Windows: VirtualTerminalInput native console

Signed-off-by: John Howard <jhoward@microsoft.com>

pkg/term/term_windows.go

@@ -15,7 +15,8 @@ import (
 
 // State holds the console mode for the terminal.
 type State struct {
-	mode uint32
+	inMode, outMode     uint32
+	inHandle, outHandle syscall.Handle
 }
 
 // Winsize is used for window size.
@@ -26,6 +27,15 @@ type Winsize struct {
 	y      uint16
 }
 
+const (
+	// https://msdn.microsoft.com/en-us/library/windows/desktop/ms683167(v=vs.85).aspx
+	enableVirtualTerminalInput      = 0x0200
+	enableVirtualTerminalProcessing = 0x0004
+)
+
+// usingNativeConsole is true if we are using the Windows native console
+var usingNativeConsole bool
+
 // StdStreams returns the standard streams (stdin, stdout, stedrr).
 func StdStreams() (stdIn io.ReadCloser, stdOut, stdErr io.Writer) {
 	switch {
@@ -37,6 +47,7 @@ func StdStreams() (stdIn io.ReadCloser, stdOut, stdErr io.Writer) {
 		return windows.ConsoleStreams()
 	default:
 		if useNativeConsole() {
+			usingNativeConsole = true
 			return os.Stdin, os.Stdout, os.Stderr
 		}
 		return windows.ConsoleStreams()
@@ -52,7 +63,7 @@ func useNativeConsole() bool {
 		return false
 	}
 
-	// Native console is not available major version 10
+	// Native console is not available before major version 10
 	if osv.MajorVersion < 10 {
 		return false
 	}
@@ -62,6 +73,17 @@ func useNativeConsole() bool {
 		return false
 	}
 
+	// Get the console modes. If this fails, we can't use the native console
+	state, err := getNativeConsole()
+	if err != nil {
+		return false
+	}
+
+	// Probe the console to see if it can be enabled.
+	if nil != probeNativeConsole(state) {
+		return false
+	}
+
 	// Environment variable override
 	if e := os.Getenv("USE_NATIVE_CONSOLE"); e != "" {
 		if e == "1" {
@@ -70,30 +92,84 @@ func useNativeConsole() bool {
 		return false
 	}
 
+	// TODO Windows. The native emulator still has issues which
+	// mean it shouldn't be enabled for everyone. Change this next line to true
+	// to change the default to "enable if available". In the meantime, users
+	// can still try it out by using USE_NATIVE_CONSOLE env variable.
+	return false
+}
+
+// getNativeConsole returns the console modes ('state') for the native Windows console
+func getNativeConsole() (State, error) {
+	var (
+		err   error
+		state State
+	)
+
 	// Get the handle to stdout
-	stdOutHandle, err := syscall.GetStdHandle(syscall.STD_OUTPUT_HANDLE)
-	if err != nil {
-		return false
+	if state.outHandle, err = syscall.GetStdHandle(syscall.STD_OUTPUT_HANDLE); err != nil {
+		return state, err
 	}
 
 	// Get the console mode from the consoles stdout handle
-	var mode uint32
-	if err := syscall.GetConsoleMode(stdOutHandle, &mode); err != nil {
-		return false
+	if err = syscall.GetConsoleMode(state.outHandle, &state.outMode); err != nil {
+		return state, err
 	}
 
-	// Legacy mode does not have native ANSI emulation.
-	// https://msdn.microsoft.com/en-us/library/windows/desktop/ms683167(v=vs.85).aspx
-	const enableVirtualTerminalProcessing = 0x0004
-	if mode&enableVirtualTerminalProcessing == 0 {
-		return false
+	// Get the handle to stdin
+	if state.inHandle, err = syscall.GetStdHandle(syscall.STD_INPUT_HANDLE); err != nil {
+		return state, err
 	}
 
