From cc06b2e1a315f151734eede5c6cc0fa6ca037d2c Mon Sep 17 00:00:00 2001
From: codeskyblue <codeskyblue@gmail.com>
Date: Tue, 30 Aug 2016 19:26:10 +0800
Subject: [PATCH] add equinox self update support

---
 Godeps/Godeps.json                            |  24 ++
 equinox.pub                                   |   5 +
 gosuv.go                                      |  48 ++-
 res/css/style.css                             |  11 +-
 res/index.html                                |   6 +-
 res/js/index.js                               |   3 +-
 .../github.com/equinox-io/equinox/.travis.yml |   5 +
 .../github.com/equinox-io/equinox/README.md   |  99 +++++
 vendor/github.com/equinox-io/equinox/doc.go   |  92 ++++
 .../equinox/internal/go-update/LICENSE        |  13 +
 .../equinox/internal/go-update/README.md      |  65 +++
 .../equinox/internal/go-update/apply.go       | 322 ++++++++++++++
 .../equinox/internal/go-update/doc.go         | 172 ++++++++
 .../equinox/internal/go-update/hide_noop.go   |   7 +
 .../internal/go-update/hide_windows.go        |  19 +
 .../go-update/internal/binarydist/License     |  22 +
 .../go-update/internal/binarydist/Readme.md   |   7 +
 .../go-update/internal/binarydist/bzip2.go    |  40 ++
 .../go-update/internal/binarydist/diff.go     | 408 ++++++++++++++++++
 .../go-update/internal/binarydist/doc.go      |  24 ++
 .../go-update/internal/binarydist/encoding.go |  53 +++
 .../go-update/internal/binarydist/patch.go    | 109 +++++
 .../go-update/internal/binarydist/seek.go     |  43 ++
 .../internal/go-update/internal/osext/LICENSE |  27 ++
 .../go-update/internal/osext/README.md        |  16 +
 .../go-update/internal/osext/osext.go         |  27 ++
 .../go-update/internal/osext/osext_plan9.go   |  20 +
 .../go-update/internal/osext/osext_procfs.go  |  36 ++
 .../go-update/internal/osext/osext_sysctl.go  |  79 ++++
 .../go-update/internal/osext/osext_windows.go |  34 ++
 .../equinox/internal/go-update/patcher.go     |  24 ++
 .../equinox/internal/go-update/verifier.go    |  74 ++++
 .../equinox-io/equinox/internal/osext/LICENSE |  27 ++
 .../equinox/internal/osext/README.md          |  16 +
 .../equinox/internal/osext/osext.go           |  27 ++
 .../equinox/internal/osext/osext_plan9.go     |  20 +
 .../equinox/internal/osext/osext_procfs.go    |  36 ++
 .../equinox/internal/osext/osext_sysctl.go    |  79 ++++
 .../equinox/internal/osext/osext_windows.go   |  34 ++
 .../equinox-io/equinox/proto/proto.go         |  42 ++
 vendor/github.com/equinox-io/equinox/sdk.go   | 305 +++++++++++++
 41 files changed, 2510 insertions(+), 10 deletions(-)
 create mode 100644 equinox.pub
 create mode 100644 vendor/github.com/equinox-io/equinox/.travis.yml
 create mode 100644 vendor/github.com/equinox-io/equinox/README.md
 create mode 100644 vendor/github.com/equinox-io/equinox/doc.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/LICENSE
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/README.md
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/apply.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/doc.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/hide_noop.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/hide_windows.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/License
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/Readme.md
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/bzip2.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/diff.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/doc.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/encoding.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/patch.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/seek.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/LICENSE
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/README.md
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_plan9.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_procfs.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_sysctl.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_windows.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/patcher.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/go-update/verifier.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/osext/LICENSE
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/osext/README.md
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/osext/osext.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/osext/osext_plan9.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/osext/osext_procfs.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/osext/osext_sysctl.go
 create mode 100644 vendor/github.com/equinox-io/equinox/internal/osext/osext_windows.go
 create mode 100644 vendor/github.com/equinox-io/equinox/proto/proto.go
 create mode 100644 vendor/github.com/equinox-io/equinox/sdk.go

diff --git a/Godeps/Godeps.json b/Godeps/Godeps.json
index c2a1f4c..6a3329c 100644
--- a/Godeps/Godeps.json
+++ b/Godeps/Godeps.json
@@ -7,6 +7,30 @@
 			"ImportPath": "github.com/codeskyblue/kexec",
 			"Rev": "098ccba5e5e7e676f3631983c5ea931a3592871f"
 		},
+		{
+			"ImportPath": "github.com/equinox-io/equinox",
+			"Rev": "6f97d0d3970881d3e53dd6f547a41109eb055e54"
+		},
+		{
+			"ImportPath": "github.com/equinox-io/equinox/internal/go-update",
+			"Rev": "6f97d0d3970881d3e53dd6f547a41109eb055e54"
+		},
+		{
+			"ImportPath": "github.com/equinox-io/equinox/internal/go-update/internal/binarydist",
+			"Rev": "6f97d0d3970881d3e53dd6f547a41109eb055e54"
+		},
+		{
+			"ImportPath": "github.com/equinox-io/equinox/internal/go-update/internal/osext",
+			"Rev": "6f97d0d3970881d3e53dd6f547a41109eb055e54"
+		},
+		{
+			"ImportPath": "github.com/equinox-io/equinox/internal/osext",
+			"Rev": "6f97d0d3970881d3e53dd6f547a41109eb055e54"
+		},
+		{
+			"ImportPath": "github.com/equinox-io/equinox/proto",
+			"Rev": "6f97d0d3970881d3e53dd6f547a41109eb055e54"
+		},
 		{
 			"ImportPath": "github.com/glycerine/rbuf",
 			"Rev": "b8b438717ac043d5224cc7f079b866e3b9ea0599"
diff --git a/equinox.pub b/equinox.pub
new file mode 100644
index 0000000..d24df2c
--- /dev/null
+++ b/equinox.pub
@@ -0,0 +1,5 @@
+-----BEGIN ECDSA PUBLIC KEY-----
+MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEY8xsSkcFs8XXUicw3n7E77qN/vqKUQ/6
+/X5aBiOVF1yTIRYRXrV3aEvJRzErvQxziT9cLxQq+BFUZqn9pISnPSf9dn0wf9kU
+TxI79zIvne9UT/rDsM0BxSydwtjG00MT
+-----END ECDSA PUBLIC KEY-----
diff --git a/gosuv.go b/gosuv.go
index d280127..34e5b98 100644
--- a/gosuv.go
+++ b/gosuv.go
@@ -8,13 +8,50 @@ import (
 	"net/http"
 	"os"
 
+	"github.com/equinox-io/equinox"
 	"github.com/urfave/cli"
 )
 
+const appID = "app_8Gji4eEAdDx"
+
 var (
-	Version string = "dev"
+	Version   string = "dev"
+	publicKey        = []byte(`
+-----BEGIN ECDSA PUBLIC KEY-----
+MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEY8xsSkcFs8XXUicw3n7E77qN/vqKUQ/6
+/X5aBiOVF1yTIRYRXrV3aEvJRzErvQxziT9cLxQq+BFUZqn9pISnPSf9dn0wf9kU
+TxI79zIvne9UT/rDsM0BxSydwtjG00MT
+-----END ECDSA PUBLIC KEY-----
+`)
 )
 
+func equinoxUpdate() error {
+	var opts equinox.Options
+	if err := opts.SetPublicKeyPEM(publicKey); err != nil {
+		return err
+	}
+
+	// check for the update
+	resp, err := equinox.Check(appID, opts)
+	switch {
+	case err == equinox.NotAvailableErr:
+		fmt.Println("No update available, already at the latest version!")
+		return nil
+	case err != nil:
+		fmt.Println("Update failed:", err)
+		return err
+	}
+
+	// fetch the update and apply it
+	err = resp.Apply()
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("Updated to new version: %s!\n", resp.ReleaseVersion)
+	return nil
+}
+
 func actionStartServer(c *cli.Context) error {
 	if err := registerHTTPHandlers(); err != nil {
 		return err
@@ -75,6 +112,10 @@ func actionConfigTest(c *cli.Context) error {
 	return nil
 }
 
+func actionUpdateSelf(c *cli.Context) error {
+	return equinoxUpdate()
+}
+
 func main() {
 	app := cli.NewApp()
 	app.Name = "gosuv"
@@ -114,6 +155,11 @@ func main() {
 			Usage:   "Test if config file is valid",
 			Action:  actionConfigTest,
 		},
+		{
+			Name:   "update-self",
+			Usage:  "Update gosuv itself",
+			Action: actionUpdateSelf,
+		},
 	}
 	if err := app.Run(os.Args); err != nil {
 		os.Exit(1)
diff --git a/res/css/style.css b/res/css/style.css
index 15b1307..38a8ec5 100644
--- a/res/css/style.css
+++ b/res/css/style.css
@@ -22,9 +22,10 @@ body {
     height: 50em;
 }
 
-.status-icon {
-    border-radius: 1.5em;
-    display: inline-block;
-    width: 1.5em;
-    font-size: 0.2em;
+.status {
+    background-color: gray;
+    border-radius: 0.3em;
+    padding-left: 0.5em;
+    padding-right: 0.5em;
+    color: white;
 }
diff --git a/res/index.html b/res/index.html
index 472a71c..fd0107c 100644
--- a/res/index.html
+++ b/res/index.html
@@ -85,7 +85,9 @@
           </tr>
           <tr class="success">
             <td>gohttpserver</td>
-            <td>Running(2h)</td>
+            <td>
+              <span class="status">Running(2h)</span>
+            </td>
             <td>
               <button class="btn btn-default btn-xs">
                 <span class="glyphicon glyphicon-play"></span> Start
@@ -94,7 +96,7 @@
                 <span class="glyphicon glyphicon-stop"></span> Stop
               </button>
               <button class="btn btn-default btn-xs" disabled="true">
-                <span class="glyphicon glyphicon-minus"></span> Tailf
+                <span class="glyphicon glyphicon-minus"></span> Tail
               </button>
               <button class="btn btn-default btn-xs">
                 <span class="glyphicon glyphicon-cog"></span> Setting
diff --git a/res/js/index.js b/res/js/index.js
index 01a8f90..0b8c4f5 100644
--- a/res/js/index.js
+++ b/res/js/index.js
@@ -88,7 +88,6 @@ var vm = new Vue({
         },
         refresh: function() {
             // ws.send("Hello")
-            console.log("RR");
             $.ajax({
                 url: "/api/programs",
                 success: function(data) {
@@ -172,7 +171,7 @@ Vue.filter('formatBytes', function(value) {
 
 Vue.filter('colorStatus', function(value) {
     var makeColorText = function(text, color) {
-        return "<span class='status-icon' style='background-color:" + color + "'>" + "&nbsp;" + "</span> " + text;
+        return "<span class='status' style='background-color:" + color + "'>" + text + "</span>";
     }
     switch (value) {
         case "running":
diff --git a/vendor/github.com/equinox-io/equinox/.travis.yml b/vendor/github.com/equinox-io/equinox/.travis.yml
new file mode 100644
index 0000000..c09d375
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/.travis.yml
@@ -0,0 +1,5 @@
+language: go
+go:
+  - 1.4
+  - 1.5
+script: go test -v github.com/equinox-io/equinox github.com/equinox-io/equinox/proto
diff --git a/vendor/github.com/equinox-io/equinox/README.md b/vendor/github.com/equinox-io/equinox/README.md
new file mode 100644
index 0000000..af274ae
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/README.md
@@ -0,0 +1,99 @@
+# equinox client SDK [![godoc reference](https://godoc.org/github.com/equinox-io/equinox?status.png)](https://godoc.org/github.com/equinox-io/equinox)
+
+Package equinox allows applications to remotely update themselves with the [equinox.io](https://equinox.io) service.
