Add cp command to transfer file in and out of a machine

Uses scp syntax; a ':' prefix will be replaced by 'user@host:'.

Signed-off-by: Jan Dubois <jan.dubois@suse.com>

cmd/cp.go

@@ -0,0 +1,77 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+
+	"github.com/docker/machine/libmachine/state"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(cpCmd)
+}
+
+var cpCmd = &cobra.Command{
+	Use:   "cp [SOURCE] [DEST]",
+	Short: "Copy files into or out of a machine.",
+	Long:  `Copy files into or out of a machine.`,
+	Args:  cobra.ExactArgs(2),
+	RunE:  cpCommand,
+}
+
+func cpCommand(cmd *cobra.Command, args []string) error {
+	api := newAPI()
+	defer api.Close()
+
+	host, err := api.Load(machineName)
+	if err != nil {
+		return err
+	}
+
+	currentState, err := host.Driver.GetState()
+	if err != nil {
+		return err
+	}
+
+	if currentState != state.Running {
+		return fmt.Errorf("cannot run cp command: Host %q is not running", host.Name)
+	}
+
+	port, err := host.Driver.GetSSHPort()
+	if err != nil {
+		return err
+	}
+
+	scpArgs := []string{
+		"-P", strconv.Itoa(port),
+		"-i", host.Driver.GetSSHKeyPath(),
+		"-o", "IdentitiesOnly=yes",
+		"-o", "LogLevel=quiet",
+		"-o", "PasswordAuthentication=no",
+		"-o", "StrictHostKeyChecking=no",
+		"-o", "UserKnownHostsFile=/dev/null",
+	}
+
+	sshUserame := host.Driver.GetSSHUsername()
+	sshHostname, err := host.Driver.GetSSHHostname()
+	if err != nil {
+		return err
+	}
+
+	for _, arg := range args {
+		if strings.HasPrefix(arg, ":") {
+			scpArgs = append(scpArgs, fmt.Sprintf("%s@%s%s", sshUserame, sshHostname, arg))
+		} else {
+			scpArgs = append(scpArgs, arg)
+		}
+	}
+
+	command := exec.Command("scp", scpArgs...)
+	command.Stdout = os.Stdout
+	command.Stderr = os.Stderr
+	return command.Run()
+}