-	// TODO Windows (Post TP4). The native emulator still has issues which
-	// mean it shouldn't be enabled for everyone. Change this next line to true
-	// to change the default to "enable if available". In the meantime, users
-	// can still try it out by using USE_NATIVE_CONSOLE env variable.
-	return false
+	// Get the console mode from the consoles stdin handle
+	if err = syscall.GetConsoleMode(state.inHandle, &state.inMode); err != nil {
+		return state, err
+	}
+
+	return state, nil
+}
+
+// probeNativeConsole probes the console to determine if native can be supported,
+func probeNativeConsole(state State) error {
+	if err := winterm.SetConsoleMode(uintptr(state.outHandle), state.outMode|enableVirtualTerminalProcessing); err != nil {
+		return err
+	}
+	defer winterm.SetConsoleMode(uintptr(state.outHandle), state.outMode)
+
+	if err := winterm.SetConsoleMode(uintptr(state.inHandle), state.inMode|enableVirtualTerminalInput); err != nil {
+		return err
+	}
+	defer winterm.SetConsoleMode(uintptr(state.inHandle), state.inMode)
+
+	return nil
+}
+
+// enableNativeConsole turns on native console mode
+func enableNativeConsole(state State) error {
+	if err := winterm.SetConsoleMode(uintptr(state.outHandle), state.outMode|enableVirtualTerminalProcessing); err != nil {
+		return err
+	}
+
+	if err := winterm.SetConsoleMode(uintptr(state.inHandle), state.inMode|enableVirtualTerminalInput); err != nil {
+		winterm.SetConsoleMode(uintptr(state.outHandle), state.outMode) // restore out if we can
+		return err
+	}
+
+	return nil
+}
+
+// disableNativeConsole turns off native console mode
+func disableNativeConsole(state *State) error {
+	// Try and restore both in an out before error checking.
+	errout := winterm.SetConsoleMode(uintptr(state.outHandle), state.outMode)
+	errin := winterm.SetConsoleMode(uintptr(state.inHandle), state.inMode)
+	if errout != nil {
+		return errout
+	}
+	if errin != nil {
+		return errin
+	}
+	return nil
 }
 
 // GetFdInfo returns the file descriptor for an os.File and indicates whether the file represents a terminal.
@@ -103,7 +179,6 @@ func GetFdInfo(in interface{}) (uintptr, bool) {
 
 // GetWinsize returns the window size based on the specified file descriptor.
 func GetWinsize(fd uintptr) (*Winsize, error) {
-
 	info, err := winterm.GetConsoleScreenBufferInfo(fd)
 	if err != nil {
 		return nil, err
@@ -115,9 +190,6 @@ func GetWinsize(fd uintptr) (*Winsize, error) {
 		x:      0,
 		y:      0}
 
-	// Note: GetWinsize is called frequently -- uncomment only for excessive details
-	// logrus.Debugf("[windows] GetWinsize: Console(%v)", info.String())
-	// logrus.Debugf("[windows] GetWinsize: Width(%v), Height(%v), x(%v), y(%v)", winsize.Width, winsize.Height, winsize.x, winsize.y)
 	return winsize, nil
 }
 
@@ -129,25 +201,36 @@ func IsTerminal(fd uintptr) bool {
 // RestoreTerminal restores the terminal connected to the given file descriptor
 // to a previous state.
 func RestoreTerminal(fd uintptr, state *State) error {
-	return winterm.SetConsoleMode(fd, state.mode)
+	if usingNativeConsole {
+		return disableNativeConsole(state)
+	}
+	return winterm.SetConsoleMode(fd, state.outMode)
 }
 
 // SaveState saves the state of the terminal connected to the given file descriptor.
 func SaveState(fd uintptr) (*State, error) {
+	if usingNativeConsole {
+		state, err := getNativeConsole()
+		if err != nil {
+			return nil, err
+		}
+		return &state, nil
+	}
+
 	mode, e := winterm.GetConsoleMode(fd)
 	if e != nil {
 		return nil, e
 	}
-	return &State{mode}, nil
+
+	return &State{outMode: mode}, nil
 }
 
 // DisableEcho disables echo for the terminal connected to the given file descriptor.
 // -- See https://msdn.microsoft.com/en-us/library/windows/desktop/ms683462(v=vs.85).aspx
 func DisableEcho(fd uintptr, state *State) error {
-	mode := state.mode
+	mode := state.inMode
 	mode &^= winterm.ENABLE_ECHO_INPUT
 	mode |= winterm.ENABLE_PROCESSED_INPUT | winterm.ENABLE_LINE_INPUT
-
 	err := winterm.SetConsoleMode(fd, mode)
 	if err != nil {
 		return err
@@ -179,10 +262,17 @@ func MakeRaw(fd uintptr) (*State, error) {
 		return nil, err
 	}
 
+	mode := state.inMode
+	if usingNativeConsole {
+		if err := enableNativeConsole(*state); err != nil {
+			return nil, err
+		}
+		mode |= enableVirtualTerminalInput
+	}
+
 	// See
 	// -- https://msdn.microsoft.com/en-us/library/windows/desktop/ms686033(v=vs.85).aspx
 	// -- https://msdn.microsoft.com/en-us/library/windows/desktop/ms683462(v=vs.85).aspx
-	mode := state.mode
 
 	// Disable these modes
 	mode &^= winterm.ENABLE_ECHO_INPUT