src/library_wasmfs.js

/**
 * @license
 * Copyright 2022 The Emscripten Authors
 * SPDX-License-Identifier: MIT
 */

mergeInto(LibraryManager.library, {
  $wasmFSPreloadedFiles: [],
  $wasmFSPreloadedDirs: [],
  // We must note when preloading has been "flushed", that is, the time at which
  // WasmFS has started up and read the preloaded data. After that time, no more
  // data needs to be preloaded (and it would be invalid to do so, as any
  // further additions to wasmFSPreloadedFiles|Dirs would be ignored).
  $wasmFSPreloadingFlushed: false,

  $FS__postset: `
FS.init();
FS.createPreloadedFile = FS_createPreloadedFile;
`,
  $FS__deps: [
    '$wasmFSPreloadedFiles',
    '$wasmFSPreloadedDirs',
    '$wasmFSPreloadingFlushed',
    '$PATH',
    '$stringToUTF8OnStack',
    '$withStackSave',
    '$readI53FromI64',
    '$readI53FromU64',
    '$FS_createPreloadedFile',
    '$FS_getMode',
    // For FS.readFile
    '$UTF8ArrayToString',
#if FORCE_FILESYSTEM || INCLUDE_FULL_LIBRARY // FULL_LIBRARY will include JS
                                             // code in other places that ends
                                             // up requiring all of our code
                                             // here.
    '$FS_modeStringToFlags',
    'malloc',
    'free',
#endif
  ],
  $FS : {
    init: () => {
      FS.ensureErrnoError();
    },
    ErrnoError: null,
    handleError: (returnValue) => {
      // Assume errors correspond to negative returnValues
      // since some functions like _wasmfs_open() return positive
      // numbers on success (some callers of this function may need to negate the parameter).
      if (returnValue < 0) {
        throw new FS.ErrnoError(-returnValue);
      }

      return returnValue;
    },
    ensureErrnoError: () => {
      if (FS.ErrnoError) return;
      FS.ErrnoError = /** @this{Object} */ function ErrnoError(code) {
        this.errno = code;
        this.message = 'FS error';
        this.name = "ErrnoError";
      }
      FS.ErrnoError.prototype = new Error();
      FS.ErrnoError.prototype.constructor = FS.ErrnoError;
    },
    createDataFile: (parent, name, fileData, canRead, canWrite, canOwn) => {
      var pathName = name ? parent + '/' + name : parent;
      var mode = FS_getMode(canRead, canWrite);

      if (!wasmFSPreloadingFlushed) {
        // WasmFS code in the wasm is not ready to be called yet. Cache the
        // files we want to create here in JS, and WasmFS will read them
        // later.
        wasmFSPreloadedFiles.push({pathName, fileData, mode});
      } else {
        // WasmFS is already running, so create the file normally.
        FS.create(pathName, mode);
        FS.writeFile(pathName, fileData);
      }
    },
    createPath: (parent, path, canRead, canWrite) => {
      // Cache file path directory names.
      var parts = path.split('/').reverse();
      while (parts.length) {
        var part = parts.pop();
        if (!part) continue;
        var current = PATH.join2(parent, part);
        if (!wasmFSPreloadingFlushed) {
          wasmFSPreloadedDirs.push({parentPath: parent, childName: part});
        } else {
          FS.mkdir(current);
        }
        parent = current;
      }
      return current;
    },

#if hasExportedSymbol('_wasmfs_read_file') // Support the JS function exactly
                                           // when the __wasmfs_* function is
                                           // present to be called (otherwise,
                                           // we'd error anyhow). This depends
                                           // on other code including the
                                           // __wasmfs_* method properly.
    readFile: (path, opts = {}) => {
      opts.encoding = opts.encoding || 'binary';
      if (opts.encoding !== 'utf8' && opts.encoding !== 'binary') {
        throw new Error('Invalid encoding type "' + opts.encoding + '"');
      }

      // Copy the file into a JS buffer on the heap.
      var buf = withStackSave(() => __wasmfs_read_file(stringToUTF8OnStack(path)));

      // The signed integer length resides in the first 8 bytes of the buffer.
      var length = {{{ makeGetValue('buf', '0', 'i53') }}};

