#!/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 or x64"
    echo "-c <text>            : append item to kernel commandline"
    echo "-d                   : run with emulated disk"
    echo "-D <disk file|device>: specify disk file or device path on host, default is blk.bin"
    echo "--disktype[=<type>]  : should be one of (ahci, virtio, nvme, virtio-scsi), default is ahci"
    echo "--diskfmt[=<format>] : disk format (raw, qcow2, etc), default is raw"
    echo "-g                   : use graphical console"
    echo "-I <interface name>  : network interface name, default is qemu."
    echo "-k, --kvm            : use KVM (Linux host 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                   : try to use virtio devices"
    echo "-z <zbi>             : boot specified complete 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 "--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 "--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 Botanist (//tools/botanist/cmd/qemu.go)
# and in `fx emu` (//tools/devshell/emu).
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
DISK=0
DISKFILE="blk.bin"
DISKTYPE=
DISKFMT="raw"
GIC=max
GRAPHICS=0
DO_KVM=
MEMSIZE=$MEMSIZE_DEFAULT
NET=0
QEMUDIR=
UPSCRIPT=no
VNC=
VIRTIO=0
SERIAL=1
SMP=$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
}

while getopts "a:c:dD:gI:km:nNq:s:t::u:Vz:h-:" FLAG; do
    case $FLAG in
        a) ARCH=$OPTARG;;
        c) OPT_CMDLINE+="$OPTARG ";;
        d) DISK=1;;
        D) DISKFILE="$(abspath "$OPTARG")";;
        g) GRAPHICS=1;;
        I) IFNAME=$OPTARG;;
        k)
            if [[ "$(uname -s)" == "Darwin" ]]; then
                echo "error: KVM option (-k) is not supported on MacOS"
                exit 1
            fi
            DO_KVM=1
            if [[ ! -w "/dev/kvm" ]]; then
                echo "To use KVM acceleration, adjust permissions to /dev/kvm using:"
                echo
                echo "sudo chmod 666 /dev/kvm"
                exit 1
            fi
            ;;
        m) MEMSIZE=$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")";;
        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#*=};;
            gic=*) GIC=${OPTARG#*=};;
            no-serial) SERIAL=0;;
            vnc=*) VNC=${OPTARG#*=};;
            no-kvm) DO_KVM=0;;
            kvm) DO_KVM=1;;
            *)
                echo unrecognized long option
                HELP
                ;;
            esac
            ;;
    esac
done
shift $((OPTIND-1))

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

if [[ -z "$QEMU_KERNEL" ]]; then
    echo -t switch is mandatory
    HELP
fi

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

if (( !$GRAPHICS  )); then
    ARGS+=" -nographic"
else
    ARGS+=" -serial stdio"
    if [[ "$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 (( $DISK )); then
    # if disktype wasn't set on the command line, default to ahci unless VIRTIO is set
    if [[ -z $DISKTYPE ]]; then
        if (( $VIRTIO )); then
            DISKTYPE="virtio"
        else
            DISKTYPE="ahci"
        fi
    fi

    ARGS+=" -drive file=${DISKFILE},format=${DISKFMT},if=none,id=mydisk"
    if [[ "$DISKTYPE" == "virtio" ]]; then
        ARGS+=" -device virtio-blk-pci,drive=mydisk"
    elif [[ "$DISKTYPE" == "ahci" ]]; then
        ARGS+=" -device ich9-ahci,id=ahci -device ide-hd,drive=mydisk,bus=ahci.0"
    elif [[ "$DISKTYPE" == "nvme" ]]; then
        ARGS+=" -device nvme,drive=mydisk,serial=zircon"
    elif [[ "$DISKTYPE" == "virtio-scsi" ]]; then
        ARGS+=" -device virtio-scsi-pci,id=scsi -device scsi-hd,drive=mydisk,scsi-id=1,lun=1"
    else
        echo unrecognized disk type \"$DISKTYPE\"
        exit
    fi
fi

