ext2fs

node-ext2fs

NodeJS native bindings to the linux ext{2,3,4} filesystem library

node-ext2fs uses the e2fsprogs project to provide access to ext filesystem from NodeJS in a cross-platform way.

Some things you can do with this module:

• Read/write files in a filesystem image directly without mounting
• Use familiar APIs, node-ext2fs has the exact same interface as node's fs module
• Combine node-ext2fs filesystem streams with host filesystem streams (e.g copy files)
• Create a tar archive from a filesystem image
• Perform a TRIM operation to obtain discard regions of a filesystem

Warning: The API exposed by this library is still forming and can change at any time!

Installation

To install node-ext2fs you need to have gcc and make available to your environment. For Linux and Mac having a working node-gyp installation is enough. To install on windows, you have to install MingW64 and make sure mingw32-make and gcc are available in your Powershell or cmd.exe terminal.

Simply compile and install node-ext2fs using npm:

$ npm install ext2fs

Usage

Mount a disk image and use the returned fs object. The fs returned object behaves like node's fs except it doesn't provide any xxxxSync method. You can also issue DISCARD requests using ext2fs.trim(filesystem, callback)

See the examples below.

Example

const ext2fs = require('ext2fs');
const filedisk = require('file-disk');
const fs = require('fs');

const fd = fs.openSync('/path/to/ext4_filesystem.img', 'r+');
const disk = new filedisk.FileDisk(fd);

ext2fs.mount(disk, function(err, filesystem) {
	if (err) {
		return;
	}
	// filesystem behaves like node's fs
	console.log('Mounted filesystem successfully');
	filesystem.readFile('/some_file', 'utf8', function(err, contents) {
		if (err) {
			return;
		}
		console.log('contents:', contents);
		ext2fs.trim(filesystem, function(err) {
			if (err) {
				return;
			}
			console.log('TRIMed filesystem');
			// don't forget to umount
			ext2fs.umount(filesystem, function(err) {
				if (err) {
					return;
				}
				console.log('filesystem umounted')
				fs.closeSync(fd)
			});
		});
	});
});

Example using promises

The code above isn't very practical as it requires a new level of indentation for each call. Let's simplify it using promises.

You can use ext2fs.mountDisposer with Promise.using so the filesystem is umounted automatically when you're done using it.

const Promise = require('bluebird')
const ext2fs = Promise.promisifyAll(require('ext2fs'));
const filedisk = require('file-disk');

const path = 'test/fixtures/ext2.img';

Promise.using(filedisk.openFile(path, 'r+'), function(fd) {
	const disk = new filedisk.FileDisk(fd);
	return Promise.using(ext2fs.mountDisposer(disk), function(filesystem) {
		filesystem = Promise.promisifyAll(filesystem);
		// filesystem behaves like node's fs
		console.log('Mounted filesystem successfully');
		return filesystem.readFileAsync('/1', 'utf8')
		.then(function(contents) {
			console.log('contents:', contents);
			return ext2fs.trimAsync(filesystem);
		})
		.then(function() {
			console.log('TRIMed filesystem');
		});
	});
})

Support

If you're having any problems, please raise an issue on GitHub.

Package fails to install as no pre-built package is available

Node-ext2fs is pre-built for a range of OSs and Node versions, but we don't have perfect coverage here yet, and it may fail to install if you're not on an pre-built version and you don't have local build tools available.

If you have an issue with this, and your platform is one you feel we should support, please raise an issue on this repo, so we can look at adding your configuration to the pre-built versions that works automatically.

In the meantime, you can typically install this package by updating to a newer Node release which does have pre-built binaries, or by setting up a local environment so the build is successful (see 'Installation' above).

License

node-ext2fs is free software, and may be redistributed under the terms specified in the license.

Changelog

v1.0.5 - 2018-04-27

• Move eslint to dev dependencies #25 [Tim Perry]