      // Default return type is binary.
      // The buffer contents exist 8 bytes after the returned pointer.
      var ret = new Uint8Array(HEAPU8.subarray(buf + 8, buf + 8 + length));
      if (opts.encoding === 'utf8') {
        ret = UTF8ArrayToString(ret, 0);
      }

      return ret;
    },
#endif

#if hasExportedSymbol('_wasmfs_get_cwd') // Similar to readFile, above.
    cwd: () => UTF8ToString(__wasmfs_get_cwd()),
#endif

#if FORCE_FILESYSTEM || INCLUDE_FULL_LIBRARY // see comment above
    // Full JS API support

    analyzePath: (path) => {
      // TODO: Consider simplifying this API, which for now matches the JS FS.
      var exists = !!FS.findObject(path);
      return {
        exists,
        object: {
          contents: exists ? FS.readFile(path) : null
        }
      };
    },

    // libc methods

    mkdir: (path, mode) => FS.handleError(withStackSave(() => {
      mode = mode !== undefined ? mode : 511 /* 0777 */;
      var buffer = stringToUTF8OnStack(path);
      return __wasmfs_mkdir(buffer, mode);
    })),
    mkdirTree: (path, mode) => {
      var dirs = path.split('/');
      var d = '';
      for (var i = 0; i < dirs.length; ++i) {
        if (!dirs[i]) continue;
        d += '/' + dirs[i];
        try {
          FS.mkdir(d, mode);
        } catch(e) {
          if (e.errno != {{{ cDefs.EEXIST }}}) throw e;
        }
      }
    },
    rmdir: (path) => FS.handleError(
      withStackSave(() => __wasmfs_rmdir(stringToUTF8OnStack(path)))
    ),
    open: (path, flags, mode) => withStackSave(() => {
      flags = typeof flags == 'string' ? FS_modeStringToFlags(flags) : flags;
      mode = typeof mode == 'undefined' ? 438 /* 0666 */ : mode;
      var buffer = stringToUTF8OnStack(path);
      var fd = FS.handleError(__wasmfs_open(buffer, flags, mode));
      return { fd : fd };
    }),
    create: (path, mode) => {
      // Default settings copied from the legacy JS FS API.
      mode = mode !== undefined ? mode : 438 /* 0666 */;
      mode &= {{{ cDefs.S_IALLUGO }}};
      mode |= {{{ cDefs.S_IFREG }}};
      return FS.mknod(path, mode, 0);
    },
    close: (stream) => FS.handleError(-__wasmfs_close(stream.fd)),
    unlink: (path) => withStackSave(() => {
      var buffer = stringToUTF8OnStack(path);
      return __wasmfs_unlink(buffer);
    }),
    chdir: (path) => withStackSave(() => {
      var buffer = stringToUTF8OnStack(path);
      return __wasmfs_chdir(buffer);
    }),
    read: (stream, buffer, offset, length, position) => {
      var seeking = typeof position != 'undefined';

      var dataBuffer = _malloc(length);

      var bytesRead;
      if (seeking) {
        bytesRead = __wasmfs_pread(stream.fd, dataBuffer, length, position);
      } else {
        bytesRead = __wasmfs_read(stream.fd, dataBuffer, length);
      }
      bytesRead = FS.handleError(bytesRead);

      for (var i = 0; i < length; i++) {
        buffer[offset + i] = {{{ makeGetValue('dataBuffer', 'i', 'i8')}}}
      }

      _free(dataBuffer);
      return bytesRead;
    },
    // Note that canOwn is an optimization that we ignore for now in WasmFS.
    write: (stream, buffer, offset, length, position, canOwn) => {
      var seeking = typeof position != 'undefined';

      var dataBuffer = _malloc(length);
      for (var i = 0; i < length; i++) {
        {{{ makeSetValue('dataBuffer', 'i', 'buffer[offset + i]', 'i8') }}};
      }

      var bytesRead;
      if (seeking) {
        bytesRead = __wasmfs_pwrite(stream.fd, dataBuffer, length, position);
      } else {
        bytesRead = __wasmfs_write(stream.fd, dataBuffer, length);
      }
      bytesRead = FS.handleError(bytesRead);
      _free(dataBuffer);

