#!/bin/sh
# wipefile - completely overwrite a file
# Originally by Heiner Steven (heiner.steven@odn.de), 7/96
# Expanded by Lorance Stinson <LoranceStinson AT gmail DOT com>.
# Last modified 2006-06-11

# To adapt to System V vs. BSD 'echo'
if echo '\c' | grep -s c > /dev/null ; then
    # BSD
    NOCR1='-n'
    NOCR2=""
else
    # System V
    NOCR1=""
    NOCR2='\c'
fi

BASENAME=`basename $0` # This programs name.
PASSES=1 # The default number of passes to make.
RANDEV='/dev/random' # The default random device.

#**************************************************************************
# usage() - Display the command line help text.
#**************************************************************************
usage(){
    if [ "$1" ] ; then
        echo "$1"
        echo ""
    fi
    shift
    cat<<EOHELP
Usage:  $BASENAME [options] [file...]
Overwrites a file or files with different data.
5 operations are performed per pass.
1) Fill the file with 0x00. (Uses /dev/zero).
2) Fill the file with 0xFF.
3) Fill the file with 0XAA, binary 10101010.
4) Fill the file with 0x55, binary 01010101.
5) Use /dev/random to fill with random data.
After each operation sync is called to force data to the disk.
Use on networked file systems is not recommended.
Options:
    -h          This text.
    -p <pass>   The number of passes to make. Default: $PASSES
    -q          Quite mode. No output is generated, assumes -y.
    -r          Remove the file(s) when finished.
    -u          Use /dev/urandom instead of /dev/random.
    -y          Do not request confirmation.
EOHELP
    exit 1
}

#**************************************************************************
# Parse the command line arguments.
#**************************************************************************
FILES=""
while [ "$#" -gt 0 ] ; do
    case "$1" in
        # Print the help text.
        -h) usage;;
        # The number of passes to make
        -p) PASSES="$2"; shift 2;;
        # Quite.
        -q) QUIET="Y"; shift;;
        # Remove the file when finished.
        -r) REMOVE="Y"; shift;;
        # Use /dev/urandom.
        -u) RANDEV='/dev/urandom'; shift;;
        # Assume yes.
        -y) ASSYES="Y"; shift;;
        # Anything after -- is files to process.
        --) FILES="$FILES $@"; break;;
        # Check for invalid options.
        -*) usage "Invalid option $1";;
        # Anything should be a file.
        *)  FILES="$FILES $1"; shift;;
    esac
done

# Restore the files.
eval set X "$FILES"
shift

#**************************************************************************
# Wipe the files given on the command line.
#**************************************************************************
for FILE ; do
    [ ! -w "$FILE" -a "$QUITE" = "" ] &&
        echo "$BASENAME: $FILE: File not found or is not writable." && continue

    SIZE=`ls -ld "$FILE" | awk '{print $(NF-4)}'`
    if [ "$QUITE" = ""  -a "$ASSYES" = "" ] ; then
        echo $NOCR1 "$BASENAME: really overwrite $NOCR2"
        [ "$REMOVE" = "Y" ] && echo $NOCR1 "and delete $NOCR2"
        echo $NOCR1 "$FILE ($SIZE bytes) (y/n)? $NOCR2"
        read RESPONSE || exit 2
        case "$RESPONSE" in
            y*|Y*)  ;;
            *)      continue;;
        esac
    fi

    [ "$QUIET" = "" ] && echo "$BASENAME: wiping $FILE for $PASSES passes..."
    PASS=0
    while [ $PASS -lt $PASSES ] ; do
        [ "$QUIET" = "" ] && echo "$BASENAME: $FILE: Pass `expr "$PASS" + 1`: filling with 0x00"
        [ `dd if=/dev/zero of="$FILE" bs=1 count="$SIZE" 2>/dev/null` ] &&
            echo "Error wiping $FILE." 1>&2 && continue 2
        sync
        [ "$QUIET" = "" ] && echo "$BASENAME: $FILE: Pass `expr "$PASS" + 1`: filling with 0xFF"
        [ `yes | tr "y\\n" "\\377" | dd of="$FILE" bs=1 count="$SIZE" 2>/dev/null` ] &&
            echo "Error wiping $FILE." 1>&2 && continue 2
        sync
        [ "$QUIET" = "" ] && echo "$BASENAME: $FILE: Pass `expr "$PASS" + 1`: filling with 0XAA"
        [ `yes | tr "y\\n" "\\252" | dd of="$FILE" bs=1 count="$SIZE" 2>/dev/null` ] &&
            echo "Error wiping $FILE." 1>&2 && continue 2
        sync
        [ "$QUIET" = "" ] && echo "$BASENAME: $FILE: Pass `expr "$PASS" + 1`: filling with 0x55"
        [ `yes | tr "y\\n" "\\125" | dd of="$FILE" bs=1 count="$SIZE" 2>/dev/null` ] &&
            echo "Error wiping $FILE." 1>&2 && continue 2
        sync
        [ "$QUIET" = "" ] && echo "$BASENAME: $FILE: Pass `expr "$PASS" + 1`: using $RANDEV"
        [ `dd if=$RANDEV of="$FILE" bs=1 count="$SIZE" 2>/dev/null` ] &&
            echo "Error wiping $FILE." 1>&2 && continue 2
        sync
        PASS=`expr $PASS + 1`
    done
    [ "$REMOVE" = "Y" -a "$QUIET" = "" ] && echo "$BASENAME: deleting $FILE."
    [ "$REMOVE" = "Y" ] && rm -f "$FILE"
done