fix(keys): preserve invalid split alt utf8 input

commit: de4decf704b65137395f76223b798160d3e2eb42
author: brice · 3mo ago · 2026-07-03 21:28 UTC
parent: 3a2ff56
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

2 files · +20 -3

M internal/usecase/keys/router.go +8 -3


@@ -71,7 +71,7 @@ func (r *Router) Route(data []byte) {
71	71		r.pending = false
72	72		r.pendingAlt = nil
73	73		combined := append(append([]byte(nil), pendingAlt...), data...)
74		-	if consumed := r.routeAfterPendingESC(combined); consumed > len(pendingAlt) {
	74	+	if consumed := r.routeAfterPendingESC(combined, len(pendingAlt)); consumed > len(pendingAlt) {
75	75		data = data[consumed-len(pendingAlt):]
76	76		}
77	77		}

@@ -122,7 +122,7 @@ func (r *Router) route(data []byte) {
122	122		flush()
123	123		}
124	124
125		-	func (r *Router) routeAfterPendingESC(data []byte) int {
	125	+	func (r *Router) routeAfterPendingESC(data []byte, pendingAltLen int) int {
126	126		next := data[0]
127	127		if passThroughPrefix(next) {
128	128		r.forward([]byte{ESC, next})

@@ -136,10 +136,15 @@ func (r *Router) routeAfterPendingESC(data []byte) int {
136	136		r.retainESC(data)
137	137		return len(data)
138	138		}
139		-	if _, size := utf8.DecodeRune(data); size > 1 {
	139	+	key, size := utf8.DecodeRune(data)
	140	+	if size > 1 {
140	141		r.forward(append([]byte{ESC}, data[:size]...))
141	142		return size
142	143		}
	144	+	if key == utf8.RuneError && pendingAltLen > 0 {
	145	+	r.forward(append([]byte{ESC}, data[:pendingAltLen]...))
	146	+	return pendingAltLen
	147	+	}
143	148		r.forward([]byte{ESC})
144	149		return 0
145	150		}

 		r.pending = false
 		r.pendingAlt = nil
 		combined := append(append([]byte(nil), pendingAlt...), data...)
-		if consumed := r.routeAfterPendingESC(combined); consumed > len(pendingAlt) {
+		if consumed := r.routeAfterPendingESC(combined, len(pendingAlt)); consumed > len(pendingAlt) {
 			data = data[consumed-len(pendingAlt):]
 		}
 	}
 	flush()
 }
-func (r *Router) routeAfterPendingESC(data []byte) int {
+func (r *Router) routeAfterPendingESC(data []byte, pendingAltLen int) int {
 	next := data[0]
 	if passThroughPrefix(next) {
 		r.forward([]byte{ESC, next})
 		r.retainESC(data)
 		return len(data)
 	}
-	if _, size := utf8.DecodeRune(data); size > 1 {
+	key, size := utf8.DecodeRune(data)
+	if size > 1 {
 		r.forward(append([]byte{ESC}, data[:size]...))
 		return size
 	}
+	if key == utf8.RuneError && pendingAltLen > 0 {
+		r.forward(append([]byte{ESC}, data[:pendingAltLen]...))
+		return pendingAltLen
+	}
 	r.forward([]byte{ESC})
 	return 0
 }

M internal/usecase/keys/router_test.go +12 -0


@@ -119,6 +119,18 @@ func TestRouterForwardsUnboundAltUTF8SplitAcrossReads(t *testing.T) {
119	119		require.Equal(t, [][]byte{{ESC, 0xc3, 0xb1}}, h.forwards)
120	120		}
121	121
	122	+	func TestRouterForwardsInvalidSplitAltUTF8WithoutDroppingBytes(t *testing.T) {
	123	+	clk := &fakeClock{}
	124	+	h := &captureHandler{}
	125	+	r := NewRouter(clk, h)
	126	+
	127	+	r.Route([]byte{ESC, 0xc3})
	128	+	r.Route([]byte("X"))
	129	+
	130	+	require.Empty(t, h.actions)
	131	+	require.Equal(t, [][]byte{{ESC, 0xc3}, []byte("X")}, h.forwards)
	132	+	}
	133	+
122	134		func TestTopRowDigitIndexAcceptsQWERTYAndAZERTYVariants(t *testing.T) {
123	135		cases := []struct {
124	136		key rune


@@ -119,6 +119,18 @@ func TestRouterForwardsUnboundAltUTF8SplitAcrossReads(t *testing.T) {
119	require.Equal(t, [][]byte{{ESC, 0xc3, 0xb1}}, h.forwards)	119		require.Equal(t, [][]byte{{ESC, 0xc3, 0xb1}}, h.forwards)
120	}	120		}
121		121
		122	+	func TestRouterForwardsInvalidSplitAltUTF8WithoutDroppingBytes(t *testing.T) {
		123	+	clk := &fakeClock{}
		124	+	h := &captureHandler{}
		125	+	r := NewRouter(clk, h)
		126	+
		127	+	r.Route([]byte{ESC, 0xc3})
		128	+	r.Route([]byte("X"))
		129	+
		130	+	require.Empty(t, h.actions)
		131	+	require.Equal(t, [][]byte{{ESC, 0xc3}, []byte("X")}, h.forwards)
		132	+	}
		133	+
122	func TestTopRowDigitIndexAcceptsQWERTYAndAZERTYVariants(t *testing.T) {	134		func TestTopRowDigitIndexAcceptsQWERTYAndAZERTYVariants(t *testing.T) {
123	cases := []struct {	135		cases := []struct {
124	key rune	136		key rune