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moby--moby/pkg/term/term.go

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// +build !windows
// Package term provides provides structures and helper functions to work with
// terminal (state, sizes).
package term
import (
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"errors"
"io"
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"os"
"os/signal"
"syscall"
"unsafe"
)
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var (
// ErrInvalidState is returned if the state of the terminal is invalid.
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ErrInvalidState = errors.New("Invalid terminal state")
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)
// State represents the state of the terminal.
type State struct {
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termios Termios
}
// Winsize represents the size of the terminal window.
type Winsize struct {
Height uint16
Width uint16
x uint16
y uint16
}
// StdStreams returns the standard streams (stdin, stdout, stedrr).
func StdStreams() (stdIn io.ReadCloser, stdOut, stdErr io.Writer) {
return os.Stdin, os.Stdout, os.Stderr
}
// GetFdInfo returns the file descriptor for an os.File and indicates whether the file represents a terminal.
func GetFdInfo(in interface{}) (uintptr, bool) {
var inFd uintptr
var isTerminalIn bool
if file, ok := in.(*os.File); ok {
inFd = file.Fd()
isTerminalIn = IsTerminal(inFd)
}
return inFd, isTerminalIn
}
// GetWinsize returns the window size based on the specified file descriptor.
func GetWinsize(fd uintptr) (*Winsize, error) {
ws := &Winsize{}
_, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, uintptr(syscall.TIOCGWINSZ), uintptr(unsafe.Pointer(ws)))
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// Skipp errno = 0
if err == 0 {
return ws, nil
}
return ws, err
}
// SetWinsize tries to set the specified window size for the specified file descriptor.
func SetWinsize(fd uintptr, ws *Winsize) error {
_, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, uintptr(syscall.TIOCSWINSZ), uintptr(unsafe.Pointer(ws)))
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// Skipp errno = 0
if err == 0 {
return nil
}
return err
}
// IsTerminal returns true if the given file descriptor is a terminal.
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func IsTerminal(fd uintptr) bool {
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var termios Termios
return tcget(fd, &termios) == 0
}
// RestoreTerminal restores the terminal connected to the given file descriptor
// to a previous state.
func RestoreTerminal(fd uintptr, state *State) error {
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if state == nil {
return ErrInvalidState
}
if err := tcset(fd, &state.termios); err != 0 {
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return err
}
return nil
}
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// SaveState saves the state of the terminal connected to the given file descriptor.
func SaveState(fd uintptr) (*State, error) {
var oldState State
if err := tcget(fd, &oldState.termios); err != 0 {
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return nil, err
}
return &oldState, nil
}
// DisableEcho applies the specified state to the terminal connected to the file
// descriptor, with echo disabled.
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func DisableEcho(fd uintptr, state *State) error {
newState := state.termios
newState.Lflag &^= syscall.ECHO
if err := tcset(fd, &newState); err != 0 {
return err
}
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handleInterrupt(fd, state)
return nil
}
// SetRawTerminal puts the terminal connected to the given file descriptor into
// raw mode and returns the previous state.
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func SetRawTerminal(fd uintptr) (*State, error) {
oldState, err := MakeRaw(fd)
if err != nil {
return nil, err
}
handleInterrupt(fd, oldState)
return oldState, err
}
func handleInterrupt(fd uintptr, state *State) {
sigchan := make(chan os.Signal, 1)
signal.Notify(sigchan, os.Interrupt)
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go func() {
_ = <-sigchan
RestoreTerminal(fd, state)
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os.Exit(0)
}()
}