#!/bin/sh

MODE=$1
ARRAY=$2
DRIVE=$3

alias logger="logger -s -t mdadm_replace"

function DISK_REMOVE {

  mdadm -D $ARRAY | grep -E "${DRIVE}$" > /dev/null
  MD_DEV_PRESENT="$?"
  if [ "$MD_DEV_PRESENT" == "0" ] ; then
    echo "// SETTING DRIVE($DRIVE) STATE TO FAULTY "
    echo mdadm $ARRAY -f $DRIVE
    mdadm $ARRAY -f $DRIVE
    sleep 5
    echo "// REMOVING DRIVE($DRIVE) FROM ARRAY($ARRAY) "
    echo mdadm $ARRAY -r $DRIVE
    mdadm $ARRAY -r $DRIVE
    MD_DEV_REMOVE="$?"
    if [ "$MD_DEV_REMOVE" != "0" ] ; then
      echo "// DEVICE ($DRIVE) FAILED TO REMOVE, EXITING UNCLEANLY! "
      exit 1
    fi

  else
    echo "// DEVICE ($DRIVE) NOT LISTED, EXITING (PERHAPS REMOVED ALREADY...) "
    return 1
  fi

} #/FUNCTION DISK_REMOVE

function DISK_READMIT {

  echo "// ZEROING DRIVE BEFORE ADMITTING BACK TO ARRAY "
  # set 1MB blocksize for 'dd'
  BS="1048576"
  # get blockdev size in bytes:
  DISK_BYTES=`fdisk -l ${DRIVE} 2>/dev/null | grep bytes | head -1 | awk '{print $5}'`
  # calculate for DD, to write at offset 64MB from the end of device -> end of device
  (( DISK_BYTES_OFFSET=( $DISK_BYTES / $BS ) - 64 ))

  # zero 64MB at start of drive
  dd if=/dev/zero of=${DRIVE} bs=1M count=64
  DD_ERR=$?
  # check and make sure we are writing to the drive, else exit with an error
  if [ "${DD_ERR}" != "0" ] ; then
    echo "COULD NOT ZERO DEVICE ${DRIVE}, EXITING WITH ERROR ${DD_ERR} "
    exit 1
  fi
  # zero drive starting at offset 64MB from end until it hits the wall
  dd if=/dev/zero of=${DRIVE} bs=1M seek=$DISK_BYTES_OFFSET

  # hackey-like reload of device now that it's been b0rked:
  echo "// RE-LOADING DRIVE BY KERNEL "
  MASTER=`basename $DRIVE`
  for SLAVE in /sys/block/$MASTER/slaves/* ; do 
    #echo "SLAVE is $SLAVE "
    RDEV=`basename $SLAVE`
    echo 1 > $SLAVE/device/rescan 
    sleep 1
    blockdev --rereadpt /dev/$RDEV >/dev/null 2>&1
  done
  blockdev --rereadpt $DRIVE >/dev/null 2>&1

  # sleep a few to let udev/kernel catch up
  sleep 10

  # add device back to array now:
  echo "// mdadm $ARRAY -a $DRIVE"
  mdadm $ARRAY -a $DRIVE
  MD_ADD_ERR="$?"
  if [ "${MD_ADD_ERR}" != "0" ] ; then
    echo "COULD NOT ADD DEVICE($DRIVE) BACK TO ARRAY($ARRAY), EXITING WITH ERROR ${DD_ERR} "
    exit 1
  fi

  # array now has the replacement drive.  show status and exit:
  echo -e "\n#### ARRAY $ARRAY STATUS: " | logger
  cat /proc/mdstat | logger
  echo -e "\n#### DEVICE $DRIVE STATUS: " | logger
  mdadm --examine $DRIVE | logger
  exit 0

} #/FUNCTION DISK_READMIT


### END SETUP.
### START PROGRAM FLOW:

if [[ (( x"${ARRAY}" == "x" )) &&  (( x"${DRIVE}" == "x" )) ]] ; then

  ### necessary input vals not defined, exit.
  echo "VALUES NOT SET "
  exit 1

else

  ### ALL CLEAR, run program
  # function
  $MODE
  
fi