+
+## Minimal Working Example
+
+```go
+import "github.com/equinox-io/equinox"
+
+const appID = "<YOUR EQUINOX APP ID>"
+
+var publicKey = []byte(`
+-----BEGIN PUBLIC KEY-----
+MFYwEAYHKoZIzj0CAQYFK4EEAAoDQgAEtrVmBxQvheRArXjg2vG1xIprWGuCyESx
+MMY8pjmjepSy2kuz+nl9aFLqmr+rDNdYvEBqQaZrYMc6k29gjvoQnQ==
+-----END PUBLIC KEY-----
+`)
+
+func update(channel string) error {
+    opts := equinox.Options{Channel: channel}
+    if err := opts.SetPublicKeyPEM(publicKey); err != nil {
+        return err
+    }
+
+    // check for the update
+    resp, err := equinox.Check(appID, opts)
+    switch {
+    case err == equinox.NotAvailableErr:
+        fmt.Println("No update available, already at the latest version!")
+        return nil
+    case err != nil:
+        return err
+    }
+
+    // fetch the update and apply it
+    err = resp.Apply()
+    if err != nil {
+        return err
+    }
+
+    fmt.Printf("Updated to new version: %s!\n", resp.ReleaseVersion)
+    return nil
+}
+```
+
+
+## Update To Specific Version
+
+When you specify a channel in the update options, equinox will try to update the application
+to the latest release of your application published to that channel. Instead, you may wish to
+update the application to a specific (possibly older) version. You can do this by explicitly setting
+Version in the Options struct:
+
+```go
+opts := equinox.Options{Version: "0.1.2"}
+```
+
+## Prompt For Update
+
+You may wish to ask the user for approval before updating to a new version. This is as simple
+as calling the Check function and only calling Apply on the returned result if the user approves.
+Example:
+
+```go
+// check for the update
+resp, err := equinox.Check(appID, opts)
+switch {
+case err == equinox.NotAvailableErr:
+    fmt.Println("No update available, already at the latest version!")
+    return nil
+case err != nil:
+    return err
+}
+
+fmt.Println("New version available!")
+fmt.Println("Version:", resp.ReleaseVersion)
+fmt.Println("Name:", resp.ReleaseTitle)
+fmt.Println("Details:", resp.ReleaseDescription)
+
+ok := prompt("Would you like to update?")
+
+if !ok {
+    return
+}
+
+err = resp.Apply()
+// ...
+```
+
+## Generating Keys
+
+All equinox releases must be signed with a private ECDSA key, and all updates verified with the
+public key portion. To do that, you'll need to generate a key pair. The equinox release tool can
+generate an ecdsa key pair for you easily:
+
+```shell
+equinox genkey
+```
+
diff --git a/vendor/github.com/equinox-io/equinox/doc.go b/vendor/github.com/equinox-io/equinox/doc.go
new file mode 100644
index 0000000..4a3454e
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/doc.go
@@ -0,0 +1,92 @@
+/*
+Package equinox allows applications to remotely update themselves with the equinox.io service.
+
+Minimal Working Example
+
+	import "github.com/equinox-io/equinox"
+
+	const appID = "<YOUR EQUINOX APP ID>"
+
+	var publicKey = []byte(`
+	-----BEGIN PUBLIC KEY-----
+	MFYwEAYHKoZIzj0CAQYFK4EEAAoDQgAEtrVmBxQvheRArXjg2vG1xIprWGuCyESx
+	MMY8pjmjepSy2kuz+nl9aFLqmr+rDNdYvEBqQaZrYMc6k29gjvoQnQ==
+	-----END PUBLIC KEY-----
+	`)
+
+	func update(channel string) error {
+		opts := equinox.Options{Channel: channel}
+		if err := opts.SetPublicKeyPEM(publicKey); err != nil {
+			return err
+		}
+
+		// check for the update
+		resp, err := equinox.Check(appID, opts)
+		switch {
+		case err == equinox.NotAvailableErr:
+			fmt.Println("No update available, already at the latest version!")
+			return nil
+		case err != nil:
+			return err
+		}
+
+		// fetch the update and apply it
+		err = resp.Apply()
+		if err != nil {
+			return err
+		}
+
+		fmt.Printf("Updated to new version: %s!\n", resp.ReleaseVersion)
+		return nil
+	}
+
+
+Update To Specific Version
+
+When you specify a channel in the update options, equinox will try to update the application
+to the latest release of your application published to that channel. Instead, you may wish to
+update the application to a specific (possibly older) version. You can do this by explicitly setting
+Version in the Options struct:
+
+		opts := equinox.Options{Version: "0.1.2"}
+
+Prompt For Update
+
+You may wish to ask the user for approval before updating to a new version. This is as simple
+as calling the Check function and only calling Apply on the returned result if the user approves.
+Example:
+
+	// check for the update
+	resp, err := equinox.Check(appID, opts)
+	switch {
+	case err == equinox.NotAvailableErr:
+		fmt.Println("No update available, already at the latest version!")
+		return nil
+	case err != nil:
+		return err
+	}
+
+	fmt.Println("New version available!")
+	fmt.Println("Version:", resp.ReleaseVersion)
+	fmt.Println("Name:", resp.ReleaseTitle)
+	fmt.Println("Details:", resp.ReleaseDescription)
+
+	ok := prompt("Would you like to update?")
+
+	if !ok {
+		return
+	}
+
+	err = resp.Apply()
+	// ...
+
+Generating Keys
+
+All equinox releases must be signed with a private ECDSA key, and all updates verified with the
+public key portion. To do that, you'll need to generate a key pair. The equinox release tool can
+generate an ecdsa key pair for you easily:
+
+	equinox genkey
+
+*/
+package equinox
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/LICENSE b/vendor/github.com/equinox-io/equinox/internal/go-update/LICENSE
new file mode 100644
index 0000000..418a5d1
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/LICENSE
@@ -0,0 +1,13 @@
+Copyright 2015 Alan Shreve
+
+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.
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/README.md b/vendor/github.com/equinox-io/equinox/internal/go-update/README.md
new file mode 100644
index 0000000..438ffd4
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/README.md
@@ -0,0 +1,65 @@
+# go-update: Build self-updating Go programs [![godoc reference](https://godoc.org/github.com/inconshreveable/go-update?status.png)](https://godoc.org/github.com/inconshreveable/go-update)
+
+Package update provides functionality to implement secure, self-updating Go programs (or other single-file targets)
+A program can update itself by replacing its executable file with a new version.
+
+It provides the flexibility to implement different updating user experiences
+like auto-updating, or manual user-initiated updates. It also boasts
+advanced features like binary patching and code signing verification.
+
+Example of updating from a URL:
+
+```go
+import (
+    "fmt"
+    "net/http"
+
+    "github.com/inconshreveable/go-update"
+)
+
+func doUpdate(url string) error {
+    resp, err := http.Get(url)
+    if err != nil {
+        return err
+    }
+    defer resp.Body.Close()
+    err := update.Apply(resp.Body, update.Options{})
+    if err != nil {
+        // error handling
+    }
+    return err
+}
+```
+
+## Features
+
+- Cross platform support (Windows too!)
+- Binary patch application
+- Checksum verification
+- Code signing verification
+- Support for updating arbitrary files
+
+## [equinox.io](https://equinox.io)
+[equinox.io](https://equinox.io) is a complete ready-to-go updating solution built on top of go-update that provides:
+
+- Hosted updates
+- Update channels (stable, beta, nightly, ...)
+- Dynamically computed binary diffs
+- Automatic key generation and code
+- Release tooling with proper code signing
+- Update/download metrics
+
+## API Compatibility Promises
+The master branch of `go-update` is *not* guaranteed to have a stable API over time. For any production application, you should vendor
+your dependency on `go-update` with a tool like git submodules, [gb](http://getgb.io/) or [govendor](https://github.com/kardianos/govendor).
+
+The `go-update` package makes the following promises about API compatibility:
+1. A list of all API-breaking changes will be documented in this README.
+1. `go-update` will strive for as few API-breaking changes as possible.
+
+## API Breaking Changes
+- **Sept 3, 2015**: The `Options` struct passed to `Apply` was changed to be passed by value instead of passed by pointer. Old API at `28de026`.
+- **Aug 9, 2015**: 2.0 API. Old API at `221d034` or `gopkg.in/inconshreveable/go-update.v0`.
+
+## License
+Apache
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/apply.go b/vendor/github.com/equinox-io/equinox/internal/go-update/apply.go
new file mode 100644
index 0000000..e81ff60
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/apply.go
@@ -0,0 +1,322 @@
+package update
+
+import (
+	"bytes"
+	"crypto"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/equinox-io/equinox/internal/go-update/internal/osext"
+)
+
+var (
+	openFile = os.OpenFile
+)
+
+// Apply performs an update of the current executable (or opts.TargetFile, if set) with the contents of the given io.Reader.
+//
+// Apply performs the following actions to ensure a safe cross-platform update:
+//
+// 1. If configured, applies the contents of the update io.Reader as a binary patch.
+//
+// 2. If configured, computes the checksum of the new executable and verifies it matches.
+//
+// 3. If configured, verifies the signature with a public key.
