github.com/llvm-mirror/llgo@v0.0.0-20190322182713-bf6f0a60fce1/third_party/gofrontend/libgo/go/exp/terminal/util.go (about)

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build linux
     6  
     7  // Package terminal provides support functions for dealing with terminals, as
     8  // commonly found on UNIX systems.
     9  //
    10  // Putting a terminal into raw mode is the most common requirement:
    11  //
    12  // 	oldState, err := terminal.MakeRaw(0)
    13  // 	if err != nil {
    14  // 	        panic(err)
    15  // 	}
    16  // 	defer terminal.Restore(0, oldState)
    17  package terminal
    18  
    19  import (
    20  	"io"
    21  	"syscall"
    22  	"unsafe"
    23  )
    24  
    25  // State contains the state of a terminal.
    26  type State struct {
    27  	termios syscall.Termios
    28  }
    29  
    30  // IsTerminal returns true if the given file descriptor is a terminal.
    31  func IsTerminal(fd int) bool {
    32  	var termios syscall.Termios
    33  	err := syscall.Tcgetattr(fd, &termios)
    34  	return err == nil
    35  }
    36  
    37  // MakeRaw put the terminal connected to the given file descriptor into raw
    38  // mode and returns the previous state of the terminal so that it can be
    39  // restored.
    40  func MakeRaw(fd int) (*State, error) {
    41  	var oldState State
    42  	if err := syscall.Tcgetattr(fd, &oldState.termios); err != nil {
    43  		return nil, err
    44  	}
    45  
    46  	newState := oldState.termios
    47  	newState.Iflag &^= syscall.ISTRIP | syscall.INLCR | syscall.ICRNL | syscall.IGNCR | syscall.IXON | syscall.IXOFF
    48  	newState.Lflag &^= syscall.ECHO | syscall.ICANON | syscall.ISIG
    49  	if err := syscall.Tcsetattr(fd, syscall.TCSANOW, &newState); err != nil {
    50  		return nil, err
    51  	}
    52  
    53  	return &oldState, nil
    54  }
    55  
    56  // Restore restores the terminal connected to the given file descriptor to a
    57  // previous state.
    58  func Restore(fd int, state *State) error {
    59  	err := syscall.Tcsetattr(fd, syscall.TCSANOW, &state.termios)
    60  	return err
    61  }
    62  
    63  //extern ioctl
    64  func ioctl(int, int, unsafe.Pointer) int
    65  
    66  // GetSize returns the dimensions of the given terminal.
    67  func GetSize(fd int) (width, height int, err error) {
    68  	var dimensions [4]uint16
    69  
    70  	if ioctl(fd, syscall.TIOCGWINSZ, unsafe.Pointer(&dimensions)) < 0 {
    71  		return -1, -1, syscall.GetErrno()
    72  	}
    73  	return int(dimensions[1]), int(dimensions[0]), nil
    74  }
    75  
    76  // ReadPassword reads a line of input from a terminal without local echo.  This
    77  // is commonly used for inputting passwords and other sensitive data. The slice
    78  // returned does not include the \n.
    79  func ReadPassword(fd int) ([]byte, error) {
    80  	var oldState syscall.Termios
    81  	if err := syscall.Tcgetattr(fd, &oldState); err != nil {
    82  		return nil, err
    83  	}
    84  
    85  	newState := oldState
    86  	newState.Lflag &^= syscall.ECHO
    87  	if err := syscall.Tcsetattr(fd, syscall.TCSANOW, &newState); err != nil {
    88  		return nil, err
    89  	}
    90  
    91  	defer func() {
    92  		syscall.Tcsetattr(fd, syscall.TCSANOW, &oldState)
    93  	}()
    94  
    95  	var buf [16]byte
    96  	var ret []byte
    97  	for {
    98  		n, err := syscall.Read(fd, buf[:])
    99  		if err != nil {
   100  			return nil, err
   101  		}
   102  		if n == 0 {
   103  			if len(ret) == 0 {
   104  				return nil, io.EOF
   105  			}
   106  			break
   107  		}
   108  		if buf[n-1] == '\n' {
   109  			n--
   110  		}
   111  		ret = append(ret, buf[:n]...)
   112  		if n < len(buf) {
   113  			break
   114  		}
   115  	}
   116  
   117  	return ret, nil
   118  }