refactor(image-stream): get rid of gzip-uncompressed-size (#1247)

Signed-off-by: Juan Cruz Viotti <jviotti@openmailbox.org>

lib/image-stream/gzip.js

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2016 resin.io
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+const Bluebird = require('bluebird');
+const fs = Bluebird.promisifyAll(require('fs'));
+
+/**
+ * @summary The byte length of ISIZE
+ * @type {Number}
+ * @constant
+ * @description
+ * See https://tools.ietf.org/html/rfc1952
+ */
+const ISIZE_LENGTH = 4;
+
+/**
+ * @summary Get a gzip file uncompressed size
+ * @function
+ * @public
+ *
+ * @description
+ * This function determines the uncompressed size of the gzip file
+ * by reading its `ISIZE`. The specification clarifies that this
+ * value is just an estimation.
+ *
+ * @param {String} file - path to gzip file
+ * @fulfil {Number} - uncompressed size
+ * @returns {Promise}
+ *
+ * @example
+ * gzip.getUncompressedSize('path/to/file.gz').then((uncompressedSize) => {
+ *   console.log(`The uncompressed size is: ${uncompressedSize}`);
+ * });
+ */
+exports.getUncompressedSize = (file) => {
+  return Bluebird.using(fs.openAsync(file, 'r').disposer((fileDescriptor) => {
+    return fs.closeAsync(fileDescriptor);
+  }), (fileDescriptor) => {
+    return fs.fstatAsync(fileDescriptor).then((stats) => {
+      const ISIZE_BUFFER_FILL_VALUE = 0;
+      const ISIZE_BUFFER_START = 0;
+      const isizeBuffer = Buffer.alloc(ISIZE_LENGTH, ISIZE_BUFFER_FILL_VALUE);
+
+      return fs.readAsync(
+        fileDescriptor,
+        isizeBuffer,
+        ISIZE_BUFFER_START,
+        ISIZE_LENGTH,
+        stats.size - ISIZE_LENGTH
+      ).then((bytesRead) => {
+        if (bytesRead !== ISIZE_LENGTH) {
+          throw new Error(`Bytes read mismatch: ${bytesRead} != ${ISIZE_LENGTH}`);
+        }
+
+        return isizeBuffer.readUInt32LE(ISIZE_BUFFER_START);
+      });
+    });
+  });
+};

lib/image-stream/handlers.js

@@ -22,7 +22,7 @@ const PassThroughStream = require('stream').PassThrough;
 const lzma = Bluebird.promisifyAll(require('lzma-native'));
 const zlib = require('zlib');
 const unbzip2Stream = require('unbzip2-stream');
-const gzipUncompressedSize = Bluebird.promisifyAll(require('gzip-uncompressed-size'));
+const gzip = require('./gzip');
 const archive = require('./archive');
 const zipArchiveHooks = require('./archive-hooks/zip');
 
@@ -74,7 +74,7 @@ module.exports = {
    * @returns {Promise}
    */
   'application/gzip': (file, options) => {
-    return gzipUncompressedSize.fromFileAsync(file).then((uncompressedSize) => {
+    return gzip.getUncompressedSize(file).then((uncompressedSize) => {
       return Bluebird.props({
         stream: fs.createReadStream(file),
         size: {

npm-shrinkwrap.json

@@ -374,7 +374,8 @@
     "async": {
       "version": "2.0.0",
       "from": "async@>=2.0.0-rc.2 <3.0.0",
-      "resolved": "https://registry.npmjs.org/async/-/async-2.0.0.tgz"
+      "resolved": "https://registry.npmjs.org/async/-/async-2.0.0.tgz",
+      "dev": true
     },
     "async-foreach": {
       "version": "0.1.3",
@@ -684,11 +685,6 @@
       "resolved": "https://registry.npmjs.org/buffer-xor/-/buffer-xor-1.0.3.tgz",
       "dev": true
     },
-    "bufferpack": {
-      "version": "0.0.6",
-      "from": "bufferpack@0.0.6",
-      "resolved": "https://registry.npmjs.org/bufferpack/-/bufferpack-0.0.6.tgz"
-    },
     "buffers": {
       "version": "0.1.1",
       "from": "buffers@>=0.1.1 <0.2.0",
@@ -2895,11 +2891,6 @@
       "resolved": "https://registry.npmjs.org/growl/-/growl-1.9.2.tgz",
       "dev": true
     },
-    "gzip-uncompressed-size": {
-      "version": "1.0.0",
-      "from": "gzip-uncompressed-size@>=1.0.0 <2.0.0",
-      "resolved": "https://registry.npmjs.com/gzip-uncompressed-size/-/gzip-uncompressed-size-1.0.0.tgz"
-    },
     "handlebars": {
       "version": "4.0.6",
       "from": "handlebars@>=4.0.5 <5.0.0",

package.json

@@ -82,7 +82,6 @@
     "etcher-latest-version": "^1.0.0",
     "flat": "^2.0.1",
     "flexboxgrid": "^6.3.0",
-    "gzip-uncompressed-size": "^1.0.0",
     "immutable": "^3.8.1",
     "is-elevated": "^2.0.1",
     "lodash": "^4.5.1",