Guess the filesystem when none is given.

Change-Type: patch

Author: zvin

README.md

@@ -36,6 +36,9 @@ Example
 Here's an example of using `node-lkl` to read a file inside a disk image of
 a ext4 partition and pipe it to `process.stdout`:
 
+If you can omit the `filesystem` options parameter, all supported filesystems
+will be tried.
+
 ``` javascript
 const Promise = require('bluebird');
 const filedisk = Promise.promisifyAll(require('file-disk'), { multiArgs: true });

lib/lkl.js

@@ -4,12 +4,17 @@ const bindings = require('bindings')('bindings');
 const binding = require('./binding');
 
 const queue = require('./queue');
+const constants = require('./constants');
 
 const lkl = exports;
 
 lkl.fs = require('./fs');
 lkl.disk = require('./disk');
 
+const SUPPORTED_FILESYSTEMS = [  // TODO: get this list from lkl
+	'ext4', 'ext3', 'ext2', 'btrfs', 'xfs', 'vfat'
+];
+
 lkl.startKernelSync = function(memory) {
 	bindings.startKernel(memory);
 	binding.clock_settime(null, function(){});
@@ -39,6 +44,35 @@ function mount(diskId, opts, callback) {
 	);
 }
 
+function mountGuessFS(disk, opts, callback, fsIndex) {
+	fsIndex = (fsIndex === undefined) ? 0 : fsIndex;
+	opts.filesystem = SUPPORTED_FILESYSTEMS[fsIndex];
+	mount(disk, opts, function(err, mountpoint) {
+		if (err) {
+			if (
+				(err.errno === constants.EINVAL) &&
+				(fsIndex < SUPPORTED_FILESYSTEMS.length - 1)
+			) {
+				return mountGuessFS(disk, opts, callback, fsIndex + 1)
+			}
+			return callback(err);
+		}
+		return callback(null, mountpoint);
+	})
+};
+
+lkl.mount = function(disk, opts, callback) {
+	if ((callback === undefined) && (typeof opts === 'function')) {
+		callback = opts;
+		opts = {};
+	}
+	if (SUPPORTED_FILESYSTEMS.indexOf(opts.filesystem) !== -1) {
+		queue.addOperation(mount, [disk, opts, callback]);
+	} else {
+		queue.addOperation(mountGuessFS, [disk, opts, callback]);
+	}
+}
+
 function umount(mountpoint, callback) {
 	const info = mounts[mountpoint];
 	bindings.umount(info.diskId, info.partition, function(err) {
@@ -50,6 +84,10 @@ function umount(mountpoint, callback) {
 	});
 }
 
+lkl.umount = function(mountpoint, callback) {
+	queue.addOperation(umount, [mountpoint, callback]);
+};
+
 lkl.diskAdd = function(disk, callback) {
 	queue.addOperation(
 		bindings.disk_add,
@@ -61,12 +99,4 @@ lkl.diskRemove = function(diskId, callback) {
 	queue.addOperation(bindings.disk_remove, [ diskId, callback ]);
 };
 
-lkl.mount = function(diskId, opts, callback) {
-	queue.addOperation(mount, [diskId, opts, callback]);
-};
-
-lkl.umount = function(mountpoint, callback) {
-	queue.addOperation(umount, [mountpoint, callback]);
-};
-
 lkl.utils = require('./utils');

test/index.js

@@ -44,8 +44,8 @@ describe('node-lkl', function() {
 			});
 
 			it('should mount', function() {
-				return lkl.mountAsync(this.diskId, { readOnly: true, filesystem: 'ext4'})
-				.then(lkl.umountAsync);
+				return lkl.mountAsync(this.diskId, { readOnly: true })
+				.then(lkl.umountAsync)
 			});
 
 			after(function(){
@@ -80,28 +80,28 @@ describe('node-lkl', function() {
 			});
 
 			it('should mount vfat', function() {
-				return lkl.mountAsync(this.diskId, {readOnly: true, filesystem: 'vfat', partition: 1})
-				.then(lkl.umountAsync);
+				return lkl.mountAsync(this.diskId, {readOnly: true, partition: 1})
+				.then(lkl.umountAsync)
 			});
 
 			it('should mount ext2', function() {
-				return lkl.mountAsync(this.diskId, {readOnly: true, filesystem: 'ext2', partition: 2})
-				.then(lkl.umountAsync);
+				return lkl.mountAsync(this.diskId, {readOnly: true, partition: 2})
+				.then(lkl.umountAsync)
 			});
 
 			it('should mount ext4', function() {
-				return lkl.mountAsync(this.diskId, {readOnly: true, filesystem: 'ext4', partition: 3})
-				.then(lkl.umountAsync);
+				return lkl.mountAsync(this.diskId, {readOnly: true, partition: 3})
+				.then(lkl.umountAsync)
 			});
 
 			it('should mount btrfs', function() {
-				return lkl.mountAsync(this.diskId, {readOnly: true, filesystem: 'btrfs', partition: 5})
-				.then(lkl.umountAsync);
+				return lkl.mountAsync(this.diskId, {readOnly: true, partition: 5})
+				.then(lkl.umountAsync)
 			});
 
 			it('should mount xfs', function() {
-				return lkl.mountAsync(this.diskId, {readOnly: true, filesystem: 'xfs', partition: 6})
-				.then(lkl.umountAsync);
+				return lkl.mountAsync(this.diskId, {readOnly: true, partition: 6})
+				.then(lkl.umountAsync)
 			});
 
 			it('should be able to mount 4 partitions', function() {
@@ -161,7 +161,7 @@ describe('node-lkl', function() {
 				})
 				.then(function(diskId) {
 					self.diskId = diskId;
-					return lkl.mountAsync(diskId, {filesystem: 'ext4'});
+					return lkl.mountAsync(diskId);
 				})
 				.then(function (mountpoint) {
 					self.mountpoint = mountpoint;