#!/bin/sh
# This small script will fix the "missing space" caused by dd-ing fatdog isohybrid to a flash drive
# making the rest of the space available again for use.
# Only run this after dd-ing fatdog iso and not after anything else.
# (C) jamesbond 2013

### configuration
setvar RESERVED_SPACE = '786432'	# reserve this amount of sectors by default, it will be made larger if necessary.

### can't run from X to prevent accident
if ! test -t 0 {
	Xdialog --title "Error!" --infobox "Please run this from console." 0 0 10000
	exit
}

### usage
if test -z $1 {
	cat <<< """
This is a small tool to make the extra space that was lost when you dd
fatdog.iso to a USB flash drive to be usable again.

Usage: $0 /dev/xxx

Where xxx is the your USB flash drive (e.g. sdb, sdc etc).

Warning: Please make sure you pass the correct device, if you pass the wrong
one you can EASILY DESTROY your harddisk irrecoverably.

"""
	exit
}
setvar DEV = ${1##*/}

### paranoia check - make sure sfdisk exist
if ! which sfdisk > /dev/null {
	echo "This tool needs to use sfdisk"
	echo "Aborting."
	exit
}

### paranoia check - make sure we have rights to write to it
if ! test -w $1 {
	echo "You don't have the rights to write to $1"
	echo "Become root or become a member of the disk group first."
	echo "Aborting."
	exit
}

### paranoia check - block device must exist
if ! test -e /sys/block/$DEV {
	echo "$1 isn't a block device. Please specify the block device (e.g. /dev/sdb)"
	echo "and NOT the partition (e.g. /dev/sdb1)"
	echo "Aborting."
	exit
}

### paranoia check - must be removable
read check < /sys/block/$DEV/removable
if test $check -eq 0 {
	echo "$1 is non-removable, I don't think you want to do this."
	echo "Aborting."
	exit
}

### paranoia check - must be symlinked to "usb" bus
case{
	*/usb[0-9]* { }
	* {	echo "$1 is not a USB device."
		echo "Aborting."
		exit
}
}

### paranoia check - partition 3 must be empty
setvar check = $(sfdisk -uS -l $1 2>/dev/null| awk -v dev=${1}3 '$1==dev {print $6}')
case (check) {
	Empty { }
	* {	echo "Partition 3 of $1 (${1}3) is not empty."
		echo "Aborting."
		exit
}
}

### ask filesystem type
cat <<< """
Specify filesystem type (in hex number). These are common ones:
L  - linux (ext2/3/4)
b  - FAT32
7  - NTFS or exFAT
ef - UEFI boot partition
Default is FAT32
"""
read partition
if test -z $partition {
	echo "No partition type is supplied, will assume FAT32"
	setvar partition = 'b'
}
echo You choose '"'$partition'"' as the type.

### check reserved space
setvar ACTUAL_USED = $(sfdisk -uS -l $1 2>/dev/null | awk '/\*/ {print $4}')
if test $RESERVED_SPACE -lt $ACTUAL_USED {
	setvar RESERVED_SPACE = $(( (($ACTUAL_USED/4096)+4)*4096 )) # round up to next nearest 4096 
}
echo "Reserving space for $RESERVED_SPACE sectors."

### all checks go, one more time to confirm
read -p "Last chance to abort - are you sure to you want to fix $1 [y/N]? " check
case (check) {
	y|Y|yes|Yes|YES { }
	* {	echo "Aborting."
		exit }
}

### create the partition
echo "$RESERVED_SPACE,$(( $(sfdisk -s $1 2>/dev/null) * 2 - $RESERVED_SPACE)),$partition" | sfdisk -f -N3 -uS $1

### final message
cat <<< """

Done. Now you need to make filesystem in it. How to do it depends on the
filesystem you have chosen.
For FAT32, do "mkdosfs ${1}3"
For NTFS,  do "mkntfs ${1}3"
For exFAT, do "mkfs -t exfat ${1}3"
For Linux, do "mkfs -t ext4 ${1}3" (or ext3 or ext2 as you wish)
For other filesystem - I assume you know what you're doing :)

If you already have a previous filesystem there (ie you dd fatdog.iso to 
a USB flash drive that has previously been "fixed"), you may not need to 
format it.

If you need to format it, after formatting type "sfdisk -R $1" to refresh
the drive icons.

=== THE END ===

"""