Refactor pkg/term package for Windows tty support

Signed-off-by: John Gossman <johngos@microsoft.com>

term/term_windows.go

@@ -0,0 +1,89 @@
+// +build windows
+
+package term
+
+type State struct {
+	mode uint32
+}
+
+type Winsize struct {
+	Height uint16
+	Width  uint16
+	x      uint16
+	y      uint16
+}
+
+func GetWinsize(fd uintptr) (*Winsize, error) {
+	ws := &Winsize{}
+	var info *CONSOLE_SCREEN_BUFFER_INFO
+	info, err := GetConsoleScreenBufferInfo(fd)
+	if err != nil {
+		return nil, err
+	}
+	ws.Height = uint16(info.srWindow.Right - info.srWindow.Left + 1)
+	ws.Width = uint16(info.srWindow.Bottom - info.srWindow.Top + 1)
+
+	ws.x = 0 // todo azlinux -- this is the pixel size of the Window, and not currently used by any caller
+	ws.y = 0
+
+	return ws, nil
+}
+
+func SetWinsize(fd uintptr, ws *Winsize) error {
+	return nil
+}
+
+// IsTerminal returns true if the given file descriptor is a terminal.
+func IsTerminal(fd uintptr) bool {
+	_, e := GetConsoleMode(fd)
+	return e == nil
+}
+
+// Restore restores the terminal connected to the given file descriptor to a
+// previous state.
+func RestoreTerminal(fd uintptr, state *State) error {
+	return SetConsoleMode(fd, state.mode)
+}
+
+func SaveState(fd uintptr) (*State, error) {
+	mode, e := GetConsoleMode(fd)
+	if e != nil {
+		return nil, e
+	}
+	return &State{mode}, nil
+}
+
+// see http://msdn.microsoft.com/en-us/library/windows/desktop/ms683462(v=vs.85).aspx for these flag settings
+func DisableEcho(fd uintptr, state *State) error {
+	state.mode &^= (ENABLE_ECHO_INPUT)
+	state.mode |= (ENABLE_PROCESSED_INPUT | ENABLE_LINE_INPUT)
+	return SetConsoleMode(fd, state.mode)
+}
+
+func SetRawTerminal(fd uintptr) (*State, error) {
+	oldState, err := MakeRaw(fd)
+	if err != nil {
+		return nil, err
+	}
+	// TODO (azlinux): implement handling interrupt and restore state of terminal
+	return oldState, err
+}
+
+// MakeRaw puts the terminal connected to the given file descriptor into raw
+// mode and returns the previous state of the terminal so that it can be
+// restored.
+func MakeRaw(fd uintptr) (*State, error) {
+	var state *State
+	state, err := SaveState(fd)
+	if err != nil {
+		return nil, err
+	}
+
+	// see http://msdn.microsoft.com/en-us/library/windows/desktop/ms683462(v=vs.85).aspx for these flag settings
+	state.mode &^= (ENABLE_ECHO_INPUT | ENABLE_PROCESSED_INPUT | ENABLE_LINE_INPUT)
+	err = SetConsoleMode(fd, state.mode)
+	if err != nil {
+		return nil, err
+	}
+	return state, nil
+}