#!/usr/bin/env bash

# Copyright 2016 The Fuchsia Authors
#
# Use of this source code is governed by a MIT-style
# license that can be found in the LICENSE file or at
# https://opensource.org/licenses/MIT

function HELP {
    echo "help:"
    echo "-a <arch>            : arm64, riscv64, or x64"
    echo "-c <text>            : append item to kernel commandline"
    echo "-D <disk file|device>: specify disk file or device path on host"
    echo "--disktype[=<type>]  : should be one of (ahci, virtio, nvme, virtio-scsi, usb), default is ahci"
    echo "--diskfmt[=<format>] : disk format (raw, qcow2, etc), default is raw"
    echo "-g                   : use graphical console"
    echo "-H, --hvf            : use HVF (macOS hosts only); defaults to true if supported."
    echo "    --no-hvf         : don't use HVF, even if supported."
    echo "-I <interface name>  : network interface name, default is qemu."
    echo "-k, --kvm            : use KVM (Linux hosts only); defaults to true if supported."
    echo "    --no-kvm         : don't use KVM, even if supported."
    echo "-m <memory in MB>    : memory size, default is ${MEMSIZE_DEFAULT}MB"
    echo "-n                   : run with emulated nic"
    echo "-N                   : run with emulated nic via tun/tap"
    echo "-q <directory>       : location of qemu, defaults to looking in prebuilt/downloads/qemu/bin, then \$PATH"
    echo "-s <number of cpus>  : number of cpus, 1 for uniprocessor, default is $SMP_DEFAULT"
    echo "-t <binary>          : use <binary> as the QEMU->ZBI trampoline"
    echo "-u <path>            : execute qemu startUp script, default is no script"
    echo "-V, --virtio         : use virtio devices; defaults to true."
    echo "    --no-virtio      : don't use virtio devices."
    echo "-z <zbi>             : boot specified ZBI via trampoline"
    echo "--audio[=<host_drv>] : use Intel HD Audio"
    echo "                       <host_drv> should be one of (alsa, oss, pa, wav, none)"
    echo "--ahci=<disk image>  : run with disk image file as raw ahci drive"
    echo "--debugger           : Enable gdb stub and wait for connection"
    echo "--dry-run            : do everything but start qemu"
    echo "--gic=<version>      : use GIC 2, 3, or max supported. default is max"
    echo "--no-serial          : Disable writing out to the guest's serial port"
    echo "-S <device>          : output serial port to a QEMU character device. Default is stdio."
    echo "-M <device>          : output QEMU monitor console to a QEMU character device"
    echo "--uefi               : Boot QEMU through UEFI. With this setting, one of -t or -D must be"
    echo "                       supplied: if -t is supplied, then that value is assumed to be a"
    echo "                       UEFI executable; else, the value under -D is assumbed to be a "
    echo "                       bootable, UEFI FAT filesystem or disk image. In the second case,"
    echo "                       if --disktype is unset, the image is specified as the contents of"
    echo "                       a USB disk drive. -z may be passed alongside -t to specify a"
    echo "                       ramdisk that the UEFI boot application should in turn boot;"
    echo "                       however, no UEFI such boot shims are yet supported."
    echo "--vnc=<display>      : use vnc based display"
    echo "--wavfile=<file>     : When audio host_drv == wav, output to the specified WAV file"
    echo "-h for help"
    echo "all arguments after -- are passed to qemu directly"
    exit 1
}

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

# Note these match the defaults in [virtual device specs](/build/images/flash/BUILD.gn;l=517)
# and https://source.corp.google.com/fuchsia/build/sdk/virtual_device.gni
# (//src/developer/ffx/plugins/emulator/src/vdl_files.rs).This can be overriden by the emulator
# configs in the infra/recipe repo
# (https://fuchsia.googlesource.com/infra/recipes/+/refs/heads/main/recipe_modules/emu/api.py).
readonly MEMSIZE_DEFAULT=8192
readonly SMP_DEFAULT=4

# Host operating system. Will either be "Linux" or "Darwin" (macOS) on
# supported platforms.
readonly HOST_OS=$(uname -s)

