bootableusb

#!/bin/bash
#+
# Use this script to create a bootable USB flash drive.
#-
source scripts/mistify-functions.sh

# Where buildmistify settings are maintained.
statedir=$projectdir/.buildmistify

# Default values some of which could be parameterized.
imagesdir=images
stagedir=usb
tmpdir=/tmp
mountdir=$tmpdir/$id/mnt
bootimage=$tmpdir/boot.img

usage () {
    cat << EOF
Usage: ./$id [options]
  This script installs the Mistify-OS images onto a target drive so that it
  can be booted on the target. In most cases this is a USB flashdrive.
  
  WARNING: This is a potentially destructive script which will destroy existing
  content on the target device. To help avoid unintended destruction of data
  this script first verifies that the target device is a removable device.
  
  Options:
    -b|--builddir <dir>
        Where to find the target images. This location is read from the
        file $statedir/builddir. NOTE: This is normally set by the buildmistify
        script.
        [builddir=`cat $statedir/builddir`]
    -t|--targetdev <device>
        The device on which to install the bootable images. This is typically
        sdX where X indicates a removable device in the /dev directory. If this
        is equal to "default" then this script will scan for removable devices
        and use the highest ordered one. e.g. sdd will be used before sdc.
        [targetdev=`cat $statedir/targetdev`]
    --install
        Install onto the target device. Otherwise only create the image.
EOF
}

#+
# Handle the command line options.
#-
a=`getopt -l "\
targetdev:,\
builddir:,\
install,\
help" \
   -o "t:b:h" -- "$@"`

if [ $? -gt 0 ]; then
    usage
    exit 1
fi

eval set -- $a

while [ $# -ge 1 ]; do
    case "$1" in
	--)
	    shift
	    break
	    ;;
	-t|--targetdev)
	    targetdev=$2
	    shift
	    ;;
	-b|--builddir)
	    builddir=$2
	    shift
	    ;;
	--install)
	    install=yes
	    ;;
	-h|--help)
	    usage
	    exit 0
	    ;;
	# using getopt should avoid needing this catchall but just in case...
	*)
	    error "Invalid option: $1"
	    usage
	    exit 1
	    ;;
    esac
    shift
done
if [[ $# -ne 0 ]]; then
  usage
  exit 1
fi

is_removable () {
    local _retval=$1
    if [ -e "/sys/block/$1/removable" ]; then
        r=`cat /sys/block/$1/removable`
        if [ "$r" = "1" ]; then
	    return 0
	fi
    fi
    return 1
}

#+
# Scan for a removable device starting with the highest and working down.
#-
find_removable_device () {
    local _retval=$1
    for d in sdi sdj sdh sdg sdf sde sdd sdc; do
        message "Checking /dev/$d"
        if is_removable $d; then
            message "Device $d is removable."
	    eval $_retval=$d
	    return
        fi
    done
    error "No removable devices found."
    exit 1
}

function setup_img() {
    [ -d $builddir/$stagedir ] || mkdir $builddir/$stagedir

    cp $builddir/$imagesdir/bzImage.buildroot $builddir/$stagedir/bzImage
    cp $builddir/$imagesdir/initrd.buildroot $builddir/$stagedir/initrd
}

function syslinux_config() {
    #+
    # TODO: For now this is simply a copy but in the future may want to use sed
    # to customize the syslinux menu using parameters passed to this script
    # from the command line.
    #-
    cp scripts/syslinux.cfg $1
}

function make_usb_img() {

    mkdir -p $builddir/$stagedir/syslinux
    syslinux_config $builddir/$stagedir/syslinux/syslinux.cfg

    _size=`du -ms $builddir/$stagedir | awk '
    function ceiling(x)
    {
    return (x == int(x)) ? x : int(x)+1
    }
    {printf "%s", ceiling($1/256)*256}
    '`

    _size=`printf "%sM" $_size`

    echo _size=$_size

    rm -f $bootimage
    truncate -s $_size $bootimage

    printf "0,32,b,*\n0,0\n0,0\n0,0\n;\n" | sfdisk $bootimage

    run sudo scripts/makediskimage $mountdir $builddir/$stagedir $bootimage
    #+
    # No longer need root access.
    #-
    mv $bootimage $builddir/$imagesdir/mistify-usb.img
    # TODO: Need to remove the mount directory.
}

message "Creating a bootable USB flashdrive."

#+
# Determine the location of the build directory.
# NOTE: The directory does not need to exist because the Buildroot make will
# create it if necessary.
#-
if [ -z "$builddir" ]; then
    if [ -f $statedir/builddir ]; then
        builddir=`cat $statedir/builddir`
    else
        error "No build directory specified."
        exit 1
    fi
fi
if [ ! -d "$builddir" ]; then
    error "The build directory $builddir doesn't exist."
    exit 1
fi
message "Build output directory is: $builddir"

#+
# Prepare the target image.
#-
setup_img
make_usb_img

message "USB image file is: $builddir/$imagesdir/mistify-usb.img"

if [ -z "$install" ]; then
  exit 0
fi

#+
# Validate the target device.
#-
if [[ "$targetdev" == "default" ]]; then
    find_removable_device targetdev
fi
if [ -z "$targetdev" ]; then
    if [ -f $statedir/targetdev ]; then
        targetdev=`cat $statedir/targetdev`
    else
        find_removable_device targetdev
    fi
fi
if ! is_removable $targetdev; then
    error "The target device $targetdev is not removable."
    exit 1
fi

#+
# If the device is mounted then don't use it. As a precaution force the user
# to manually unmount it.
#-
if is_mounted /dev/$targetdev; then
    error "The target device $targetdev is mounted."
fi

warning "This is destructive. Install onto /dev/$targetdev?"
select yn in "Yes" "No"; do
    case $yn in
        Yes )
            echo $targetdev >$statedir/targetdev
            message "Installing to /dev/$targetdev"
            run dd if=$builddir/$imagesdir/mistify-usb.img | pv | sudo dd of=/dev/$targetdev
	    break;;
        No )
            message "Exiting"
	    exit 1;;
    esac
done

exit 0