#!/bin/bash
#
# This script provides a wrapper around /sbin/init that demonstrates
# bug plymouth bug 71996 https://bugs.freedesktop.org/show_bug.cgi?id=71996
# (aka http://pad.lv/1235231 and http://pad.lv/682831)
#
# Call the script with 'install <target>' to wrap /sbin/init inside <target>
# with this program.  Then, on boot this program will start writing output
# to its standard out (/dev/console) every NAPLEN seconds. and will
# also record information into LOGNAME.
#
# You should generally be able to just install this script as /sbin/init
# and then reboot, and check logs of /dev/console to verify data is missing.
#
# To reproduce on ubuntu 13.10 within lxc:
#   sudo apt-get --quiet --assume-yes install lxc
#   sudo lxc-create -t ubuntu-cloud -n source-precise-amd64 -- \
#      --arch=amd64 --release=precise
#   
#   sudo lxc-clone -o source-precise-amd64 -n test1
#   sudo bash ./bug71996-init-logger install /var/lib/lxc/test1/rootfs
#   sudo lxc-start -n test1
#
#   This should result in 'XX: i=N' messages for all values of N > 0 and < 150.
#   In lxc, I will often lose writes 0 - 6.
#
# You can also reproduce this in a ubuntu cloud image via kvm 
#  http://tinyurl.com/k5v4ff6
# or on an instance in EC2 or openstack.
# 
export NAPLEN=".2" MAX="150" LOGNAME="/run/my.log"

# call with 'install target' to install into root at target
# ie, install /
if [ "$1" = "install" ]; then
   [ "$(id -u)" = "0" ] || { echo "must be root"; exit 1; }
   target=${2:-""}
   target=${target%/}
   [ -e "$target/sbin/init.real" ] ||
      mv "$target/sbin/init" "$target/sbin/init.real" ||
      { echo "failed mv $target/sbin/init"; exit 1; }
   [ "$0" -ef "$target/sbin/init" ] &&
      { echo "already good"; exit 0; }
   cp "$0" "$target/sbin/init" ||
      { echo "failed cp $0 $target/sbin/init"; exit 1; }
   chmod 755 "$target/sbin/init" ||
      { echo "failed chmod 755 $target/sbin/init"; exit 1; }
   echo "installed into $target/sbin/init"
   exit
elif [ "$1" = "uninstall" ]; then
   [ "$(id -u)" = "0" ] || { echo "must be root"; exit 1; }
   target=${2:-""}
   mv "$target/sbin/init.real" "$target/sbin/init"
   echo "uninstalled wraper around $target/sbin/init"
   exit
fi

if [ "$0" = "/sbin/init" ]; then
  sh -c '
  LOG=""

  say() {
    local pre="XX:" up="" idle="" ret=""
    if [ "$1" = "UPTIME:" ]; then
      read up idle < /proc/uptime
      shift;
    fi
    ret="${up:+${up} }$*"
    if [ -z "$LOG" ]; then
       if sh -fc "echo $upmsg > \"$LOGNAME\"" >/dev/null 2>&1; then
          LOG="$LOGNAME"
          echo "$UPMSG" >> "$LOG"
          say "initialized log at $up"
       fi
    else
       echo $pre $ret >> "$LOG"
    fi
    echo $pre $ret
    _RET="$ret"
  }

  i=0
  say UPTIME: "first up"
  UPMSG="$_RET"
  while [ $i -lt $MAX ]; do
    say "i=$i"
    i=$(($i+1))
    sleep $NAPLEN
  done
  read up idle < /proc/uptime
  say UPTIME: "finished. i=$i"
  ' bug71996-logger &
else
   unset NAPLEN MAX LOGNAME
fi

exec -a /sbin/init "/sbin/init.real" "$@"