# Determine host architecture.
case "$(uname -m)" in
  aarch64*|arm64)
    readonly HOST_ARCH="arm64"
    ;;
  x86_64)
    readonly HOST_ARCH="x64"
    ;;
  *)
    echo "unknown host architecture: $(uname -m)"
    exit 1
    ;;
esac

AHCI=()
ARCH=
AUDIO=
AUDIO_WAVFILE="/tmp/qemu.wav"
DEBUGGER=0
DISKFILE=
DISKTYPE=
DISKFMT="raw"
DRY_RUN=0
GIC=max
GRAPHICS=0
DO_HVF=
DO_KVM=
MEMSIZE=$MEMSIZE_DEFAULT
NET=0
QEMUDIR=
UEFI=0
UPSCRIPT=no
VNC=
VIRTIO=1
SERIAL=1
SERIAL_DEV="stdio"
MONITOR_DEV=
SMP=$SMP_DEFAULT
CMDLINE=""
OPT_CMDLINE=""
QEMU_KERNEL=
QEMU_INITRD=

if [[ $HOST_OS == "Darwin" ]]; then
  IFNAME="tap0"
else
  IFNAME="qemu"
fi

# Propagate our TERM environment variable as a kernel command line
# argument.  This is first so that an explicit -c TERM=foo argument
# goes into CMDLINE later and overrides this.
if [[ -n $TERM ]]; then
    CMDLINE+="TERM=$TERM "
fi

# QEMU looks for its own files in its current directory before looking in its
# data directory (.../share/qemu/).  So a file in the current directory that
# happens to match one of those internal files' names will be used instead of
# the proper file and make things go awry.  There's no way to tell QEMU not to
# look in the current directory first.  So to make it safe to have files by any
# name in the current directory, we cd to / before running QEMU (on the more
# reasonable presumption that / won't contain any files by those names).  Hence,
# we have to convert any relative file names we're passing to QEMU to absolute.
abspath() {
  local path="$1"
  case "$path" in
      /*) echo "$path";;
      *) echo "`pwd`/$path";;
  esac
}

# The QEMU command-line arguments to be built up below.
ARGS=""

# The running number of certain disks by type.
AHCI_NUM=0
VIRTIO_SCSI_NUM=0
USB_NUM=0

#######################################
# Append disk-related arguments to ARGS.
#
# Globals:
#   ARGS
#   AHCI_NUM
#   VIRTIO_SCSI_NUM
#   USB_NUM
#
# Arguments:
#   Disk type, a string.
#   Disk file, a path.
#   Disk format, a string.
#   Disk ID, a string.
#   Extra -device argunents, a string.
#######################################
function append-disk-args {
   local type="$1"
   local file="$2"
   local fmt="$3"
   local id="$4"
   local extra_args="$5"
   ARGS+=" -drive if=none,format=${fmt},file=${file},id=${id}"
    if [[ "${type}" == "virtio" ]]; then
        ARGS+=" -device virtio-blk-pci,drive=${id}"
    elif [[ "${type}" == "ahci" ]]; then
        if [[ $AHCI_NUM -eq 0 ]]; then
            ARGS+=" -device ich9-ahci,id=ahci0"
        fi
        ARGS+=" -device ide-hd,drive=${id},bus=ahci0.${AHCI_NUM}"
        AHCI_NUM=$((AHCI_NUM + 1))
    elif [[ "${type}" == "nvme" ]]; then
        ARGS+=" -device nvme,drive=${id},serial=zircon"
    elif [[ "${type}" == "virtio-scsi" ]]; then
        if [[ $VIRTIO_SCSI_NUM -eq 0 ]]; then
            ARGS+=" -device virtio-scsi-pci,id=scsi0"
        fi
        ARGS+=" -device scsi-hd,drive=${id},scsi-id=${VIRTIO_SCSI_NUM},lun=1"
        VIRTIO_SCSI_NUM=$((VIRTIO_SCSI_NUM + 1))
    elif [[ "${type}" == "usb" ]]; then
        if [[ $USB_NUM -eq 0 ]]; then
            ARGS+=" -device nec-usb-xhci,id=xhci0"
        fi
        ARGS+=" -device usb-storage,bus=xhci0.0,removable=on,drive=${id}"
        USB_NUM=$((USB_NUM + 1))
    else
        echo unrecognized disk type "${type}"
        exit
    fi
    ARGS+="$extra_args"
}

