Add image creator helper script for OBBs

#!/bin/bash

#

# Copyright (C) 2010 The Android Open Source Project

# 

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#      http://www.apache.org/licenses/LICENSE-2.0

# 

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

#

# mkobb.sh - Creates OBB files on Linux machines

# Directory where we should temporarily mount the OBB loopback to copy files

MOUNTDIR=/tmp

# Presets. Changing these will probably break your OBB on the device

CRYPTO=blowfish

FS=vfat

MKFS=mkfs.vfat

LOSETUP=losetup

BLOCK_SIZE=512

SLOP=512 # Amount of filesystem slop in ${BLOCK_SIZE} blocks

find_binaries() {

    MKFSBIN=`which ${MKFS}`

    LOSETUPBIN=`which ${LOSETUP}`

    MOUNTBIN=`which mount`

    UMOUNTBIN=`which umount`

    DDBIN=`which dd`

    RSYNCBIN=`which rsync`

}

check_prereqs() {

    if [ "`uname -s`x" != "Linuxx" ]; then \

        echo "ERROR: This script only works on Linux!"

        exit 1

    fi

    if ! egrep -q "^cryptoloop " /proc/modules; then \

        echo "ERROR: Could not find cryptoloop in the kernel."

        echo "Perhaps you need to: modprobe cryptoloop"

        exit 1

    fi

    if ! egrep -q "name\s*:\s*${CRYPTO}$" /proc/crypto; then \

        echo "ERROR: Could not find crypto \`${CRYPTO}' in the kernel."

        echo "Perhaps you need to: modprobe ${CRYPTO}"

        exit 1

    fi

    if ! egrep -q "^\s*${FS}$" /proc/filesystems; then \

        echo "ERROR: Could not find filesystem \`${FS}' in the kernel."

        echo "Perhaps you need to: modprobe ${FS}"

        exit 1

    fi

    if [ "${MKFSBIN}x" = "x" ]; then \

        echo "ERROR: Could not find ${MKFS} in your path!"

        exit 1

    elif [ ! -x "${MKFSBIN}" ]; then \

        echo "ERROR: ${MKFSBIN} is not executable!"

        exit 1

    fi

    if [ "${LOSETUPBIN}x" = "x" ]; then \

        echo "ERROR: Could not find ${LOSETUP} in your path!"

        exit 1

    elif [ ! -x "${LOSETUPBIN}" ]; then \

        echo "ERROR: ${LOSETUPBIN} is not executable!"

        exit 1

    fi

}

cleanup() {

    if [ "${loopdev}x" != "x" ]; then \

        ${LOSETUPBIN} -d ${loopdev}

    fi

}

hidden_prompt() {

    unset output

    prompt="$1"

    outvar="$2"

    while read -s -n 1 -p "$prompt" c; do \

        if [ "x$c" = "x" ]; then \

            break

        fi

        prompt='*'

        output="${output}${c}"

    done

    echo

    eval $outvar="$output"

    unset output

}

read_key() {

    hidden_prompt "        Encryption key: " key

    if [ "${key}x" = "x" ]; then \

        echo "ERROR: An empty key is not allowed!"

        exit 1

    fi

    hidden_prompt "Encryption key (again): " key2

    if [ "${key}x" != "${key2}x" ]; then \

        echo "ERROR: Encryption keys do not match!"

        exit 1

    fi

}

onexit() {

    if [ "x${temp_mount}" != "x" ]; then \

        ${UMOUNTBIN} ${temp_mount}

        rmdir ${temp_mount}

    fi

    if [ "x${loop_dev}" != "x" ]; then \

        ${LOSETUPBIN} -d ${loop_dev}

    fi

    if [ "x${tempfile}" != "x" -a -f "${tempfile}" ]; then \

        rm -f ${tempfile}

    fi

    if [ "x${keyfile}" != "x" -a -f "${keyfile}" ]; then \

        rm -f ${keyfile}

    fi

    echo "Fatal error."

