subfs

Create subfilesystems that are rooted at a specific directory.

Motivation

Node's filesystem api isn't very composable because you can't pass a filesystem referecne to a directory, you only can pass path prefixes to libraries that do something with the filesystem.

That approach has the downside that all those libraries require the fs module themselves, so they don't run on the client, because you can't pass in a custom filesystem instance (which could be backed by IndexDB or LocalStore for example). Yes, dependency injection.

So with this module, you can pass references to file system paths, that a module can treat as the root filesystem and can't write outside of (unless it's doing some magic native bindings stuff). Now you just need to encourage developers to accept subfs instances instead of paths in their modules!

Example

var fs = require('fs');
var subfs = require('subfs');

var sub = subfs(fs, __dirname + '/dir');

// write file.txt into the filesystem mounted at ./dir
sub.writeFile('file.txt', 'foobar', function(err) {
  if (err) throw err;

  fs.readFile(__dirname + '/dir/file.txt', function(err, value) {
    if (err) throw err;
    console.log('value: %s', value);
    // value: foobar
  });
});

A module that consumes subfs could be called like this:

var fs = require('fs');
var subfs = require('subfs');
var Logs = require('your-logs-module');

var logs = Logs(subfs(fs, __dirname + '/logs'));

In the browser, initialize it like this:

var fs = require('level-fs-browser');
var subfs = require('subfs');
var Logs = require('your-logs-module');

var logs = Logs(subfs(fs, __dirname + '/logs'));

You just need to change one line!

API

var subfs = require('subfs');

var sub = subfs(fs, dir)

Create a fs clone that prefixes each operation with the given dir.

Installation

With npm do:

npm install subfs

License

(MIT)

Copyright (c) 2013 Julian Gruber <[email protected]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.