#!/usr/bin/env bash

#variables:
random_pass=2
zeroing_pass=1
prereq_list="pv smartmontools hdparm"
YUM_CMD=$(which yum)
APT_CMD=$(which apt-get)

#check that a disk has been provided:
if [ -z "$1" ]
then
	echo "USAGE: \"./wiper.sh diskname\", for example: \"./wiper.sh sdb\""
	exit
fi

#check the disk exists:
if [ ! -e "/dev/$1" ]; then
	echo "ERROR: /dev/$1 does not exists. exiting."
	exit
fi

#prerequisites:

if [[ ! -z $APT_CMD ]]; then
  for prereq in $prereq_list; do
	PKG_OK=$(dpkg-query -W --showformat='${Status}\n' $prereq|grep "install ok installed")
	#echo Checking for $prereq: $PKG_OK
	if [ "" = "$PKG_OK" ]; then
	  echo "INFO: $prereq is not present. Setting up $prereq."
	  sudo apt-get --yes install $prereq
	fi
  done
elif [[ ! -z $YUM_CMD ]]; then
  for prereq in $prereq_list; do
	if ! rpm -qa | grep -qw $prereq; then
		yum install $prereq
	fi
  done
else
	echo "ERROR: error can't find the correct installer for the prerequisites"
	exit 1;
fi

echo "---"




#collect data about disk type:
disk_type=$(smartctl -a /dev/$1 | grep -i "Rotation Rate:" | cut -d':' -f2 | tr -d " ")

#store if the disk is an ssd:
if [[ $disk_type == *"SolidStateDevice"* ]]; then
	disk_ssd=1
#	echo "disk is ssd"
elif [[ $disk_type == *"rpm"* ]]; then
	disk_ssd=0
#	echo "disk is not ssd"
else
	echo "disk type unknown, exiting"
	exit
fi

#check for disk errors, differntiating by device type since smart output is different between sata and sas drives:
if smartctl -a /dev/$1 | grep -q "SATA"; then
	#echo "Type of disk: SATA"
	if smartctl -a /dev/$1 | grep -q "No Errors Logged"; then
		echo "INFO: This is a SATA disk, detecting no errors, going on:"
	else
		sata_model=$(smartctl -a /dev/$1 | grep -i "Device Model:" | cut -d':' -f2 | tr -d " ")
		sata_serial=$(smartctl -a /dev/$1 | grep -i "Serial number:" | cut -d':' -f2 | tr -d " ")
		echo "!!! ERRORS !!!"
		echo "SATA errors, aborting!!!"
		echo "NO WIPING NEEDED, JUST DESTROY THE DISK MECHANICALLY"
		echo "!!! EXITING !!!"
		echo ""
		echo "Model:  $sata_model"
		echo "Serial: $sata_serial"
		exit
	fi
elif smartctl -a /dev/$1 | grep -q "SAS"; then
	#echo "Type of disk: SAS"
	sas_errors=$(smartctl -a /dev/$1 | grep "Elements in grown defect list" | cut -d':' -f2 | tr -d " ")
	if [ "$sas_errors" -gt 0 ]; then
		sas_vendor=$(smartctl -a /dev/$1 | grep -i "Vendor:" | cut -d':' -f2 | tr -d " ")
		sas_model=$(smartctl -a /dev/$1 | grep -i "Product:" | cut -d':' -f2 | tr -d " ")
		sas_serial=$(smartctl -a /dev/$1 | grep -i "Serial number:" | cut -d':' -f2 | tr -d " ")
		echo "!!! ERRORS !!!"
		echo "Elements in grown defect list: " $sas_errors
		echo "NO WIPING NEEDED, JUST DESTROY THE DISK MECHANICALLY"
		echo "!!! EXITING !!!"
		echo ""
		echo "Vendor: $sas_vendor"
		echo "Model:  $sas_model"
		echo "Serial: $sas_serial"
		exit
	else
		echo "INFO: This is a SAS disk, detecting no errors, going on:"
	fi
else
	echo "ERROR: the disk type is none of the expected ones, exiting"
	exit
fi


#warning if is an ssd
if [ "$disk_ssd" -eq 1 ]; then
	echo "WARNING: DISK IS AN SSD, Remember that sectors are reallocated thus unwanted data might remain on the flash."
	#TODO: ATA Secure erase? https://grok.lsu.edu/article.aspx?articleid=16716
fi

#calculate disk bytes:
disk_blocks=$(cat /proc/partitions | grep -w $1 | tr -s ' ' | cut -d " " -f4);
disk_bytes=$(( 1024*disk_blocks ))


#wipe:
#see: https://wiki.archlinux.org/title/Securely_wipe_disk/Tips_and_tricks#dd_-_advanced_example

for r_pass in $(seq 1 $random_pass); do
	echo "INFO: Random pass $r_pass of $random_pass :"
	openssl enc -pbkdf2 -pass pass:"$(dd if=/dev/urandom bs=128 count=1 2>/dev/null | base64)" -nosalt </dev/zero | pv --progress --eta --rate --bytes --size $disk_bytes | dd of=/dev/$1 bs=2M oflag=direct iflag=fullblock
done

for z_pass in $(seq 1 $zeroing_pass); do
	echo "INFO: Zeroing pass $z_pass of $zeroing_pass :"
	dd if=/dev/zero | pv --progress --eta --rate --bytes --size $disk_bytes | dd of=/dev/$1 bs=2M oflag=direct iflag=fullblock
done

echo "!!! FINISHED wiping $1 !!!"



#some of the sources used:
#https://stackoverflow.com/questions/12806176/checking-for-installed-packages-and-if-not-found-install
#https://stackoverflow.com/questions/19477682/bash-script-determine-vendor-and-install-system-apt-get-yum-etc
#https://jschumacher.info/2016/03/erasing-with-openssl/
#https://wiki.archlinux.org/title/Securely_wipe_disk/Tips_and_tricks#dd_-_advanced_example
#https://serverfault.com/questions/6440/is-there-an-alternative-to-dev-urandom