fix(native): ignore terminal calls after Close

CHANGELOG.md

@@ -94,6 +94,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **The native window writes agent prompts in your prompt language.** The
   pull request and issue handoffs and a batch of review comments were
   always typed in English.
+- **A theme change during a reconnect no longer crashes the native window.**
+  Switching the theme, or the system switching light and dark, while the
+  window reattached to a restarted lich could paint terminals the reconnect
+  had just freed and take the window down.
 - **Chinese, Japanese and Korean text no longer freezes the native window on
   Linux.** A session, a Review or a pull request full of CJK text could hang
   the window for seconds, long enough for "not responding", and a zoom

native/cmd/lich-native/main.go

@@ -7,6 +7,7 @@ package main
 import (
 	"context"
 	"crypto/rand"
+	"errors"
 	"flag"
 	"fmt"
 	"image"
@@ -728,7 +729,14 @@ func (u *window) content(gtx C, active sessionView) error {
 	if err != nil {
 		return err
 	}
-	return u.terms.layout(gtx, t, u.terminalTakesKeys(gtx))
+	err = u.terms.layout(gtx, t, u.terminalTakesKeys(gtx))
+	// A reconnect frees every terminal off the frame goroutine; one shown
+	// since is replaced on the next frame, which the window must survive.
+	if errors.Is(err, gioterm.ErrClosed) {
+		gtx.Execute(op.InvalidateCmd{})
+		return nil
+	}
+	return err
 }
 
 // terminalTakesKeys is whether the terminal on screen takes the keyboard back

native/gioterm/links.go

@@ -66,6 +66,9 @@ type Link struct {
 func (v *Terminal) LinkAt(x, y float32) (l Link, ok bool) {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return Link{}, false
+	}
 	col, row := v.cellAt(x, y)
 	if uri := v.hyperlink(col, row); uri != "" {
 		from, to := col, col

native/gioterm/mouse.go

@@ -161,6 +161,9 @@ func MouseButtonOf(b pointer.Buttons) MouseButton {
 func (v *Terminal) MouseTracking() bool {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return false
+	}
 	return C.mouse_tracking(v.t) != C.GHOSTTY_MOUSE_TRACKING_NONE
 }
 
@@ -171,6 +174,9 @@ func (v *Terminal) MouseTracking() bool {
 func (v *Terminal) EncodeMouse(action MouseAction, button MouseButton, mods key.Modifiers, x, y float32, anyPressed bool) []byte {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return nil
+	}
 	if v.mouseEnc == nil {
 		if C.ghostty_mouse_encoder_new(nil, &v.mouseEnc) != C.GHOSTTY_SUCCESS {
 			return nil
@@ -218,6 +224,9 @@ func (v *Terminal) SelectRelease(x, y float32) {
 func (v *Terminal) gesture(kind C.GhosttySelectionGestureEventType, x, y float32, at time.Duration) {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return
+	}
 	if v.gest == nil && C.ghostty_selection_gesture_new(nil, &v.gest) != C.GHOSTTY_SUCCESS {
 		return
 	}
@@ -243,6 +252,9 @@ func (v *Terminal) cellAt(x, y float32) (col, row int) {
 func (v *Terminal) ClearSelection() {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return
+	}
 	C.ghostty_terminal_set(v.t, C.GHOSTTY_TERMINAL_OPT_SELECTION, nil)
 }
 
@@ -251,6 +263,9 @@ func (v *Terminal) ClearSelection() {
 func (v *Terminal) SelectionText() string {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return ""
+	}
 	var out *C.uint8_t
 	var n C.size_t
 	if C.selection_text(v.t, &out, &n) != C.GHOSTTY_SUCCESS {

native/gioterm/paste.go

@@ -33,6 +33,10 @@ const pasteFrame = 12
 // with spaces either way.
 func (v *Terminal) Paste(text string) []byte {
 	v.mu.Lock()
+	if v.closed {
+		v.mu.Unlock()
+		return nil
+	}
 	bracketed := C.bracketed_paste(v.t)
 	v.mu.Unlock()
 	data := C.CBytes([]byte(text))
@@ -52,5 +56,8 @@ func (v *Terminal) Paste(text string) []byte {
 func (v *Terminal) AlternateScroll() bool {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return false
+	}
 	return bool(C.alternate_scroll(v.t))
 }

native/gioterm/vt.go

@@ -183,6 +183,7 @@ static GhosttyResult scroll_delta(GhosttyTerminal t, intptr_t delta) {
 import "C"
 
 import (
+	"errors"
 	"fmt"
 	"image/color"
 	"runtime/cgo"
@@ -231,6 +232,7 @@ type Terminal struct {
 	// runs inside Write with mu held; schemeSet is SetColors having set it.
 	dark      atomic.Bool
 	schemeSet bool
+	closed    bool
 	t         C.GhosttyTerminal
 	rs        C.GhosttyRenderState
 	it        C.GhosttyRenderStateRowIterator
@@ -260,6 +262,9 @@ type Terminal struct {
 	wheelRest float32
 }
 