+//
+// 4. Creates a new file, /path/to/.target.new with the TargetMode with the contents of the updated file
+//
+// 5. Renames /path/to/target to /path/to/.target.old
+//
+// 6. Renames /path/to/.target.new to /path/to/target
+//
+// 7. If the final rename is successful, deletes /path/to/.target.old, returns no error. On Windows,
+// the removal of /path/to/target.old always fails, so instead Apply hides the old file instead.
+//
+// 8. If the final rename fails, attempts to roll back by renaming /path/to/.target.old
+// back to /path/to/target.
+//
+// If the roll back operation fails, the file system is left in an inconsistent state (betweet steps 5 and 6) where
+// there is no new executable file and the old executable file could not be be moved to its original location. In this
+// case you should notify the user of the bad news and ask them to recover manually. Applications can determine whether
+// the rollback failed by calling RollbackError, see the documentation on that function for additional detail.
+func Apply(update io.Reader, opts Options) error {
+	// validate
+	verify := false
+	switch {
+	case opts.Signature != nil && opts.PublicKey != nil:
+		// okay
+		verify = true
+	case opts.Signature != nil:
+		return errors.New("no public key to verify signature with")
+	case opts.PublicKey != nil:
+		return errors.New("No signature to verify with")
+	}
+
+	// set defaults
+	if opts.Hash == 0 {
+		opts.Hash = crypto.SHA256
+	}
+	if opts.Verifier == nil {
+		opts.Verifier = NewECDSAVerifier()
+	}
+	if opts.TargetMode == 0 {
+		opts.TargetMode = 0755
+	}
+
+	// get target path
+	var err error
+	opts.TargetPath, err = opts.getPath()
+	if err != nil {
+		return err
+	}
+
+	var newBytes []byte
+	if opts.Patcher != nil {
+		if newBytes, err = opts.applyPatch(update); err != nil {
+			return err
+		}
+	} else {
+		// no patch to apply, go on through
+		if newBytes, err = ioutil.ReadAll(update); err != nil {
+			return err
+		}
+	}
+
+	// verify checksum if requested
+	if opts.Checksum != nil {
+		if err = opts.verifyChecksum(newBytes); err != nil {
+			return err
+		}
+	}
+
+	if verify {
+		if err = opts.verifySignature(newBytes); err != nil {
+			return err
+		}
+	}
+
+	// get the directory the executable exists in
+	updateDir := filepath.Dir(opts.TargetPath)
+	filename := filepath.Base(opts.TargetPath)
+
+	// Copy the contents of newbinary to a new executable file
+	newPath := filepath.Join(updateDir, fmt.Sprintf(".%s.new", filename))
+	fp, err := openFile(newPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, opts.TargetMode)
+	if err != nil {
+		return err
+	}
+	defer fp.Close()
+
+	_, err = io.Copy(fp, bytes.NewReader(newBytes))
+	if err != nil {
+		return err
+	}
+
+	// if we don't call fp.Close(), windows won't let us move the new executable
+	// because the file will still be "in use"
+	fp.Close()
+
+	// this is where we'll move the executable to so that we can swap in the updated replacement
+	oldPath := opts.OldSavePath
+	removeOld := opts.OldSavePath == ""
+	if removeOld {
+		oldPath = filepath.Join(updateDir, fmt.Sprintf(".%s.old", filename))
+	}
+
+	// delete any existing old exec file - this is necessary on Windows for two reasons:
+	// 1. after a successful update, Windows can't remove the .old file because the process is still running
+	// 2. windows rename operations fail if the destination file already exists
+	_ = os.Remove(oldPath)
+
+	// move the existing executable to a new file in the same directory
+	err = os.Rename(opts.TargetPath, oldPath)
+	if err != nil {
+		return err
+	}
+
+	// move the new exectuable in to become the new program
+	err = os.Rename(newPath, opts.TargetPath)
+
+	if err != nil {
+		// move unsuccessful
+		//
+		// The filesystem is now in a bad state. We have successfully
+		// moved the existing binary to a new location, but we couldn't move the new
+		// binary to take its place. That means there is no file where the current executable binary
+		// used to be!
+		// Try to rollback by restoring the old binary to its original path.
+		rerr := os.Rename(oldPath, opts.TargetPath)
+		if rerr != nil {
+			return &rollbackErr{err, rerr}
+		}
+
+		return err
+	}
+
+	// move successful, remove the old binary if needed
+	if removeOld {
+		errRemove := os.Remove(oldPath)
+
+		// windows has trouble with removing old binaries, so hide it instead
+		if errRemove != nil {
+			_ = hideFile(oldPath)
+		}
+	}
+
+	return nil
+}
+
+// RollbackError takes an error value returned by Apply and returns the error, if any,
+// that occurred when attempting to roll back from a failed update. Applications should
+// always call this function on any non-nil errors returned by Apply.
+//
+// If no rollback was needed or if the rollback was successful, RollbackError returns nil,
+// otherwise it returns the error encountered when trying to roll back.
+func RollbackError(err error) error {
+	if err == nil {
+		return nil
+	}
+	if rerr, ok := err.(*rollbackErr); ok {
+		return rerr.rollbackErr
+	}
+	return nil
+}
+
+type rollbackErr struct {
+	error             // original error
+	rollbackErr error // error encountered while rolling back
+}
+
+type Options struct {
+	// TargetPath defines the path to the file to update.
+	// The emptry string means 'the executable file of the running program'.
+	TargetPath string
+
+	// Create TargetPath replacement with this file mode. If zero, defaults to 0755.
+	TargetMode os.FileMode
+
+	// Checksum of the new binary to verify against. If nil, no checksum or signature verification is done.
+	Checksum []byte
+
+	// Public key to use for signature verification. If nil, no signature verification is done.
+	PublicKey crypto.PublicKey
+
+	// Signature to verify the updated file. If nil, no signature verification is done.
+	Signature []byte
+
+	// Pluggable signature verification algorithm. If nil, ECDSA is used.
+	Verifier Verifier
+
+	// Use this hash function to generate the checksum. If not set, SHA256 is used.
+	Hash crypto.Hash
+
+	// If nil, treat the update as a complete replacement for the contents of the file at TargetPath.
+	// If non-nil, treat the update contents as a patch and use this object to apply the patch.
+	Patcher Patcher
+
+	// Store the old executable file at this path after a successful update.
+	// The empty string means the old executable file will be removed after the update.
+	OldSavePath string
+}
+
+// CheckPermissions determines whether the process has the correct permissions to
+// perform the requested update. If the update can proceed, it returns nil, otherwise
+// it returns the error that would occur if an update were attempted.
+func (o *Options) CheckPermissions() error {
+	// get the directory the file exists in
+	path, err := o.getPath()
+	if err != nil {
+		return err
+	}
+
+	fileDir := filepath.Dir(path)
+	fileName := filepath.Base(path)
+
+	// attempt to open a file in the file's directory
+	newPath := filepath.Join(fileDir, fmt.Sprintf(".%s.new", fileName))
+	fp, err := openFile(newPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, o.TargetMode)
+	if err != nil {
+		return err
+	}
+	fp.Close()
+
+	_ = os.Remove(newPath)
+	return nil
+}
+
+// SetPublicKeyPEM is a convenience method to set the PublicKey property
+// used for checking a completed update's signature by parsing a
+// Public Key formatted as PEM data.
+func (o *Options) SetPublicKeyPEM(pembytes []byte) error {
+	block, _ := pem.Decode(pembytes)
+	if block == nil {
+		return errors.New("couldn't parse PEM data")
+	}
+
+	pub, err := x509.ParsePKIXPublicKey(block.Bytes)
+	if err != nil {
+		return err
+	}
+	o.PublicKey = pub
+	return nil
+}
+
+func (o *Options) getPath() (string, error) {
+	if o.TargetPath == "" {
+		return osext.Executable()
+	} else {
+		return o.TargetPath, nil
+	}
+}
+
+func (o *Options) applyPatch(patch io.Reader) ([]byte, error) {
+	// open the file to patch
+	old, err := os.Open(o.TargetPath)
+	if err != nil {
+		return nil, err
+	}
+	defer old.Close()
+
+	// apply the patch
+	var applied bytes.Buffer
+	if err = o.Patcher.Patch(old, &applied, patch); err != nil {
+		return nil, err
+	}
+
+	return applied.Bytes(), nil
+}
+
+func (o *Options) verifyChecksum(updated []byte) error {
+	checksum, err := checksumFor(o.Hash, updated)
+	if err != nil {
+		return err
+	}
+
+	if !bytes.Equal(o.Checksum, checksum) {
+		return fmt.Errorf("Updated file has wrong checksum. Expected: %x, got: %x", o.Checksum, checksum)
+	}
+	return nil
+}
+
+func (o *Options) verifySignature(updated []byte) error {
+	checksum, err := checksumFor(o.Hash, updated)
+	if err != nil {
+		return err
+	}
+	return o.Verifier.VerifySignature(checksum, o.Signature, o.Hash, o.PublicKey)
+}
+
+func checksumFor(h crypto.Hash, payload []byte) ([]byte, error) {
+	if !h.Available() {
+		return nil, errors.New("requested hash function not available")
+	}
+	hash := h.New()
+	hash.Write(payload) // guaranteed not to error
+	return hash.Sum([]byte{}), nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/doc.go b/vendor/github.com/equinox-io/equinox/internal/go-update/doc.go
new file mode 100644
index 0000000..468411f
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/doc.go
@@ -0,0 +1,172 @@
+/*
+Package update provides functionality to implement secure, self-updating Go programs (or other single-file targets).
+
+For complete updating solutions please see Equinox (https://equinox.io) and go-tuf (https://github.com/flynn/go-tuf).
+
+Basic Example
+
+This example shows how to update a program remotely from a URL.
+
+	import (
+		"fmt"
+		"net/http"
+
+		"github.com/inconshreveable/go-update"
+	)
+
+	func doUpdate(url string) error {
+		// request the new file
+		resp, err := http.Get(url)
+		if err != nil {
+			return err
+		}
+		defer resp.Body.Close()
+		err := update.Apply(resp.Body, update.Options{})
+		if err != nil {
+			if rerr := update.RollbackError(err); rerr != nil {
+				fmt.Println("Failed to rollback from bad update: %v", rerr)
+			}
+		}
+		return err
+	}
+
+
+Binary Patching
+
+Go binaries can often be large. It can be advantageous to only ship a binary patch to a client
+instead of the complete program text of a new version.
+
+This example shows how to update a program with a bsdiff binary patch. Other patch formats
+may be applied by implementing the Patcher interface.