while getopts "a:c:D:gHI:km:nNq:s:t::u:Vz:S:M:h-:" FLAG; do
    case $FLAG in
        a) ARCH=$OPTARG;;
        c) OPT_CMDLINE+="$OPTARG ";;
        D) DISKFILE="$(abspath "$OPTARG")";;
        g) GRAPHICS=1;;
        H)
            if [[ "$HOST_OS" != "Darwin" ]]; then
                echo "error: HVF option (-H) is only supported on MacOS"
                exit 1
            fi
            if [[ "$HOST_ARCH" != "${ARCH}" ]]; then
                echo "error: HVF option (-H) is only supported on a ${ARCH} host architecture"
                exit 1
            fi
            if !$(sysctl -n kern.hv_support) ; then
                echo "error: HVF is not supported"
            fi
            DO_HVF=1
            ;;
        I) IFNAME=$OPTARG;;
        k)
            if [[ "$HOST_OS" != "Linux" ]]; then
                echo "error: KVM option (-k) is only supported on Linux"
                exit 1
            fi
            if [[ "$HOST_ARCH" != "${ARCH}" ]]; then
                echo "error: KVM option (-k) is only supported on a ${ARCH} host architecture"
                exit 1
            fi
            if [[ ! -w "/dev/kvm" ]]; then
                echo "To use KVM acceleration, adjust permissions to /dev/kvm using:"
                echo
                echo "sudo chmod 666 /dev/kvm"
                exit 1
            fi
            DO_KVM=1
            ;;
        m) MEMSIZE=$OPTARG;;
        n) NET=1;;
        N) NET=2;;
        q) QEMUDIR=${OPTARG}/;;
        s) SMP=$OPTARG;;
        t) QEMU_KERNEL="$(abspath "$OPTARG")";;
        u) UPSCRIPT="$(abspath "$OPTARG")";;
        V) VIRTIO=1;;
        z) QEMU_INITRD="$(abspath "$OPTARG")";;
        S) SERIAL_DEV=$OPTARG;;
        M) MONITOR_DEV=$OPTARG;;
        h) HELP;;
        \?)
            echo unrecognized option
            HELP
            ;;
        -)
            case $OPTARG in
            ahci=*) AHCI+=("$(abspath "${OPTARG#*=}")");;
            audio) AUDIO=none;;
            audio=*) AUDIO=${OPTARG#*=};;
            wavfile=*) AUDIO_WAVFILE="$(abspath "${OPTARG#*=}")";;
            debugger) DEBUGGER=1;;
            disktype=*) DISKTYPE=${OPTARG#*=};;
            diskfmt=*) DISKFMT=${OPTARG#*=};;
            dry-run) DRY_RUN=1;;
            gic=*) GIC=${OPTARG#*=};;
            no-serial) SERIAL=0;;
            vnc=*) VNC=${OPTARG#*=};;
            no-kvm) DO_KVM=0;;
            kvm) DO_KVM=1;;
            no-hvf) DO_HVF=0;;
            hvf) DO_HVF=1;;
            no-virtio) VIRTIO=0;;
            virtio) VIRTIO=1;;
            uefi) UEFI=1;;
            *)
                echo unrecognized long option "$OPTARG"
                HELP
                ;;
            esac
            ;;
    esac
done
shift $((OPTIND-1))

