fix: renderer race condition

Guard accessing the underlying Termenv output behind a mutex. Multiple goroutines can set/get the color profile causing a race condition.

Needs: muesli/termenv#146

go.mod

@@ -5,13 +5,13 @@ go 1.17
 require (
 	github.com/mattn/go-runewidth v0.0.14
 	github.com/muesli/reflow v0.3.0
-	github.com/muesli/termenv v0.15.1
+	github.com/muesli/termenv v0.15.3-0.20230728171558-3c898b2ce7c3
 )
 
 require (
 	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
-	github.com/mattn/go-isatty v0.0.17 // indirect
+	github.com/mattn/go-isatty v0.0.19 // indirect
 	github.com/rivo/uniseg v0.2.0 // indirect
-	golang.org/x/sys v0.6.0 // indirect
+	golang.org/x/sys v0.10.0 // indirect
 )

go.sum

@@ -4,16 +4,26 @@ github.com/lucasb-eyer/go-colorful v1.2.0 h1:1nnpGOrhyZZuNyfu1QjKiUICQ74+3FNCN69
 github.com/lucasb-eyer/go-colorful v1.2.0/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
 github.com/mattn/go-isatty v0.0.17 h1:BTarxUcIeDqL27Mc+vyvdWYSL28zpIhv3RoTdsLMPng=
 github.com/mattn/go-isatty v0.0.17/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/mattn/go-isatty v0.0.19 h1:JITubQf0MOLdlGRuRq+jtsDlekdYPia9ZFsB8h/APPA=
+github.com/mattn/go-isatty v0.0.19/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/mattn/go-runewidth v0.0.12/go.mod h1:RAqKPSqVFrSLVXbA8x7dzmKdmGzieGRCM46jaSJTDAk=
 github.com/mattn/go-runewidth v0.0.14 h1:+xnbZSEeDbOIg5/mE6JF0w6n9duR1l3/WmbinWVwUuU=
 github.com/mattn/go-runewidth v0.0.14/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
 github.com/muesli/reflow v0.3.0 h1:IFsN6K9NfGtjeggFP+68I4chLZV2yIKsXJFNZ+eWh6s=
 github.com/muesli/reflow v0.3.0/go.mod h1:pbwTDkVPibjO2kyvBQRBxTWEEGDGq0FlB1BIKtnHY/8=
 github.com/muesli/termenv v0.15.1 h1:UzuTb/+hhlBugQz28rpzey4ZuKcZ03MeKsoG7IJZIxs=
 github.com/muesli/termenv v0.15.1/go.mod h1:HeAQPTzpfs016yGtA4g00CsdYnVLJvxsS4ANqrZs2sQ=
+github.com/muesli/termenv v0.15.3-0.20230728162136-de1ed946b031 h1:mSQxHDNYTlwIFgiPPz8W+rulsHVCFzFAbbc/XQo7BfI=
+github.com/muesli/termenv v0.15.3-0.20230728162136-de1ed946b031/go.mod h1:cTIDIpWz9VkemD0+7lFZuZ8my3zF4iDi115tBmAocz0=
+github.com/muesli/termenv v0.15.3-0.20230728164039-3cf3563b77d7 h1:FNxK5hfhxljbUS5MbiZs6iAyo6dMI2qLI+G8q0GJhVE=
+github.com/muesli/termenv v0.15.3-0.20230728164039-3cf3563b77d7/go.mod h1:cTIDIpWz9VkemD0+7lFZuZ8my3zF4iDi115tBmAocz0=
+github.com/muesli/termenv v0.15.3-0.20230728171558-3c898b2ce7c3 h1:9Sx5BlHeicxZHFBqfA4zcPtcTpmSLdxW1l4DgNszt+U=
+github.com/muesli/termenv v0.15.3-0.20230728171558-3c898b2ce7c3/go.mod h1:cTIDIpWz9VkemD0+7lFZuZ8my3zF4iDi115tBmAocz0=
 github.com/rivo/uniseg v0.1.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/rivo/uniseg v0.2.0 h1:S1pD9weZBuJdFmowNwbpi7BJ8TNftyUImj/0WQi72jY=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0 h1:MVltZSvRTcU2ljQOhs94SXPftV6DCNnZViHeQps87pQ=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.10.0 h1:SqMFp9UcQJZa+pmYuAKjd9xq1f0j5rLcDIk0mj4qAsA=
+golang.org/x/sys v0.10.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

renderer.go

@@ -2,6 +2,7 @@ package lipgloss
 
 import (
 	"io"
+	"sync"
 
 	"github.com/muesli/termenv"
 )
@@ -16,6 +17,7 @@ var renderer = &Renderer{
 type Renderer struct {
 	output            *termenv.Output
 	hasDarkBackground *bool
+	mtx               sync.RWMutex
 }
 
 // RendererOption is a function that can be used to configure a [Renderer].
@@ -43,17 +45,21 @@ func NewRenderer(w io.Writer, opts ...termenv.OutputOption) *Renderer {
 
 // Output returns the termenv output.
 func (r *Renderer) Output() *termenv.Output {
+	r.mtx.RLock()
+	defer r.mtx.RUnlock()
 	return r.output
 }
 
