From 35772b0370e5ad7eb8d7bb25f407e358f8cbfe04 Mon Sep 17 00:00:00 2001
From: Jonas Hermsmeier <jhermsmeier@gmail.com>
Date: Thu, 8 Mar 2018 20:13:51 +0100
Subject: [PATCH 1/2] fix(perf): Remove support for CRC32 checksumming

As crc32-stream was identified as a massive performance bottleneck,
we remove it, and default to Node's crypto API with md5 instead.

Change-Type: minor
---
 lib/cli/etcher.js                 |  4 +--
 lib/cli/writer.js                 |  2 +-
 lib/sdk/writer/checksum-stream.js | 41 ++++++-------------------------
 3 files changed, 10 insertions(+), 37 deletions(-)

diff --git a/lib/cli/etcher.js b/lib/cli/etcher.js
index d3ba3ecb..e027e0f5 100644
--- a/lib/cli/etcher.js
+++ b/lib/cli/etcher.js
@@ -90,8 +90,8 @@ permissions.isElevated().then((elevated) => {
   return Bluebird.try(() => {
     console.log(messages.info.flashComplete(path.basename(results.imagePath), results.flash.drive))
 
-    if (results.flash.checksum.crc32) {
-      console.log(`Checksum: ${results.flash.checksum.crc32}`)
+    if (results.flash.checksum.md5) {
+      console.log(`Checksum: ${results.flash.checksum.md5}`)
     }
 
     return Bluebird.resolve()
diff --git a/lib/cli/writer.js b/lib/cli/writer.js
index 378e8528..d8424516 100644
--- a/lib/cli/writer.js
+++ b/lib/cli/writer.js
@@ -49,7 +49,7 @@ exports.writeImage = (imagePath, drive, options, onProgress) => {
     path: drive,
     imagePath,
     verify: options.validateWriteOnSuccess,
-    checksumAlgorithms: [ 'crc32' ],
+    checksumAlgorithms: [ 'md5' ],
     unmountOnSuccess: options.unmountOnSuccess
   })
 
diff --git a/lib/sdk/writer/checksum-stream.js b/lib/sdk/writer/checksum-stream.js
index 1e9585b8..68e33cee 100644
--- a/lib/sdk/writer/checksum-stream.js
+++ b/lib/sdk/writer/checksum-stream.js
@@ -18,26 +18,8 @@
 
 const stream = require('readable-stream')
 const crypto = require('crypto')
-const CRC32Stream = require('crc32-stream')
 const _ = require('lodash')
 
-/**
- * @summary Get a hash stream
- * @function
- * @private
- * @example
- * var md5Stream = getHashStream('md5')
- *
- * @param {String} algorithm - either `crc32` or anything supported by `crypto.Hash`
- * @returns {Stream.Transform}
- */
-const getHashStream = (algorithm) => {
-  if (algorithm === 'crc32') {
-    return new CRC32Stream()
-  }
-  return crypto.createHash(algorithm)
-}
-
 /**
  * @summary Create an instance of ChecksumStream
  * @name ChecksumStream
@@ -52,13 +34,12 @@ class ChecksumStream extends stream.Transform {
    * @param {String[]} options.algorithms - hash algorithms
    * @example
    * var checksum = new ChecksumStream({
-   *   algorithms: [ 'crc32', 'md5' ]
+   *   algorithms: [ 'md5' ]
    * })
    *
    * checksum.once('checksum', (checksum) => {
    *   // checksum: {
-   *   //   crc32: 'EF28AF1C',
-   *   //   md5: ''
+   *   //   md5: '55a4eb779e08f604c41ba1cbfff47ada'
    *   // }
    * })
    *
@@ -85,7 +66,7 @@ class ChecksumStream extends stream.Transform {
    * const hash = this._createHash(algorithm)
    */
   _createHash (algorithm) {
-    const hash = _.attempt(getHashStream, algorithm)
+    const hash = _.attempt(crypto.createHash, algorithm)
 
     if (_.isError(hash)) {
       hash.message += ` "${algorithm}"`
@@ -108,18 +89,10 @@ class ChecksumStream extends stream.Transform {
       return this.emit('error', error)
     })
 
-    if (algorithm === 'crc32') {
-      hash.once('end', () => {
-        this.results[algorithm] = hash.digest('hex')
-        check()
-      })
-      hash.resume()
-    } else {
-      hash.once('readable', () => {
-        this.results[algorithm] = hash.read().toString('hex')
-        check()
-      })
-    }
+    hash.once('readable', () => {
+      this.results[algorithm] = hash.read().toString('hex')
+      check()
+    })
 
     return hash
   }

From 49dd6553fb6e1363dac2546f935790dcbbf8e5d7 Mon Sep 17 00:00:00 2001
From: Jonas Hermsmeier <jhermsmeier@gmail.com>
Date: Thu, 8 Mar 2018 20:17:33 +0100
Subject: [PATCH 2/2] chore(package): Remove crc32-stream dependency

---
 npm-shrinkwrap.json | 8 +++++---
 package.json        | 1 -
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/npm-shrinkwrap.json b/npm-shrinkwrap.json
index 28ceaeba..21127cc1 100644
--- a/npm-shrinkwrap.json
+++ b/npm-shrinkwrap.json
@@ -1706,12 +1706,14 @@
       "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.2.tgz"
     },
     "crc": {
-      "version": "3.4.4",
-      "resolved": "https://registry.npmjs.org/crc/-/crc-3.4.4.tgz"
+      "version": "3.5.0",
+      "resolved": "https://registry.npmjs.org/crc/-/crc-3.5.0.tgz",
+      "dev": true
     },
     "crc32-stream": {
       "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/crc32-stream/-/crc32-stream-2.0.0.tgz"
+      "resolved": "https://registry.npmjs.org/crc32-stream/-/crc32-stream-2.0.0.tgz",
+      "dev": true
     },
     "create-ecdh": {
       "version": "4.0.0",
diff --git a/package.json b/package.json
index 4827eb1c..79d87e0b 100644
--- a/package.json
+++ b/package.json
@@ -52,7 +52,6 @@
     "bootstrap-sass": "3.3.6",
     "chalk": "1.1.3",
     "command-join": "2.0.0",
-    "crc32-stream": "2.0.0",
     "debug": "3.1.0",
     "drivelist": "6.0.4",
     "electron-is-running-in-asar": "1.0.0",