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#!/bin/busybox sh
# vim:ft=sh
# Init must have pid 1 otherwise switch_root won't work.
if [ $$ -ne 1 ]; then
echo "init must have pid 1!"
exit 1
fi
# Predefice colors
C_NO="\e[0m"
C_GRAY="\e[1;30m"
C_RED="\e[1;31m"
C_GREEN="\e[1;32m"
C_YELLOW="\e[1;33m"
PATH="$PATH:/bin:/sbin"
# disable kernel message from terminal and clear screen
echo 0 > /proc/sys/kernel/printk
clear
# TODO print some welcome ascii art :-)
# Function called if we fail. Argument is error message.
fail() {
echo -e "${C_RED}$@${C_NO}"
echo -e "${C_YELLOW}Dropping to interactive shell${C_NO}"
busybox --install -s
while true; do
echo -e "${C_GRAY}Mount root to /mnt/root and exit shell to switch root.${C_NO}"
# Note: this is hack to enable job control
setsid sh -c 'exec sh </dev/tty1 >/dev/tty1 2>&1'
echo
exec switch_root /mnt/root /sbin/init || echo -e "${C_RED}Root switch failed!${C_NO}"
done
}
# Preliminary mounts
busybox mount -t proc none /proc || fail "/proc mount failed!"
busybox mount -t sysfs none /sys || fail "/sys mount failed!"
busybox mount -t devtmpfs none /dev || fail "/dev mount failed!"
# Now open and mount root
root=""
rootflags=""
recovery=false
for opt in $(cat /proc/cmdline); do
case "$opt" in
root=*)
root=${opt:5}
;;
rootflags=*)
rootflags=${opt:10}
;;
recovery)
recovery=true
;;
BOOT_IMAGE=*|initrd=*)
# Ignore those
;;
*)
echo -e "${C_YELLOW}Unknown kernel argument: $opt${C_NO}"
;;
esac
done
$recovery && fail "Requested recovery."
[ -z "$root" ] && fail "Missing root argument!"
echo -ne "${C_GRAY}Waiting for root ($root)..."
CNT=10
while [ ! -e "$root" ] && [ $CNT -gt 0 ]; do
CNT=$(expr $CNT - 1)
sleep 1
echo -n " $CNT"
done
echo -e "${C_NO}"
[ -e "$root" ] || fail "Root not located!"
echo -e "${C_GREEN}Mounting root...${C_NO}"
mount -t btrfs -o "$rootflags" "$root" /mnt/root \
|| fail "Mounting root failed! /proc/cmdline=$(cat /proc/cmdline)"
echo -e "${C_GREEN}Switching to real root${C_NO}"
# First clean up. The init process will remount proc, sys and dev later on
busybox umount /dev /sys /proc || fail "Unmouns failed!"
# Now do switch
exec switch_root /mnt/root /sbin/init || fail "Root switch failed!"
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