linkNodeModulesHook: respect NODE_PATH (#493427)

const fs = require("fs");

const path = require("path");

const node_modules = process.env.NODE_PATH || "node_modules"

async function asyncFilter(arr, pred) {

  const filtered = [];

  for (const elem of arr) {

// This means every file in node_modules that is _not_ a symlink to the Nix store.

async function getUnmanagedFiles(storePrefix, files) {

  return await asyncFilter(files, async (file) => {

    const filePath = path.join("node_modules", file);

    const filePath = path.join(node_modules, file);

    // Is file a symlink

    const stat = await fs.promises.lstat(filePath);

  // Ensure node_modules exists

  try {

    await fs.promises.mkdir("node_modules");

    await fs.promises.mkdir(node_modules);

  } catch (err) {

    if (err.code !== "EEXIST") {

      throw err;

    }

  }

  const files = await fs.promises.readdir("node_modules");

  const files = await fs.promises.readdir(node_modules);

  // Get deny list of files that we don't manage.

  // We do manage nix store symlinks, but not other files.

  await Promise.all(

    sourceFiles.map(async (file) => {

      const sourcePath = path.join(sourceModules, file);

      const targetPath = path.join("node_modules", file);

      const targetPath = path.join(node_modules, file);

      // Skip file if it's not a symlink to a store path

      if (unmanaged.includes(file)) {

  // Clean up store symlinks not included in this generation of node_modules

  await Promise.all(

    Array.from(managed).map((file) =>

      fs.promises.unlink(path.join("node_modules", file)),

      fs.promises.unlink(path.join(node_modules, file)),

    )

  );

}