+
+	import (
+		"encoding/hex"
+		"io"
+
+		"github.com/inconshreveable/go-update"
+	)
+
+	func updateWithPatch(patch io.Reader) error {
+		err := update.Apply(patch, update.Options{
+			Patcher: update.NewBSDiffPatcher()
+		})
+		if err != nil {
+			// error handling
+		}
+		return err
+	}
+
+Checksum Verification
+
+Updating executable code on a computer can be a dangerous operation unless you
+take the appropriate steps to guarantee the authenticity of the new code. While
+checksum verification is important, it should always be combined with signature
+verification (next section) to guarantee that the code came from a trusted party.
+
+go-update validates SHA256 checksums by default, but this is pluggable via the Hash
+property on the Options struct.
+
+This example shows how to guarantee that the newly-updated binary is verified to
+have an appropriate checksum (that was otherwise retrived via a secure channel)
+specified as a hex string.
+
+	import (
+		"crypto"
+		_ "crypto/sha256"
+		"encoding/hex"
+		"io"
+
+		"github.com/inconshreveable/go-update"
+	)
+
+	func updateWithChecksum(binary io.Reader, hexChecksum string) error {
+		checksum, err := hex.DecodeString(hexChecksum)
+		if err != nil {
+			return err
+		}
+		err = update.Apply(binary, update.Options{
+			Hash: crypto.SHA256, 	// this is the default, you don't need to specify it
+			Checksum: checksum,
+		})
+		if err != nil {
+			// error handling
+		}
+		return err
+	}
+
+Cryptographic Signature Verification
+
+Cryptographic verification of new code from an update is an extremely important way to guarantee the
+security and integrity of your updates.
+
+Verification is performed by validating the signature of a hash of the new file. This
+means nothing changes if you apply your update with a patch.
+
+This example shows how to add signature verification to your updates. To make all of this work
+an application distributor must first create a public/private key pair and embed the public key
+into their application. When they issue a new release, the issuer must sign the new executable file
+with the private key and distribute the signature along with the update.
+
+	import (
+		"crypto"
+		_ "crypto/sha256"
+		"encoding/hex"
+		"io"
+
+		"github.com/inconshreveable/go-update"
+	)
+
+	var publicKey = []byte(`
+	-----BEGIN PUBLIC KEY-----
+	MFYwEAYHKoZIzj0CAQYFK4EEAAoDQgAEtrVmBxQvheRArXjg2vG1xIprWGuCyESx
+	MMY8pjmjepSy2kuz+nl9aFLqmr+rDNdYvEBqQaZrYMc6k29gjvoQnQ==
+	-----END PUBLIC KEY-----
+	`)
+
+	func verifiedUpdate(binary io.Reader, hexChecksum, hexSignature string) {
+		checksum, err := hex.DecodeString(hexChecksum)
+		if err != nil {
+			return err
+		}
+		signature, err := hex.DecodeString(hexSignature)
+		if err != nil {
+			return err
+		}
+		opts := update.Options{
+			Checksum: checksum,
+			Signature: signature,
+			Hash: crypto.SHA256, 	                 // this is the default, you don't need to specify it
+			Verifier: update.NewECDSAVerifier(),   // this is the default, you don't need to specify it
+		}
+		err = opts.SetPublicKeyPEM(publicKey)
+		if err != nil {
+			return err
+		}
+		err = update.Apply(binary, opts)
+		if err != nil {
+			// error handling
+		}
+		return err
+	}
+
+
+Building Single-File Go Binaries
+
+In order to update a Go application with go-update, you must distributed it as a single executable.
+This is often easy, but some applications require static assets (like HTML and CSS asset files or TLS certificates).
+In order to update applications like these, you'll want to make sure to embed those asset files into
+the distributed binary with a tool like go-bindata (my favorite): https://github.com/jteeuwen/go-bindata
+
+Non-Goals
+
+Mechanisms and protocols for determining whether an update should be applied and, if so, which one are
+out of scope for this package. Please consult go-tuf (https://github.com/flynn/go-tuf) or Equinox (https://equinox.io)
+for more complete solutions.
+
+go-update only works for self-updating applications that are distributed as a single binary, i.e.
+applications that do not have additional assets or dependency files.
+Updating application that are distributed as mutliple on-disk files is out of scope, although this
+may change in future versions of this library.
+
+*/
+package update
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/hide_noop.go b/vendor/github.com/equinox-io/equinox/internal/go-update/hide_noop.go
new file mode 100644
index 0000000..3707756
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/hide_noop.go
@@ -0,0 +1,7 @@
+// +build !windows
+
+package update
+
+func hideFile(path string) error {
+	return nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/hide_windows.go b/vendor/github.com/equinox-io/equinox/internal/go-update/hide_windows.go
new file mode 100644
index 0000000..c368b9c
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/hide_windows.go
@@ -0,0 +1,19 @@
+package update
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+func hideFile(path string) error {
+	kernel32 := syscall.NewLazyDLL("kernel32.dll")
+	setFileAttributes := kernel32.NewProc("SetFileAttributesW")
+
+	r1, _, err := setFileAttributes.Call(uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(path))), 2)
+
+	if r1 == 0 {
+		return err
+	} else {
+		return nil
+	}
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/License b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/License
new file mode 100644
index 0000000..183c389
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/License
@@ -0,0 +1,22 @@
+Copyright 2012 Keith Rarick
+
+Permission is hereby granted, free of charge, to any person
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without
+restriction, including without limitation the rights to use,
+copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/Readme.md b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/Readme.md
new file mode 100644
index 0000000..dadc368
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/Readme.md
@@ -0,0 +1,7 @@
+# binarydist
+
+Package binarydist implements binary diff and patch as described on
+<http://www.daemonology.net/bsdiff/>. It reads and writes files
+compatible with the tools there.
+
+Documentation at <http://go.pkgdoc.org/github.com/kr/binarydist>.
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/bzip2.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/bzip2.go
new file mode 100644
index 0000000..a2516b8
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/bzip2.go
@@ -0,0 +1,40 @@
+package binarydist
+
+import (
+	"io"
+	"os/exec"
+)
+
+type bzip2Writer struct {
+	c *exec.Cmd
+	w io.WriteCloser
+}
+
+func (w bzip2Writer) Write(b []byte) (int, error) {
+	return w.w.Write(b)
+}
+
+func (w bzip2Writer) Close() error {
+	if err := w.w.Close(); err != nil {
+		return err
+	}
+	return w.c.Wait()
+}
+
+// Package compress/bzip2 implements only decompression,
+// so we'll fake it by running bzip2 in another process.
+func newBzip2Writer(w io.Writer) (wc io.WriteCloser, err error) {
+	var bw bzip2Writer
+	bw.c = exec.Command("bzip2", "-c")
+	bw.c.Stdout = w
+
+	if bw.w, err = bw.c.StdinPipe(); err != nil {
+		return nil, err
+	}
+
+	if err = bw.c.Start(); err != nil {
+		return nil, err
+	}
+
+	return bw, nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/diff.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/diff.go
new file mode 100644
index 0000000..1d2d951
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/diff.go
@@ -0,0 +1,408 @@
+package binarydist
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+	"io/ioutil"
+)
+
+func swap(a []int, i, j int) { a[i], a[j] = a[j], a[i] }
+
+func split(I, V []int, start, length, h int) {
+	var i, j, k, x, jj, kk int
+
+	if length < 16 {
+		for k = start; k < start+length; k += j {
+			j = 1
+			x = V[I[k]+h]
+			for i = 1; k+i < start+length; i++ {
+				if V[I[k+i]+h] < x {
+					x = V[I[k+i]+h]
+					j = 0
+				}
+				if V[I[k+i]+h] == x {
+					swap(I, k+i, k+j)
+					j++
+				}
+			}
+			for i = 0; i < j; i++ {
+				V[I[k+i]] = k + j - 1
+			}
+			if j == 1 {
+				I[k] = -1
+			}
+		}
+		return
+	}
+
+	x = V[I[start+length/2]+h]
+	jj = 0
+	kk = 0
+	for i = start; i < start+length; i++ {
+		if V[I[i]+h] < x {
+			jj++
+		}
+		if V[I[i]+h] == x {
+			kk++
+		}
+	}
+	jj += start
+	kk += jj
+
+	i = start
+	j = 0
+	k = 0
+	for i < jj {
+		if V[I[i]+h] < x {
+			i++
+		} else if V[I[i]+h] == x {
+			swap(I, i, jj+j)
+			j++
+		} else {
+			swap(I, i, kk+k)
+			k++
+		}
+	}
+
+	for jj+j < kk {
+		if V[I[jj+j]+h] == x {
+			j++
+		} else {
+			swap(I, jj+j, kk+k)
+			k++
+		}
+	}
+
+	if jj > start {
+		split(I, V, start, jj-start, h)
+	}
+
+	for i = 0; i < kk-jj; i++ {
+		V[I[jj+i]] = kk - 1
+	}
+	if jj == kk-1 {
+		I[jj] = -1
+	}
+
+	if start+length > kk {
+		split(I, V, kk, start+length-kk, h)
+	}
+}
+
+func qsufsort(obuf []byte) []int {
+	var buckets [256]int
+	var i, h int
+	I := make([]int, len(obuf)+1)
+	V := make([]int, len(obuf)+1)
+
+	for _, c := range obuf {
+		buckets[c]++
+	}
+	for i = 1; i < 256; i++ {
+		buckets[i] += buckets[i-1]
+	}
+	copy(buckets[1:], buckets[:])
+	buckets[0] = 0
+
+	for i, c := range obuf {
+		buckets[c]++
+		I[buckets[c]] = i
+	}
+
+	I[0] = len(obuf)
+	for i, c := range obuf {
+		V[i] = buckets[c]
+	}
+
+	V[len(obuf)] = 0
+	for i = 1; i < 256; i++ {
+		if buckets[i] == buckets[i-1]+1 {
+			I[buckets[i]] = -1
+		}
+	}
+	I[0] = -1
+
+	for h = 1; I[0] != -(len(obuf) + 1); h += h {
+		var n int
+		for i = 0; i < len(obuf)+1; {
+			if I[i] < 0 {
+				n -= I[i]
+				i -= I[i]
+			} else {
+				if n != 0 {
+					I[i-n] = -n
+				}
+				n = V[I[i]] + 1 - i
+				split(I, V, i, n, h)
+				i += n
+				n = 0
+			}
+		}
+		if n != 0 {
+			I[i-n] = -n
+		}
+	}
+
+	for i = 0; i < len(obuf)+1; i++ {
+		I[V[i]] = i
+	}
+	return I
+}
+
+func matchlen(a, b []byte) (i int) {
+	for i < len(a) && i < len(b) && a[i] == b[i] {
+		i++
+	}
+	return i
+}
+
+func search(I []int, obuf, nbuf []byte, st, en int) (pos, n int) {
+	if en-st < 2 {
+		x := matchlen(obuf[I[st]:], nbuf)
+		y := matchlen(obuf[I[en]:], nbuf)
+
+		if x > y {
+			return I[st], x
+		} else {
+			return I[en], y
+		}
+	}
+
+	x := st + (en-st)/2
+	if bytes.Compare(obuf[I[x]:], nbuf) < 0 {
+		return search(I, obuf, nbuf, x, en)
+	} else {
+		return search(I, obuf, nbuf, st, x)
+	}
+	panic("unreached")
+}
+
+// Diff computes the difference between old and new, according to the bsdiff
+// algorithm, and writes the result to patch.