+// ErrClosed is a call on a Terminal after Close.
+var ErrClosed = errors.New("terminal closed")
+
 func check(what string, r C.GhosttyResult) error {
 	if r != C.GHOSTTY_SUCCESS {
 		return fmt.Errorf("%s: ghostty result %d", what, int(r))
@@ -312,6 +317,10 @@ func (v *Terminal) Write(b []byte) {
 		return
 	}
 	v.mu.Lock()
+	if v.closed {
+		v.mu.Unlock()
+		return
+	}
 	C.ghostty_terminal_vt_write(v.t, (*C.uint8_t)(unsafe.Pointer(&b[0])), C.size_t(len(b)))
 	v.mu.Unlock()
 }
@@ -321,6 +330,9 @@ func (v *Terminal) Write(b []byte) {
 func (v *Terminal) Resize(cols, rows, cellW, cellH int) error {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return ErrClosed
+	}
 	if err := check("terminal_resize", C.ghostty_terminal_resize(v.t, C.uint16_t(cols), C.uint16_t(rows), C.uint32_t(cellW), C.uint32_t(cellH))); err != nil {
 		return err
 	}
@@ -333,6 +345,10 @@ func (v *Terminal) Resize(cols, rows, cellW, cellH int) error {
 // Scroll moves the viewport through scrollback, negative is up.
 func (v *Terminal) Scroll(delta int) {
 	v.mu.Lock()
+	if v.closed {
+		v.mu.Unlock()
+		return
+	}
 	C.scroll_delta(v.t, C.intptr_t(delta))
 	v.mu.Unlock()
 }
@@ -394,6 +410,9 @@ type Colors struct {
 func (v *Terminal) SetColors(c Colors) error {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return ErrClosed
+	}
 	if err := check("set colors", C.set_default_colors(v.t, cRGB(c.Foreground), cRGB(c.Background))); err != nil {
 		return err
 	}
@@ -420,10 +439,15 @@ func cRGB(c color.NRGBA) C.GhosttyColorRgb {
 	return C.GhosttyColorRgb{r: C.uint8_t(c.R), g: C.uint8_t(c.G), b: C.uint8_t(c.B)}
 }
 
-// Close frees the terminal. It must not be used afterwards.
+// Close frees the terminal. Calls after it do nothing: those returning an
+// error return ErrClosed, the rest their zero value. Closing twice is a no-op.
 func (v *Terminal) Close() {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return
+	}
+	v.closed = true
 	C.ghostty_selection_gesture_free(v.gest, v.t)
 	C.ghostty_mouse_event_free(v.mouseEv)
 	C.ghostty_mouse_encoder_free(v.mouseEnc)
@@ -440,6 +464,9 @@ func (v *Terminal) Close() {
 func (v *Terminal) update() (snap, []uint8, error) {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return snap{}, nil, ErrClosed
+	}
 	clear(v.dirty)
 	s := C.snapshot(v.rs, v.t, v.it, v.cells, &v.raw[0], (*C.uint8_t)(&v.dirty[0]), C.uint16_t(v.cols), C.uint16_t(v.rows))
 	if s.dirty == -1 {
@@ -515,6 +542,9 @@ const (
 func (v *Terminal) encodeKey(key int, mods int, unshifted rune, text string) []byte {
 	v.mu.Lock()
 	defer v.mu.Unlock()
+	if v.closed {
+		return nil
+	}
 	C.ghostty_key_encoder_setopt_from_terminal(v.enc, v.t)
 	C.ghostty_key_event_set_action(v.ev, C.GHOSTTY_KEY_ACTION_PRESS)
 	C.ghostty_key_event_set_key(v.ev, C.GhosttyKey(key))

native/gioterm/vt_test.go

@@ -1,6 +1,8 @@
 package gioterm
 
 import (
+	"errors"
+	"image/color"
 	"testing"
 )
 
@@ -55,3 +57,36 @@ func TestEncodeSpecialKeysUnderKitty(t *testing.T) {
 		})
 	}
 }
+
+// A window frees a terminal on one goroutine while another may still hold it:
+// a reconnect closes every terminal as a theme switch paints them.
+func TestClosedTerminalIgnoresCalls(t *testing.T) {
+	v, err := New(80, 24, testCellW, testCellH, func([]byte) {})
+	if err != nil {
+		t.Fatal(err)
+	}
+	v.Close()
+	if err := v.SetColors(Colors{Background: color.NRGBA{A: 0xff}}); !errors.Is(err, ErrClosed) {
+		t.Fatalf("SetColors after Close: %v, want ErrClosed", err)
+	}
+	if err := v.Resize(100, 30, testCellW, testCellH); !errors.Is(err, ErrClosed) {
+		t.Fatalf("Resize after Close: %v, want ErrClosed", err)
+	}
+	if _, err := v.Update(); !errors.Is(err, ErrClosed) {
+		t.Fatalf("Update after Close: %v, want ErrClosed", err)
+	}
+	v.Write([]byte("text"))
+	v.Scroll(-1)
+	v.ClearSelection()
+	v.SelectPress(1, 1, 0)
+	if v.Paste("x") != nil || v.EncodeMouse(0, 0, 0, 1, 1, false) != nil || v.encodeKey(keyEnter, 0, 0, "") != nil {
+		t.Fatal("a closed terminal encoded input")
+	}
+	if v.MouseTracking() || v.AlternateScroll() || v.SelectionText() != "" {
+		t.Fatal("a closed terminal reported a mode")
+	}
+	if _, ok := v.LinkAt(1, 1); ok {
+		t.Fatal("a closed terminal found a link")
+	}
+	v.Close()
+}