Add support for XZ compressed images

This PR introduces `etcher-image-stream`:

https://github.com/resin-io-modules/etcher-image-stream

a module that will handle support for decompression, URL streaming, and
any other way to get a source of data to write in Etcher.

Most of the changes in this PR are because XZ decompression includes a
native dependency (no pure JS implementations out there for now), so we
had to tweak various things for the dependency to work correctly on
Etcher/Electron.

See: #325
Signed-off-by: Juan Cruz Viotti <jviottidc@gmail.com>

.travis.yml

@@ -2,7 +2,7 @@ language: cpp
 sudo: false
 
 env:
-  - NODE_VERSION="4"
+  - NODE_VERSION="5"
 os:
   - linux
   - osx

README.md

@@ -27,6 +27,10 @@ Developing
 
 You can manually run the application with the following steps:
 
+- Install [NodeJS v5.10.0](https://nodejs.org/en/).
+
+Sadly we need to enforce the same NodeJS version that the Electron version we use is running to avoid module version mismatches when building native dependencies (`electron-rebuild` doesn't seem to be enough).
+
 - Clone the repository.
 
 ```sh

appveyor.yml

@@ -11,7 +11,7 @@ cache:
 # what combinations to test
 environment:
   matrix:
-    - nodejs_version: 4
+    - nodejs_version: 5
 
 install:
   - ps: Install-Product node $env:nodejs_version x64

lib/gui/dialog.js

@@ -19,6 +19,7 @@
 const electron = require('electron');
 const Bluebird = require('bluebird');
 const zipImage = require('resin-zip-image');
+const imageStream = require('etcher-image-stream');
 const packageJSON = require('../../package.json');
 
 /**
@@ -46,12 +47,8 @@ exports.selectImage = function() {
       properties: [ 'openFile' ],
       filters: [
         {
-          name: 'IMG/ISO/ZIP',
-          extensions: [
-            'zip',
-            'img',
-            'iso'
-          ]
+          name: 'OS Images',
+          extensions: imageStream.supportedFileTypes
         }
       ]
     }, function(files) {

lib/src/writer.js

@@ -17,10 +17,10 @@
 'use strict';
 
 const imageWrite = require('resin-image-write');
+const imageStream = require('etcher-image-stream');
 const zipImage = require('resin-zip-image');
 const Bluebird = require('bluebird');
 const umount = Bluebird.promisifyAll(require('umount'));
-const fs = require('fs');
 const os = require('os');
 const isWindows = os.platform() === 'win32';
 
@@ -33,28 +33,37 @@ if (isWindows) {
  * @function
  * @private
  *
- * @description
- * This function adds a custom `.length` property
- * to the stream which equals the image size in bytes.
- *
  * @param {String} image - path to image
- * @returns {ReadableStream} image stream
+ * @fulfil {Object} - image stream
+ * @returns {Promise}
  *
  * @example
- * const stream = writer.getImageStream('foo/bar/baz.img');
+ * writer.getImageStream('foo/bar/baz.img').then(function(image) {
+ *   console.log(image.size);
+ *
+ *   if (image.transform) {
+ *     stream.pipe(image.transform).pipe(output);
+ *   } else {
+ *     stream.pipe(output);
+ *   }
+ * });
  */
 exports.getImageStream = function(image) {
   if (zipImage.isZip(image)) {
     if (!zipImage.isValidZipImage(image)) {
       return Bluebird.reject(new Error('Invalid zip image'));
     }
 
-    return zipImage.extractImage(image);
+    return zipImage.extractImage(image).then(function(stream) {
+      return {
+        stream: stream,
+        size: stream.length,
+        transform: null
+      };
+    });
   }
 
-  let stream = fs.createReadStream(image);
-  stream.length = fs.statSync(image).size;
-  return Bluebird.resolve(stream);
+  return imageStream.getFromFilePath(image);
 };
 
 /**
@@ -66,7 +75,7 @@ exports.getImageStream = function(image) {
  * See https://github.com/resin-io/resin-image-write for information
  * about the `state` object passed to `onProgress` callback.
  *
- * @param {String} image - path to image
+ * @param {String} imagePath - path to image
  * @param {Object} drive - drive
  * @param {Object} options - options
  * @param {Boolean} [options.unmountOnSuccess=false] - unmount on success
@@ -88,13 +97,14 @@ exports.getImageStream = function(image) {
  *   console.log('Done!');
  * });
  */
-exports.writeImage = function(image, drive, options, onProgress) {
+exports.writeImage = function(imagePath, drive, options, onProgress) {
   return umount.umountAsync(drive.device).then(function() {
-    return exports.getImageStream(image);
-  }).then(function(stream) {
-    return imageWrite.write(drive.device, stream, {
+    return exports.getImageStream(imagePath);
+  }).then(function(image) {
+    return imageWrite.write(drive.device, image.stream, {
       check: options.validateWriteOnSuccess,
-      size: stream.length
+      size: image.size,
+      transform: image.transform
     });
   }).then(function(writer) {
     return new Bluebird(function(resolve, reject) {

package.json

@@ -56,15 +56,16 @@
     "bootstrap-sass": "^3.3.5",
     "chalk": "^1.1.3",
     "drivelist": "^3.0.0",
+    "etcher-image-stream": "^1.1.0",
     "flexboxgrid": "^6.3.0",
     "is-elevated": "^1.0.0",
     "lodash": "^4.5.1",
     "ngstorage": "^0.3.10",
     "open": "0.0.5",
-    "resin-image-write": "^4.0.0",
     "resin-cli-errors": "^1.2.0",
     "resin-cli-form": "^1.4.1",
     "resin-cli-visuals": "^1.2.8",
+    "resin-image-write": "^4.0.0",
     "resin-zip-image": "^1.1.2",
     "sudo-prompt": "^3.1.0",
     "trackjs": "^2.1.16",