119 lines
3.2 KiB
Bash
119 lines
3.2 KiB
Bash
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#!/bin/sh
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#
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# https://shellcheck.net/wiki/SC2154
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# https://shellcheck.net/wiki/SC2034
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# shellcheck disable=2154,2034
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init_base()
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{
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mount -t proc -o nosuid,noexec,nodev proc /proc
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mount -t sysfs -o nosuid,noexec,nodev sys /sys
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mount -t tmpfs -o nosuid,nodev,mode=0755 run /run
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mount -t devtmpfs -o nosuid,noexec,mode=0755 dev /dev
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ln -s /proc/self/fd /dev/fd
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ln -s fd/0 /dev/stdin
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ln -s fd/1 /dev/stdout
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ln -s fd/2 /dev/stderr
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}
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eval_hooks()
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{
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_type=$1
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# https://shellcheck.net/wiki/SC2086
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# shellcheck disable=2086
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{ IFS=,; set -- $hooks; unset IFS; }
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for _hook; do
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[ -f "/lib/tinyramfs/hook.d/${_hook}/${_hook}.${_type}" ] || continue
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[ "$rdbreak" = "$_hook" ] && panic "break before: ${_hook}.${_type}"
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# https://shellcheck.net/wiki/SC1090
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# shellcheck disable=1090
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. "/lib/tinyramfs/hook.d/${_hook}/${_hook}.${_type}"
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done
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}
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parse_cmdline()
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{
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# XXX /proc/cmdline can contain multiline data?
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read -r cmdline < /proc/cmdline
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# https://kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
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# ... parameters with '=' go into init's environment ...
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for _param in $cmdline; do case $_param in
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rdpanic) trap - EXIT ;;
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rddebug) set -x ;;
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# Maintain backward compatibility with kernel parameters.
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ro | rw) rorw=$_param ;;
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rootwait) root_wait=-1 ;;
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--) init_args=${_param##*--}; break ;;
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rootfstype=*) root_type=${_param#*=} ;;
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rootflags=*) root_opts=${_param#*=} ;;
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rootdelay=*) root_wait=${_param#*=} ;;
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esac; done
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}
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mount_root()
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{
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[ "$rdbreak" = root ] && panic 'break before: mount_root()'
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resolve_device "$root" "$root_wait"
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# https://shellcheck.net/wiki/SC2086
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# shellcheck disable=2086
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mount \
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-o "${rorw:-ro}${root_opts:+,$root_opts}" ${root_type:+-t "$root_type"} \
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-- "$device" /mnt/root || panic "failed to mount rootfs: $device"
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}
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boot_system()
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{
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[ "$rdbreak" = boot ] && panic 'break before: boot_system()'
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for _dir in run dev sys proc; do
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mount -o move "/${_dir}" "/mnt/root/${_dir}" || :
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done
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# POSIX 'exec' has no '-c' flag to execute command with empty environment.
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# Use 'env -i' instead to prevent leaking exported variables.
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#
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# Some implementations of 'switch_root' doesn't conform to POSIX utility
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# guidelines and doesn't support '--'. This means that safety of init_args
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# isn't guaranteed.
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#
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# https://shellcheck.net/wiki/SC2086
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# shellcheck disable=2086
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exec \
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env -i TERM=linux PATH=/bin:/sbin:/usr/bin:/usr/sbin \
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switch_root /mnt/root "${init:-/sbin/init}" $init_args ||
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panic "failed to boot system"
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}
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# TODO add `quiet` support
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# -e: Exit if command return status greater than 0
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# -f: Disable globbing *?[]
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set -ef
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# Run emergency shell if init unexpectedly exiting due to error.
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# TODO prompt to continue
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trap panic EXIT
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# https://shellcheck.net/wiki/SC1091
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# shellcheck disable=1091
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. /lib/tinyramfs/common.sh
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# https://shellcheck.net/wiki/SC1091
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# shellcheck disable=1091
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. /etc/tinyramfs/config
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init_base
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parse_cmdline
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eval_hooks init
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mount_root
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eval_hooks init.late
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boot_system
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