#!/bin/bash -e
#
# dummy Xen block device hotplug script
#
# Author George Dunlap <george.dunlap@eu.citrix.com>
#
# Based on block-iscsi by Roger Pau Monné <roger.pau@citrix.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation; version 2.1 only. with the special
# exception on linking described in file LICENSE.
#
# This program 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 Lesser General Public License for more details.
#
# Usage:
#
# Target should be specified using the following syntax:
#
# script=block-dummy,vdev=xvda,target=dummy:<file>

dir=$(dirname "$0")
. "$dir/block-common.sh"

check_tools()
{
    if ! command -v losetup > /dev/null 2>&1; then
        fatal "Unable to find losetup"
    fi
}

# Sets the following global variables based on the params field passed in as
# a parameter: type file
parse_target()
{
    params=($(echo "$1" | tr ":" "\n"))

    type=${params[0]}
    file=${params[1]}
    if [ -z "$type" ] || [ -z "$file" ]; then
        fatal "Cannot parse required parameters"
    fi

    if [ "$type" != "dummy" ] ; then
	fatal "Invalid type: $type"
    fi
}

# Attaches the device and writes xenstore backend entries to connect
# the device
add()
{
    test -f "$file" || fatal "$file does not exist."

    loopdev=$(losetup -f 2>/dev/null || find_free_loopback_dev)
    if [ "$loopdev" = '' ]
    then
        fatal 'Failed to find an unused loop device'
    fi
    
    if LANG=C losetup -h 2>&1 | grep read-only >/dev/null
    then
        roflag="-$mode"; roflag="${roflag#-w}"; roflag="${roflag#-!}"
    else
        roflag=''
    fi

    do_or_die losetup $roflag "$loopdev" "$file"
    # FIXME Is this OK?
    xenstore_write "$XENBUS_PATH/node" "$loopdev"
    write_dev "$loopdev"
}

# Disconnects the device
remove()
{
    node=$(xenstore_read "$XENBUS_PATH/node")
    losetup -d "$node"
}

command=$1
target=$(xenstore-read $XENBUS_PATH/params || true)
if [ -z "$target" ]; then
    fatal "No information about the target"
fi

parse_target "$target"

mode=$(xenstore_read "$XENBUS_PATH/mode")
mode=$(canonicalise_mode "$mode")

check_tools || exit 1

case $command in
add)
    add
    ;;
remove)
    remove
    ;;
*)
    exit 1
    ;;
esac