tscreen_darwin.go

// +build darwin

// Copyright 2019 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.

package tcell

// The Darwin system is *almost* a real BSD system, but it suffers from
// a brain damaged TTY driver.  This TTY driver does not actually
// wake up in poll() or similar calls, which means that we cannot reliably
// shut down the terminal without resorting to obscene custom C code
// and a dedicated poller thread.
//
// So instead, we do a best effort, and simply try to do the close in the
// background.  Probably this will cause a leak of two goroutines and
// maybe also the file descriptor, meaning that applications on Darwin
// can't reinitialize the screen, but that's probably a very rare behavior,
// and accepting that is the best of some very poor alternative options.
//
// Maybe someday Apple will fix there tty driver, but its been broken for
// a long time (probably forever) so holding one's breath is contraindicated.

import (
	"os"
	"os/signal"
	"syscall"
	"unsafe"
)

type termiosPrivate syscall.Termios

func (t *tScreen) termioInit() error {
	var e error
	var newtios termiosPrivate
	var fd uintptr
	var tios uintptr
	var ioc uintptr
	t.tiosp = &termiosPrivate{}

	if t.in, e = os.OpenFile("/dev/tty", os.O_RDONLY, 0); e != nil {
		goto failed
	}
	if t.out, e = os.OpenFile("/dev/tty", os.O_WRONLY, 0); e != nil {
		goto failed
	}

	tios = uintptr(unsafe.Pointer(t.tiosp))
	ioc = uintptr(syscall.TIOCGETA)
	fd = uintptr(t.out.Fd())
	if _, _, e1 := syscall.Syscall6(syscall.SYS_IOCTL, fd, ioc, tios, 0, 0, 0); e1 != 0 {
		e = e1
		goto failed
	}

	newtios = *t.tiosp
	newtios.Iflag &^= syscall.IGNBRK | syscall.BRKINT | syscall.PARMRK |
		syscall.ISTRIP | syscall.INLCR | syscall.IGNCR |
		syscall.ICRNL | syscall.IXON
	newtios.Oflag &^= syscall.OPOST
	newtios.Lflag &^= syscall.ECHO | syscall.ECHONL | syscall.ICANON |
		syscall.ISIG | syscall.IEXTEN
	newtios.Cflag &^= syscall.CSIZE | syscall.PARENB
	newtios.Cflag |= syscall.CS8

	tios = uintptr(unsafe.Pointer(&newtios))

	ioc = uintptr(syscall.TIOCSETA)
	if _, _, e1 := syscall.Syscall6(syscall.SYS_IOCTL, fd, ioc, tios, 0, 0, 0); e1 != 0 {
		e = e1
		goto failed
	}

	signal.Notify(t.sigwinch, syscall.SIGWINCH)

	if w, h, e := t.getWinSize(); e == nil && w != 0 && h != 0 {
		t.cells.Resize(w, h)
	}

	return nil

failed:
	if t.in != nil {
		t.in.Close()
	}
	if t.out != nil {
		t.out.Close()
	}
	return e
}

func (t *tScreen) termioFini() {

	signal.Stop(t.sigwinch)

	<-t.indoneq

	if t.out != nil {
		fd := uintptr(t.out.Fd())
		ioc := uintptr(syscall.TIOCSETAF)
		tios := uintptr(unsafe.Pointer(t.tiosp))
		syscall.Syscall6(syscall.SYS_IOCTL, fd, ioc, tios, 0, 0, 0)
		t.out.Close()
	}

	// See above -- we background this call which might help, but
	// really the tty is probably open.

	go func() {
		if t.in != nil {
			t.in.Close()
		}
	}()
}

func (t *tScreen) getWinSize() (int, int, error) {

	fd := uintptr(t.out.Fd())
	dim := [4]uint16{}
	dimp := uintptr(unsafe.Pointer(&dim))
	ioc := uintptr(syscall.TIOCGWINSZ)
	if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL,
		fd, ioc, dimp, 0, 0, 0); err != 0 {
		return -1, -1, err
	}
	return int(dim[1]), int(dim[0]), nil
}