text: // Copyright 2011 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // +build windows
  
  // Package terminal provides support functions for dealing with terminals, as
  // commonly found on UNIX systems.
  //
  // Putting a terminal into raw mode is the most common requirement:
  //
  // 	oldState, err := terminal.MakeRaw(0)
  // 	if err != nil {
  // 	        panic(err)
  // 	}
  // 	defer terminal.Restore(0, oldState)
  package terminal
  
  import (
  	"golang.org/x/sys/windows"
  )
  
  type State struct {
  	mode uint32
  }
  
  // IsTerminal returns true if the given file descriptor is a terminal.
  func IsTerminal(fd int) bool {
  	var st uint32
  	err := windows.GetConsoleMode(windows.Handle(fd), &st)
  	return err == nil
  }
  
  // MakeRaw put 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 int) (*State, error) {
  	var st uint32
  	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
  		return nil, err
  	}
  	raw := st &^ (windows.ENABLE_ECHO_INPUT | windows.ENABLE_PROCESSED_INPUT | windows.ENABLE_LINE_INPUT | windows.ENABLE_PROCESSED_OUTPUT)
  	if err := windows.SetConsoleMode(windows.Handle(fd), raw); err != nil {
  		return nil, err
  	}
  	return &State{st}, nil
  }
  
  // GetState returns the current state of a terminal which may be useful to
  // restore the terminal after a signal.
  func GetState(fd int) (*State, error) {
  	var st uint32
  	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
  		return nil, err
  	}
  	return &State{st}, nil
  }
  
  // Restore restores the terminal connected to the given file descriptor to a
  // previous state.
  func Restore(fd int, state *State) error {
  	return windows.SetConsoleMode(windows.Handle(fd), state.mode)
  }
  
  // GetSize returns the dimensions of the given terminal.
  func GetSize(fd int) (width, height int, err error) {
  	var info windows.ConsoleScreenBufferInfo
  	if err := windows.GetConsoleScreenBufferInfo(windows.Handle(fd), &info); err != nil {
  		return 0, 0, err
  	}
  	return int(info.Size.X), int(info.Size.Y), nil
  }
  
  // passwordReader is an io.Reader that reads from a specific Windows HANDLE.
  type passwordReader int
  
  func (r passwordReader) Read(buf []byte) (int, error) {
  	return windows.Read(windows.Handle(r), buf)
  }
  
  // ReadPassword reads a line of input from a terminal without local echo.  This
  // is commonly used for inputting passwords and other sensitive data. The slice
  // returned does not include the \n.
  func ReadPassword(fd int) ([]byte, error) {
  	var st uint32
  	if err := windows.GetConsoleMode(windows.Handle(fd), &st); err != nil {
  		return nil, err
  	}
  	old := st
  
  	st &^= (windows.ENABLE_ECHO_INPUT)
  	st |= (windows.ENABLE_PROCESSED_INPUT | windows.ENABLE_LINE_INPUT | windows.ENABLE_PROCESSED_OUTPUT)
  	if err := windows.SetConsoleMode(windows.Handle(fd), st); err != nil {
  		return nil, err
  	}
  
  	defer func() {
  		windows.SetConsoleMode(windows.Handle(fd), old)
  	}()
  
  	return readPasswordLine(passwordReader(fd))
  }
  