      return bytesRead;
    },
    allocate: (stream, offset, length) => {
      return FS.handleError(__wasmfs_allocate(stream.fd, {{{ splitI64('offset') }}}, {{{ splitI64('length') }}}));
    },
    // TODO: mmap
    // TODO: msync
    // TODO: munmap
    writeFile: (path, data) => withStackSave(() => {
      var pathBuffer = stringToUTF8OnStack(path);
      if (typeof data == 'string') {
        var buf = new Uint8Array(lengthBytesUTF8(data) + 1);
        var actualNumBytes = stringToUTF8Array(data, buf, 0, buf.length);
        data = buf.slice(0, actualNumBytes);
      }
      var dataBuffer = _malloc(data.length);
#if ASSERTIONS
      assert(dataBuffer);
#endif
      for (var i = 0; i < data.length; i++) {
        {{{ makeSetValue('dataBuffer', 'i', 'data[i]', 'i8') }}};
      }
      var ret = __wasmfs_write_file(pathBuffer, dataBuffer, data.length);
      _free(dataBuffer);
      return ret;
    }),
    symlink: (target, linkpath) => withStackSave(() => (
      __wasmfs_symlink(stringToUTF8OnStack(target), stringToUTF8OnStack(linkpath))
    )),
    readlink: (path) => {
      var readBuffer = FS.handleError(withStackSave(() => __wasmfs_readlink(stringToUTF8OnStack(path))));
      return UTF8ToString(readBuffer);
    },
    statBufToObject : (statBuf) => {
      // i53/u53 are enough for times and ino in practice.
      return {
          dev: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_dev, "u32") }}},
          mode: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_mode, "u32") }}},
          nlink: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_nlink, "u32") }}},
          uid: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_uid, "u32") }}},
          gid: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_gid, "u32") }}},
          rdev: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_rdev, "u32") }}},
          size: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_size, "i53") }}},
          blksize: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_blksize, "u32") }}},
          blocks: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_blocks, "u32") }}},
          atime: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_atim.tv_sec, "i53") }}},
          mtime: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_mtim.tv_sec, "i53") }}},
          ctime: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_ctim.tv_sec, "i53") }}},
          ino: {{{ makeGetValue('statBuf', C_STRUCTS.stat.st_ino, "u53") }}}
      }
    },
    stat: (path) => {
      var statBuf = _malloc({{{ C_STRUCTS.stat.__size__ }}});
      FS.handleError(withStackSave(() => {
        return __wasmfs_stat(stringToUTF8OnStack(path), statBuf);
      }));
      var stats = FS.statBufToObject(statBuf);
      _free(statBuf);

      return stats;
    },
    lstat: (path) => {
      var statBuf = _malloc({{{ C_STRUCTS.stat.__size__ }}});
      FS.handleError(withStackSave(() => {
        return __wasmfs_lstat(stringToUTF8OnStack(path), statBuf);
      }));
      var stats = FS.statBufToObject(statBuf);
      _free(statBuf);

      return stats;
    },
    chmod: (path, mode) => {
      return FS.handleError(withStackSave(() => {
        var buffer = stringToUTF8OnStack(path);
        return __wasmfs_chmod(buffer, mode);
      }));
    },
    lchmod: (path, mode) => {
      return FS.handleError(withStackSave(() => {
        var buffer = stringToUTF8OnStack(path);
        return __wasmfs_lchmod(buffer, mode);
      }));
    },
    fchmod: (fd, mode) => {
      return FS.handleError(__wasmfs_fchmod(fd, mode));
    },
    utime: (path, atime, mtime) => (
      FS.handleError(withStackSave(() => (
        __wasmfs_utime(stringToUTF8OnStack(path), atime, mtime)
      )))
    ),
    truncate: (path, len) => {
      return FS.handleError(withStackSave(() => (__wasmfs_truncate(stringToUTF8OnStack(path), {{{ splitI64('len') }}}))));
    },
    ftruncate: (fd, len) => {
      return FS.handleError(__wasmfs_ftruncate(fd, {{{ splitI64('len') }}}));
    },
    findObject: (path) => {
      var result = withStackSave(() => __wasmfs_identify(stringToUTF8OnStack(path)));
      if (result == {{{ cDefs.ENOENT }}}) {
        return null;
      }
      return {
        isFolder: result == {{{ cDefs.EISDIR }}},
        isDevice: false, // TODO: wasmfs support for devices
      };
    },
    readdir: (path) => withStackSave(() => {
      var pathBuffer = stringToUTF8OnStack(path);
      var entries = [];
      var state = __wasmfs_readdir_start(pathBuffer);
      if (!state) {
        // TODO: The old FS threw an ErrnoError here.
        throw new Error("No such directory");
      }
      var entry;
      while (entry = __wasmfs_readdir_get(state)) {
        entries.push(UTF8ToString(entry));
      }
      __wasmfs_readdir_finish(state);
      return entries;
    }),
    // TODO: mount
    // TODO: unmount
    // TODO: lookup
    mknod: (path, mode, dev) => {
      return FS.handleError(withStackSave(() => {
        var pathBuffer = stringToUTF8OnStack(path);
        return __wasmfs_mknod(pathBuffer, mode, dev);
      }));
    },
    // TODO: mkdev
    rename: (oldPath, newPath) => {
      return FS.handleError(withStackSave(() => {
        var oldPathBuffer = stringToUTF8OnStack(oldPath);
        var newPathBuffer = stringToUTF8OnStack(newPath);
        return __wasmfs_rename(oldPathBuffer, newPathBuffer);
      }));
    },
    // TODO: syncfs
    llseek: (stream, offset, whence) => {
      return FS.handleError(__wasmfs_llseek(stream.fd, {{{ splitI64('offset') }}}, whence));
    }
    // TODO: ioctl

