#!/bin/sh
set -e
image="$1"
bridge=br0
[ -e "$image" ] || { echo "Usage: $0 <image> [options...]" >&2; exit 1; }
shift

# generate tap setup script
script=`mktemp --tmpdir qemu.tap.script.XXXXXX`
/bin/echo -e '#!/bin/sh\nip link set "$1" up\nip link set "$1" master' $bridge > $script
chmod 755 $script

# find a free MAC adddress
i=0
while [ $i -lt 255 ]; do
    MAC=$(printf '52:54:00:12:34:%02x' $i)
    arp -ani $bridge | grep -q $MAC || break
    i=$((i+1))
done
echo "MAC address: $MAC"

sudo qemu-system-x86_64 -enable-kvm -m 2048 -drive file="$image",if=virtio \
    -net tap,script=$script,downscript=no -net nic,model=virtio,macaddr=$MAC "$@"
rm $script