147 lines
3.7 KiB
Bash
Executable File
147 lines
3.7 KiB
Bash
Executable File
#!/bin/sh
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#
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# Tiny init
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#
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# https://www.shellcheck.net/wiki/SC2154
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# shellcheck disable=2154
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print()
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{
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printf "%b %s\n" "${2:-"\033[1;37m>>\033[m"}" "$1"
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}
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panic()
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{
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print "${1:-unexpected error occurred}" \
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"\033[1;31m!!\033[m"
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sh
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} >&2
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resolve_device()
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{
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count=0; device="$1"
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case "${device%%=*}" in
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UUID) device="/dev/disk/by-uuid/${device#*=}" ;;
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LABEL) device="/dev/disk/by-label/${device#*=}" ;;
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PARTUUID) device="/dev/disk/by-partuuid/${device#*=}" ;;
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/dev/*) ;;
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*) return 0 ;;
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esac
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# Race condition may occur if device manager is not yet initialized device.
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# To fix this, we simply waiting until device is available. If device
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# didn't appear in specified time, we panic.
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while :; do
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if [ -b "$device" ]; then
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return 0
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elif [ "$((count += 1))" = "${rootdelay:=30}" ]; then
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break
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else
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sleep 1
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fi
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done
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panic "failed to lookup partition"
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}
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run_hook()
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{
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type="$1"
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# Run hooks if any exist.
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#
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# https://www.shellcheck.net/wiki/SC1090
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# shellcheck disable=1090
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for hook in $hooks; do
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[ -f "/usr/share/tinyramfs/hooks/${hook}/${hook}.${type}" ] || continue
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. "/usr/share/tinyramfs/hooks/${hook}/${hook}.${type}"
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done
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}
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prepare_environment()
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{
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# https://www.shellcheck.net/wiki/SC1091
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# shellcheck disable=1091
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. /etc/tinyramfs/config
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export \
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PATH=/bin TERM=linux SHELL=/bin/sh \
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LANG=C LC_ALL=C PS1="# " HOME=/root
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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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parse_cmdline()
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{
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read -r cmdline < /proc/cmdline
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for line in $cmdline; do case "$line" in
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rootfstype=*) root_type="${line#*=}" ;;
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rootflags=*) root_opts="${line#*=}" ;;
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debug=1) set -x ;;
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ro | rw) rorw="-o $line" ;;
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--*) init_args="${cmdline#*-- }"; break ;;
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*=*) command export "$line" ;;
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*) command export "${line}=1" ;;
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esac 2> /dev/null || :; done
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}
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mount_root()
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{
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[ "$break" = root ] && { print "break before mount_root()"; sh; }
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resolve_device "$root"
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# https://www.shellcheck.net/wiki/SC2086
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# shellcheck disable=2086
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mount \
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${rorw:--o ro}${root_opts:+,$root_opts} ${root_type:+-t $root_type} \
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-- "$device" /mnt/root || panic "failed to mount root"
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}
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boot_system()
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{
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[ "$break" = boot ] && { print "break before boot_system()"; sh; }
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for dir in run dev sys proc; do
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mount -o move "$dir" "/mnt/root/${dir}"
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done
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# POSIX 'exec' has no '-c' flag to execute command with empty environment.
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# Using 'env -i' instead to prevent leaking exported variables.
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#
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# Some implementations of 'switch_root' doesn't conform to POSIX utility
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# guidelines and doesn't support '--'. This means that we can't guarantee
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# safety of init_args.
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# shellcheck disable=2086
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exec \
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env -i TERM=linux PATH=/bin:/sbin:/usr/bin:/usr/sbin \
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switch_root /mnt/root "${init-/sbin/init}" $init_args ||
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panic "failed to boot system"
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}
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# Exit if command fails and 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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trap panic EXIT
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# TODO display fancy colored status info
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prepare_environment
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parse_cmdline
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run_hook init
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mount_root
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run_hook init.late
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boot_system
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