emscripten-wasm-loader/src/path/mountDirectory.ts

Common interface to load wasm module into isomorphic environment

import * as unixify from 'unixify';
import { FS } from '../BaseAsmModule';
import { isNode } from '../util/isNode';
import { log } from '../util/logger';
import { isMounted } from './isMounted';
import { mkdirTree } from './mkdirTree';

/**
 * Creates a function to mount phsyical path into wasm internal memory filesystem
 * to allow wasm can access phsyical file directly.
 *
 * @param {FS} FS wasm module filesystem
 * @param {string} nodePathId root path in memory filesystem to mount given path under.
 * This prefix path is generated automatically each time wasm module is loaded.
 *
 * @return {(dirPath: string) => string} function to mount given phsical path under memory filesystem.
 */
const mountDirectory = (FS: FS, nodePathId: string): ((dirPath: string) => string) => (dirPath: string): string => {
  if (!isNode()) {
    throw new Error('Mounting physical directory is not supported other than node.js environment');
  }

  const path = require('path'); //tslint:disable-line:no-require-imports
  const mountedDirPath = unixify(path.join(nodePathId, unixify(path.resolve(dirPath))));
  if (isMounted(FS, mountedDirPath, 'dir')) {
    log(`mountNodeFile: file is already mounted, return it`);
  } else {
    mkdirTree(FS, mountedDirPath);
    FS.mount(FS.filesystems.NODEFS, { root: path.resolve(dirPath) }, mountedDirPath);
  }

  return mountedDirPath;
};

export { mountDirectory };