#!/bin/bash
# SPDX-License-Identifier: MIT

# Virtual machine control script for QEMU/KVM VMs.
# Tested on Gentoo (~amd64/hardened) with qemu-6.0.

# Version: 2021-10-08
# Author:  Nils Freydank <holgersson@posteo.de>
# License: MIT

# TODO (not in specific order):
# 1. Fix different ARCHes (-cpu host won't work for non-x86)
# 2. qemu-img commit
# 3. clipboard support via spice
# 4. Support boot from CD for first installations.
# 5. query status
# 6. save and stop in a single command?
#    same for restore: stop, restore, cont(inue)
# 7. shared dir without smb, but via FUSE
# 8. bash and zsh-completion
# 9. don't rely on the PID to check if the VM is running, query socket?
# 10. shellsheck?

# === Installation ===
# The following packages are necessary on Gentoo/Linux:
#   app-emulation/qemu net-misc/socat app-emulation/virt-viewer
# To use an EFI for the clients you will need also sys-firmware/edk2-ovmf
# which is pulled into the depgraph by USE="binary" on qemu.

# === How to use this script ===
# Create a directory to store your VM images and metadata.
# Let it be readable and writeable for the user who executes QEMU.
# Copy this script into that directory.
# For each Guest do the following:
#   Create a directory named exactly as the guest (case sensitive).
#   Create an qcow2 image named virtual-machine.img inside
#   the newly created directory.
#   Create a configuration file named exactly as the guest plus a suffix '.sh'.
#   Fill in the data from the example below into the configuration file.
#   Control the vm by calling: ./<name-of-this-script.sh> <guest> <operation>,
#   e.g. ./control-vm.sh Gentoo-guest start
#   or   ./control-vm.sh Gentoo-guest connect
#   or   ./control-vm.sh Gentoo-guest shudown
#
# You should now have a setup like:
# ${HOME}/vm/
# ${HOME}/vm/control-vm.sh
# ${HOME}/vm/Gentoo-guest/virtual-machine.img
# ${HOME}/vm/Gentoo-guest.sh

# === Configuration of the guest ===
# Create a file with the guest's parameters and name it same as the "GUEST_NAME"
# plus a "sh" suffix, so we can easily assume the name later.
#
# cat << _EOF > "${GUEST_NAME}.sh"
# # Provide the GUEST_NAME which is used in further configuration.
# GUEST_NAME="Guest-OS"
# # Configure the number of CPUs.
# CPUS="2"
# CPU_CORES="8"
# MEMORY="16384"
# NET="True"
# SOUND="True"
# SSH_PORT=""
# # Configure any of the arches QEMU supports in QEMU's notation.
# Leave it empty or omit it for x86_64.
# ARCH=""
# # Disable EFI and enable BIOS fallback mode with unsetting EFI_MACHINE.
# #EFI=""
# Enable the SPICE socket.
# UI="True"
# CLIPBOARD="True"
# _EOF

# Provide a sanity check first.
[[ -z "${1}" ]] && echo "Please provide a guest name!" && exit 1

# === Define default values ===
CLIPBOARD="${CLIPBOARD:-}"
CPUS="${CPUS:-16}"
CPU_CORES="${CPU_CORES:-1}"
EFI="${EFI:-True}"
GUEST_NAME="${1}"
LIVE_ONLY="${LIVE_ONLY:-}"
MACHINE="${MACHINE:-pc-q35-6.0}"
MEMORY="${MEMORY:-16384}"
NET="${NET:-}"
NETDEV_NAME="vmnic-${GUEST_NAME}"
SOUND="${SOUND:-}"
SSH_PORT="${SSH_PORT:-}"
UI="${UI:-}"
# Define paths.
# Note: Sort in alphabetical order as long as inheritance is respected.
BASE_PATH="${BASE_PATH:-${HOME}/vm/${GUEST_NAME}}"
GUEST_CONFIG_FILE="${HOME}/vm/${GUEST_NAME}.sh"
IMAGE_PATH="${IMAGE_PATH:-${BASE_PATH}/virtual-machine.img}"
ISO_PATH="${ISO_PATH:-${BASE_PATH}/../installer/${GUEST_NAME}.iso}"
MONITOR_SOCKET="${MONITOR_SOCKET:-${BASE_PATH}/monitor.socket}"
PID_FILE="${PID_FILE:-${BASE_PATH}/qemu.pid}"
QMP_SOCKET="${QMP_SOCKET:-${BASE_PATH}/qmp.socket}"
SNAPSHOT_INFO_FILE="${SNAPSHOT_INFO_FILE:-${BASE_PATH}/last-snapshot-info}"
SPICE_SOCKET="${SPICE_SOCKET:-${BASE_PATH}/spice.socket}"

