320d98709f
This is a JavaScript fuzzer originally authored by Oliver Chang. It is a mutation based fuzzer using Babel code transformations. For more information see the included README.md. The original code was altered: - Add new V8 copyright headers. - Make the test expectation generator aware of the headers. - Fix file endings for presubmit checks. - Fix `npm test` on fresh checkout with a new fake DB. - Make test skipping work with new v8/tools location. - OWNERS file. - New title section in README.md. No-Try: true Bug: chromium:1109770 Change-Id: Ie71752c0a37491a50500c49060a3c526716ef933 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2320330 Commit-Queue: Michael Achenbach <machenbach@chromium.org> Reviewed-by: Maya Lekova <mslekova@chromium.org> Cr-Commit-Position: refs/heads/master@{#69164}
114 lines
2.7 KiB
JavaScript
114 lines
2.7 KiB
JavaScript
// Copyright 2020 the V8 project authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file.
|
|
|
|
/**
|
|
* @fileoverview Random helpers.
|
|
*/
|
|
|
|
'use strict';
|
|
|
|
const assert = require('assert');
|
|
|
|
function randInt(min, max) {
|
|
return Math.floor(Math.random() * (max - min + 1)) + min;
|
|
}
|
|
|
|
function choose(probability) {
|
|
return Math.random() < probability;
|
|
}
|
|
|
|
function random() {
|
|
return Math.random();
|
|
}
|
|
|
|
function uniform(min, max) {
|
|
return Math.random() * (max - min) + min;
|
|
}
|
|
|
|
function sample(iterable, count) {
|
|
const result = new Array(count);
|
|
let index = 0;
|
|
|
|
for (const item of iterable) {
|
|
if (index < count) {
|
|
result[index] = item;
|
|
} else {
|
|
const randIndex = randInt(0, index);
|
|
if (randIndex < count) {
|
|
result[randIndex] = item;
|
|
}
|
|
}
|
|
|
|
index++;
|
|
}
|
|
|
|
if (index < count) {
|
|
// Not enough items.
|
|
result.length = index;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
function swap(array, p1, p2) {
|
|
[array[p1], array[p2]] = [array[p2], array[p1]];
|
|
}
|
|
|
|
/**
|
|
* Returns "count" elements, randomly selected from "highProbArray" and
|
|
* "lowProbArray". Elements from highProbArray have a "factor" times
|
|
* higher chance to be chosen. As a side effect, this swaps the chosen
|
|
* elements to the end of the respective input arrays. The complexity is
|
|
* O(count).
|
|
*/
|
|
function twoBucketSample(lowProbArray, highProbArray, factor, count) {
|
|
// Track number of available elements for choosing.
|
|
let low = lowProbArray.length;
|
|
let high = highProbArray.length;
|
|
assert(low + high >= count);
|
|
const result = [];
|
|
for (let i = 0; i < count; i++) {
|
|
// Map a random number to the summarized indices of both arrays. Give
|
|
// highProbArray elements a "factor" times higher probability.
|
|
const p = random();
|
|
const index = Math.floor(p * (high * factor + low));
|
|
if (index < low) {
|
|
// If the index is in the low part, draw the element and discard it.
|
|
result.push(lowProbArray[index]);
|
|
swap(lowProbArray, index, --low);
|
|
} else {
|
|
// Same as above but for a highProbArray element. The index is first
|
|
// mapped back to the array's range.
|
|
const highIndex = Math.floor((index - low) / factor);
|
|
result.push(highProbArray[highIndex]);
|
|
swap(highProbArray, highIndex, --high);
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
function single(array) {
|
|
return array[randInt(0, array.length - 1)];
|
|
}
|
|
|
|
function shuffle(array) {
|
|
for (let i = 0; i < array.length - 1; i++) {
|
|
const j = randInt(i, array.length - 1);
|
|
swap(array, i, j);
|
|
}
|
|
|
|
return array;
|
|
}
|
|
|
|
module.exports = {
|
|
choose: choose,
|
|
randInt: randInt,
|
|
random: random,
|
|
sample: sample,
|
|
shuffle: shuffle,
|
|
single: single,
|
|
twoBucketSample: twoBucketSample,
|
|
uniform: uniform,
|
|
}
|