# arch argument is non optional
if [[ -z $ARCH ]]; then
    echo must specify arch
    HELP
fi

if [[ -z "$QEMU_KERNEL" ]]; then
  if (( $UEFI )); then
    if [[ -z "$DISKFILE" ]]; then
        echo "with --uefi, one of -t or -D must be set"
        HELP
    fi
  else
    echo "-t switch is mandatory if --uefi is unset"
    HELP
  fi

  if [[ -n "$OPT_CMDLINE" ]]; then
      echo "-c cannot be set without -t"
      HELP
  fi
fi

if (( $UEFI )) && [[ -z "$QEMU_KERNEL" ]]; then
  readonly UEFI_DISK_BOOT=1
else
  readonly UEFI_DISK_BOOT=0
fi

# Fall back to disk type defaults if left unspecified with a provided emulated
# disk file.
if [[ -n "$DISKFILE" ]] && [[ -z "$DISKTYPE" ]]; then
  if (( $VIRTIO )); then
    DISKTYPE="virtio"
  else
    DISKTYPE="ahci"
  fi
fi

# by default use the qemu binary located in the fuchsia //prebuilt
# repo if we can find it, but allow -q to override it for people
# who want to use their own.
if [[ -z $QEMUDIR && -d "$DIR/../prebuilt/downloads/qemu/bin" ]]; then
    QEMUDIR="$DIR/../prebuilt/downloads/qemu/bin/"
fi

if (( $UEFI )); then
  readonly EDK2DIR="$DIR/../../prebuilt/third_party/edk2/qemu-${ARCH}"
  case $ARCH in
    x64)
    readonly UEFI_FIRMWARE="${EDK2DIR}/OVMF_CODE.fd"
    readonly UEFI_VARS="${EDK2DIR}/OVMF_VARS.fd"
    ;;
    arm64)
    readonly UEFI_FIRMWARE="${EDK2DIR}/QEMU_EFI.fd"
    readonly UEFI_VARS="${EDK2DIR}/QEMU_VARS.fd"
    ;;
  esac

  ARGS+=" -drive if=pflash,format=raw,readonly=on,file=${UEFI_FIRMWARE}"
  # The UEFI variable store. Without 'snapshot=true' this file would need to be
  # writable and state would persist across invocations; with it, the image
  # will be copy-on-write and state should persist across reboots.
  ARGS+=" -drive if=pflash,format=raw,snapshot=true,file=${UEFI_VARS}"
fi

if [[ -n "$QEMU_KERNEL" ]]; then
  ARGS+=" -kernel $QEMU_KERNEL"
fi

if [[ -n "$QEMU_INITRD" ]]; then
  ARGS+=" -initrd $QEMU_INITRD"
fi

if [[ -n $DISKFILE ]]; then
  NAME="mydisk"
  EXTRA_ARGS=""
  if (( $UEFI_DISK_BOOT )); then
    NAME="uefi"
    # `bootindex=0` ensures that this is the highest priority boot option.
    EXTRA_ARGS=",bootindex=0"
  fi
  append-disk-args "${DISKTYPE}" "${DISKFILE}" "${DISKFMT}" "${NAME}"
fi

# construct the args for qemu
ARGS+=" -m $MEMSIZE"
if [[ -n $VNC ]]; then
    ARGS+=" -vnc $VNC"
fi

# Always use virtio as the rng source
ARGS+=" -device virtio-rng-pci"

if [[ -n "$MONITOR_DEV" ]]; then
  ARGS+=" -monitor $MONITOR_DEV"
fi

ADD_SERIAL_ARG=1
if (( !$GRAPHICS )); then
  ARGS+=" -nographic -vga none"

  # -nographic implies -serial stdio and will complain if you
  # try to set anything else pointing at stdio.
  if [[ "$SERIAL_DEV" == "stdio" ]]; then
    ADD_SERIAL_ARG=0
  fi
else
  if [[ "$ARCH" == "x64" && $VIRTIO == 0 ]]; then
    # Enable Bochs VBE device, which Zircon has a device for
    ARGS+=" -vga std"
  else
    # use the virtio gpu for display
    ARGS+=" -vga none"
    ARGS+=" -device virtio-gpu-pci"
  fi
fi