# === Source the guest configuration to overwrite defaults if necessary. ===
if [[ -f "${GUEST_CONFIG_FILE}" ]]; then
    source "${GUEST_CONFIG_FILE}"
else
    echo "No configuration found. Aborting."
    exit 2
fi

# === Define a base and glue everything together. ===
QEMU_COMMON_ARGS=(
    # Provide a pretty name for the guest.
    -name "${GUEST_NAME}"
    # Disable some less document user configuration loading.
    -no-user-config
    # Configure some seccomp mode 2 filters.
    -sandbox on,obsolete=deny,elevateprivileges=allow,spawn=allow,resourcecontrol=allow
    # Enable KVM and hardware acceleration.
    -enable-kvm
    # Use the same CPU as the host has for maximum performoance and configure
    # the amount of memory and CPU cores as configured per-host.
    -cpu host
    -smp cpus="${CPUS}",maxcpus="${CPUS}",cores="${CPU_CORES}"
    -m "${MEMORY}"
    # Detach from the current shell and monitor by pid file and a unix socket.
    -daemonize
    -pidfile "${PID_FILE}"
    -monitor unix:"${MONITOR_SOCKET}",server,nowait
    -qmp-pretty unix:"${QMP_SOCKET}",server,nowait
)
QEMU_DISK_ARGS=( -drive id=hd0,media=disk,if=virtio,file="${IMAGE_PATH}",aio=io_uring,cache=none,cache-size=16M,discard=on )
QEMU_DISPLAY_NONE_ARGS=( -vga none -display none )
QEMU_DISPLAY_VIRTIO_ARGS=( -vga virtio )
QEMU_DISPLAY_STD_ARGS=( -vga std )
QEMU_DISPLAY_SPICE_ARGS=( -spice unix=on,addr="${SPICE_SOCKET}",disable-ticketing=on,gl=off )
QEMU_CLIPBOARD_SPICE_ARGS=(
    -device virtio-serial-pci
    -device virtserialport,chardev=spicechannel0,name=com.redhat.spice.0
    -chardev spicevmc,id=spicechannel0,name=vdagent
)
QEMU_EFI_ARGS=(
    -M "${MACHINE}",accel=kvm
    -drive file=/usr/share/edk2-ovmf/OVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on
)
QEMU_BIOS_ARGS=(
    -M "${MACHINE}",accel=kvm
)
QEMU_ISO_ARGS=( -cdrom "${ISO_PATH}" )
QEMU_NET_ARGS=(
    -device virtio-net,netdev="${NETDEV_NAME}"
    -netdev user,id="${NETDEV_NAME}"
)
QEMU_SOUND_ARGS=( -device ich9-intel-hda -device hda-duplex )
QEMU_SSH_ARGS=(
    -device virtio-net,netdev="${NETDEV_NAME}"
    -netdev user,id="${NETDEV_NAME}",hostfwd=tcp:127.0.0.1:"${SSH_PORT}"-:22
)

# === Start the final QEMU parameter array. ===
QEMU_ARGS=( "${QEMU_COMMON_ARGS[@]}" )
if [[ "${EFI}" ]]; then
    QEMU_ARGS+=( "${QEMU_EFI_ARGS[@]}" )
else
    QEMU_ARGS+=( "${QEMU_BIOS_ARGS[@]}" )
fi
# The following block checks only agains live vs non-live.
if [[ "${LIVE_ONLY}" ]]; then
    QEMU_ARGS+=(
        "${QEMU_ISO_ARGS[@]}"
        # d: CD-ROM
        -boot d
    )
else
    QEMU_ARGS+=(
        "${QEMU_DISK_ARGS[@]}"
        # c: hard disk
        -boot c
    )
fi
#
[[ -n "${NET}" && -z "${SSH_PORT}" ]] && QEMU_ARGS+=( "${QEMU_NET_ARGS[@]}" )
[[ -n "${SOUND}" ]] && QEMU_ARGS+=( "${QEMU_SOUND_ARGS[@]}" )
[[ -n "${SSH_PORT}" ]] && QEMU_ARGS+=( "${QEMU_SSH_ARGS[@]}" )
if [[ -n "${UI}" ]]; then
    case "${UI}" in
        std|stdvga ) QEMU_ARGS+=( "${QEMU_DISPLAY_STD_ARGS[@]}" );;
        *) QEMU_ARGS+=( "${QEMU_DISPLAY_VIRTIO_ARGS[@]}" );;
    esac
    QEMU_ARGS+=( "${QEMU_DISPLAY_SPICE_ARGS[@]}" )
    # Only check for clipboard support here as clipoard w/o UI doesn't make
    # sense in this context.
    if [[ -n "${CLIPBOARD}" ]]; then
        QEMU_ARGS+=( "${QEMU_CLIPBOARD_SPICE_ARGS[@]}" )
    fi
else
    QEMU_ARGS+=( "${QEMU_DISPLAY_NONE_ARGS[@]}" )
fi

