copy-file.js

// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
const fs = require('fs');
const path = require('path');
const {writeIfChanged} = require('./write-if-changed.js');
const [, , src, dest] = process.argv;

const srcPath = path.join(process.cwd(), src);
const destPath = path.join(process.cwd(), dest);

// If there's a file there from a previous build, unlink it first. This
// is because the file in that location might be a hardlinked file, and
// overwriting it doesn't change the fact that it's hardlinked.
const srcContents = fs.readFileSync(srcPath);
if (fileExists(destPath)) {
  // Check contents, return early if match
  const destContents = fs.readFileSync(destPath);
  if (srcContents.equals(destContents)) {
    return;
  }
}

// Force a write to the target filesystem, since by default the ninja
// toolchain will create a hardlink, which in turn reflects changes in
// gen and resources/inspector back to //front_end.
writeIfChanged(destPath, srcContents);

/**
 * Case sensitive implementation of a file look up.
 */
function fileExists(filePath) {
  const dir = path.dirname(filePath);
  const files = fs.readdirSync(dir);
  return files.includes(path.basename(filePath));
}