_cmdline() {
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# TODO parse /proc/cmdline
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#}
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# mount pseudofs's
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mnt_pseudofs() {
mount -t proc none /proc
mount -t sysfs none /sys
mount -t devtmpfs none /dev
mount -t tmpfs none /tmp
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}
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# setup mdev
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use_mdev() {
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# setup hotplugger
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if [ -e /proc/sys/kernel/hotplug ]; then
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printf /sbin/mdev > /proc/sys/kernel/hotplug
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else
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uevent mdev &
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fi
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# trigger mdev
mdev -s
# trigger uevent for usb devices
for u in /sys/bus/usb/devices/*; do
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case ${u##*/} in
[0-9]*-[0-9]*)
printf add > "${u}/uevent"
;;
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esac
done
# load drivers
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find /sys -name "modalias" -type f -exec sort -u "{}" "+" | xargs modprobe -qba
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}
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# setup mdevd
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use_mdevd() {
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# setup daemon
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mdevd &
# trigger uevents
mdevd-coldplug
# TODO investigate this
# avoid race condition
sleep 1.5
}
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# setup udev
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use_udev() {
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udevd --daemon
udevadm trigger --action=add --type=subsystems
udevadm trigger --action=add --type=devices
udevadm settle
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}
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# shell findfs
findfs_sh() {
case "${1%%=*}" in
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LABEL)
printf "/dev/disk/by-label/%s\n" "${1##*=}"
;;
UUID)
printf "/dev/disk/by-uuid/%s\n" "${1##*=}"
;;
PARTUUID)
printf "/dev/disk/by-partuuid/%s\n" "${1##*=}"
;;
/dev/*)
printf "%s\n" "$1"
;;
*)
panic "findfs option broken"
;;
esac
}
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# unlock LUKS container
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unlock_luks() {
# find device of luks root
luks_root="$(findfs_sh $luks_root)"
# TODO investigate this
# avoid race condition
[ "$devmgr" != "udev" ] && sleep 1.5
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# TODO improve mapper name ( crypttab or config option )
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# unlock luks container
cryptsetup $luks_args luksOpen "$luks_root" luks_root || panic "failed to unlock luks container"
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}
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# manually trigger LVM if udev disabled
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trigger_lvm() {
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lvm vgchange --quiet --sysinit -a y > /dev/null
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}
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# mount rootfs to /mnt/root
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mnt_rootfs() {
# merge mount flags
[ -n "$root_args" ] && mount_args="$root_args"
[ -n "$root_type" ] && mount_args="$mount_args -t $root_type"
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# find root
root="$(findfs_sh $root)"
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# mount rootfs
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mount $mount_args "$root" /mnt/root || panic "failed to mount rootfs"
}
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# kill and unmount
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cleanup() {
case "$devmgr" in
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mdev)
# stop mdev
{ printf "" > /proc/sys/kernel/hotplug || killall uevent; } > /dev/null 2>&1
;;
mdevd)
# stop mdevd
killall mdevd
;;
udev)
# stop udev
udevadm control --exit
;;
esac
# TODO re-do
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# if debug mode off then restore kernel logging
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[ "$debug" = 0 ] && printf 1 > /proc/sys/kernel/printk
# unmount pseudofs's
umount /dev /sys /proc /tmp
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}
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# exec /mnt/root/sbin/init
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boot_system() {
exec switch_root /mnt/root /sbin/init || panic "failed to boot system"
}
# install busybox
/sbin/busybox --install -s
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# source config
. /config || panic "config doesn't exists"
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# TODO re-do
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if [ "$debug" = 1 ]; then
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# debug shell commands
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set -x
else
# silence is golden
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printf 0 > /proc/sys/kernel/printk
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fi
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#parse_cmdline
mnt_pseudofs
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case "$devmgr" in
mdev) use_mdev ;;
mdevd) use_mdevd ;;
udev) use_udev ;;
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*) panic "devmgr option broken" ;;
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esac
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# TODO handle situations when LUKS on LVM
[ "$use_luks" = 1 ] && unlock_luks
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[ "$use_lvm" = 1 ] && [ "$devmgr" != "udev" ] && trigger_lvm
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mnt_rootfs
cleanup
boot_system