#endif
  },

  _wasmfs_get_num_preloaded_files__deps: [
    '$wasmFSPreloadedFiles',
    '$wasmFSPreloadingFlushed'],
  _wasmfs_get_num_preloaded_files: function() {
    // When this method is called from WasmFS it means that we are about to
    // flush all the preloaded data, so mark that. (There is no call that
    // occurs at the end of that flushing, which would be more natural, but it
    // is fine to mark the flushing here as during the flushing itself no user
    // code can run, so nothing will check whether we have flushed or not.)
    wasmFSPreloadingFlushed = true;
    return wasmFSPreloadedFiles.length;
  },
  _wasmfs_get_num_preloaded_dirs__deps: ['$wasmFSPreloadedDirs'],
  _wasmfs_get_num_preloaded_dirs: function() {
    return wasmFSPreloadedDirs.length;
  },
  _wasmfs_get_preloaded_file_mode: function(index) {
    return wasmFSPreloadedFiles[index].mode;
  },
  _wasmfs_get_preloaded_parent_path: function(index, parentPathBuffer) {
    var s = wasmFSPreloadedDirs[index].parentPath;
    var len = lengthBytesUTF8(s) + 1;
    stringToUTF8(s, parentPathBuffer, len);
  },
  _wasmfs_get_preloaded_child_path: function(index, childNameBuffer) {
    var s = wasmFSPreloadedDirs[index].childName;
    var len = lengthBytesUTF8(s) + 1;
    stringToUTF8(s, childNameBuffer, len);
  },
  _wasmfs_get_preloaded_path_name__deps: ['$lengthBytesUTF8', '$stringToUTF8'],
  _wasmfs_get_preloaded_path_name: function(index, fileNameBuffer) {
    var s = wasmFSPreloadedFiles[index].pathName;
    var len = lengthBytesUTF8(s) + 1;
    stringToUTF8(s, fileNameBuffer, len);
  },
  _wasmfs_get_preloaded_file_size: function(index) {
    return wasmFSPreloadedFiles[index].fileData.length;
  },
  _wasmfs_copy_preloaded_file_data: function(index, buffer) {
    HEAPU8.set(wasmFSPreloadedFiles[index].fileData, buffer);
  },

  _wasmfs_thread_utils_heartbeat__deps: ['emscripten_proxy_execute_queue'],
  _wasmfs_thread_utils_heartbeat: (queue) => {
    var intervalID =
      setInterval(() => {
        if (ABORT) {
          clearInterval(intervalID);
        } else {
          _emscripten_proxy_execute_queue(queue);
        }
      }, 50);
  },

  _wasmfs_stdin_get_char__deps: ['$FS_stdin_getChar'],
  _wasmfs_stdin_get_char: () => {
    // Return the read character, or -1 to indicate EOF.
    var c = FS_stdin_getChar();
    if (typeof c === 'number') {
      return c;
    }
    return -1;
  }
});