tty: move IO of master pty to be done with epoll

This moves all console code to use github.com/containerd/console library to
handle console I/O. Also move to use EpollConsole by default when user requests
a terminal so we can still cope when the other side temporarily goes away.

Signed-off-by: Daniel Dao <dqminh89@gmail.com>

vendor/github.com/containerd/console/console_unix.go

@@ -0,0 +1,134 @@
+// +build darwin freebsd linux
+
+package console
+
+import (
+	"os"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+// NewPty creates a new pty pair
+// The master is returned as the first console and a string
+// with the path to the pty slave is returned as the second
+func NewPty() (Console, string, error) {
+	f, err := os.OpenFile("/dev/ptmx", unix.O_RDWR|unix.O_NOCTTY|unix.O_CLOEXEC, 0)
+	if err != nil {
+		return nil, "", err
+	}
+	if err := saneTerminal(f); err != nil {
+		return nil, "", err
+	}
+	slave, err := ptsname(f)
+	if err != nil {
+		return nil, "", err
+	}
+	if err := unlockpt(f); err != nil {
+		return nil, "", err
+	}
+	return &master{
+		f: f,
+	}, slave, nil
+}
+
+type master struct {
+	f        *os.File
+	original *unix.Termios
+}
+
+func (m *master) Read(b []byte) (int, error) {
+	return m.f.Read(b)
+}
+
+func (m *master) Write(b []byte) (int, error) {
+	return m.f.Write(b)
+}
+
+func (m *master) Close() error {
+	return m.f.Close()
+}
+
+func (m *master) Resize(ws WinSize) error {
+	return ioctl(
+		m.f.Fd(),
+		uintptr(unix.TIOCSWINSZ),
+		uintptr(unsafe.Pointer(&ws)),
+	)
+}
+
+func (m *master) ResizeFrom(c Console) error {
+	ws, err := c.Size()
+	if err != nil {
+		return err
+	}
+	return m.Resize(ws)
+}
+
+func (m *master) Reset() error {
+	if m.original == nil {
+		return nil
+	}
+	return tcset(m.f.Fd(), m.original)
+}
+
+func (m *master) getCurrent() (unix.Termios, error) {
+	var termios unix.Termios
+	if err := tcget(m.f.Fd(), &termios); err != nil {
+		return unix.Termios{}, err
+	}
+	if m.original == nil {
+		m.original = &termios
+	}
+	return termios, nil
+}
+
+func (m *master) SetRaw() error {
+	rawState, err := m.getCurrent()
+	if err != nil {
+		return err
+	}
+	rawState = cfmakeraw(rawState)
+	rawState.Oflag = rawState.Oflag | unix.OPOST
+	return tcset(m.f.Fd(), &rawState)
+}
+
+func (m *master) DisableEcho() error {
+	rawState, err := m.getCurrent()
+	if err != nil {
+		return err
+	}
+	rawState.Lflag = rawState.Lflag &^ unix.ECHO
+	return tcset(m.f.Fd(), &rawState)
+}
+
+func (m *master) Size() (WinSize, error) {
+	var ws WinSize
+	if err := ioctl(
+		m.f.Fd(),
+		uintptr(unix.TIOCGWINSZ),
+		uintptr(unsafe.Pointer(&ws)),
+	); err != nil {
+		return ws, err
+	}
+	return ws, nil
+}
+
+func (m *master) Fd() uintptr {
+	return m.f.Fd()
+}
+
+// checkConsole checks if the provided file is a console
+func checkConsole(f *os.File) error {
+	var termios unix.Termios
+	if tcget(f.Fd(), &termios) != nil {
+		return ErrNotAConsole
+	}
+	return nil
+}
+
+func newMaster(f *os.File) Console {
+	return &master{
+		f: f,
+	}
+}