+func Diff(old, new io.Reader, patch io.Writer) error {
+	obuf, err := ioutil.ReadAll(old)
+	if err != nil {
+		return err
+	}
+
+	nbuf, err := ioutil.ReadAll(new)
+	if err != nil {
+		return err
+	}
+
+	pbuf, err := diffBytes(obuf, nbuf)
+	if err != nil {
+		return err
+	}
+
+	_, err = patch.Write(pbuf)
+	return err
+}
+
+func diffBytes(obuf, nbuf []byte) ([]byte, error) {
+	var patch seekBuffer
+	err := diff(obuf, nbuf, &patch)
+	if err != nil {
+		return nil, err
+	}
+	return patch.buf, nil
+}
+
+func diff(obuf, nbuf []byte, patch io.WriteSeeker) error {
+	var lenf int
+	I := qsufsort(obuf)
+	db := make([]byte, len(nbuf))
+	eb := make([]byte, len(nbuf))
+	var dblen, eblen int
+
+	var hdr header
+	hdr.Magic = magic
+	hdr.NewSize = int64(len(nbuf))
+	err := binary.Write(patch, signMagLittleEndian{}, &hdr)
+	if err != nil {
+		return err
+	}
+
+	// Compute the differences, writing ctrl as we go
+	pfbz2, err := newBzip2Writer(patch)
+	if err != nil {
+		return err
+	}
+	var scan, pos, length int
+	var lastscan, lastpos, lastoffset int
+	for scan < len(nbuf) {
+		var oldscore int
+		scan += length
+		for scsc := scan; scan < len(nbuf); scan++ {
+			pos, length = search(I, obuf, nbuf[scan:], 0, len(obuf))
+
+			for ; scsc < scan+length; scsc++ {
+				if scsc+lastoffset < len(obuf) &&
+					obuf[scsc+lastoffset] == nbuf[scsc] {
+					oldscore++
+				}
+			}
+
+			if (length == oldscore && length != 0) || length > oldscore+8 {
+				break
+			}
+
+			if scan+lastoffset < len(obuf) && obuf[scan+lastoffset] == nbuf[scan] {
+				oldscore--
+			}
+		}
+
+		if length != oldscore || scan == len(nbuf) {
+			var s, Sf int
+			lenf = 0
+			for i := 0; lastscan+i < scan && lastpos+i < len(obuf); {
+				if obuf[lastpos+i] == nbuf[lastscan+i] {
+					s++
+				}
+				i++
+				if s*2-i > Sf*2-lenf {
+					Sf = s
+					lenf = i
+				}
+			}
+
+			lenb := 0
+			if scan < len(nbuf) {
+				var s, Sb int
+				for i := 1; (scan >= lastscan+i) && (pos >= i); i++ {
+					if obuf[pos-i] == nbuf[scan-i] {
+						s++
+					}
+					if s*2-i > Sb*2-lenb {
+						Sb = s
+						lenb = i
+					}
+				}
+			}
+
+			if lastscan+lenf > scan-lenb {
+				overlap := (lastscan + lenf) - (scan - lenb)
+				s := 0
+				Ss := 0
+				lens := 0
+				for i := 0; i < overlap; i++ {
+					if nbuf[lastscan+lenf-overlap+i] == obuf[lastpos+lenf-overlap+i] {
+						s++
+					}
+					if nbuf[scan-lenb+i] == obuf[pos-lenb+i] {
+						s--
+					}
+					if s > Ss {
+						Ss = s
+						lens = i + 1
+					}
+				}
+
+				lenf += lens - overlap
+				lenb -= lens
+			}
+
+			for i := 0; i < lenf; i++ {
+				db[dblen+i] = nbuf[lastscan+i] - obuf[lastpos+i]
+			}
+			for i := 0; i < (scan-lenb)-(lastscan+lenf); i++ {
+				eb[eblen+i] = nbuf[lastscan+lenf+i]
+			}
+
+			dblen += lenf
+			eblen += (scan - lenb) - (lastscan + lenf)
+
+			err = binary.Write(pfbz2, signMagLittleEndian{}, int64(lenf))
+			if err != nil {
+				pfbz2.Close()
+				return err
+			}
+
+			val := (scan - lenb) - (lastscan + lenf)
+			err = binary.Write(pfbz2, signMagLittleEndian{}, int64(val))
+			if err != nil {
+				pfbz2.Close()
+				return err
+			}
+
+			val = (pos - lenb) - (lastpos + lenf)
+			err = binary.Write(pfbz2, signMagLittleEndian{}, int64(val))
+			if err != nil {
+				pfbz2.Close()
+				return err
+			}
+
+			lastscan = scan - lenb
+			lastpos = pos - lenb
+			lastoffset = pos - scan
+		}
+	}
+	err = pfbz2.Close()
+	if err != nil {
+		return err
+	}
+
+	// Compute size of compressed ctrl data
+	l64, err := patch.Seek(0, 1)
+	if err != nil {
+		return err
+	}
+	hdr.CtrlLen = int64(l64 - 32)
+
+	// Write compressed diff data
+	pfbz2, err = newBzip2Writer(patch)
+	if err != nil {
+		return err
+	}
+	n, err := pfbz2.Write(db[:dblen])
+	if err != nil {
+		pfbz2.Close()
+		return err
+	}
+	if n != dblen {
+		pfbz2.Close()
+		return io.ErrShortWrite
+	}
+	err = pfbz2.Close()
+	if err != nil {
+		return err
+	}
+
+	// Compute size of compressed diff data
+	n64, err := patch.Seek(0, 1)
+	if err != nil {
+		return err
+	}
+	hdr.DiffLen = n64 - l64
+
+	// Write compressed extra data
+	pfbz2, err = newBzip2Writer(patch)
+	if err != nil {
+		return err
+	}
+	n, err = pfbz2.Write(eb[:eblen])
+	if err != nil {
+		pfbz2.Close()
+		return err
+	}
+	if n != eblen {
+		pfbz2.Close()
+		return io.ErrShortWrite
+	}
+	err = pfbz2.Close()
+	if err != nil {
+		return err
+	}
+
+	// Seek to the beginning, write the header, and close the file
+	_, err = patch.Seek(0, 0)
+	if err != nil {
+		return err
+	}
+	err = binary.Write(patch, signMagLittleEndian{}, &hdr)
+	if err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/doc.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/doc.go
new file mode 100644
index 0000000..3c92d87
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/doc.go
@@ -0,0 +1,24 @@
+// Package binarydist implements binary diff and patch as described on
+// http://www.daemonology.net/bsdiff/. It reads and writes files
+// compatible with the tools there.
+package binarydist
+
+var magic = [8]byte{'B', 'S', 'D', 'I', 'F', 'F', '4', '0'}
+
+// File format:
+//   0       8    "BSDIFF40"
+//   8       8    X
+//   16      8    Y
+//   24      8    sizeof(newfile)
+//   32      X    bzip2(control block)
+//   32+X    Y    bzip2(diff block)
+//   32+X+Y  ???  bzip2(extra block)
+// with control block a set of triples (x,y,z) meaning "add x bytes
+// from oldfile to x bytes from the diff block; copy y bytes from the
+// extra block; seek forwards in oldfile by z bytes".
+type header struct {
+	Magic   [8]byte
+	CtrlLen int64
+	DiffLen int64
+	NewSize int64
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/encoding.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/encoding.go
new file mode 100644
index 0000000..75ba585
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/encoding.go
@@ -0,0 +1,53 @@
+package binarydist
+
+// SignMagLittleEndian is the numeric encoding used by the bsdiff tools.
+// It implements binary.ByteOrder using a sign-magnitude format
+// and little-endian byte order. Only methods Uint64 and String
+// have been written; the rest panic.
+type signMagLittleEndian struct{}
+
+func (signMagLittleEndian) Uint16(b []byte) uint16 { panic("unimplemented") }
+
+func (signMagLittleEndian) PutUint16(b []byte, v uint16) { panic("unimplemented") }
+
+func (signMagLittleEndian) Uint32(b []byte) uint32 { panic("unimplemented") }
+
+func (signMagLittleEndian) PutUint32(b []byte, v uint32) { panic("unimplemented") }
+
+func (signMagLittleEndian) Uint64(b []byte) uint64 {
+	y := int64(b[0]) |
+		int64(b[1])<<8 |
+		int64(b[2])<<16 |
+		int64(b[3])<<24 |
+		int64(b[4])<<32 |
+		int64(b[5])<<40 |
+		int64(b[6])<<48 |
+		int64(b[7]&0x7f)<<56
+
+	if b[7]&0x80 != 0 {
+		y = -y
+	}
+	return uint64(y)
+}
+
+func (signMagLittleEndian) PutUint64(b []byte, v uint64) {
+	x := int64(v)
+	neg := x < 0
+	if neg {
+		x = -x
+	}
+
+	b[0] = byte(x)
+	b[1] = byte(x >> 8)
+	b[2] = byte(x >> 16)
+	b[3] = byte(x >> 24)
+	b[4] = byte(x >> 32)
+	b[5] = byte(x >> 40)
+	b[6] = byte(x >> 48)
+	b[7] = byte(x >> 56)
+	if neg {
+		b[7] |= 0x80
+	}
+}
+
+func (signMagLittleEndian) String() string { return "signMagLittleEndian" }
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/patch.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/patch.go
new file mode 100644
index 0000000..eb03225
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/patch.go
@@ -0,0 +1,109 @@
+package binarydist
+
+import (
+	"bytes"
+	"compress/bzip2"
+	"encoding/binary"
+	"errors"
+	"io"
+	"io/ioutil"
+)
+
+var ErrCorrupt = errors.New("corrupt patch")
+
+// Patch applies patch to old, according to the bspatch algorithm,
+// and writes the result to new.
