add driver for setting up tty file descriptors, allowing use with SSH…

… servers

Signed-off-by: Jeff Lindsay <progrium@gmail.com>

driver.go

@@ -0,0 +1,59 @@
+package tcell
+
+import (
+	"errors"
+	"os"
+	"os/signal"
+	"syscall"
+)
+
+// ErrWinSizeUnused is for TermDrivers to signal to use the default platform
+// window size lookup method
+var ErrWinSizeUnused = errors.New("driver does not provide WinSize")
+
+// TermDriver allows you to customize the TTY used by Screen,
+// most notably to support a PTY pair that can be used with SSH servers.
+type TermDriver interface {
+	// Init sets up two file TTY/PTY file descriptors, which may be the same
+	// in some cases. It also takes a chan that is used to notify the Screen
+	// refresh the window size.
+	Init(winch chan os.Signal) (in *os.File, out *os.File, err error)
+
+	// Fini is called before the cleanup of Screen's Fini. It's typically used
+	// to unsubscribe window change signals.
+	Fini()
+
+	// WinSize returns the current window width and height. It can also return
+	// ErrWinSizeUnused to tell Screen to use platform syscalls to get the
+	// window size from the out file descriptor.
+	WinSize() (width int, height int, err error)
+}
+
+// defaultTermDriver is what's used when you don't specify a custom TermDriver
+type defaultTermDriver struct {
+	winch chan os.Signal
+	out   *os.File
+}
+
+func (d *defaultTermDriver) Init(winch chan os.Signal) (in *os.File, out *os.File, err error) {
+	in, err = os.OpenFile("/dev/tty", os.O_RDONLY, 0)
+	if err != nil {
+		return
+	}
+	out, err = os.OpenFile("/dev/tty", os.O_WRONLY, 0)
+	if err != nil {
+		return
+	}
+	signal.Notify(winch, syscall.SIGWINCH)
+	d.winch = winch
+	d.out = out
+	return
+}
+
+func (d *defaultTermDriver) Fini() {
+	signal.Stop(d.winch)
+}
+
+func (d *defaultTermDriver) WinSize() (int, int, error) {
+	return 0, 0, ErrWinSizeUnused
+}

tscreen.go

@@ -42,6 +42,7 @@ func NewTerminfoScreen() (Screen, error) {
 		return nil, e
 	}
 	t := &tScreen{ti: ti}
+	t.driver = &defaultTermDriver{}
 
 	t.keyexist = make(map[Key]bool)
 	t.keycodes = make(map[string]*tKeyCode)
@@ -68,6 +69,7 @@ type tKeyCode struct {
 // tScreen represents a screen backed by a terminfo implementation.
 type tScreen struct {
 	ti        *terminfo.Terminfo
+	driver    TermDriver
 	h         int
 	w         int
 	fini      bool
@@ -1386,3 +1388,10 @@ func (t *tScreen) HasKey(k Key) bool {
 }
 
 func (t *tScreen) Resize(int, int, int, int) {}
+
+// SetDriver is used to replace the default TermDriver.
+// When using this package, you'll want to make an interface
+// and type assert your Screen to get this method.
+func (t *tScreen) SetDriver(driver TermDriver) {
+	t.driver = driver
+}

tscreen_bsd.go

@@ -17,8 +17,6 @@
 package tcell
 
 import (
-	"os"
-	"os/signal"
 	"syscall"
 	"unsafe"
 )
@@ -33,10 +31,7 @@ func (t *tScreen) termioInit() error {
 	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 {
+	if t.in, t.out, e = t.driver.Init(t.sigwinch); e != nil {
 		goto failed
 	}
 
@@ -69,8 +64,6 @@ func (t *tScreen) termioInit() error {
 		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)
 	}
@@ -89,7 +82,7 @@ failed:
 
 func (t *tScreen) termioFini() {
 
-	signal.Stop(t.sigwinch)
+	t.driver.Fini()
 
