rewrite checkpoint

vendor/github.com/AlecAivazis/survey/terminal/runereader_posix.go

@@ -0,0 +1,84 @@
+// +build !windows
+
+// The terminal mode manipluation code is derived heavily from:
+// https://github.com/golang/crypto/blob/master/ssh/terminal/util.go:
+// 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.
+
+package terminal
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+type runeReaderState struct {
+	term syscall.Termios
+	buf  *bufio.Reader
+}
+
+func newRuneReaderState(input *os.File) runeReaderState {
+	return runeReaderState{
+		buf: bufio.NewReader(input),
+	}
+}
+
+// For reading runes we just want to disable echo.
+func (rr *RuneReader) SetTermMode() error {
+	if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(rr.Input.Fd()), ioctlReadTermios, uintptr(unsafe.Pointer(&rr.state.term)), 0, 0, 0); err != 0 {
+		return err
+	}
+
+	newState := rr.state.term
+	newState.Lflag &^= syscall.ECHO | syscall.ECHONL | syscall.ICANON | syscall.ISIG
+
+	if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(rr.Input.Fd()), ioctlWriteTermios, uintptr(unsafe.Pointer(&newState)), 0, 0, 0); err != 0 {
+		return err
+	}
+
+	return nil
+}
+
+func (rr *RuneReader) RestoreTermMode() error {
+	if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(rr.Input.Fd()), ioctlWriteTermios, uintptr(unsafe.Pointer(&rr.state.term)), 0, 0, 0); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func (rr *RuneReader) ReadRune() (rune, int, error) {
+	r, size, err := rr.state.buf.ReadRune()
+	if err != nil {
+		return r, size, err
+	}
+	// parse ^[ sequences to look for arrow keys
+	if r == '\033' {
+		r, size, err = rr.state.buf.ReadRune()
+		if err != nil {
+			return r, size, err
+		}
+		if r != '[' {
+			return r, size, fmt.Errorf("Unexpected Escape Sequence: %q", []rune{'\033', r})
+		}
+		r, size, err = rr.state.buf.ReadRune()
+		if err != nil {
+			return r, size, err
+		}
+		switch r {
+		case 'D':
+			return KeyArrowLeft, 1, nil
+		case 'C':
+			return KeyArrowRight, 1, nil
+		case 'A':
+			return KeyArrowUp, 1, nil
+		case 'B':
+			return KeyArrowDown, 1, nil
+		}
+		return r, size, fmt.Errorf("Unknown Escape Sequence: %q", []rune{'\033', '[', r})
+	}
+	return r, size, err
+}