tinyramfs/init

186 lines
4.5 KiB
Plaintext
Raw Normal View History

#!/bin/sh
2020-01-30 20:10:13 +05:30
#
2020-04-12 01:01:02 +05:30
# tiny init
#
2020-07-03 21:19:09 +05:30
# false positive
# shellcheck disable=2154
2020-01-05 23:31:39 +05:30
2020-04-21 20:05:55 +05:30
print()
{
printf "%b %s\n" "${2:-"\033[1;37m>>\033[m"}" "$1"
2020-04-21 20:05:55 +05:30
}
panic()
{
print "${1:-unexpected error occurred}" \
"\033[1;31m!!\033[m" >&2; sh
2020-01-30 20:10:13 +05:30
}
2020-01-28 20:43:42 +05:30
2020-06-02 16:56:42 +05:30
resolve_device()
2020-04-12 01:01:02 +05:30
{
count=0; device="$1"
2020-04-12 01:01:02 +05:30
case "${device%%=*}" in /dev/*) ;;
UUID) device="/dev/disk/by-uuid/${device#*=}" ;;
LABEL) device="/dev/disk/by-label/${device#*=}" ;;
PARTUUID) device="/dev/disk/by-partuuid/${device#*=}" ;;
2020-04-12 01:01:02 +05:30
esac
# prevent race condition
# XXX what the hell happens here?
# why this loop sometimes trigger panic if i remove '|| :'
2020-06-02 16:56:42 +05:30
while [ ! -b "$device" ]; do sleep 1
[ "$((count += 1))" = 30 ] && {
panic "failed to lookup partition"
break
}
done || :
}
run_hook()
{
type="$1"; hksdir=/usr/share/tinyramfs/hooks
# run hooks if any
2020-07-03 21:19:09 +05:30
# false positive
# shellcheck disable=1090
for hook in $hooks; do
[ -f "${hksdir}/${hook}/${hook}.${type}" ] || continue
. "${hksdir}/${hook}/${hook}.${type}"
2020-05-26 19:14:20 +05:30
done
2020-02-21 14:27:07 +05:30
}
2020-01-05 23:31:39 +05:30
2020-04-12 01:01:02 +05:30
prepare_environment()
{
2020-07-03 21:19:09 +05:30
# false positive
# shellcheck disable=1091
. /etc/tinyramfs/config
2020-04-12 01:01:02 +05:30
export \
PATH=/bin TERM=linux SHELL=/bin/sh \
LANG=C LC_ALL=C PS1="# " HOME=/root
2020-03-08 08:59:14 +05:30
mount -t proc -o nosuid,noexec,nodev proc /proc
mount -t sysfs -o nosuid,noexec,nodev sys /sys
mount -t tmpfs -o nosuid,nodev,mode=0755 run /run
2020-04-12 01:01:02 +05:30
mount -t devtmpfs -o nosuid,noexec,mode=0755 dev /dev
2020-03-08 08:59:14 +05:30
ln -s /proc/self/fd /dev/fd
ln -s fd/0 /dev/stdin
ln -s fd/1 /dev/stdout
ln -s fd/2 /dev/stderr
2020-04-12 01:01:02 +05:30
}
parse_cmdline()
{
read -r cmdline < /proc/cmdline
2020-07-05 13:41:39 +05:30
for line in $cmdline; do case "$line" in
rootfstype=*) root_type="${line#*=}" ;;
rootflags=*) root_opts="${line#*=}" ;;
debug=1) set -x ;;
ro | rw) rorw="-o $line" ;;
--*) init_args="${cmdline#*-- }"; break ;;
*=*) command export "$line" ;;
*) command export "${line}=1" ;;
esac 2> /dev/null || :; done
2020-01-30 20:10:13 +05:30
}
2020-01-05 23:31:39 +05:30
2020-04-12 01:01:02 +05:30
setup_devmgr()
{
[ "$break" = devmgr ] && { print "break before setup_devmgr()"; sh; }
2020-04-12 01:01:02 +05:30
2020-02-26 01:13:25 +05:30
case "$devmgr" in
2020-07-16 01:56:12 +05:30
proc)
command -v device-helper > /proc/sys/kernel/hotplug
# get ready for fork bomb. kek
find /sys/devices -name uevent |
while read -r uevent; do
printf add > "$uevent"
done
;;
2020-02-26 01:13:25 +05:30
udev)
udevd -N never & devmgr_pid="$!"
