#!/bin/bash
#
# frecover - floppy recover
#
# A utility to chew through a physically damaged device and recover
# data from all of the readable clusters. The recovered data is then
# reassembled with binary nulls filling the unrecoverable addresses.
#
# Copyright (C) 2001 George Bakos
#     Written by George Bakos (alpinista@bigfoot.com)
#
# You may not want to run this from a console, as the kernel will scream
# bloody murder every time it runs into an unreadable cluster.
#
# frecover is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2, or (at your option) any later
# version.
#
# frecover is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
# for more details. A copy of the GPL is available from the Free Software
# Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

usage()
	{
	echo $'\t'"usage: $0 [device]" 1>&2
	echo $'\t'"default device is /dev/fd0 " $'\n'
	}	

if [ "$1" = "--help" ]
	then usage
        exit 0
fi
#
# Decide if we want to use fd0 or some other device
#
if [ $# -eq 1 ]
	then DSK=$1
	else DSK="/dev/fd0"
fi
#
# If you are using anything other than a 1.44MB floppy, please be
# sure to change the following to the capacity, in bytes, of your media.
#
DSKSIZE=1474560
#
# If INCR is adjusted higher, the recovery will be faster, but you stand
# a greater chance of missing something. If you are really nit-picky, you 
# are welcome to lower it, but be ready to wait a looooong time if there
# is alot of damage. In theory, lowering this below your cluster size won't
# gain you anything.  YMMV.
#
INCR=128
#
# ZDEV is a character generator to pad out the spaces between good data.
# If you don't have a /dev/zero, or wish to use something else, edit this
# next line.
#
ZDEV=/dev/zero
#
# dd should be in /bin, otherwise change this line
#
DDBIN=/bin/dd
#
######### Don't change anything below this line #########
#
DOFFSET=0
SHIMVAL=0
SHIMCNT=0
DOFFSET=0
RCRDS=0
BYTES=0
CNT=1
TMPDIR=/tmp/`date +%s`
NEWIMG=$TMPDIR/newimage.img

test -x $DDBIN ||\
		{
		echo dd not found
		exit 1
		}

test -b $DSK ||\
	{
	echo $'\n'$DSK is not a valid block device
	usage
	exit 1
	}

test -c $ZDEV ||\
	{
	echo $'\n'$ZDEV is not a valid character device
	exit 1
	}

readgood()
	{
	TMPFIL=$TMPDIR/$CNT
	RCRDS=`$DDBIN if=$DSK of=$TMPFIL bs=1 skip=$DOFFSET  2>&1 | tail -1 | cut -d \+ -f 1`
			if [ $RCRDS -eq 0 ]
			then
				{
				echo -n $DOFFSET bytes of $DSKSIZE complete$'\r'
				DOFFSET=$(($DOFFSET + $INCR))
				if [ $DOFFSET -ge $DSKSIZE ]
					then return
				fi
				SHIMVAL=$(($SHIMVAL + $INCR))
				}
			else	
				{
				DOFFSET=$(($DOFFSET + $RCRDS))
					SHIMCNT=$(($CNT - 1))
					$DDBIN if=$ZDEV of=$TMPDIR/$SHIMCNT bs=1 count=$SHIMVAL 2>/dev/null
					CNT=$(($CNT + 2))
					SHIMVAL=0
				}
			fi
	}

todisk()
	{
	echo "Remove original and insert clean diskette."
	echo "WARNING! All data on target disk will be overwritten!"
	echo "Enter to continue"
	read pause && echo $pause Writing image to $DSK
	$DDBIN if=$NEWIMG of=$DSK 2>/dev/null
	echo Finished.
	}

reconstr()
	{
	ls -1 $TMPDIR |sort -n | while read f
		do cat $TMPDIR/$f >> $NEWIMG
		echo -n \#
		done
		echo
		echo "Reconstruction complete"
		echo "Rebuilt image is $NEWIMG"
		if [ $(ls -l $NEWIMG |awk '{print $5}') != $DSKSIZE ]
		then
			{
			echo "WARNING! New image file size error. Recovery may be incomplete"
			exit 1
			}
		fi
	}
echo "Recovering disk in $DSK, $DSKSIZE bytes in $INCR byte increments."

mkdir $TMPDIR

while [ $DOFFSET -le $DSKSIZE ]
	do readgood
done

echo "Finished reading recoverable data. Reconstruction initiated"
reconstr
echo "Would you like to write the recovered image to disk? "
echo -n "Type y to to write, or anything else to exit: "

read resp
val=x$resp
	if [ $val = "xy" ]
	then todisk
	fi

exit 0