if (( $SERIAL && $ADD_SERIAL_ARG )); then
  ARGS+=" -serial $SERIAL_DEV"
fi

for ahcifile in ${AHCI[@]}; do
  ARGS+=" -drive file=${ahcifile},format=raw,if=none,id=ahcidisk${AHCI_NUM}"
  ARGS+=" -device ich9-ahci,id=ahci${AHCI_NUM}"
  ARGS+=" -device ide-hd,drive=ahcidisk${AHCI_NUM},bus=ahci.${AHCI_NUM}"
  AHCI_NUM=$((AHCI_NUM + 1))
done

if (( !$NET )); then
  ARGS+=" -nic none"
else
  if [[ $NET == 1 ]]; then
    ARGS+=" -nic user,hostname=$IFNAME"
  fi

  if [[ $NET == 2 ]]; then
    if [[ "$(uname -s)" == "Darwin" ]]; then
      if [[ ! -c "/dev/$IFNAME" ]]; then
        echo "To use qemu with networking on macOS, install the tun/tap driver:"
        echo "http://tuntaposx.sourceforge.net/download.xhtml"
        exit 1
      fi
      if [[ ! -w "/dev/$IFNAME" ]]; then
        echo "For networking /dev/$IFNAME must be owned by $USER. Please run:"
        echo "  sudo chown $USER /dev/$IFNAME"
        exit 1
      fi
    else
      TAP_IFS=$(ip tuntap show 2>/dev/null)
      if [[ ! "$TAP_IFS" =~ "${IFNAME}:" ]]; then
        echo "To use qemu with networking on Linux, configure tun/tap:"
        echo
        echo "sudo ip tuntap add dev $IFNAME mode tap user $USER && \\"
        echo "sudo ip link set $IFNAME up"
        exit 1
      fi

      # Try to detect if a firewall is active. There are only few ways to do that
      # without being root. Unfortunately, using systemd or systemctl does not work
      # on Debian, so use the following hack instead:
      if (which ufw && grep -q "^ENABLED=yes" /etc/ufw/ufw.conf) >/dev/null 2>&1; then
        echo "Active firewall detected: If this emulator is unreachable, run: fx setup-ufw"
      fi
    fi
    ARGS+=" -netdev tap,id=net0,ifname=$IFNAME,script=$UPSCRIPT,downscript=no"
  fi
  HASH=$(echo $IFNAME | shasum)
  SUFFIX=$(for i in {0..2}; do echo -n :${HASH:$(( 2 * $i )):2}; done)
  MAC="52:54:00$SUFFIX"
  if [[ "$ARCH" == "x64" ]] && [[ $VIRTIO == 0 ]]; then
    ARGS+=" -device e1000,netdev=net0,mac=$MAC"
  else
    # Disable iPXE romfile. OVMF (UEFI implementation) defaults to using iPXE to
    # talk to the network device, but iPXE's driver is more than 2x slower than
    # OVMF's own virtio-net driver.
    ARGS+=" -device virtio-net-pci,romfile=,netdev=net0,vectors=8,mac=$MAC"
  fi
fi

if [[ -n $AUDIO ]]; then
    ARGS+=" -device intel-hda -device hda-duplex -audiodev id=${AUDIO},driver=${AUDIO}"

    case $AUDIO in
        none) ;;
        alsa) ;;
        oss) ;;
        pa) ;;
        wav)
            ARGS+=",path=${AUDIO_WAVFILE}"
            ;;
        *)
            echo unrecognized QEMU host audio driver \"$AUDIO\"
            exit
            ;;
    esac
fi

if [[ $SMP != 1 ]]; then
    ARGS+=" -smp $SMP"
fi

# start a few extra harmless virtio devices that can be ignored
if (( $VIRTIO )); then
    ARGS+=" -device virtio-serial-pci"
    ARGS+=" -device virtio-mouse-pci"
    ARGS+=" -device virtio-keyboard-pci"
fi

if (( $DEBUGGER )); then
    ARGS+=" -s -S"
fi

# Auto-detect if KVM or HVF support exists if not explicitly specified.
if [[ -z $DO_KVM ]]; then
  if [[
      $HOST_OS == "Linux" &&      # Linux only.
      $HOST_ARCH == "${ARCH}" &&  # Host and target arch must match.
      -w /dev/kvm                 # /dev/kvm must exist and be writable.
  ]]; then
    echo "Enabling KVM acceleration: use '--no-kvm' to disable." >&2
    DO_KVM=1
  fi
fi