 // SetOutput sets the termenv output.
 func (r *Renderer) SetOutput(o *termenv.Output) {
+	r.mtx.Lock()
+	defer r.mtx.Unlock()
 	r.output = o
 }
 
 // ColorProfile returns the detected termenv color profile.
 func (r *Renderer) ColorProfile() termenv.Profile {
-	return r.output.Profile
+	return r.output.ColorProfile()
 }
 
 // ColorProfile returns the detected termenv color profile.
@@ -78,7 +84,9 @@ func ColorProfile() termenv.Profile {
 //
 // This function is thread-safe.
 func (r *Renderer) SetColorProfile(p termenv.Profile) {
-	r.output.Profile = p
+	r.mtx.Lock()
+	defer r.mtx.Unlock()
+	r.output.SetColorProfile(p)
 }
 
 // SetColorProfile sets the color profile on the default renderer. This
@@ -110,6 +118,8 @@ func HasDarkBackground() bool {
 // background. A dark background can either be auto-detected, or set explicitly
 // on the renderer.
 func (r *Renderer) HasDarkBackground() bool {
+	r.mtx.RLock()
+	defer r.mtx.RUnlock()
 	if r.hasDarkBackground != nil {
 		return *r.hasDarkBackground
 	}
@@ -139,5 +149,7 @@ func SetHasDarkBackground(b bool) {
 //
 // This function is thread-safe.
 func (r *Renderer) SetHasDarkBackground(b bool) {
+	r.mtx.Lock()
+	defer r.mtx.Unlock()
 	r.hasDarkBackground = &b
 }

renderer_test.go

@@ -1,6 +1,7 @@
 package lipgloss
 
 import (
+	"io"
 	"os"
 	"testing"
 
@@ -29,7 +30,24 @@ func TestRendererWithOutput(t *testing.T) {
 	defer os.Remove(f.Name())
 	r := NewRenderer(f)
 	r.SetColorProfile(termenv.TrueColor)
-	if r.output.Profile != termenv.TrueColor {
+	if r.output.ColorProfile() != termenv.TrueColor {
 		t.Error("Expected renderer to use true color")
 	}
 }
+
+func TestRace(t *testing.T) {
+	r := NewRenderer(io.Discard)
+	o := r.Output()
+
+	for i := 0; i < 100; i++ {
+		t.Run("SetColorProfile", func(t *testing.T) {
+			t.Parallel()
+			r.SetHasDarkBackground(false)
+			r.HasDarkBackground()
+			r.SetOutput(o)
+			r.SetColorProfile(termenv.ANSI256)
+			r.SetHasDarkBackground(true)
+			r.Output()
+		})
+	}
+}

style.go

@@ -182,9 +182,10 @@ func (s Style) Render(strs ...string) string {
 	var (
 		str = joinString(strs...)
 
-		te           = s.r.ColorProfile().String()
-		teSpace      = s.r.ColorProfile().String()
-		teWhitespace = s.r.ColorProfile().String()
+		p            = s.r.ColorProfile()
+		te           = p.String()
+		teSpace      = p.String()
+		teWhitespace = p.String()
 
 		bold          = s.getAsBool(boldKey, false)
 		italic        = s.getAsBool(italicKey, false)

style_test.go

@@ -9,40 +9,41 @@ import (
 )
 
 func TestStyleRender(t *testing.T) {
-	renderer.SetColorProfile(termenv.TrueColor)
-	renderer.SetHasDarkBackground(true)
+	r := NewRenderer(ioutil.Discard)
+	r.SetColorProfile(termenv.TrueColor)
+	r.SetHasDarkBackground(true)
 	t.Parallel()
 
 	tt := []struct {
 		style    Style
 		expected string
 	}{
 		{
-			NewStyle().Foreground(Color("#5A56E0")),
+			r.NewStyle().Foreground(Color("#5A56E0")),
 			"\x1b[38;2;89;86;224mhello\x1b[0m",
 		},
 		{
-			NewStyle().Foreground(AdaptiveColor{Light: "#fffe12", Dark: "#5A56E0"}),
+			r.NewStyle().Foreground(AdaptiveColor{Light: "#fffe12", Dark: "#5A56E0"}),
 			"\x1b[38;2;89;86;224mhello\x1b[0m",
 		},
 		{
-			NewStyle().Bold(true),
+			r.NewStyle().Bold(true),
 			"\x1b[1mhello\x1b[0m",
 		},
 		{
-			NewStyle().Italic(true),
+			r.NewStyle().Italic(true),
 			"\x1b[3mhello\x1b[0m",
 		},
 		{
-			NewStyle().Underline(true),
+			r.NewStyle().Underline(true),
 			"\x1b[4;4mh\x1b[0m\x1b[4;4me\x1b[0m\x1b[4;4ml\x1b[0m\x1b[4;4ml\x1b[0m\x1b[4;4mo\x1b[0m",
 		},
 		{
-			NewStyle().Blink(true),
+			r.NewStyle().Blink(true),
 			"\x1b[5mhello\x1b[0m",
 		},
 		{
-			NewStyle().Faint(true),
+			r.NewStyle().Faint(true),
 			"\x1b[2mhello\x1b[0m",
 		},
 	}