From: Damien Neil <dneil@google.com>
Date: Thu, 7 Sep 2023 16:27:50 +0000 (-0700)
Subject: context: avoid key collisions in test afterfunc map
X-Git-Tag: go1.22rc1~808
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=0f1227c507c62b635a3b4b85f5b7a967df72b59f;p=gostls13.git

context: avoid key collisions in test afterfunc map

The afterFuncContext type, used only in tests, contains a
set of registered afterfuncs indexed by an arbitrary unique key.

That key is currently a *struct{}. Unfortunately, all
*struct{} pointers are equal to each other, so all registered
funcs share the same key. Fortunately, the tests using this
type never register more than one afterfunc.

Change the key to a *byte.

Change-Id: Icadf7d6f258e328f6e3375846d29ce0f98b60924
Reviewed-on: https://go-review.googlesource.com/c/go/+/526655
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
---

diff --git a/src/context/afterfunc_test.go b/src/context/afterfunc_test.go
index 71f639a345..7b75295eb4 100644
--- a/src/context/afterfunc_test.go
+++ b/src/context/afterfunc_test.go
@@ -15,7 +15,7 @@ import (
 // defined in context.go, that supports registering AfterFuncs.
 type afterFuncContext struct {
 	mu         sync.Mutex
-	afterFuncs map[*struct{}]func()
+	afterFuncs map[*byte]func()
 	done       chan struct{}
 	err        error
 }
@@ -50,9 +50,9 @@ func (c *afterFuncContext) Value(key any) any {
 func (c *afterFuncContext) AfterFunc(f func()) func() bool {
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	k := &struct{}{}
+	k := new(byte)
 	if c.afterFuncs == nil {
-		c.afterFuncs = make(map[*struct{}]func())
+		c.afterFuncs = make(map[*byte]func())
 	}
 	c.afterFuncs[k] = f
 	return func() bool {
@@ -106,11 +106,13 @@ func TestCustomContextAfterFuncAfterFunc(t *testing.T) {
 
 func TestCustomContextAfterFuncUnregisterCancel(t *testing.T) {
 	ctx0 := &afterFuncContext{}
-	_, cancel := context.WithCancel(ctx0)
-	if got, want := len(ctx0.afterFuncs), 1; got != want {
+	_, cancel1 := context.WithCancel(ctx0)
+	_, cancel2 := context.WithCancel(ctx0)
+	if got, want := len(ctx0.afterFuncs), 2; got != want {
 		t.Errorf("after WithCancel(ctx0): ctx0 has %v afterFuncs, want %v", got, want)
 	}
-	cancel()
+	cancel1()
+	cancel2()
 	if got, want := len(ctx0.afterFuncs), 0; got != want {
 		t.Errorf("after canceling WithCancel(ctx0): ctx0 has %v afterFuncs, want %v", got, want)
 	}