    exit 1

}

usage() {

    echo "mkobb.sh -- Create OBB files for use on Android"

    echo ""

    echo " -c             Use an encrypted OBB; must specify key"

    echo " -d <directory> Use <directory> as input for OBB files"

    echo " -k <key>       Use <key> to encrypt OBB file"

    echo " -K             Prompt for key to encrypt OBB file"

    echo " -o <filename>  Write OBB file out to <filename>"

    echo " -v             Verbose mode"

    echo " -h             Help; this usage screen"

}

find_binaries

check_prereqs

use_crypto=0

args=`getopt -o cd:hk:Ko:v -- "$@"`

eval set -- "$args"

while true; do \

    case "$1" in

        -c) use_crypto=1; shift;;

        -d) directory=$2; shift 2;;

        -h) usage; exit 1;;

        -k) key=$2; shift 2;;

        -K) prompt_key=1; shift;;

        -v) verbose=1; shift;;

        -o) filename=$2; shift 2;;

        --) shift; break;;

        *) echo "ERROR: Invalid argument in option parsing! Cannot recover. Ever."; exit 1;;

    esac

done

if [ "${directory}x" = "x" -o ! -d "${directory}" ]; then \

    echo "ERROR: Must specify valid input directory"

    echo ""

    usage

    exit 1;

fi

if [ "${filename}x" = "x" ]; then \

    echo "ERROR: Must specify filename"

    echo ""

    usage

    exit 1;

fi

if [ ${use_crypto} -eq 1 -a "${key}x" = "x" -a 0${prompt_key} -eq 0 ]; then \

    echo "ERROR: Crypto desired, but no key supplied or requested to prompt for."

    exit 1

fi

if [ 0${prompt_key} -eq 1 ]; then \

    read_key

fi

outdir=`dirname ${filename}`

if [ ! -d "${outdir}" ]; then \

    echo "ERROR: Output directory does not exist: ${outdir}"

    exit 1

fi

# Make sure we clean up any stuff we create from here on during error conditions

trap onexit ERR

tempfile=$(tempfile -d ${outdir}) || ( echo "ERROR: couldn't create temporary file in ${outdir}"; exit 1 )

block_count=`du --apparent-size --block-size=512 ${directory} | awk '{ print $1; }'`

if [ $? -ne 0 ]; then \

    echo "ERROR: Couldn't read size of input directory ${directory}"

    exit 1

fi

echo "Creating temporary file..."

${DDBIN} if=/dev/zero of=${tempfile} bs=${BLOCK_SIZE} count=$((${block_count} + ${SLOP})) > /dev/null 2>&1

if [ $? -ne 0 ]; then \

    echo "ERROR: creating temporary file: $?"

fi

loop_dev=$(${LOSETUPBIN} -f) || ( echo "ERROR: losetup wouldn't tell us the next unused device"; exit 1 )

if [ ${use_crypto} -eq 1 ]; then \

    keyfile=$(tempfile -d ${outdir}) || ( echo "ERROR: could not create temporary key file"; exit 1 )

    ${LOSETUPBIN} -p 5 -e ${CRYPTO} ${loop_dev} ${tempfile} 5< ${keyfile} || ( echo "ERROR: couldn't create loopback device"; exit 1 )

    rm -f ${keyfile}

else \

    ${LOSETUPBIN} ${loop_dev} ${tempfile} || ( echo "ERROR: couldn't create loopback device"; exit 1 )

fi

#

# Create the filesystem

#

echo ""

${MKFSBIN} -I ${loop_dev}

echo ""

#

# Make the temporary mount point and mount it

#

temp_mount="${MOUNTDIR}/${RANDOM}"

mkdir ${temp_mount}

${MOUNTBIN} -t ${FS} -o loop ${loop_dev} ${temp_mount}

#

# rsync the files!

#

echo "Copying files:"

${RSYNCBIN} -av --no-owner --no-group ${directory}/ ${temp_mount}/

echo ""

echo "Successfully created \`${filename}'"

#

# Undo all the temporaries

#

umount ${temp_mount}

rmdir ${temp_mount}

${LOSETUPBIN} -d ${loop_dev}

mv ${tempfile} ${filename}

trap - ERR

exit 0