#!/bin/execlineb -W
# SPDX-License-Identifier: EUPL-1.2+
# SPDX-FileCopyrightText: 2024-2025 Alyssa Ross <hi@alyssa.is>

backtick id {
  backtick -E dir { mktemp -d /run/vm/by-id/XXXXXX }
  basename -- $dir
}

if {
  importas -Siu id

  if { useradd -P /run -Urd / -s /bin/nologin gpu-${id} }
  if { useradd -P /run -Urd / -s /bin/nologin -G tty,vmm vmm-${id} }
  if { useradd -P /run -Urd / -s /bin/nologin xdp-spectrum-${id} }
  if { mkdir /run/vsock/${id} }
  if { chown vmm-${id} /run/vm/by-id/${id} /run/vsock/${id} }

  if { install -do fs /run/configs/${id}/fs }

  if {
    ln -s /usr/lib/spectrum/img/appvm/blk /usr/lib/spectrum/img/appvm/vmlinux
      /run/configs/${id}
  }

  if { ln -s /run/configs/${id} /run/vm/by-id/${id}/config }

  if { create-vm-dependencies $id }
}

backtick diskdir {
  backtick mountpoint {
    importas -Siu 1
    findmnt -no TARGET -T $1
  }

  if -tn {
    redirfd -w 2 /dev/null
    multisubstitute {
      importas -Siu mountpoint
      importas -Siu 2
    }
    printf "%s/Spectrum/data/spectrum/storage/persist.%s\n" $mountpoint $2
  }

  s6-setuidgid fs

  importas -Siu mountpoint
  if { mkdir -p -- ${mountpoint}/Spectrum/data/spectrum/storage }
  mktemp -d -- ${mountpoint}/Spectrum/data/spectrum/storage/tmp.XXXXXX
}

if {
  s6-envuidgid fs
  s6-applyuidgid -Uzu 0

  multisubstitute {
    importas -Siu id
    importas -Siu 1
    importas -Siu diskdir
  }

  nsenter --preserve-credentials -S0
    --mount=/run/vm/by-id/${id}/ns/mnt
    --user=/run/vm/by-id/${id}/ns/user
  cd /run/fs/${id}
  if { redirfd -w 1 config/type echo appimage }
  if { touch config/run }
  if { mount --bind $1 config/run }
  mount --bind -- $diskdir disk
}

multisubstitute {
  importas -Siu diskdir
  importas -Siu id
}

piperw 4 3
background {
  fdclose 3
  fdmove 0 4

  # Wait for the VMM to be up, then start the VM.
  if { redirfd -w 1 /dev/null head -1 }
  vm-start $id
}
fdclose 4

foreground { run-vmm $id }
fdclose 3

if {
  # Even if s6-instance-delete fails, cgroup-purge is enough
  # to ensure that the VMM and all per-VM services are killed.
  foreground { s6-instance-delete /run/service/vm-services $id }
  cgroup-purge /vm-services.slice/vm-${id}.slice
}

if { umount -R /run/vm/by-id/${id}/ns }
rm -r -- $diskdir /run/vm/by-id/${id} /run/configs/${id}