 	<-t.indoneq
 
@@ -106,7 +99,9 @@ func (t *tScreen) termioFini() {
 }
 
 func (t *tScreen) getWinSize() (int, int, error) {
-
+	if w, h, err := t.driver.WinSize(); err != ErrWinSizeUnused {
+		return w, h, err
+	}
 	fd := uintptr(t.out.Fd())
 	dim := [4]uint16{}
 	dimp := uintptr(unsafe.Pointer(&dim))

tscreen_darwin.go

@@ -32,8 +32,6 @@ package tcell
 // a long time (probably forever) so holding one's breath is contraindicated.
 
 import (
-	"os"
-	"os/signal"
 	"syscall"
 	"unsafe"
 )
@@ -48,10 +46,7 @@ func (t *tScreen) termioInit() error {
 	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 {
+	if t.in, t.out, e = t.driver.Init(t.sigwinch); e != nil {
 		goto failed
 	}
 
@@ -84,8 +79,6 @@ func (t *tScreen) termioInit() error {
 		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)
 	}
@@ -104,7 +97,7 @@ failed:
 
 func (t *tScreen) termioFini() {
 
-	signal.Stop(t.sigwinch)
+	t.driver.Fini()
 
 	<-t.indoneq
 
@@ -127,7 +120,9 @@ func (t *tScreen) termioFini() {
 }
 
 func (t *tScreen) getWinSize() (int, int, error) {
-
+	if w, h, err := t.driver.WinSize(); err != ErrWinSizeUnused {
+		return w, h, err
+	}
 	fd := uintptr(t.out.Fd())
 	dim := [4]uint16{}
 	dimp := uintptr(unsafe.Pointer(&dim))

tscreen_linux.go

@@ -17,7 +17,6 @@
 package tcell
 
 import (
-	"os"
 	"os/signal"
 	"syscall"
 	"unsafe"
@@ -33,10 +32,7 @@ func (t *tScreen) termioInit() error {
 	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 {
+	if t.in, t.out, e = t.driver.Init(t.sigwinch); e != nil {
 		goto failed
 	}
 
@@ -98,7 +94,7 @@ failed:
 
 func (t *tScreen) termioFini() {
 
-	signal.Stop(t.sigwinch)
+	t.driver.Fini()
 
 	<-t.indoneq
 
@@ -116,7 +112,9 @@ func (t *tScreen) termioFini() {
 }
 
 func (t *tScreen) getWinSize() (int, int, error) {
-
+	if w, h, err := t.driver.WinSize(); err != ErrWinSizeUnused {
+		return w, h, err
+	}
 	fd := uintptr(t.out.Fd())
 	dim := [4]uint16{}
 	dimp := uintptr(unsafe.Pointer(&dim))

tscreen_posix.go

@@ -17,7 +17,6 @@
 package tcell
 
 import (
-	"os"
 	"os/signal"
 	"syscall"
 )
@@ -128,10 +127,7 @@ func (t *tScreen) termioInit() error {
 	var newtios C.struct_termios
 	var fd C.int
 
-	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 {
+	if t.in, t.out, e = t.driver.Init(t.sigwinch); e != nil {
 		goto failed
 	}
 
@@ -183,7 +179,7 @@ failed:
 
 func (t *tScreen) termioFini() {
 
-	signal.Stop(t.sigwinch)
+	t.driver.Fini()
 
 	<-t.indoneq
 
@@ -198,6 +194,9 @@ func (t *tScreen) termioFini() {
 }
 
 func (t *tScreen) getWinSize() (int, int, error) {
+	if w, h, err := t.driver.WinSize(); err != ErrWinSizeUnused {
+		return w, h, err
+	}
 	var cx, cy C.int
 	if r, e := C.getwinsize(C.int(t.out.Fd()), &cx, &cy); r != 0 {
 		return 0, 0, e