Move the terminal setup to execdriver, instead of ./pkg/term

It is independent of any particular driver, but likely used by
  multiple execdrivers. Also, pkg/... is not to have any links to
  docker, which this terminal setup does.

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)

execdriver/termconsole.go

@@ -0,0 +1,125 @@
+package execdriver
+
+import (
+	"github.com/dotcloud/docker/pkg/term"
+	"github.com/kr/pty"
+	"io"
+	"os"
+)
+
+func SetTerminal(command *Command, pipes *Pipes) error {
+	var (
+		term Terminal
+		err  error
+	)
+	if command.Tty {
+		term, err = NewTtyConsole(command, pipes)
+	} else {
+		term, err = NewStdConsole(command, pipes)
+	}
+	if err != nil {
+		return err
+	}
+	command.Terminal = term
+	return nil
+}
+
+type TtyConsole struct {
+	master *os.File
+	slave  *os.File
+}
+
+func NewTtyConsole(command *Command, pipes *Pipes) (*TtyConsole, error) {
+	ptyMaster, ptySlave, err := pty.Open()
+	if err != nil {
+		return nil, err
+	}
+	tty := &TtyConsole{
+		master: ptyMaster,
+		slave:  ptySlave,
+	}
+	if err := tty.attach(command, pipes); err != nil {
+		tty.Close()
+		return nil, err
+	}
+	return tty, nil
+}
+
+func (t *TtyConsole) Master() *os.File {
+	return t.master
+}
+
+func (t *TtyConsole) Resize(h, w int) error {
+	return term.SetWinsize(t.master.Fd(), &term.Winsize{Height: uint16(h), Width: uint16(w)})
+}
+
+func (t *TtyConsole) attach(command *Command, pipes *Pipes) error {
+	command.Stdout = t.slave
+	command.Stderr = t.slave
+	command.Console = t.slave.Name()
+
+	go func() {
+		if wb, ok := pipes.Stdout.(interface {
+			CloseWriters() error
+		}); ok {
+			defer wb.CloseWriters()
+		}
+		io.Copy(pipes.Stdout, t.master)
+	}()
+
+	if pipes.Stdin != nil {
+		command.Stdin = t.slave
+		command.SysProcAttr.Setctty = true
+
+		go func() {
+			defer pipes.Stdin.Close()
+			io.Copy(t.master, pipes.Stdin)
+		}()
+	}
+	return nil
+}
+
+func (t *TtyConsole) Close() error {
+	t.slave.Close()
+	return t.master.Close()
+}
+
+type StdConsole struct {
+}
+
+func NewStdConsole(command *Command, pipes *Pipes) (*StdConsole, error) {
+	std := &StdConsole{}
+
+	if err := std.attach(command, pipes); err != nil {
+		return nil, err
+	}
+	return std, nil
+}
+
+func (s *StdConsole) attach(command *Command, pipes *Pipes) error {
+	command.Stdout = pipes.Stdout
+	command.Stderr = pipes.Stderr
+
+	if pipes.Stdin != nil {
+		stdin, err := command.StdinPipe()
+		if err != nil {
+			return err
+		}
+
+		go func() {
+			defer stdin.Close()
+			io.Copy(stdin, pipes.Stdin)
+		}()
+	}
+	return nil
+}
+
+func (s *StdConsole) Resize(h, w int) error {
+	// we do not need to reside a non tty
+	return nil
+}
+
+func (s *StdConsole) Close() error {
+	// nothing to close here
+	return nil
+}