zvm.js fails on Windows w/node v9.2.0 about ifvms.js

[curiousdannii]

I can't reproduce this in Win 10/Node 9.3. Do you have a test file?

[DLehenbauer]

I think the trick is that the *.z3 file needs to be shorter than Node.js's minimum/default I/O buffer size.

Give this a try:

const fs = require('fs');

const z3 = new Uint8Array([
    0x03, 0x00, 0x00, 0x00, 0x00, 0x83, 0x00, 0x83, 0x00, 0x7E, 0x00, 0x40, 0x00, 0x00, 0x00, 0x7E,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x5A,
    0x04, 0x00, 0x00, 0xB2, 0x54, 0xD8, 0xE0, 0xA5, 0xBB, 0xBA]);

fs.writeFileSync('./repro.z3', z3);

If for some reason the above doesn't work, you can construct the test case with something like:

const extraByte = new Uint8Array([0xFF, ...followed by bytes from above...]);
const z3 = new Uint8Array(extraByte.buffer, 1);  // Elide the extra byte
vm.prepare(z3, ...);

(BTW - I also repro'd w/Ubuntu and node v8.9.1. I think the trick is that that the z-code file needs to be short enough that fs.readFileSync() copies into a default/minimum sized I/O buffer.)