ahcinum=1
for ahcifile in ${AHCI[@]}; do
    ARGS+=" -drive file=${ahcifile},format=raw,if=none,id=ahcidisk${ahcinum}"
    ARGS+=" -device ich9-ahci,id=ahci${ahcinum}"
    ARGS+=" -device ide-hd,drive=ahcidisk${ahcinum},bus=ahci.${ahcinum}"
    ahcinum=$((ahcinum + 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+=" -nic tap,ifname=$IFNAME,script=$UPSCRIPT,downscript=no"
  fi
  HASH=$(echo $IFNAME | shasum)
  SUFFIX=$(for i in {0..2}; do echo -n :${HASH:$(( 2 * $i )):2}; done)
  ARGS+=",mac=52:54:00$SUFFIX"
  if [[ "$ARCH" == "x64" ]] && [[ $VIRTIO == 0 ]]; then
    ARGS+=",model=e1000"
  else
    ARGS+=",model=virtio-net-pci"
  fi
fi

if [[ -n $AUDIO ]]; then
    ARGS+=" -soundhw hda"
    export QEMU_AUDIO_DRV=$AUDIO
    export QEMU_AUDIO_DAC_FIXED_FREQ=48000
    export QEMU_AUDIO_TIMER_PERIOD=20

    case $AUDIO in
        none) ;;
        alsa) ;;
        oss) ;;
        pa) ;;
        wav)
            export QEMU_WAV_FREQUENCY=48000
            export QEMU_WAV_PATH=${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-rng-pci"
    ARGS+=" -device virtio-mouse-pci"
    ARGS+=" -device virtio-keyboard-pci"
fi

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

# Auto-detect if KVM support exists if not explicitly specified.
if [[ -z $DO_KVM ]]; then
  if [[
      # We only support linux for KVM at the moment.
      $HOST_OS == "Linux" &&
      # Ensure the host and target arch match.
      $HOST_ARCH == "${ARCH}" &&
      # Ensure we have "/dev/kvm" and it is writable.
      -w /dev/kvm
  ]]; then
    echo "Enabling KVM acceleration: use '--no-kvm' to disable." >&2
    DO_KVM=1
  else
    DO_KVM=0
  fi
fi

case $ARCH in
    arm64)
        QEMU=${QEMUDIR}qemu-system-aarch64
        if (( $DO_KVM )); then
          ARGS+=" -enable-kvm -cpu host"
          GIC=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(fxbug.dev/54317) 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 (( !$SERIAL )); then
          CMDLINE+="kernel.serial=none "
        fi
        ;;
    x64)
        QEMU=${QEMUDIR}qemu-system-x86_64
        ARGS+=" -machine q35"
        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 (( $DO_KVM )); then
          ARGS+=" -enable-kvm -cpu host,migratable=no,+invtsc"
          # fxbug.dev/33174: Work around KVM bug on AMD Zen machines
          # where SMAP and CPL=3 MMIO accesses trigger a loop
          # in the Linux kernel.
          #
          # fxbug.dev/63110: Work around KVM bug on AMD Zen machines
          # where XSAVES is enumerated but the IA32_XSS MSR is not
          # available. The bug fix is in 864e2ab2b46db1ac266c46a7c
          # in upstream Linux but has not percolated to popular
          # distributions yet.
          if [[ "$(uname -s)" == "Linux" ]]; then
            if [[ "$(lsmod | grep kvm_amd)" != "" ]]; then
              # Add topoext to properly report hyperthreading on AMD CPUs
              ARGS+=",-smap,-xsaves,+topoext"
            fi
          fi
        else
          ARGS+=" -cpu Haswell,+smap,-check,-fsgsbase"
        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

# run qemu
echo CMDLINE: $CMDLINE
cd /
set -x
exec $QEMU -kernel "$QEMU_KERNEL" -initrd "$QEMU_INITRD" \
     	   $ARGS -append "$CMDLINE" "$@"