#!/usr/bin/env bash
# Start a private dbus-daemon and a QEMU guest that exports its display and audio on it.
#
# Usage: run_vm.sh <work-dir> <disk-image> [extra qemu args...]
#
# Environment:
#   QEMU           QEMU binary (default: qemu-system-x86_64 from PATH)
#   VM_NAME        VM name (default: e2e-guest)
#   VM_ACCEL       "kvm" or "tcg" (default: kvm when /dev/kvm is usable, else tcg)
#   VM_START_WAIT  seconds to wait for org.qemu on the bus (default: 30)
#
# Writes into <work-dir>:
#   bus.sock      the private bus socket; bus address is unix:path=<work-dir>/bus.sock
#   dbus.pid      dbus-daemon pid
#   qemu.pid      QEMU pid
#   qmp.sock      QMP socket
#   qemu.log      QEMU stdout/stderr
#   dbus.log      dbus-daemon stdout/stderr
set -euo pipefail

work="${1:?usage: run_vm.sh <work-dir> <disk-image> [qemu args...]}"
image="${2:?usage: run_vm.sh <work-dir> <disk-image> [qemu args...]}"
shift 2

qemu="${QEMU:-qemu-system-x86_64}"
name="${VM_NAME:-e2e-guest}"
wait_s="${VM_START_WAIT:-30}"

if [[ -z "${VM_ACCEL:-}" ]]; then
  if [[ -r /dev/kvm && -w /dev/kvm ]]; then
    VM_ACCEL=kvm
  else
    VM_ACCEL=tcg
  fi
fi

mkdir -p "${work}"
bus_socket="${work}/bus.sock"
bus_address="unix:path=${bus_socket}"
rm -f "${bus_socket}" "${work}/qmp.sock"

dbus-daemon --session --nofork --nopidfile --address="${bus_address}" > "${work}/dbus.log" 2>&1 &
echo $! > "${work}/dbus.pid"

for _ in $(seq 1 100); do
  [[ -S "${bus_socket}" ]] && break
  sleep 0.05
done
if [[ ! -S "${bus_socket}" ]]; then
  echo "dbus-daemon didn't create ${bus_socket}" >&2
  exit 1
fi

"${qemu}" \
  -name "${name}" \
  -accel "${VM_ACCEL}" \
  -m 128 \
  -nodefaults \
  -device virtio-vga \
  -display dbus,addr="${bus_address}" \
  -audiodev dbus,id=snd0 \
  -device intel-hda -device hda-output,audiodev=snd0 \
  -device virtio-tablet-pci \
  -device virtio-keyboard-pci \
  -drive file="${image}",format=raw,if=ide,snapshot=on \
  -qmp unix:"${work}/qmp.sock",server=on,wait=off \
  "$@" > "${work}/qemu.log" 2>&1 &
echo $! > "${work}/qemu.pid"

for _ in $(seq 1 $((wait_s * 10))); do
  if ! kill -0 "$(cat "${work}/qemu.pid")" 2>/dev/null; then
    echo "QEMU exited early; see ${work}/qemu.log" >&2
    cat "${work}/qemu.log" >&2
    exit 1
  fi
  if gdbus call --address "${bus_address}" --dest org.freedesktop.DBus --object-path /org/freedesktop/DBus \
      --method org.freedesktop.DBus.NameHasOwner org.qemu 2>/dev/null | grep -q true; then
    echo "${bus_address}"
    exit 0
  fi
  sleep 0.1
done

echo "QEMU didn't own org.qemu within ${wait_s}s" >&2
exit 1