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// Copyright 2021 The TCell Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use file except in compliance with the License.
// You may obtain a copy of the license at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
package tcell
import (
"errors"
"fmt"
"os"
"os/signal"
"strconv"
"sync"
"syscall"
"time"
"golang.org/x/term"
)
// devTty is an implementation of the Tty API based upon /dev/tty.
type devTty struct {
fd int
f *os.File
of *os.File // the first open of /dev/tty
saved *term.State
sig chan os.Signal
cb func()
stopQ chan struct{}
dev string
wg sync.WaitGroup
l sync.Mutex
}
func (tty *devTty) Read(b []byte) (int, error) {
return tty.f.Read(b)
}
func (tty *devTty) Write(b []byte) (int, error) {
return tty.f.Write(b)
}
func (tty *devTty) Close() error {
return tty.f.Close()
}
func (tty *devTty) Start() error {
tty.l.Lock()
defer tty.l.Unlock()
// We open another copy of /dev/tty. This is a workaround for unusual behavior
// observed in macOS, apparently caused when a subshell (for example) closes our
// own tty device (when it exits for example). Getting a fresh new one seems to
// resolve the problem. (We believe this is a bug in the macOS tty driver that
// fails to account for dup() references to the same file before applying close()
// related behaviors to the tty.) We're also holding the original copy we opened
// since closing that might have deleterious effects as well. The upshot is that
// we will have up to two separate file handles open on /dev/tty. (Note that when
// using stdin/stdout instead of /dev/tty this problem is not observed.)
var err error
if tty.f, err = os.OpenFile(tty.dev, os.O_RDWR, 0); err != nil {
return err
}
tty.fd = int(tty.of.Fd())
if !term.IsTerminal(tty.fd) {
return errors.New("device is not a terminal")
}
_ = tty.f.SetReadDeadline(time.Time{})
saved, err := term.MakeRaw(tty.fd) // also sets vMin and vTime
if err != nil {
return err
}
tty.saved = saved
tty.stopQ = make(chan struct{})
tty.wg.Add(1)
go func(stopQ chan struct{}) {
defer tty.wg.Done()
for {
select {
case <-tty.sig:
tty.l.Lock()
cb := tty.cb
tty.l.Unlock()
if cb != nil {
cb()
}
case <-stopQ:
return
}
}
}(tty.stopQ)
signal.Notify(tty.sig, syscall.SIGWINCH)
return nil
}
func (tty *devTty) Drain() error {
_ = tty.f.SetReadDeadline(time.Now())
if err := tcSetBufParams(tty.fd, 0, 0); err != nil {
return err
}
return nil
}
func (tty *devTty) Stop() error {
tty.l.Lock()
if err := term.Restore(tty.fd, tty.saved); err != nil {
tty.l.Unlock()
return err
}
_ = tty.f.SetReadDeadline(time.Now())
signal.Stop(tty.sig)
close(tty.stopQ)
tty.l.Unlock()
tty.wg.Wait()
// close our tty device -- we'll get another one if we Start again later.
_ = tty.f.Close()
return nil
}
func (tty *devTty) WindowSize() (int, int, error) {
w, h, err := term.GetSize(tty.fd)
if err != nil {
return 0, 0, err
}
if w == 0 {
w, _ = strconv.Atoi(os.Getenv("COLUMNS"))
}
if w == 0 {
w = 80 // default
}
if h == 0 {
h, _ = strconv.Atoi(os.Getenv("LINES"))
}
if h == 0 {
h = 25 // default
}
return w, h, nil
}
func (tty *devTty) NotifyResize(cb func()) {
tty.l.Lock()
tty.cb = cb
tty.l.Unlock()
}
// NewDevTty opens a /dev/tty based Tty.
func NewDevTty() (Tty, error) {
return NewDevTtyFromDev("/dev/tty")
}
// NewDevTtyFromDev opens a tty device given a path. This can be useful to bind to other nodes.
func NewDevTtyFromDev(dev string) (Tty, error) {
tty := &devTty{
dev: dev,
sig: make(chan os.Signal),
}
var err error
if tty.of, err = os.OpenFile(dev, os.O_RDWR, 0); err != nil {
return nil, err
}
tty.fd = int(tty.of.Fd())
if !term.IsTerminal(tty.fd) {
_ = tty.f.Close()
return nil, errors.New("not a terminal")
}
if tty.saved, err = term.GetState(tty.fd); err != nil {
_ = tty.f.Close()
return nil, fmt.Errorf("failed to get state: %w", err)
}
return tty, nil
}
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