test-fs-largefile.js

// Copyright Joyent, Inc. and other Node contributors.
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'use strict';
const common = require('../common');

const assert = require('assert');
const fs = require('fs');
const path = require('path');

const tmpdir = require('../common/tmpdir');
tmpdir.refresh();

const filepath = path.join(tmpdir.path, 'large.txt');
const fd = fs.openSync(filepath, 'w+');
const offset = 5 * 1024 * 1024 * 1024; // 5GB
const message = 'Large File';

fs.truncateSync(fd, offset);
assert.strictEqual(fs.statSync(filepath).size, offset);
const writeBuf = Buffer.from(message);
fs.writeSync(fd, writeBuf, 0, writeBuf.length, offset);
const readBuf = Buffer.allocUnsafe(writeBuf.length);
fs.readSync(fd, readBuf, 0, readBuf.length, offset);
assert.strictEqual(readBuf.toString(), message);
fs.readSync(fd, readBuf, 0, 1, 0);
assert.strictEqual(readBuf[0], 0);

// Verify that floating point positions do not throw.
fs.writeSync(fd, writeBuf, 0, writeBuf.length, 42.000001);
fs.close(fd, common.mustCall());