system/lib/wasmfs/wasmfs.h

// Copyright 2021 The Emscripten Authors.  All rights reserved.
// Emscripten is available under two separate licenses, the MIT license and the
// University of Illinois/NCSA Open Source License.  Both these licenses can be
// found in the LICENSE file.
// This file defines the global state of the new file system.
// Current Status: Work in Progress.
// See https://github.com/emscripten-core/emscripten/issues/15041.

#pragma once

#include "backend.h"
#include "file.h"
#include "file_table.h"
#include <assert.h>
#include <emscripten/html5.h>
#include <mutex>
#include <sys/stat.h>
#include <vector>
#include <wasi/api.h>

namespace wasmfs {

class WasmFS {

  std::vector<std::unique_ptr<Backend>> backendTable;
  FileTable fileTable;
  std::shared_ptr<Directory> rootDirectory;
  std::shared_ptr<Directory> cwd;
  std::mutex mutex;

  // Private method to initialize root directory once.
  // Initializes default directories including dev/stdin, dev/stdout,
  // dev/stderr. Refers to the same std streams in the open file table.
  std::shared_ptr<Directory> initRootDirectory();

  // Initialize files specified by --preload-file option.
  void preloadFiles();

public:
  WasmFS();
  ~WasmFS();

  FileTable& getFileTable() { return fileTable; }

  std::shared_ptr<Directory> getRootDirectory() { return rootDirectory; };

  std::shared_ptr<Directory> getCWD() {
    const std::lock_guard<std::mutex> lock(mutex);
    return cwd;
  };

  void setCWD(std::shared_ptr<Directory> directory) {
    const std::lock_guard<std::mutex> lock(mutex);
    cwd = directory;
  };

  backend_t addBackend(std::unique_ptr<Backend> backend) {
    const std::lock_guard<std::mutex> lock(mutex);
    backendTable.push_back(std::move(backend));
    return backendTable.back().get();
  }
};

// Global state instance.
extern WasmFS wasmFS;

} // namespace wasmfs