securityos/contexts/fileSystem/useAsyncFs.ts

import type * as IBrowserFS from "browserfs";
import type MountableFileSystem from "browserfs/dist/node/backend/MountableFileSystem";
import type { FSModule } from "browserfs/dist/node/core/FS";
import type Stats from "browserfs/dist/node/core/node_fs_stats";
import FileSystemConfig from "contexts/fileSystem/FileSystemConfig";
import { resetStorage, supportsIndexedDB } from "contexts/fileSystem/functions";
import { join } from "path";
import * as BrowserFS from "public/System/BrowserFS/browserfs.min.js";
import { useEffect, useMemo, useRef, useState } from "react";
import {
  ICON_CACHE,
  ICON_CACHE_EXTENSION,
  SESSION_FILE,
} from "utils/constants";

export type AsyncFS = {
  exists: (path: string) => Promise<boolean>;
  lstat: (path: string) => Promise<Stats>;
  mkdir: (path: string, overwrite?: boolean) => Promise<boolean>;
  readFile: (path: string) => Promise<Buffer>;
  readdir: (path: string) => Promise<string[]>;
  rename: (oldPath: string, newPath: string) => Promise<boolean>;
  rmdir: (path: string) => Promise<boolean>;
  stat: (path: string) => Promise<Stats>;
  unlink: (path: string) => Promise<boolean>;
  writeFile: (
    path: string,
    data: Buffer | string,
    overwrite?: boolean
  ) => Promise<boolean>;
};

const { BFSRequire, configure } = BrowserFS as typeof IBrowserFS;

export type RootFileSystem = Omit<
  MountableFileSystem,
  "mntMap" | "mountList"
> & {
  mntMap: Record<
    string,
    {
      _data: Buffer;
      getName: () => string;
    }
  >;
  mountList: string[];
};

type AsyncFSModule = AsyncFS & {
  fs?: FSModule;
  rootFs?: RootFileSystem;
};

type FsQueueCall = [string, unknown[]];

const mockFsCallQueue: FsQueueCall[] = [];

const runQueuedFsCalls = (fs: FSModule): void => {
  if (mockFsCallQueue.length > 0) {
    const [name, args] = mockFsCallQueue.shift() as FsQueueCall;

    if (name in fs) {
      const fsCall = fs[name as keyof FSModule];

      if (typeof fsCall === "function") {
        // eslint-disable-next-line @typescript-eslint/ban-types
        (fsCall as unknown as Function)(...args);
      }
    }

    runQueuedFsCalls(fs);
  }
};

const useAsyncFs = (): AsyncFSModule => {
  const [fs, setFs] = useState<FSModule>();
  const fsRef = useRef<FSModule>();
  const [rootFs, setRootFs] = useState<RootFileSystem>();
  const asyncFs: AsyncFS = useMemo(
    () => ({
      exists: (path) =>
        new Promise((resolve) => {
          fs?.exists(path, resolve);
        }),
      lstat: (path) =>
        new Promise((resolve, reject) => {
          fs?.lstat(path, (error, stats = Object.create(null) as Stats) =>
            error ? reject(error) : resolve(stats)
          );
        }),
      mkdir: (path, overwrite = false) =>
        new Promise((resolve, reject) => {
          fs?.mkdir(path, { flag: overwrite ? "w" : "wx" }, (error) =>
            error ? reject(error) : resolve(true)
          );
        }),
      readFile: (path) =>
        new Promise((resolve, reject) => {
          fs?.readFile(path, (error, data = Buffer.from("")) => {
            if (!error) return resolve(data);

            if (error.code === "EISDIR" && rootFs?.mntMap[path]?._data) {
              return resolve(rootFs.mntMap[path]._data);
            }

