CHORE: Vendor go-powershell (#2837)

pkg/powershell/backend/local.go

@@ -0,0 +1,38 @@
+// Copyright (c) 2017 Gorillalabs. All rights reserved.
+
+package backend
+
+import (
+	"io"
+	"os/exec"
+
+	"github.com/juju/errors"
+)
+
+type Local struct{}
+
+func (b *Local) StartProcess(cmd string, args ...string) (Waiter, io.Writer, io.Reader, io.Reader, error) {
+	command := exec.Command(cmd, args...)
+
+	stdin, err := command.StdinPipe()
+	if err != nil {
+		return nil, nil, nil, nil, errors.Annotate(err, "Could not get hold of the PowerShell's stdin stream")
+	}
+
+	stdout, err := command.StdoutPipe()
+	if err != nil {
+		return nil, nil, nil, nil, errors.Annotate(err, "Could not get hold of the PowerShell's stdout stream")
+	}
+
+	stderr, err := command.StderrPipe()
+	if err != nil {
+		return nil, nil, nil, nil, errors.Annotate(err, "Could not get hold of the PowerShell's stderr stream")
+	}
+
+	err = command.Start()
+	if err != nil {
+		return nil, nil, nil, nil, errors.Annotate(err, "Could not spawn PowerShell process")
+	}
+
+	return command, stdin, stdout, stderr, nil
+}

pkg/powershell/backend/ssh.go

@@ -0,0 +1,69 @@
+// Copyright (c) 2017 Gorillalabs. All rights reserved.
+
+package backend
+
+import (
+	"fmt"
+	"io"
+	"regexp"
+	"strings"
+
+	"github.com/juju/errors"
+)
+
+// sshSession exists so we don't create a hard dependency on crypto/ssh.
+type sshSession interface {
+	Waiter
+
+	StdinPipe() (io.WriteCloser, error)
+	StdoutPipe() (io.Reader, error)
+	StderrPipe() (io.Reader, error)
+	Start(string) error
+}
+
+type SSH struct {
+	Session sshSession
+}
+
+func (b *SSH) StartProcess(cmd string, args ...string) (Waiter, io.Writer, io.Reader, io.Reader, error) {
+	stdin, err := b.Session.StdinPipe()
+	if err != nil {
+		return nil, nil, nil, nil, errors.Annotate(err, "Could not get hold of the SSH session's stdin stream")
+	}
+
+	stdout, err := b.Session.StdoutPipe()
+	if err != nil {
+		return nil, nil, nil, nil, errors.Annotate(err, "Could not get hold of the SSH session's stdout stream")
+	}
+
+	stderr, err := b.Session.StderrPipe()
+	if err != nil {
+		return nil, nil, nil, nil, errors.Annotate(err, "Could not get hold of the SSH session's stderr stream")
+	}
+
+	err = b.Session.Start(b.createCmd(cmd, args))
+	if err != nil {
+		return nil, nil, nil, nil, errors.Annotate(err, "Could not spawn process via SSH")
+	}
+
+	return b.Session, stdin, stdout, stderr, nil
+}
+
+func (b *SSH) createCmd(cmd string, args []string) string {
+	parts := []string{cmd}
+	simple := regexp.MustCompile(`^[a-z0-9_/.~+-]+$`)
+
+	for _, arg := range args {
+		if !simple.MatchString(arg) {
+			arg = b.quote(arg)
+		}
+
+		parts = append(parts, arg)
+	}
+
+	return strings.Join(parts, " ")
+}
+
+func (b *SSH) quote(s string) string {
+	return fmt.Sprintf(`"%s"`, s)
+}

pkg/powershell/backend/types.go

@@ -0,0 +1,13 @@
+// Copyright (c) 2017 Gorillalabs. All rights reserved.
+
+package backend
+
+import "io"
+
+type Waiter interface {
+	Wait() error
+}
+
+type Starter interface {
+	StartProcess(cmd string, args ...string) (Waiter, io.Writer, io.Reader, io.Reader, error)
+}