+func Patch(old io.Reader, new io.Writer, patch io.Reader) error {
+	var hdr header
+	err := binary.Read(patch, signMagLittleEndian{}, &hdr)
+	if err != nil {
+		return err
+	}
+	if hdr.Magic != magic {
+		return ErrCorrupt
+	}
+	if hdr.CtrlLen < 0 || hdr.DiffLen < 0 || hdr.NewSize < 0 {
+		return ErrCorrupt
+	}
+
+	ctrlbuf := make([]byte, hdr.CtrlLen)
+	_, err = io.ReadFull(patch, ctrlbuf)
+	if err != nil {
+		return err
+	}
+	cpfbz2 := bzip2.NewReader(bytes.NewReader(ctrlbuf))
+
+	diffbuf := make([]byte, hdr.DiffLen)
+	_, err = io.ReadFull(patch, diffbuf)
+	if err != nil {
+		return err
+	}
+	dpfbz2 := bzip2.NewReader(bytes.NewReader(diffbuf))
+
+	// The entire rest of the file is the extra block.
+	epfbz2 := bzip2.NewReader(patch)
+
+	obuf, err := ioutil.ReadAll(old)
+	if err != nil {
+		return err
+	}
+
+	nbuf := make([]byte, hdr.NewSize)
+
+	var oldpos, newpos int64
+	for newpos < hdr.NewSize {
+		var ctrl struct{ Add, Copy, Seek int64 }
+		err = binary.Read(cpfbz2, signMagLittleEndian{}, &ctrl)
+		if err != nil {
+			return err
+		}
+
+		// Sanity-check
+		if newpos+ctrl.Add > hdr.NewSize {
+			return ErrCorrupt
+		}
+
+		// Read diff string
+		_, err = io.ReadFull(dpfbz2, nbuf[newpos:newpos+ctrl.Add])
+		if err != nil {
+			return ErrCorrupt
+		}
+
+		// Add old data to diff string
+		for i := int64(0); i < ctrl.Add; i++ {
+			if oldpos+i >= 0 && oldpos+i < int64(len(obuf)) {
+				nbuf[newpos+i] += obuf[oldpos+i]
+			}
+		}
+
+		// Adjust pointers
+		newpos += ctrl.Add
+		oldpos += ctrl.Add
+
+		// Sanity-check
+		if newpos+ctrl.Copy > hdr.NewSize {
+			return ErrCorrupt
+		}
+
+		// Read extra string
+		_, err = io.ReadFull(epfbz2, nbuf[newpos:newpos+ctrl.Copy])
+		if err != nil {
+			return ErrCorrupt
+		}
+
+		// Adjust pointers
+		newpos += ctrl.Copy
+		oldpos += ctrl.Seek
+	}
+
+	// Write the new file
+	for len(nbuf) > 0 {
+		n, err := new.Write(nbuf)
+		if err != nil {
+			return err
+		}
+		nbuf = nbuf[n:]
+	}
+
+	return nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/seek.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/seek.go
new file mode 100644
index 0000000..96c0346
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/binarydist/seek.go
@@ -0,0 +1,43 @@
+package binarydist
+
+import (
+	"errors"
+)
+
+type seekBuffer struct {
+	buf []byte
+	pos int
+}
+
+func (b *seekBuffer) Write(p []byte) (n int, err error) {
+	n = copy(b.buf[b.pos:], p)
+	if n == len(p) {
+		b.pos += n
+		return n, nil
+	}
+	b.buf = append(b.buf, p[n:]...)
+	b.pos += len(p)
+	return len(p), nil
+}
+
+func (b *seekBuffer) Seek(offset int64, whence int) (ret int64, err error) {
+	var abs int64
+	switch whence {
+	case 0:
+		abs = offset
+	case 1:
+		abs = int64(b.pos) + offset
+	case 2:
+		abs = int64(len(b.buf)) + offset
+	default:
+		return 0, errors.New("binarydist: invalid whence")
+	}
+	if abs < 0 {
+		return 0, errors.New("binarydist: negative position")
+	}
+	if abs >= 1<<31 {
+		return 0, errors.New("binarydist: position out of range")
+	}
+	b.pos = int(abs)
+	return abs, nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/LICENSE b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/LICENSE
new file mode 100644
index 0000000..7448756
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/README.md b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/README.md
new file mode 100644
index 0000000..61350ba
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/README.md
@@ -0,0 +1,16 @@
+### Extensions to the "os" package.
+
+## Find the current Executable and ExecutableFolder.
+
+There is sometimes utility in finding the current executable file
+that is running. This can be used for upgrading the current executable
+or finding resources located relative to the executable file. Both
+working directory and the os.Args[0] value are arbitrary and cannot
+be relied on; os.Args[0] can be "faked".
+
+Multi-platform and supports:
+ * Linux
+ * OS X
+ * Windows
+ * Plan 9
+ * BSDs.
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext.go
new file mode 100644
index 0000000..7bef46f
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext.go
@@ -0,0 +1,27 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Extensions to the standard "os" package.
+package osext
+
+import "path/filepath"
+
+// Executable returns an absolute path that can be used to
+// re-invoke the current program.
+// It may not be valid after the current program exits.
+func Executable() (string, error) {
+	p, err := executable()
+	return filepath.Clean(p), err
+}
+
+// Returns same path as Executable, returns just the folder
+// path. Excludes the executable name and any trailing slash.
+func ExecutableFolder() (string, error) {
+	p, err := Executable()
+	if err != nil {
+		return "", err
+	}
+
+	return filepath.Dir(p), nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_plan9.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_plan9.go
new file mode 100644
index 0000000..655750c
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_plan9.go
@@ -0,0 +1,20 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package osext
+
+import (
+	"os"
+	"strconv"
+	"syscall"
+)
+
+func executable() (string, error) {
+	f, err := os.Open("/proc/" + strconv.Itoa(os.Getpid()) + "/text")
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	return syscall.Fd2path(int(f.Fd()))
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_procfs.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_procfs.go
new file mode 100644
index 0000000..b2598bc
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_procfs.go
@@ -0,0 +1,36 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux netbsd openbsd solaris dragonfly
+
+package osext
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"runtime"
+	"strings"
+)
+
+func executable() (string, error) {
+	switch runtime.GOOS {
+	case "linux":
+		const deletedTag = " (deleted)"
+		execpath, err := os.Readlink("/proc/self/exe")
+		if err != nil {
+			return execpath, err
+		}
+		execpath = strings.TrimSuffix(execpath, deletedTag)
+		execpath = strings.TrimPrefix(execpath, deletedTag)
+		return execpath, nil
+	case "netbsd":
+		return os.Readlink("/proc/curproc/exe")
+	case "openbsd", "dragonfly":
+		return os.Readlink("/proc/curproc/file")
+	case "solaris":
+		return os.Readlink(fmt.Sprintf("/proc/%d/path/a.out", os.Getpid()))
+	}
+	return "", errors.New("ExecPath not implemented for " + runtime.GOOS)
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_sysctl.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_sysctl.go
new file mode 100644
index 0000000..b66cac8
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_sysctl.go
@@ -0,0 +1,79 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin freebsd
+
+package osext
+
+import (
+	"os"
+	"path/filepath"
+	"runtime"
+	"syscall"
+	"unsafe"
+)
+
+var initCwd, initCwdErr = os.Getwd()
+
+func executable() (string, error) {
+	var mib [4]int32
+	switch runtime.GOOS {
+	case "freebsd":
+		mib = [4]int32{1 /* CTL_KERN */, 14 /* KERN_PROC */, 12 /* KERN_PROC_PATHNAME */, -1}
+	case "darwin":
+		mib = [4]int32{1 /* CTL_KERN */, 38 /* KERN_PROCARGS */, int32(os.Getpid()), -1}
+	}
+
+	n := uintptr(0)
+	// Get length.
+	_, _, errNum := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0)
+	if errNum != 0 {
+		return "", errNum
+	}
+	if n == 0 { // This shouldn't happen.
+		return "", nil
+	}
+	buf := make([]byte, n)
+	_, _, errNum = syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&n)), 0, 0)
+	if errNum != 0 {
+		return "", errNum
+	}
+	if n == 0 { // This shouldn't happen.
+		return "", nil
+	}
+	for i, v := range buf {
+		if v == 0 {
+			buf = buf[:i]
+			break
+		}
+	}
+	var err error
+	execPath := string(buf)
+	// execPath will not be empty due to above checks.
+	// Try to get the absolute path if the execPath is not rooted.
+	if execPath[0] != '/' {
+		execPath, err = getAbs(execPath)
+		if err != nil {
+			return execPath, err
+		}
+	}
+	// For darwin KERN_PROCARGS may return the path to a symlink rather than the
+	// actual executable.
+	if runtime.GOOS == "darwin" {
+		if execPath, err = filepath.EvalSymlinks(execPath); err != nil {
+			return execPath, err
+		}
+	}
+	return execPath, nil
+}
+
+func getAbs(execPath string) (string, error) {
+	if initCwdErr != nil {
+		return execPath, initCwdErr
+	}
+	// The execPath may begin with a "../" or a "./" so clean it first.
+	// Join the two paths, trailing and starting slashes undetermined, so use
+	// the generic Join function.
+	return filepath.Join(initCwd, filepath.Clean(execPath)), nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_windows.go b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_windows.go
new file mode 100644
index 0000000..72d282c
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/internal/osext/osext_windows.go
@@ -0,0 +1,34 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package osext
+
+import (
+	"syscall"
+	"unicode/utf16"
+	"unsafe"
+)
+
+var (
+	kernel                = syscall.MustLoadDLL("kernel32.dll")
+	getModuleFileNameProc = kernel.MustFindProc("GetModuleFileNameW")
+)
+
+// GetModuleFileName() with hModule = NULL
+func executable() (exePath string, err error) {
+	return getModuleFileName()
+}
+
+func getModuleFileName() (string, error) {
+	var n uint32
+	b := make([]uint16, syscall.MAX_PATH)
+	size := uint32(len(b))
+
+	r0, _, e1 := getModuleFileNameProc.Call(0, uintptr(unsafe.Pointer(&b[0])), uintptr(size))
+	n = uint32(r0)
+	if n == 0 {
+		return "", e1
+	}
+	return string(utf16.Decode(b[0:n])), nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/patcher.go b/vendor/github.com/equinox-io/equinox/internal/go-update/patcher.go
new file mode 100644
index 0000000..8b36754
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/patcher.go
@@ -0,0 +1,24 @@
+package update
+
+import (
+	"io"
+
+	"github.com/equinox-io/equinox/internal/go-update/internal/binarydist"
+)
+
+// Patcher defines an interface for applying binary patches to an old item to get an updated item.