            return reject(error);
          });
        }),
      readdir: (path) =>
        new Promise((resolve, reject) => {
          fs?.readdir(path, (error, data = []) =>
            error ? reject(error) : resolve(data)
          );
        }),
      rename: (oldPath, newPath) =>
        new Promise((resolve, reject) => {
          fs?.rename(oldPath, newPath, (renameError) => {
            if (!renameError) {
              resolve(true);
            } else if (renameError.code === "ENOTSUP") {
              fs.lstat(
                oldPath,
                (_statsError, stats = Object.create(null) as Stats) => {
                  if (stats.isDirectory()) {
                    reject();
                  } else {
                    fs.readFile(oldPath, (readError, data) =>
                      fs.writeFile(newPath, data, (writeError) =>
                        readError || writeError
                          ? reject(readError || writeError)
                          : resolve(false)
                      )
                    );
                  }
                }
              );
            } else if (renameError.code === "EISDIR") {
              rootFs?.umount(oldPath);
              asyncFs.rename(oldPath, newPath).then(resolve, reject);
            } else {
              reject(renameError);
            }
          });
        }),
      rmdir: (path) =>
        new Promise((resolve, reject) => {
          fs?.rmdir(path, (error) => (error ? reject(error) : resolve(true)));
        }),
      stat: (path) =>
        new Promise((resolve, reject) => {
          fs?.stat(path, (error, stats = Object.create(null) as Stats) =>
            error ? reject(error) : resolve(stats)
          );
        }),
      unlink: (path) =>
        new Promise((resolve, reject) => {
          fs?.unlink(path, (error) => (error ? reject(error) : resolve(true)));
        }),
      writeFile: (path, data, overwrite = false) =>
        new Promise((resolve, reject) => {
          fs?.writeFile(
            path,
            data,
            { flag: overwrite ? "w" : "wx" },
            (error) => {
              if (error && (!overwrite || error.code !== "EEXIST")) {
                if (error.code === "ENOENT" && error.path === "/") {
                  resetStorage(rootFs).finally(() => window.location.reload());
                }

                reject(error);
              } else {
                resolve(!error);

                try {
                  if (path !== SESSION_FILE) {
                    const cachedIconPath = join(
                      ICON_CACHE,
                      `${path}${ICON_CACHE_EXTENSION}`
                    );

                    fs?.exists(
                      cachedIconPath,
                      (exists) => exists && fs?.unlink(cachedIconPath)
                    );
                  }
                } catch {
                  // Ignore icon cache issues
                }
              }
            }
          );
        }),
    }),
    [fs, rootFs]
  );

  useEffect(() => {
    if (!fs) {
      const queueFsCall =
        (name: string) =>
        (...args: unknown[]) => {
          if (fsRef.current) {
            // eslint-disable-next-line @typescript-eslint/ban-types
            (fsRef.current[name as keyof FSModule] as unknown as Function)(
              ...args
            );
          } else mockFsCallQueue.push([name, args]);
        };

      setFs({
        exists: queueFsCall("exists"),
        lstat: queueFsCall("lstat"),
        mkdir: queueFsCall("mkdir"),
        readFile: queueFsCall("readFile"),
        readdir: queueFsCall("readdir"),
        rename: queueFsCall("rename"),
        rmdir: queueFsCall("rmdir"),
        stat: queueFsCall("stat"),
        unlink: queueFsCall("unlink"),
        writeFile: queueFsCall("writeFile"),
      } as Partial<FSModule> as FSModule);
    } else if ("getRootFS" in fs) {
      runQueuedFsCalls(fs);
    } else {
      const setupFs = (writeToIndexedDB: boolean): void =>
        configure(FileSystemConfig(!writeToIndexedDB), () => {
          const loadedFs = BFSRequire("fs");

          fsRef.current = loadedFs;
          setFs(loadedFs);
          setRootFs(loadedFs.getRootFS() as RootFileSystem);
        });

      supportsIndexedDB().then(setupFs);
    }
  }, [fs]);

  return useMemo(
    () => ({
      ...asyncFs,
      fs,
      rootFs,
    }),
    [asyncFs, fs, rootFs]
  );
};

export default useAsyncFs;