/etc/xen/scripts/block-tap is in xen-utils-common 4.9.2-0ubuntu1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123  | #!/bin/bash -e
#
# tapdisk 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-tap,vdev=xvda,target=<type>:<file>
#
# Type is either "aio" (for raw files), or "vhd"
dir=$(dirname "$0")
. "$dir/block-common.sh"
remove_label()
{
    echo $1 | sed "s/^\("$2"\)//"
}
check_tools()
{
    if ! command -v tap-ctl > /dev/null 2>&1; then
        fatal "Unable to find tap-ctl tool"
    fi
    modprobe blktap
    if ! tap-ctl check >& /dev/null ; then
	fatal "Blocktap kernel module not available"
    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
}
# Sets $pid and $minor to point to the device associated with the target
find_device()
{
    local info
    local param
    if [ -z "$type" ] || [ -z "$file" ]; then
        fatal "required parameters not set"
    fi
    info=$(tap-ctl list -t $type -f $file)
    for param in $(echo "$info" | tr "," "\n")
    do
        case $param in
        pid=*)
            pid=$(remove_label $param "pid=")
            ;;
        minor=*)
            minor=$(remove_label $param "minor=")
            ;;
        esac
    done
    if [ -z "$pid" ] || [ -z "$minor" ]; then
        fatal "cannot find required parameters"
    fi
}
# Attaches the device and writes xenstore backend entries to connect
# the device
add()
{
    dev=$(tap-ctl create -a $target)
    write_dev $dev
}
# Disconnects the device
remove()
{
    find_device
    do_or_die tap-ctl destroy -p ${pid} -m ${minor} > /dev/null
}
command=$1
target=$(xenstore-read $XENBUS_PATH/params || true)
if [ -z "$target" ]; then
    fatal "No information about the target"
fi
parse_target "$target"
check_tools || exit 1
case $command in
add)
    add
    ;;
remove)
    remove
    ;;
*)
    exit 1
    ;;
esac
 |