135 lines
3.3 KiB
Bash
Executable File
135 lines
3.3 KiB
Bash
Executable File
#!/bin/sh
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#
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# tiny init
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#
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# false positive
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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" >&2; sh
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}
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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 /dev/*) ;;
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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/${device#*=}" ;;
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esac
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# prevent race condition
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# XXX what the hell happens here?
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# why this loop sometimes trigger panic if i remove '|| :'
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while [ ! -b "$device" ]; do sleep 1
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[ "$((count += 1))" = 30 ] && {
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panic "failed to lookup partition"
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break
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}
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done || :
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}
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run_hook()
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{
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type="$1"; hksdir=/usr/share/tinyramfs/hooks
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# run hooks if any
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# false positive
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# shellcheck disable=1090
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for hook in $hooks; do
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[ -f "${hksdir}/${hook}/${hook}.${type}" ] || continue
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. "${hksdir}/${hook}/${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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# false positive
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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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set -- \
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"${rorw:--o ro}${root_opts:+,$root_opts}" \
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"${root_type:+-t $root_type}" "$device" "/mnt/root"
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# word splitting is safe by design
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# shellcheck disable=2068
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mount $@ || panic "failed to mount root"
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}
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boot_system()
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{
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[ "$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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set -- "/mnt/root" "${init:-/sbin/init}" "$init_args"
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# POSIX exec has no -c flag to execute command with empty environment
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# use 'env -i' to prevent leaking exported variables
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# word splitting is safe by design
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# shellcheck disable=2068
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exec env -i TERM=linux PATH=/bin:/sbin:/usr/bin:/usr/sbin \
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switch_root $@ || panic "failed to boot system"
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}
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# int main()
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{
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# enable exit on error and disable globbing
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# trap EXIT signal
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set -ef; trap panic EXIT
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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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}
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