if [[ -z $DO_HVF ]]; then
  if [[
      $HOST_OS == "Darwin" &&              # macOS only.
      $HOST_ARCH == "${ARCH}" &&           # Host and target arch must match.
      $(sysctl -n kern.hv_support) == "1"  # https://developer.apple.com/documentation/hypervisor
  ]]; then
    echo "Enabling HVF acceleration: use '--no-hvf' to disable." >&2
    DO_HVF=1
  fi
fi

case $ARCH in
    arm64)
        QEMU=${QEMUDIR}qemu-system-aarch64
        if (( $DO_KVM )); then
          ARGS+=" -enable-kvm -cpu host"
          GIC=host
        elif (( $DO_HVF )); then
          ARGS+=" -machine accel=hvf"
          ARGS+=" -cpu host"
        else
          # Ask for all of the features TCG emulates
          ARGS+=" -machine virtualization=true -cpu max"
        fi
        # Ask for a specific virt machine version.
        # TODO(https://fxbug.dev/42131826) add support for high PCIe aperture
        # Can switch to plain 'virt' once this is fixed.
        ARGS+=" -machine virt-2.12"
        # append a gic version to the machine specifier
        if [[ $GIC != 0 ]]; then
            ARGS+=",gic-version=${GIC}"
        fi

        if (( !$SERIAL )); then
          CMDLINE+="kernel.serial=none "
        fi
        ;;
    riscv64)
        QEMU=${QEMUDIR}qemu-system-riscv64
        ARGS+=" -cpu rv64,svpbmt=true,v=true,vext_spec=v1.0"
        ARGS+=" -machine virt"
        ARGS+=" -object rng-random,filename=/dev/urandom,id=rng0"
        ARGS+=" -device virtio-rng-device,rng=rng0"
        if (( !$SERIAL )); then
          CMDLINE+="kernel.serial=none "
        fi
        ;;
    x64)
        QEMU=${QEMUDIR}qemu-system-x86_64
        # The kernel only supports the v2.1 (32-bit) SMBIOS entry point.
        ARGS+=" -machine q35,smbios-entry-point-type=32"
        ARGS+=" -device isa-debug-exit,iobase=0xf4,iosize=0x04"

        # Override the SeaBIOS serial port to keep it from outputting
        # a terminal reset on start.
        ARGS+=" -fw_cfg name=etc/sercon-port,string=0"

        if (( $DO_KVM )); then
          ARGS+=" -enable-kvm -cpu host,migratable=no,+invtsc"
        else
          ARGS+=" -cpu Skylake-Client,-check"
        fi

        if (( $SERIAL )); then
          CMDLINE+="kernel.serial=legacy "
        else
          CMDLINE+="kernel.serial=none "
        fi
        ;;
    *)
        echo unsupported arch
        HELP
        ;;
esac

# Add entropy to the kernel
CMDLINE+="kernel.entropy-mixin=$(head -c 32 /dev/urandom | shasum -a 256 | awk '{ print $1 }') "

# Don't 'reboot' the emulator if the kernel crashes
CMDLINE+="kernel.halt-on-panic=true "

# Finally, append any values received via option. We save them for last so that
# they can override others since "last value wins".
CMDLINE+=$OPT_CMDLINE

cd /

# If dry run is set, simply echo all commands run from here on out.
if (( $DRY_RUN )); then
  RUN_CMD="echo"
else
  RUN_CMD="exec"
  set -x
fi

# TODO(joshuaseaton): this and other command-line building logic above can be
# tidied up in having $ARGS be an array.
if (( $UEFI_DISK_BOOT )); then
  $RUN_CMD $QEMU $ARGS "$@"
else
  echo "CMDLINE: $CMDLINE"
  $RUN_CMD $QEMU $ARGS -append "$CMDLINE" "$@"
fi