+type Patcher interface {
+	Patch(old io.Reader, new io.Writer, patch io.Reader) error
+}
+
+type patchFn func(io.Reader, io.Writer, io.Reader) error
+
+func (fn patchFn) Patch(old io.Reader, new io.Writer, patch io.Reader) error {
+	return fn(old, new, patch)
+}
+
+// NewBSDifferPatcher returns a new Patcher that applies binary patches using
+// the bsdiff algorithm. See http://www.daemonology.net/bsdiff/
+func NewBSDiffPatcher() Patcher {
+	return patchFn(binarydist.Patch)
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/go-update/verifier.go b/vendor/github.com/equinox-io/equinox/internal/go-update/verifier.go
new file mode 100644
index 0000000..af1fc57
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/go-update/verifier.go
@@ -0,0 +1,74 @@
+package update
+
+import (
+	"crypto"
+	"crypto/dsa"
+	"crypto/ecdsa"
+	"crypto/rsa"
+	"encoding/asn1"
+	"errors"
+	"math/big"
+)
+
+// Verifier defines an interface for verfiying an update's signature with a public key.
+type Verifier interface {
+	VerifySignature(checksum, signature []byte, h crypto.Hash, publicKey crypto.PublicKey) error
+}
+
+type verifyFn func([]byte, []byte, crypto.Hash, crypto.PublicKey) error
+
+func (fn verifyFn) VerifySignature(checksum []byte, signature []byte, hash crypto.Hash, publicKey crypto.PublicKey) error {
+	return fn(checksum, signature, hash, publicKey)
+}
+
+// NewRSAVerifier returns a Verifier that uses the RSA algorithm to verify updates.
+func NewRSAVerifier() Verifier {
+	return verifyFn(func(checksum, signature []byte, hash crypto.Hash, publicKey crypto.PublicKey) error {
+		key, ok := publicKey.(*rsa.PublicKey)
+		if !ok {
+			return errors.New("not a valid RSA public key")
+		}
+		return rsa.VerifyPKCS1v15(key, hash, checksum, signature)
+	})
+}
+
+type rsDER struct {
+	R *big.Int
+	S *big.Int
+}
+
+// NewECDSAVerifier returns a Verifier that uses the ECDSA algorithm to verify updates.
+func NewECDSAVerifier() Verifier {
+	return verifyFn(func(checksum, signature []byte, hash crypto.Hash, publicKey crypto.PublicKey) error {
+		key, ok := publicKey.(*ecdsa.PublicKey)
+		if !ok {
+			return errors.New("not a valid ECDSA public key")
+		}
+		var rs rsDER
+		if _, err := asn1.Unmarshal(signature, &rs); err != nil {
+			return err
+		}
+		if !ecdsa.Verify(key, checksum, rs.R, rs.S) {
+			return errors.New("failed to verify ecsda signature")
+		}
+		return nil
+	})
+}
+
+// NewDSAVerifier returns a Verifier that uses the DSA algorithm to verify updates.
+func NewDSAVerifier() Verifier {
+	return verifyFn(func(checksum, signature []byte, hash crypto.Hash, publicKey crypto.PublicKey) error {
+		key, ok := publicKey.(*dsa.PublicKey)
+		if !ok {
+			return errors.New("not a valid DSA public key")
+		}
+		var rs rsDER
+		if _, err := asn1.Unmarshal(signature, &rs); err != nil {
+			return err
+		}
+		if !dsa.Verify(key, checksum, rs.R, rs.S) {
+			return errors.New("failed to verify ecsda signature")
+		}
+		return nil
+	})
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/osext/LICENSE b/vendor/github.com/equinox-io/equinox/internal/osext/LICENSE
new file mode 100644
index 0000000..7448756
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/osext/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/github.com/equinox-io/equinox/internal/osext/README.md b/vendor/github.com/equinox-io/equinox/internal/osext/README.md
new file mode 100644
index 0000000..61350ba
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/osext/README.md
@@ -0,0 +1,16 @@
+### Extensions to the "os" package.
+
+## Find the current Executable and ExecutableFolder.
+
+There is sometimes utility in finding the current executable file
+that is running. This can be used for upgrading the current executable
+or finding resources located relative to the executable file. Both
+working directory and the os.Args[0] value are arbitrary and cannot
+be relied on; os.Args[0] can be "faked".
+
+Multi-platform and supports:
+ * Linux
+ * OS X
+ * Windows
+ * Plan 9
+ * BSDs.
diff --git a/vendor/github.com/equinox-io/equinox/internal/osext/osext.go b/vendor/github.com/equinox-io/equinox/internal/osext/osext.go
new file mode 100644
index 0000000..7bef46f
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/osext/osext.go
@@ -0,0 +1,27 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Extensions to the standard "os" package.
+package osext
+
+import "path/filepath"
+
+// Executable returns an absolute path that can be used to
+// re-invoke the current program.
+// It may not be valid after the current program exits.
+func Executable() (string, error) {
+	p, err := executable()
+	return filepath.Clean(p), err
+}
+
+// Returns same path as Executable, returns just the folder
+// path. Excludes the executable name and any trailing slash.
+func ExecutableFolder() (string, error) {
+	p, err := Executable()
+	if err != nil {
+		return "", err
+	}
+
+	return filepath.Dir(p), nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/osext/osext_plan9.go b/vendor/github.com/equinox-io/equinox/internal/osext/osext_plan9.go
new file mode 100644
index 0000000..655750c
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/osext/osext_plan9.go
@@ -0,0 +1,20 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package osext
+
+import (
+	"os"
+	"strconv"
+	"syscall"
+)
+
+func executable() (string, error) {
+	f, err := os.Open("/proc/" + strconv.Itoa(os.Getpid()) + "/text")
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	return syscall.Fd2path(int(f.Fd()))
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/osext/osext_procfs.go b/vendor/github.com/equinox-io/equinox/internal/osext/osext_procfs.go
new file mode 100644
index 0000000..b2598bc
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/osext/osext_procfs.go
@@ -0,0 +1,36 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux netbsd openbsd solaris dragonfly
+
+package osext
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"runtime"
+	"strings"
+)
+
+func executable() (string, error) {
+	switch runtime.GOOS {
+	case "linux":
+		const deletedTag = " (deleted)"
+		execpath, err := os.Readlink("/proc/self/exe")
+		if err != nil {
+			return execpath, err
+		}
+		execpath = strings.TrimSuffix(execpath, deletedTag)
+		execpath = strings.TrimPrefix(execpath, deletedTag)
+		return execpath, nil
+	case "netbsd":
+		return os.Readlink("/proc/curproc/exe")
+	case "openbsd", "dragonfly":
+		return os.Readlink("/proc/curproc/file")
+	case "solaris":
+		return os.Readlink(fmt.Sprintf("/proc/%d/path/a.out", os.Getpid()))
+	}
+	return "", errors.New("ExecPath not implemented for " + runtime.GOOS)
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/osext/osext_sysctl.go b/vendor/github.com/equinox-io/equinox/internal/osext/osext_sysctl.go
new file mode 100644
index 0000000..b66cac8
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/osext/osext_sysctl.go
@@ -0,0 +1,79 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin freebsd
+
+package osext
+
+import (
+	"os"
+	"path/filepath"
+	"runtime"
+	"syscall"
+	"unsafe"
+)
+
+var initCwd, initCwdErr = os.Getwd()
+
+func executable() (string, error) {
+	var mib [4]int32
+	switch runtime.GOOS {
+	case "freebsd":
+		mib = [4]int32{1 /* CTL_KERN */, 14 /* KERN_PROC */, 12 /* KERN_PROC_PATHNAME */, -1}
+	case "darwin":
+		mib = [4]int32{1 /* CTL_KERN */, 38 /* KERN_PROCARGS */, int32(os.Getpid()), -1}
+	}
+
+	n := uintptr(0)
+	// Get length.
+	_, _, errNum := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0)
+	if errNum != 0 {
+		return "", errNum
+	}
+	if n == 0 { // This shouldn't happen.
+		return "", nil
+	}
+	buf := make([]byte, n)
+	_, _, errNum = syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&n)), 0, 0)
+	if errNum != 0 {
+		return "", errNum
+	}
+	if n == 0 { // This shouldn't happen.
+		return "", nil
+	}
+	for i, v := range buf {
+		if v == 0 {
+			buf = buf[:i]
+			break
+		}
+	}
+	var err error
+	execPath := string(buf)
+	// execPath will not be empty due to above checks.
+	// Try to get the absolute path if the execPath is not rooted.
+	if execPath[0] != '/' {
+		execPath, err = getAbs(execPath)
+		if err != nil {
+			return execPath, err
+		}
+	}
+	// For darwin KERN_PROCARGS may return the path to a symlink rather than the
+	// actual executable.
+	if runtime.GOOS == "darwin" {
+		if execPath, err = filepath.EvalSymlinks(execPath); err != nil {
+			return execPath, err
+		}
+	}
+	return execPath, nil
+}
+
+func getAbs(execPath string) (string, error) {
+	if initCwdErr != nil {
+		return execPath, initCwdErr
+	}
+	// The execPath may begin with a "../" or a "./" so clean it first.
+	// Join the two paths, trailing and starting slashes undetermined, so use
+	// the generic Join function.
+	return filepath.Join(initCwd, filepath.Clean(execPath)), nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/internal/osext/osext_windows.go b/vendor/github.com/equinox-io/equinox/internal/osext/osext_windows.go
new file mode 100644
index 0000000..72d282c
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/internal/osext/osext_windows.go
@@ -0,0 +1,34 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package osext
+
+import (
+	"syscall"
+	"unicode/utf16"
+	"unsafe"
+)
+
+var (
+	kernel                = syscall.MustLoadDLL("kernel32.dll")
+	getModuleFileNameProc = kernel.MustFindProc("GetModuleFileNameW")
+)
+
+// GetModuleFileName() with hModule = NULL
+func executable() (exePath string, err error) {
+	return getModuleFileName()
+}
+
+func getModuleFileName() (string, error) {
+	var n uint32
+	b := make([]uint16, syscall.MAX_PATH)
+	size := uint32(len(b))
+
+	r0, _, e1 := getModuleFileNameProc.Call(0, uintptr(unsafe.Pointer(&b[0])), uintptr(size))
+	n = uint32(r0)
+	if n == 0 {
+		return "", e1
+	}
+	return string(utf16.Decode(b[0:n])), nil
+}
diff --git a/vendor/github.com/equinox-io/equinox/proto/proto.go b/vendor/github.com/equinox-io/equinox/proto/proto.go
new file mode 100644
index 0000000..f598b01
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/proto/proto.go
@@ -0,0 +1,42 @@
+/*
+package proto defines a set of structures used to negotiate an update between an
+an application (the client) and an Equinox update service.
