Enable the use of `context` in restic

Set up a cancelble context in global options, hook it into the ctrl-C handler
for proper cancel propegation.

Bump up minimal requirement for Go to version 1.7 in documentation
and test-build files.

.travis.yml

@@ -2,7 +2,6 @@ language: go
 sudo: false
 
 go:
-  - 1.6.4
   - 1.7.5
   - 1.8
   - tip
@@ -17,8 +16,6 @@ env:
 
 matrix:
   exclude:
-    - os: osx
-      go: 1.6.4
     - os: osx
       go: 1.7.5
     - os: osx

CONTRIBUTING.md

@@ -77,7 +77,7 @@ Just clone the repository, `cd` to it and run `gb build` to build the binary:
     [...]
     $ bin/restic version
     restic compiled manually
-    compiled at unknown time with go1.6
+    compiled at unknown time with go1.7
 
 The following commands can be used to run all the tests:
 

README.md

@@ -34,7 +34,7 @@ You can download the latest pre-compiled binary from the [restic release page](h
 Build restic
 ============
 
-Install Go/Golang (at least version 1.6), then run `go run build.go`,
+Install Go/Golang (at least version 1.7), then run `go run build.go`,
 afterwards you'll find the binary in the current directory:
 
     $ go run build.go

Vagrantfile

@@ -1,7 +1,7 @@
 # -*- mode: ruby -*-
 # vi: set ft=ruby :
 
-GO_VERSION = '1.6'
+GO_VERSION = '1.7'
 
 def packages_freebsd
   return <<-EOF

doc/Manual.md

@@ -27,7 +27,7 @@ $ pacaur -S restic-git
 
 # Building restic
 
-restic is written in the Go programming language and you need at least Go version 1.6.
+restic is written in the Go programming language and you need at least Go version 1.7.
 Building restic may also work with older versions of Go, but that's not supported.
 See the [Getting started](https://golang.org/doc/install) guide of the Go project for
 instructions how to install Go.

src/cmds/restic/global.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -33,6 +34,7 @@ type GlobalOptions struct {
 	NoLock       bool
 	JSON         bool
 
+	ctx      context.Context
 	password string
 	stdout   io.Writer
 	stderr   io.Writer
@@ -49,6 +51,13 @@ func init() {
 		globalOptions.password = pw
 	}
 
+	var cancel context.CancelFunc
+	globalOptions.ctx, cancel = context.WithCancel(context.Background())
+	AddCleanupHandler(func() error {
+		cancel()
+		return nil
+	})
+
 	f := cmdRoot.PersistentFlags()
 	f.StringVarP(&globalOptions.Repo, "repo", "r", os.Getenv("RESTIC_REPOSITORY"), "repository to backup to or restore from (default: $RESTIC_REPOSITORY)")
 	f.StringVarP(&globalOptions.PasswordFile, "password-file", "p", "", "read the repository password from a file")

src/cmds/restic/integration_helpers_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -194,6 +195,7 @@ func withTestEnvironment(t testing.TB, f func(*testEnvironment, GlobalOptions))
 	gopts := GlobalOptions{
 		Repo:     env.repo,
 		Quiet:    true,
+		ctx:      context.Background(),
 		password: TestPassword,
 		stdout:   os.Stdout,
 		stderr:   os.Stderr,