# === Define functions for the actual QEMU controlling. ===
start_qemu(){
    if [[ ! -f "${PID_FILE}" ]]; then
        echo "Starting VM ${GUEST_NAME}."
        # Define the default architecture.
        [[ -z "${ARCH}" ]] && ARCH="x86_64"
        # Check the existance of the QEMU binary.
        if [[ -x "/usr/bin/qemu-system-${ARCH}" ]]; then
            /usr/bin/qemu-system-"${ARCH}" "${QEMU_ARGS[@]}"
        else
            echo "QEMU has target ${ARCH} not installed."
            echo "Aborting."
            exit 2
        fi
    else
        echo "VM ${GUEST_NAME} seems to be running."
        echo "See ${PID_FILE} for the process ID."
    fi
}
shutdown_qemu(){
    if [[ -f "${PID_FILE}" ]]; then
        echo "Requesting shutdown for VM ${GUEST_NAME}."
        echo "system_powerdown" | socat - unix-connect:"${MONITOR_SOCKET}"
    else
        echo "Looks as VM ${GUEST_NAME} is already stopped."
    fi
}
stop_qemu(){
    if [[ -f "${PID_FILE}" ]]; then
        echo "Forcing shutdown of VM ${GUEST_NAME}."
        echo "quit" | socat - unix-connect:"${MONITOR_SOCKET}"
    else
        echo "Looks as VM ${GUEST_NAME} is already stopped."
    fi
}
connect_to_vm(){
    if [[ -f "${PID_FILE}" ]]; then
        echo "Opening a GUI for ${GUEST_NAME}."
        local REMOTE_VIEWER_OPTS=(
            --title "${GUEST_NAME}"
            --auto-resize=always
            "spice+unix://${SPICE_SOCKET}"
        )
        # Send the viewer into background and drop
        # all annoying GTK error messages to /dev/null.
        ( remote-viewer "${REMOTE_VIEWER_OPTS[@]}" &> /dev/null ) &
        # Alternativly run spicy which is part of spice-gtk
        # e.g. as 'spicy --uri="spice+unix://${SPICE_SOCKET}"'
        # or any other client like remmina. Note that _that_
        # one doesn't support unix sockets yet (as of 2021-09-30):
        # https://gitlab.com/Remmina/Remmina/-/issues/1677
    else
        echo "Looks as VM ${GUEST_NAME} is not running."
    fi
}
save_qemu(){
    if [[ -f "${PID_FILE}" ]]; then
        SNAPSHOT_NAME="snap$(date --utc +%s)"
        echo "Saving state of VM ${GUEST_NAME}."
        echo "savevm ${SNAPSHOT_NAME}" | socat - unix-connect:"${MONITOR_SOCKET}"
        echo "${SNAPSHOT_NAME}" > "${SNAPSHOT_INFO_FILE}"
    else
        echo "Guest ${GUEST_NAME} is not running."
    fi
}
pause_qemu(){
    if [[ -f "${PID_FILE}" ]]; then
        echo "Pausing the VM ${GUEST_NAME}."
        echo "stop" | socat - unix-connect:"${MONITOR_SOCKET}"
    else
        echo "Guest ${GUEST_NAME} not running, nothing to pause."
    fi
}
restore_qemu(){
    if [[ -f "${PID_FILE}" ]]; then
        SNAPSHOT_NAME="$(cat "${SNAPSHOT_INFO_FILE}")"
        echo "Restore state of VM ${GUEST_NAME}."
        pause_qemu
        echo "loadvm ${SNAPSHOT_NAME}" | socat - unix-connect:"${MONITOR_SOCKET}"
        resume_qemu
    else
        echo "Guest ${GUEST_NAME} is not running, nothing to restore."
    fi
}
resume_qemu(){
    if [[ -f "${PID_FILE}" ]]; then
        echo "Resuming the VM ${GUEST_NAME}."
        echo "cont" | socat - unix-connect:"${MONITOR_SOCKET}"
    else
        echo "Guest ${GUEST_NAME} is not running, nothing to resume."
    fi
}

# === Parse the user input. ===
# "$1 != nothing" is already checked earlier.
case "${2}" in
    start) start_qemu;;
    shutdown) shutdown_qemu;;
    stop) stop_qemu;;
    connect) connect_to_vm;;
    save) save_qemu;;
    restore) restore_qemu;;
    pause) pause_qemu;;
    resume) resume_qemu;;
    *)  echo "Unknown Operation!"
        echo "Use one of: start | shutdown | stop | connect | save | restore | pause | resume"
        echo "Note that stop means a forced stop.";;
esac
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