2020-02-26 01:13:25 +05:30
udevadm trigger -c add -t subsystems
udevadm trigger -c add -t devices
udevadm settle
2020-04-12 01:01:02 +05:30
;;
2020-02-26 01:13:25 +05:30
mdev)
mdev -s
mdev -df & devmgr_pid="$!"
2020-05-26 19:14:20 +05:30
find /sys/devices -name uevent |
while read -r uevent; do
printf add > "$uevent"
done
2020-04-12 01:01:02 +05:30
;;
2020-02-26 01:13:25 +05:30
mdevd)
mdevd & devmgr_pid="$!"
2020-02-26 01:13:25 +05:30
mdevd-coldplug
2020-04-12 01:01:02 +05:30
;;
esac 2> /dev/null
2020-01-30 20:10:13 +05:30
}
2020-01-05 23:31:39 +05:30
2020-04-12 01:01:02 +05:30
mount_root()
{
[ "$break" = root ] && { print "break before mount_root()"; sh; }
2020-04-12 01:01:02 +05:30
2020-06-02 16:56:42 +05:30
resolve_device "$root"
2020-04-12 01:01:02 +05:30
set -- \
"${rorw:--o ro}${root_opts:+,$root_opts}" \
2020-05-26 19:14:20 +05:30
"${root_type:+-t $root_type}" "$device" "/mnt/root"
2020-07-03 21:19:09 +05:30
# word splitting is safe by design
# shellcheck disable=2068
2020-04-12 01:01:02 +05:30
mount $@ || panic "failed to mount root"
2020-01-30 20:10:13 +05:30
}
2020-01-05 23:31:39 +05:30
2020-05-26 19:14:20 +05:30
boot_system()
2020-04-12 01:01:02 +05:30
{
2020-05-26 19:14:20 +05:30
[ "$break" = boot ] && { print "break before boot_system()"; sh; }
2020-04-12 01:01:02 +05:30
2020-07-16 01:56:12 +05:30
{
kill "$devmgr_pid" || printf '\n' > /proc/sys/kernel/hotplug
} 2> /dev/null || :
# temporary workaround until util-linux release a new version
2020-04-12 01:01:02 +05:30
# see https://github.com/karelzak/util-linux/issues/997
for dir in run dev sys proc; do
mount -o move "$dir" "/mnt/root/${dir}" ||
mount --move "$dir" "/mnt/root/${dir}"
2020-06-02 16:56:42 +05:30
done 2> /dev/null
2020-01-05 23:31:39 +05:30
2020-06-02 16:56:42 +05:30
set -- "/mnt/root" "${init:-/sbin/init}" "$init_args"
2020-01-30 20:10:13 +05:30
# POSIX exec has no -c flag to execute command with empty environment
2020-06-02 16:56:42 +05:30
# use 'env -i' to prevent leaking exported variables
2020-07-03 21:19:09 +05:30
# word splitting is safe by design
# shellcheck disable=2068
2020-07-16 00:20:47 +05:30
exec env -i TERM=linux PATH=/bin:/sbin:/usr/bin:/usr/sbin \
2020-06-02 16:56:42 +05:30
switch_root $@ || panic "failed to boot system"
2020-04-12 01:01:02 +05:30
}
2020-01-30 20:58:03 +05:30
2020-04-12 01:01:02 +05:30
# int main()
{
# enable exit on error and disable globbing
# trap EXIT signal
set -ef; trap panic EXIT
2020-04-12 01:01:02 +05:30
prepare_environment
parse_cmdline
2020-07-16 00:20:47 +05:30
run_hook init.early
# XXX may be moved to hooks soon
2020-04-12 01:01:02 +05:30
setup_devmgr
2020-02-26 01:13:25 +05:30
run_hook init
2020-02-26 01:13:25 +05:30
2020-04-12 01:01:02 +05:30
mount_root
boot_system
}