+*/
+package proto
+
+import "time"
+
+type PatchKind string
+
+const (
+	PatchNone   PatchKind = "none"
+	PatchBSDiff PatchKind = "bsdiff"
+)
+
+type Request struct {
+	AppID         string `json:"app_id"`
+	Channel       string `json:"channel"`
+	OS            string `json:"os"`
+	Arch          string `json:"arch"`
+	GoARM         string `json:"goarm"`
+	TargetVersion string `json:"target_version"`
+
+	CurrentVersion string `json:"current_version"`
+	CurrentSHA256  string `json:"current_sha256"`
+}
+
+type Response struct {
+	Available   bool      `json:"available"`
+	DownloadURL string    `json:"download_url"`
+	Checksum    string    `json:"checksum"`
+	Signature   string    `json:"signature"`
+	Patch       PatchKind `json:"patch_type"`
+	Release     Release   `json:"release"`
+}
+
+type Release struct {
+	Title       string    `json:"title"`
+	Version     string    `json:"version"`
+	Description string    `json:"description"`
+	CreateDate  time.Time `json:"create_date"`
+}
diff --git a/vendor/github.com/equinox-io/equinox/sdk.go b/vendor/github.com/equinox-io/equinox/sdk.go
new file mode 100644
index 0000000..9ec6a11
--- /dev/null
+++ b/vendor/github.com/equinox-io/equinox/sdk.go
@@ -0,0 +1,305 @@
+package equinox
+
+import (
+	"bytes"
+	"crypto"
+	"crypto/sha256"
+	"crypto/x509"
+	"encoding/hex"
+	"encoding/json"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"runtime"
+	"time"
+
+	"github.com/equinox-io/equinox/internal/go-update"
+	"github.com/equinox-io/equinox/internal/osext"
+	"github.com/equinox-io/equinox/proto"
+)
+
+const protocolVersion = "1"
+const defaultCheckURL = "https://update.equinox.io/check"
+const userAgent = "EquinoxSDK/1.0"
+
+var NotAvailableErr = errors.New("No update available")
+
+type Options struct {
+	// Channel specifies the name of an Equinox release channel to check for
+	// a newer version of the application.
+	//
+	// If empty, defaults to 'stable'.
+	Channel string
+
+	// Version requests an update to a specific version of the application.
+	// If specified, `Channel` is ignored.
+	Version string
+
+	// TargetPath defines the path to the file to update.
+	// The emptry string means 'the executable file of the running program'.
+	TargetPath string
+
+	// Create TargetPath replacement with this file mode. If zero, defaults to 0755.
+	TargetMode os.FileMode
+
+	// Public key to use for signature verification. If nil, no signature
+	// verification is done. Use `SetPublicKeyPEM` to set this field with PEM data.
+	PublicKey crypto.PublicKey
+
+	// Target operating system of the update. Uses the same standard OS names used
+	// by Go build tags (windows, darwin, linux, etc).
+	// If empty, it will be populated by consulting runtime.GOOS
+	OS string
+
+	// Target architecture of the update. Uses the same standard Arch names used
+	// by Go build tags (amd64, 386, arm, etc).
+	// If empty, it will be populated by consulting runtime.GOARCH
+	Arch string
+
+	// Target ARM architecture, if a specific one if required. Uses the same names
+	// as the GOARM environment variable (5, 6, 7).
+	//
+	// GoARM is ignored if Arch != 'arm'.
+	// GoARM is ignored if it is the empty string. Omit it if you do not need
+	// to distinguish between ARM versions.
+	GoARM string
+
+	// The current application version. This is used for statistics and reporting only,
+	// it is optional.
+	CurrentVersion string
+
+	// CheckURL is the URL to request an update check from. You should only set
+	// this if you are running an on-prem Equinox server.
+	// If empty the default Equinox update service endpoint is used.
+	CheckURL string
+
+	// HTTPClient is used to make all HTTP requests necessary for the update check protocol.
+	// You may configure it to use custom timeouts, proxy servers or other behaviors.
+	HTTPClient *http.Client
+}
+
+// Response is returned by Check when an update is available. It may be
+// passed to Apply to perform the update.
+type Response struct {
+	// Version of the release that will be updated to if applied.
+	ReleaseVersion string
+
+	// Title of the the release
+	ReleaseTitle string
+
+	// Additional details about the release
+	ReleaseDescription string
+
+	// Creation date of the release
+	ReleaseDate time.Time
+
+	downloadURL string
+	checksum    []byte
+	signature   []byte
+	patch       proto.PatchKind
+	opts        Options
+}
+
+// SetPublicKeyPEM is a convenience method to set the PublicKey property
+// used for checking a completed update's signature by parsing a
+// Public Key formatted as PEM data.
+func (o *Options) SetPublicKeyPEM(pembytes []byte) error {
+	block, _ := pem.Decode(pembytes)
+	if block == nil {
+		return errors.New("couldn't parse PEM data")
+	}
+
+	pub, err := x509.ParsePKIXPublicKey(block.Bytes)
+	if err != nil {
+		return err
+	}
+	o.PublicKey = pub
+	return nil
+}
+
+// Check communicates with an Equinox update service to determine if
+// an update for the given application matching the specified options is
+// available. The returned error is nil only if an update is available.
+//
+// The appID is issued to you when creating an application at https://equinox.io
+//
+// You can compare the returned error to NotAvailableErr to differentiate between
+// a successful check that found no update from other errors like a failed
+// network connection.
+func Check(appID string, opts Options) (Response, error) {
+	var r Response
+
+	if opts.Channel == "" {
+		opts.Channel = "stable"
+	}
+	if opts.TargetPath == "" {
+		var err error
+		opts.TargetPath, err = osext.Executable()
+		if err != nil {
+			return r, err
+		}
+	}
+	if opts.OS == "" {
+		opts.OS = runtime.GOOS
+	}
+	if opts.Arch == "" {
+		opts.Arch = runtime.GOARCH
+	}
+	if opts.CheckURL == "" {
+		opts.CheckURL = defaultCheckURL
+	}
+	if opts.HTTPClient == nil {
+		opts.HTTPClient = new(http.Client)
+	}
+	opts.HTTPClient.Transport = newUserAgentTransport(userAgent, opts.HTTPClient.Transport)
+
+	checksum := computeChecksum(opts.TargetPath)
+
+	payload, err := json.Marshal(proto.Request{
+		AppID:          appID,
+		Channel:        opts.Channel,
+		OS:             opts.OS,
+		Arch:           opts.Arch,
+		GoARM:          opts.GoARM,
+		TargetVersion:  opts.Version,
+		CurrentVersion: opts.CurrentVersion,
+		CurrentSHA256:  checksum,
+	})
+
+	req, err := http.NewRequest("POST", opts.CheckURL, bytes.NewReader(payload))
+	if err != nil {
+		return r, err
+	}
+	req.Header.Set("Accept", fmt.Sprintf("application/json; q=1; version=%s; charset=utf-8", protocolVersion))
+	req.Header.Set("Content-Type", "application/json; charset=utf-8")
+
+	resp, err := opts.HTTPClient.Do(req)
+	if err != nil {
+		return r, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		body, _ := ioutil.ReadAll(resp.Body)
+		return r, fmt.Errorf("Server responded with %s: %s", resp.Status, body)
+	}
+
+	var protoResp proto.Response
+	err = json.NewDecoder(resp.Body).Decode(&protoResp)
+	if err != nil {
+		return r, err
+	}
+
+	if !protoResp.Available {
+		return r, NotAvailableErr
+	}
+
+	r.ReleaseVersion = protoResp.Release.Version
+	r.ReleaseTitle = protoResp.Release.Title
+	r.ReleaseDescription = protoResp.Release.Description
+	r.ReleaseDate = protoResp.Release.CreateDate
+	r.downloadURL = protoResp.DownloadURL
+	r.patch = protoResp.Patch
+	r.opts = opts
+	r.checksum, err = hex.DecodeString(protoResp.Checksum)
+	if err != nil {
+		return r, err
+	}
+	r.signature, err = hex.DecodeString(protoResp.Signature)
+	if err != nil {
+		return r, err
+	}
+
+	return r, nil
+}
+
+func computeChecksum(path string) string {
+	f, err := os.Open(path)
+	if err != nil {
+		return ""
+	}
+	defer f.Close()
+	h := sha256.New()
+	_, err = io.Copy(h, f)
+	if err != nil {
+		return ""
+	}
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+// Apply performs an update of the current executable (or TargetFile, if it was
+// set on the Options) with the update specified by Response.
+//
+// Error is nil if and only if the entire update completes successfully.
+func (r Response) Apply() error {
+	opts := update.Options{
+		TargetPath: r.opts.TargetPath,
+		TargetMode: r.opts.TargetMode,
+		Checksum:   r.checksum,
+		Signature:  r.signature,
+		Verifier:   update.NewECDSAVerifier(),
+		PublicKey:  r.opts.PublicKey,
+	}
+	switch r.patch {
+	case proto.PatchBSDiff:
+		opts.Patcher = update.NewBSDiffPatcher()
+	}
+
+	if err := opts.CheckPermissions(); err != nil {
+		return err
+	}
+
+	req, err := http.NewRequest("GET", r.downloadURL, nil)
+	if err != nil {
+		return err
+	}
+
+	// fetch the update
+	resp, err := r.opts.HTTPClient.Do(req)
+	if err != nil {
+		return err
+	}
+
+	defer resp.Body.Close()
+
+	// check that we got a patch
+	if resp.StatusCode >= 400 {
+		msg := "error downloading patch"
+
+		id := resp.Header.Get("Request-Id")
+		if id != "" {
+			msg += ", request " + id
+		}
+
+		blob, err := ioutil.ReadAll(resp.Body)
+		if err == nil {
+			msg += ": " + string(bytes.TrimSpace(blob))
+		}
+		return fmt.Errorf(msg)
+	}
+
+	return update.Apply(resp.Body, opts)
+}
+
+type userAgentTransport struct {
+	userAgent string
+	http.RoundTripper
+}
+
+func newUserAgentTransport(userAgent string, rt http.RoundTripper) *userAgentTransport {
+	if rt == nil {
+		rt = http.DefaultTransport
+	}
+	return &userAgentTransport{userAgent, rt}
+}
+
+func (t *userAgentTransport) RoundTrip(r *http.Request) (*http.Response, error) {
+	if r.Header.Get("User-Agent") == "" {
+		r.Header.Set("User-Agent", t.userAgent)
+	}
+	return t.RoundTripper.RoundTrip(r)
+}